Jesse James has nothing on you! You've got alot of grit to stick to and complete this project. I'd like to see an itemized price list on your project. Also, the effective range. You started with a heavy vehicle, was there a reason for your choice? Do you think you'll ever do another? I'd love to do an EV, maybe a motorcycle, the only problem with EVs is our country's electric grid is already overtaxed, so there isn't room for charging many.

Peace,
Steve
elec. egr.

Hi Steve,

Thanks!; I've always thought there is something to be said for trying something new. Too bad Jesse James and crew are [at least seemingly] very stuck in their ways when it comes to gas, gas, and more gas. Oh well, I suppose they'll get be getting their dose of Electric Vehicle action soon ;-).

Sorry, I still don't have an itemized price list... it's something I've been meaning to complete. Though I can tell you that I spent about $10,000 in parts for my Jeep Cherokee EV Conversion. It is a lot of money upfront but is well worth it because with the exception of the batteries, the other EV components will easily last the life of the car and often much more (like 20+ years). Thus, many EV owners will drive their EV until the chassis is worn out, then transfer all the EV components into a new chassis (which costs very little to do) and continue to get life out of them -- EV components are _very_ modular in that respect.... cool, isn't it?

As for the effective range of my JeepEV, I can get about 30-35 miles per charge avg., 40 miles max range in city driving (i.e. speeds of 50 mph and less). Range at highway speeds is notably less, around 25 miles per charge, because the Cherokee has poor aero-dynamics, and wastes a lot of energy due to wind resistance. Luckily, I live in the city and thus can go most everywhere I need to without using the highways.

I chose the Cherokee because I already had it, I liked it, and it has sentimental value to my family. As far as EV conversions go, the Cherokee was not a great vehicle choice because it is so heavy and not aerodynamic, making it more expensive to convert, and resulting is less range than a lighter, more aerodynamic vehicle. But nonetheless, I don't regret converting the Cherokee at all, and it has been a great EV despite all the undesirable traits it possesses (compared to other vehicles).

Yes, I do plan to do future EV work. I'm now in the early stages of building my 1999 Mazda B3000 truck into a Plug-in Hybrid Electric Vehicle (I'd do 100% EV but need the truck to drive the 1200 miles from school to home 4 times a year). Plans beyond that include more 100% EVs, and hopefully work related to building better EV and Hybrid EV components.

If you are thinking about building/converting an EV of your own, I highly suggest subscribing to the Electric Vehicle Discussion List (aka. EVDL). The EVDL is an e-mail based message list where many members of the EV community chat and where you can ask questions and get advice on anything related to buying, building, converting or operating an EV. See the website http://www.evdl.org/ for information on how to subscribe.

Regaring the grid not supporting EVs, I disagree. There are several points to make regarding this topic, and I'll list some briefly below to avoid writing a book on them ;-) :

1) Most electric vehicles are charged at night, during off-peak hours. In fact, most power plants produce a large surplus of electricity at night that could be used to charge EVs rather than being wasted (it isn't exactly easy to throttle down conventional power plants).

2) There is more and more renewable energy coming on the power grid each year from wind turbines and solar photovoltaic panels. Not only do these energy sources help "clean up" the electric grid, but they provide more power capacity. A good example is Austin, TX which is getting wind-generated power from wind farms in west Texas. Most of this energy is generated during the evenings, and Austin Energy has said that they currently have enough surplus power from the wind turbines to recharge hundreds of thousands of EVs each night (and are continuing to increase the amount of wind energy they use).

3) Not all EVs are charged from the grid. There are many people right now who own EVs and have photovoltaic systems and/or wind turbines installed at there house, generating electricity that they use to charge their EVs and/or power there house -- which is clean and cheap. I suspect such energy self-generation will become more and more common place as the cost of "grid" energy continues to increase while the cost of solar panels and wind turbines is decreasing. In this scenario you aren't taxing the grid, but are doing the opposite; removing load from the grid and/or adding electricity back into the grid when you are generating a surplus (assuming you have a grid-tied solar/wind system).

