Jeep Cherokee EV conversion

[casm]

Here's a link to an article about the stupid partisan crap (a redundant phrase, if ever there was one!) going on in California:
http://www.grist.org/news/muck/2005/06/23/little-solar

From the article:

"The Governator unveiled the initiative last August under the name "Million Solar Homes," proposing a 10-year subsidy plan to stimulate solar purchases on residential buildings. It picked up bipartisan backing from the get-go: Later that month, a Democratic state senator from Los Angeles County, Kevin Murray, incorporated the proposal into his own bill requiring a fixed percentage of all new California homes to have on-site solar power. But the combined package failed to pass out of committee, largely because of objections from Republicans and fiscally conservative Democrats to the program's cost and solar-installation mandate."

Man, and I would *so* kill to be able to do this. Why do I get the impression that the scope of Murray's bill made it fiscally unworkable? The amount this would tack on to the cost of building new homes is ridiculous, and penalises mainly the person originally commissioning the building work. Spreading the cost over a 10-year subsidised amortisation makes a lot more sense.

 

[yellowxj]

How about a booster trailor for longer trips? throw a little geo metro 1.0L on the trailor with a generator?? I know it defeats the purpose a hair but those metro motors can go 40-50 mpg pushing the whole metro...bet they could do better just spinning a generator, would that work?

 

[bjoehandley]

How about a booster trailor for longer trips? throw a little geo metro 1.0L on the trailor with a generator?? I know it defeats the purpose a hair but those metro motors can go 40-50 mpg pushing the whole metro...bet they could do better just spinning a generator, would that work?

I seem to remember AC Propultion doing that some years back with their Civic EV and Rav 4 EV, I think they used a 4cylinder motorcycle engine though (just don't quote me on that)

The 35 mile range would actually work for me on most occasions, I only live 6 miles or so from work (depending on the route taken). It would be worthless in other occasions, but that's a reason to have a fuel powered vehicle too. Depending on the base vehicle (I'd try a K-Chassis based car like a Shadow/Sundance, Lebaron GTS/Lancer, or Lebaron Coupe, those would be a decent size, have room for batteries and be unique too), if you start with an old beater type vehicle thats fairly light, then put a motor like what Nick is using in it it would be a shocker at a stoplight and probably get better run time than the Cherokee too.

I'm also kinda curious about transmissions, I see that nick has kept the french tranny in his, how often do people who do this kinda thing use either some kind of auto trans or just lock a manual trans in one gear (again like AC Propultions does) and just let motor RPM and torque do the work?

 

[yellowxj]

There was a gentleman here in ocala was building geo metro's, that were using a centrifical(sp) clutch off the elec motor to a IFS center chunk with cv axles heading to the spindles. Said it had a reasonable top speed and a 40 mile range...but it looked badly executed, booger welds, cheap crimp on wire connectors, and he wanted $8 or $9k for the car...

 

[bjoehandley]

Sounds like a good reason to build it yourself to me, yellow.

 

[XJNick2]

Hi, and thanks for the welcomes, everyone.

...but particularly from a hobbyist standpoint it seems as though the available componentry really relegates them to the nifty but not completely practical category.

As for component availability, I'm not sure what you're referring to? True, we as hobbyists tend to be limited in what battery types we can choose from (and thus how much range we get) because of the current cost of advanced battery types (NiMH, Li-Ion, Li-Poly). Other than batteries, though, I wouldn't say there is any problem getting all the necessary components to build an Electric Vehicle. But maybe I'm missing your point?

Thing is, though, that 35 miles is followed by two hours of downtime.

I hope I didn't imply in my previous posts that 35 miles per charge and 2-hours of charge time is what all EVs get