4) Typical EVs use chargers that are relatively slow (i.e. take 1 to 8 hours to charge). Such chargers don't pull much instantaneous power from the grid; in fact, most pull less than 50-Amps @ 240-Volts, which is about the same amount of power that an electric hot water heater or oven uses. Yes some chargers will pull more or less instantaneous power from the grid, but the point is that most use no more power than a typical 240-Volt home appliance (some pull far less!). FYI, my battery charger pulls no more than 30-Amps at 240-Volts from the grid; and I can still recharge my JeepEV in less than 2.5 hours.

Hope that helps!
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

Hi

I found your page on electric power steering very interesting. I have a Toyota supra and have belt driven power steering. I am building a performance engine for it and need to mount a dry sump pump. Was thinking I had to lose my air con pump, when I thought about electric power steering. If I could go electric I could loose the power steering pump instead My only concern is the huge amount of amps these pumps draw. Funny enough my friend has an MR2 and this got me started on this idea. I was wondering if you had got anywhere with your idea of making a pulse width modulation control unit. As you mention this would cut down the consumption lots. If you have anything I could buy from you or any links or information you could send me I would be most grateful.

Best regards Lee

Hi Lee,

Yes, 12-Volt electric power steering pumps pull a lot of current from the car's electrical system. I believe the current draw is something around 50-60 Amps maximum (i.e. wheels turned to a stop), and more like 15-20 Amps for lighter loads. Due to the increased current draw, you may find that upgrading the car's alternator is necessary to prevent your battery from getting drained.

It is worth noting here that going to electric power steering doesn't fundamentally use much more power or energy in the end; it just transfer's the *power* usage through the vehicle's electrical system rather than directly to the engine's mechanical system. You'll loose a little energy in the mechanical to electrical conversion (through the alternator), but these losses aren't too great. Of course, electric-hydraulic power steering can actually be more efficient than straight hydraulic power steering because it is easy to electrically slow or disconnect the pump when it is not needed by using a PWM or similar speed controller.

As far as me making progress with PWM controllers, the answer is yes and no. I have been working for a while now to learn everything I can about Switch Mode Power Supply design (broad term for many types of power converters/ controllers based on PWM). Lately I've also been doing some serious development of PWM controllers. However, at this time I'm not specifically working on a PWM controller for 12-Volt power steering pumps. The reason for this is that SMPS design is not my full time job, so my time for it is limited. Also, I've got a couple other SMPS projects that have taken priority due to outside funding and greater necessity.

--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

Electric motors, and pray tell where do you get the power to run the electric plants? Nukes, coal?
Also isn't a state like California still having problems with it's electric grid? what about summer hot days where charging all the electric cars will compete with air conditioners. electric cars have been around for a hundred years and there still not efficient.

Hi all,

Sorry, Wyatt Earp, but your claims that Electric Vehicles are not efficient is bullshit.In order to understand why this idea is incorrect, we need to understand a few things about common energy storage devices. First, a standard US gallon of gasoline stores about 36,600 Watt-hours (Wh) of energy. The same gallon of gasoline weighs roughly 2.7 kg. Thus, a gallon of gasoline has an energy density of about 13,500 Wh/kg.

Lead Acid batteries, which are still the most common storage device for battery Electric Vehicles, have a very low energy density, somewhere around 30 to 35 Wh/kg. Other batteries exist which have higher energy densities then Lead Acid. For example, Nickel metal Hydride (NiMH) batteries, commonly used in Hybrid Vehicles, store around 65 Wh/kg, and Lithium-Ion (Li-Ion) and Lithium Polymer (Li-Poly) batteries have energy densities upwards of 150 Wh/kg.

So you can see just from this information that EVs from the start will typically have significantly less energy to work with then their Internal Combustion Engine (ICE) equivalents. Now let me apply this information to a very practical example:

I own and drive a Jeep Cherokee EV conversion. Before I did the EV conversion, the vehicle was stock with the 6-cylinder ICE. It had about a 15 gallon gas tank, and had a best-case efficiency of about 20 miles per gallon. Thus, with the 15 gallon gas tank my maximum range before re-fueling was about 300 miles. This means that the vehicle had over 549,000 Wh of energy on-board when the gas tank was full, and consumed over 1,800 Wh of energy per mile driven!

Now that my Jeep is an EV, it uses typical deep-cycle Lead Acid batteries as its energy storage medium. The vehicle now carries 571.5 kg of Lead Acid batteries on board. My typical upper limit on range before re-charging is about 40 miles. This means the vehicle now has around 20,000 Wh of energy on-board with the batteries fully charged, and consumes around 500 Wh of energy per mile driven.

See the difference? As an EV, my Jeep has only 3.6% of the energy on-board that it did as an ICE-powered vehicle. Yet, it still gets 13.3% of the range it got with the ICE. This is because the electric drive system in my Jeep is roughly 28% more efficient then the ICE was. To illustrate it another way, if my Jeep had the same energy storage limitation in ICE form as it now does in EV form, my range would only be 11 miles with the ICE vs. 40 miles with the Electric drive system.

So yes, energy storage methods for EVs need more improvement to allow EVs to be on par with the typical ranges achieved by ICE vehicles. However, Electric drive system efficiency is not an issue as EVs already greatly surpass ICEs in this area.

P.S. It is worth noting that my Jeep's electric drive system is not the most efficient type avaliable. For applications where efficiency is very important, it is common to use AC electric drive systems which can provide even greater efficiency (like 10% more) then the conventional DC electric drive systems that are more common in home-built EV conversions. This is likely one of the main reasons that virtually all of the production Hybrid vehicles use 3-phase AC electric drive systems.

Hope that helps clear up any misconceptions,

-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!

Would it be possible to put turbines on the wheels and axles to charge the battery?

Hi Isaac,

Yes, it is very possible to recharge the battery pack using energy generated by the motors during deceleration and/or braking. This is called Regenerative Braking or "regen" and is currently used on all OEM production Hybrid Electric Vehicles as well as many home-built EVs.The most typical way to achieve regen is to simply use the main traction motor(s) as the generator(s) as necessary.

However, regen *only* supplies energy for recharging the batteries during vehicle *deceleration* or *braking*. Thus, regen helps to recover some of the energy that would otherwise be totally wasted as heat in the vehicle's brake pads.

Now, It /is/ possible to use a generator setup to recharge the battery pack while you are co-currently using energy from the battery pack to accelerate/drive the vehicle down the road, but doing so creates a circular loop and, by of the laws of thermodynamics, you will certainly waste more energy then you would've if you didn't use the generators in the first place! This is because as the generators produce more and more electrical power, they put more and more mechanical drag on the vehicle, which in turn requires more and more power from the motor and batteries driving the vehicle, which in turn would require more power from the generators, etc, etc....

If the generator was able to output more electrical power then it consumed mechanically from the vehicle, then it would be an over-unity device which, by our current understanding of science, has not, does not, and will not ever exist.

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

Nick,

I wrote you some time ago about a very similar EV jeep project I have been working on for several years now... I have too many projects happening at once. I finally completed my drive train and have actually driven the Jeep up and down my driveway on a single 12V battery with jumper cables... needless to say it was not exciting. I'm almost ready to purchase the controller (going with the Zilla) but I want to decide on a battery pack prior to committing to the controller. I'm going with a series hybrid system and plan to tow a couple of off the shelf generators on a light trailer and rectify the 220vAC to +/- 170 vDC (I'm planning to use 12 or 13-12v modules for the pack... Hawker or ?).

My question to you (assuming our vehicles will weigh roughly the same) is what average load do you consume traveling at 25mph and/or 55mph? What minimum generator output would you recommend to get around town in a charge sustaining fashion and possibly be charge depleting in highway conditions? I'm hoping to get away with 12kW of generation though I may be grossly underestimating the power consumption.

Any advice would be great.
Thanks,

Hi Matt,

Cool! The first "power-up" is exciting because that means you're well on the way to driving EV! :-)

Regarding the controller, very good choice... the Zillas are about the best you can get for the money when it comes to DC. If you can afford it, I'd get at least the Zilla HV model because, even though its more expensive, it will allow you greater flexibility in future battery packs up to 300-Volts DC. I'm sort of kicking myself for buying the LV model, because now I'm limited to a 160-Volts DC pack or less...

Now, I don't know you're motivations for doing the conversion, but if driving a "clean" vehicle is important to you, then I'd be leery of using off-the-shelf generators. Many such generators produce upwards of 10X the emissions that a typical modern car does. The only generators I've heard of that are somewhat clean and efficient are the Honda eu1000/2000/3000i series, and even these are fairly dirty emissions-wise... not to mention being fairly low power (due to their electronic power-converter design)

I'm not real sure about average load or power usage off hand... but I can give you some rough numbers. On a flat, level road I can usually go 30mph pulling a steady 90 battery Amps. Because the batteries will sag to about 150-Volts at this current draw, this makes power consumed about 13.5kW. I'd guess that under similar conditions it takes close to 11kW to go 25mph.

50mph and above is where things get really ugly power-consumption wise. Unfortunately, the only numbers I can quote off the top of my head are those from when I had the old, dying Peugeot transmission (now replaced with an Aisin-Warner AX-15). I recall that it could take anywhere between 200-250 battery amps to maintain 50mph, with the batteries sagging to about 145 volts. This is around 36kW of power. Basically, with a vehicle as un-aerodynamic as the Cherokee, I've discovered that power usage begins to sharply go up exponentially after about 45mph. I mean, one test I did (still with the old transmission) showed that it took almost double the power to go 65mph than it did to go 45mph!

Disclaimer: As I said, I've replaced the transmission. This reduced power draw somewhat as the old transmission was dying and doing bad things. However, I've also discovered that my Jeep has stock 3.07:1 gearing in the differentials which, although adequate for the low-speed 6 cylinder engine, is really just too low a numerical gear for the high-speed electric motor. I'm planning to change the gearing to 4.11:1 or perhaps even 4.56:1 as I feel this will greatly improve efficiency by allowing the electric motor to operate on average at higher speeds (which these motors like).

FYI, In most cases, the generator you use will only supplement the power required to move the vehicle, and will not be able to power the vehicle directly. Thus, the generator is a "range-extender" device, which will allow you to go farther per battery charge.

If you need to be able to power the vehicle solely off of the gas-powered "system", then you need to do something more than use simple off-the-shelf generators, along the lines of building a true parallel hybrid

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

hi, nick---

i'm debating whether i should fix the '86 cj-7 (it needs something between medium engine work to a rebuild on it's 258 straight six, so ...) or convert it to be an ev (i've thought about it on and off, but haven't done anything for years---and that's how long it's been sitting in the garage gathering dust and debris...).

if you have any suggestions (and ballpark cost/complexity comments on what you did or what i should consider doing) i'd appreciate hearing about it! and any related pointers would be great, too.

thanks! ---K

Hi Kevin,

In regards to your '86 CJ-7, it would be a bit tricky to convert to an EV, only because there isn't a lot of room to put the number of batteries required to get a decent range per charge for a home built EV (let's say, 35-40 miles per charge)... and as CJs/Wranglers (and Cherokees, for that matter) aren't the most aerodynamic vehicles around, you'll need more battery weight for a given range than if you were doing a car conversion.

But this certainly doesn't mean it can't be done. It just means that to convert a vehicle like a CJ/Wrangler you'll have to make good use of the space and get innovative with how and where you mount the batteries. The exception would be if you have the money to use a more advanced type of battery than Lead-acid, like Lithium Ion (Li-ion) batteries (which store much more energy per pound), requiring less batteries to get a decent range.

To give you an idea of cost, the estimated cost of my Cherokee EV conversion is around $10,000 USD. Note that a more typical EV conversion could be done for as little as $6000 USD, but mine cost more because of the size of the vehicle (more batteries, bigger motor and controller) and some things I ended up having to do twice. Yet, even $10,000 is reasonable when you realize that almost all the EV parts have a long lifespan, usually 20 years or more, and can easily outlast the life of the chassis. The only exception is the lead-acid batteries, which need to be replaced every 3 years or so. Still, this means that there is very little maintenance cost required to keep an EV running for many years.

As far as other pointers, I'd say that it is very important to get the correct motor/drivetrain combo. For example, with the Jeep's stock drivetrain, using a single 9" diameter motor (such as I used in my Cherokee) will work, but is just barely adequate to do the job. This is because Jeeps are relatively heavy/un-aerodynamic and come stock with rather low numerical gears in the axles to keep the inline 6 engines at low RPMs (i.e. my Cherokee has 3.07:1 ratios). To ensure that a 9" motor really works well, you'll at the very least need to consider re-gearing the axles to a more reasonable ratio (like 4.11 or 4.56:1), because electric motors are truly most efficient and happy at high RPMs (up to 5000 RPM), as close to their max speed as you can get. Even still, you might want to use an 11" diameter motor, especially if you want better than stock performance from the vehicle. Yet another option is to get rid of the transmission and transfer-case all together and use two 9" motors, one to each differential to make a "Direct-Drive" system. There are pros and cons to going direct drive, let me know if you want to hear them.

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

I'm still unsure about the function of a motor controller. What would keep one from using a rheostat or other simple device instead?

Hi Daniel,

The primary function of the motor controller, is to control the motor's output power (and thus it's speed and torque) in some smooth manner based on throttle input. Such control is achieved differently for different motor types, but for most DC motors it is achieved by controlling the voltage the motor sees.

Theoretically, you could easily control the voltage by using a simple rheostat or variable resistor controlled mechanically by the accelerator pedal. But this isn't practical because a rheostat (or other "linear" device) will dissipate an *immense* amount of power as heat (especially at low settings) and will thus have to be impractically large and heavy to handle the kinds of power levels needed to propel a vehicle.

This is why all modern motor speed controllers are switch-mode devices that use a technique such as Pulse Width Modulation (PWM) to control the motor. Switch-mode devices pulse the power to the motor on and off thousands of times per second which allows them to operate very efficiently and be of smaller physical size and weight than a linear device.

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

Awsome web site!

I love how you did all the work your self.

I have owned two TJs now, and am going to build a rock krawler, and am looking at doing an electric one as the tourqe on start up is better than a gas engine... And no stalling on hills, etc. etc...

I am intrested in your Jeep's off road ability... what happens when you drop it in 4-low and take some trails?

What kind of terrain do you have in TX?
I am in PA...

thanks for the info, when I have time im going to read up on your jeep.

Do you have a ICE powered car as well? What if you need to go further than 30 miles?

My work is 20 one way...

Hi Josh,

Thanks! I probably wouldn't have done the conversion if I wasn't doing the work... I mean, that's what makes it fun and a learning experience!

As far as the torque thing goes... that depends on the types of motor you use. Some common types are Series DC, Shunt DC, and AC Induction... but there are many other varieties as well.

The most commonly used ones are the Series DC motors, and yes, they have AMAZING torque curves. Basically, at low speeds the motor's torque output is only limited by the amount of electrical current (Amps) you can stuff into it... and as the motor speeds up, it's torque declines. This is sort of the opposite of how an Internal Combustion Engine behaves, but it turns out to be a very useful feature :-)

For perspective, the 9" diameter series-wound DC motor I'm currently using can output about 250 ft-lbs. of torque with 1000 Amps flowing through it; and almost 500 ft-lbs. with 2000 Amps (about the absolute limit for this motor).

Larger motors, such as the common 11" and 13" diameter sizes put out much more torque and HP; tests show that the 11" Series DC motors can achieve upwards of 800 ft-lbs. while the 13" motors can achieve upwards of 1,100 ft-lbs. at 2000 Amps.

Regarding Off-Roading... well, I don't really do that... mainly because I've yet to get affiliated with any off-road/Jeep clubs, and that after spending so much time converting my Jeep to an Electric Vehicle I'd rather get some long, solid use out of it before I go and try to break things ;-). Actually, Off-roading was never at the top of my list of criteria when converting my Jeep. Thus, I ended up using flooded lead-acid batteries, which don't particularly like being bounced around a lot during operation.

But there is no reason why an EV couldn't make a truly kick-ass off-road vehicle. You just have to design for it. For example, if I had used sealed batteries such as sealed Lead-acid (AGMs), Nickel Metal Hydride (NiMH), or Lithium Ion (Li-ion) batteries, mild off roading would be no problem for my Cherokee. Extreme off roading would require some other modifications, such as using a water-cooled motor or a snorkel on the air-cooled motor to keep mud/sand out, water-proofing all the electronics, etc...

Regarding owning an ICE-powered vehicle, yes, I have a Mazda Truck that runs Ethanol E85 most of the time. But the Cherokee handles almost all of my in town driving; if I had needed a longer range, I would've done one of several things to improve range:

- Use More batteries
- Use Better batteries that store more energy (NiMH, Li-ion, etc.)
- Do efficiency upgrades (lighter wheels, fiberglass, aero mods)
- Do away with the transmission and/or transfer-case (direct drive)
- Use a more efficient donor vehicle to begin with
- Use an auxiliary generator of some kind
- All of the above

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

Nick,
I have a several questions about your conversion. It is something I thought about for a Wrangler once or twice, but haven't done much research on yet. Do you take it off road? I f you do or have, how does it perform? How does it handle and how has the center of gravity changed? Do you have a final weight yet? Were the LED lights less expesive than ready made or weren't they available at the time? And finnaly, since 03 when you started have you seen a more efficient, distance wise, combination of batteries or motors?

Most of the questions I've had are off road concerns, driving slow 3-10 MPH over varied terrain for 10-12 miles. Like I said I haven't done much research but I've thought of using a bank of deep cell marine batteries, Optima Blue tops maybe.

I know the longer I write, the more questions that I'd have. The last one I'll ask is have you looked at diferent transmissions to better utilize the power avaiable?

Have a Happy New Year. Good luck with the Cherokee and thanks for your time,
Sam

Hi Sam,

No, I don't take my Cherokee off road... mainly because I've yet to get affiliated with any off-road/Jeep clubs, and that after spending so much time converting my Jeep to an Electric Vehicle I'd rather get some long, solid use out of it before I go and try to break things ;-). Actually, Off-roading was never at the top of my list of criteria when converting my Jeep. Thus, I ended up using flooded lead-acid batteries, which don't particularly like being bounced around a lot during operation.

But there is no reason why an EV couldn't make a truly kick-ass off-road vehicle. You just have to design for it. For example, if I had used sealed batteries such as sealed Lead-acid (AGMs), Nickel Metal Hydride (Ni-MH), or Lithium Ion (Li-ion) batteries, mild off roading would be no problem for my Cherokee. Extreme off roading would require some other modifications, such as using a water-cooled motor or a snorkel on the air-cooled motor to keep mud/sand out, water-proofing all the electronics, etc...

As for the electric drive system itself, well, it is ideal for off-roading as the DC motors can produce a very good amount of torque instantly from 0RPM. For example, the 9" diameter motor in my Jeep can produce around 250ft-lbs on demand from 0RPM with my current motor speed controller, and close to 500ft-lbs with a more powerful motor speed controller. Likewise, 11" and 13" motors can be had that produce on the order of 800 and 1100ft-lbs respectfully...

My Jeep handles fine; I can't tell much difference from stock handling in most of the driving I've done. Plus, the center of gravity is lower now than it was stock (mainly due to most of the battery weight being sunk below the floor of the body). Thus, I'd say that my Jeep handles better around corners now than when it was stock, and this is important because the vehicle now weighs more than stock and is on a 2-3" lift. As for actual weight, I don't know (getting it weighed is still on my To-Do list), but I'd guess that it currently weighs about 4500lbs.

Yes, LED Bulbs were available at the time and yes they were probably slightly cheaper to buy. However, my testing of "off-the-shelf" L.E.D. lights concluded that they sucked because they were very cheaply made. By making my own LED light modules, I could ensure that the LEDs were just as bright as I wanted them and make sure they worked well with the stock lens/reflector assemblies (i.e. make sure the light diffused like it should in the lens). Plus, I enjoy working with electronics, so I had fun making the LED modules. In fact; I've been so happy with the LEDs that I'm currently in the process of converting the lighting on my Mazda Truck to LEDs as well (again, I'm making custom modules).

Yes I've seen more efficient batteries and motors; but they aren't anything new in the last 2-3 years. When I started my conversion, I could've used much more efficient motors, and much better batteries, but chose not to in order to keep the cost relatively low. FYI, the most efficient drive motors are usually 3-Phase AC motors, and the batteries with the highest energy density (i.e. which provide the most range per charge) are Lithium Ion (Li-Ion) and Lithium Polymer (Li-Poly) batteries. Electric Vehicles with Li-Ion batteries can do upwards of 300 miles per charge (or higher), so the technology for long-range EVs is already here!

3-10MPH at 10-12 miles is a piece of cake for just about any EV system, as the average range for home-built conversions is in the 30-50 mile range, and most of the production EVs built by the auto industry in the late 1990s got between 70 and 140 miles of range. Note also that in an EV you tend to get more range at slower speeds than faster ones.

In general, you NEVER want to use marine batteries for EV use, as they will not last long in this application. However, Optima batteries are an exception; and as it turns out, Optima Yellow Tops and Blue Tops are commonly used in high-performance EVs (so are Exide Orbitals and Hawker Aerobatteries). Why? Because sealed AGM lead-acid batteries such as these can provide *much* more instantaneous power output that traditional flooded-lead acid batteries. However, AGMs tend to be more expensive and provide less range and shorter cycle life than flooded lead-acids. That's why many people still use "golf-cart" flooded lead-acids in their EVs.

Yes, I have considered other transmissions, such as going direct drive (no transmission). Direct drive is done a lot in the EV world and certainly has it merits. However, for now my top priority to better utilize my power is to regear my axles from the current 3.07:1 gears to a more suitable ratio such as 4.11:1 or 4.56:1. This will, among other things, keep the DC motor operating at higher RPMs over the vehicle speed range than it is now; and the faster the DC motor is spinning, the more efficient it is!

As for questions; no problem, I like talking about this stuff. With that said, I think I'm the one that should be worried about how long I write :-)

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
----------------------------------

Hello

You mentioned that there is no compression-braking with an electric motor. Is there some way to mimic the effect (no throttle with pulses of reverse polarity)? This seems to be the main problem with off-road use. Controlled descent on loose surfaces is vital.

Also, which type of motor would you recommend for off-road AC or DC. You mentioned that DC motor have a lot of torque. Does this mean that they have more than a comparable AC motor?

Very Curious, Eric

Hi Eric,

In order for an electric motor to provide compression braking like an Internal Combustion Engine (ICE), it has to be able to pass current in the opposite direction, meaning it has to be able to act like a *generator*.

This process allows you to reclaim some energy that can be put back into the batteries (otherwise all this energy is dissipated as heat in the brake pads). We call it Regenerative Braking or regen for short.

Most EV conversions don't have regen because they use the inexpensive, commonly available drive systems based around a Series-Wound DC Motor, such as mine. However, there *are* other types of electric drive systems that offer regen. For example, virtually all electric drive systems that use AC Induction motors or DC Separately Excited (Sep-Ex) motors come with regen built-in by default. The only catch is that these systems tend to be more expensive then a comparable Series DC system.

What motor type is better for offroad use would depend on several factors, including your gearing, controller setup, and how you intend to drive the vehicle. There are many pros and cons for both AC and DC drive systems. For example, DC motors tend to have drastic torque curves, where they can produce max. torque from 0 RPM. This would be great for offroad use. However, most series DC motors are also air-cooled and not sealed. This means that they will heat up excessively at stall and low RPMs, requiring external blower fans for proper cooling. On the other hand, AC induction motors tend to have a torque curve more like an ICE, but are usually fully sealed and water-cooled. This would tend to make them more ideal for harsh environments.

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
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Hi Nick,

I'm sorry to be yet another guy asking what's probably yet another question you've had to answer for the 1000th time. I can only imagine how flooded you are with questions after having done such a brilliant project!

Have you considered adding any solar technology to your Jeep? Do you know anything about it? -snip- Now, I'm not talking about a solar-powered Jeep here, I just wonder about the possible benefits of adding solar power to an EV Jeep.

I'm also curious; do you still have 4 wheel drive capability installed in your truck? Or did you have to remove the front diff?

Patiently awaiting, but not acting entitled to a response,
Sean

Hi Sean,

Eh, it happens... I really do enjoy talking about this stuff, I just need a few more days in the week! :-D

If you're interested in knowing if anyone has installed solar panels on an EV and gotten them to produce power, well then yes, I have heard of quite a few people doing this. However, I don't know of anyone who has installed solar panels on their EV and had good enough results to make it practical from a cost standpoint.

The problem all comes down to EVs (or any vehicle, for that matter) needing a *lot* of power and energy for propulsion, while solar panels are still pretty inefficient (i.e. the power and thus energy output per square inch is pretty low).

For example, my Cherokee EV needs about 10 kiloWatt-hours of electricity to travel 20 miles, or about 0.5kWh per mile. Let's say I cover the roof of my Jeep with two solar panels that are 120-watts each, or 240-watts total. Then lets say I park my Jeep outside and the solar panels are exposed to sunlight for 8 non-stop hours. During this time, the solar panels will have produced only (0.240kWh*8hrs)= 1.92kWh. (1.92kWh/0.5kWh-mile)= 3.84 miles.

This means that I'd gain a little more than 3 miles of range... not much. Even worse, those 240-watts or solar panels will cost more than $1000. Thus, it is often not practical to attempt to gain extra range on an EV by putting solar panels on the roof.

However, you could always install a much larger solar power system on the roof of your house (say, 5 to 10 kiloWatts worth of solar panels) and store the power it generates in a battery bank in your garage. Then when you come home, you charge the EV off of this battery bank, making your EV free to operate and a true Zero-Emissions Vehicle.

Regarding 4 wheel drive; yes, my JeepEV still has 4x4. The transfer-case and transmission are new units, but other than that the 4x4 functions as it did originally.

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
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Hi Nick,

Saw your page on your Jeep conversion... I'm interested in converting my Jeep to electric also. I had a question for you... Anything you would do different if you did it all over again (would you use a different motor or batteries?) or Do you have any advice for a beginner in electric cars?
Thanks,
Jose.

Hi Jose,

Sorry for the extremely long delay in responding to your e-mail. I've been flooded/way behind on E-mail for the better part of a year now...

If I were to convert another Jeep Cherokee to an Electric Vehicle there are several things I would definitely do different, assuming they were economically feasible:

1] Re-gear the differentials. Most Cherokees come stock with numerically-low differential gear ratios such as 3.83:1 or 4.11:1 While these low ratios are great for large Internal Combustion Engines (ICE) which work best at low engine speeds (say below 3000 RPM), most electric motors are more efficient /and/ longer lived when used throughout their entire speed range, which usually goes as high as 5000 RPM for DC motors, and as high as 10000-15000 RPM for AC motors. To make better use of the electric motor, it would be best to re-gear a Cherokee's differentials to at minimum 4.56:1 gearing, or perhaps even as high as 5.11:1 gearing for an average DC motor.

2] Use a larger motor. Although re-gearing the differentials should allow a given electric motor to work notably more efficiently and generally provide better performance (especially at low vehicle speeds), it is still important to have a large enough motor to provide decent power at high vehicle speeds, have a long enough duty cycle to fit your driving habits, etc. Based on my experiences using a 9" diameter DC motor in a Cherokee, I'd suggest that up-sizing to an 11" diameter motor (or maybe even some sort of dual 8" or dual 9" motor configuration) would provide a better overall experience, despite adding more weight and cost to the conversion.

3] Don't use flooded lead-acid batteries. My experience using flooded lead acid "golf cart" style batteries in my Cherokee EV has been less than perfect. Though these batteries are inexpensive, relatively long-lived, and can take a *lot* of abuse, I'm not impressed with them enough to want to use them again nor to suggest their use in any large EV like a Jeep. Although I haven't verified this first hand, I have reason to believe that switching to batteries with higher power-density and lower Peukert exponent is the only way to go for such a large vehicle. AGM (sealed) lead acid batteries such as Hawker Odysseys or Optima Yellow Tops, etc would probably be a better fit for a Jeep EV, and would certainly make any EV a lot more fun thanks to the significantly higher power density (means better acceleration =] )

So those are the three main things I would do differently if I had the funds to convert another Jeep Cherokee to an EV all over again or to heavily modify the current configuration of my Jeep EV.

Hope that helps,
--
-Nick
http://www.DriveEV.com/
NO Gas, NO Emissions, NO Problem!
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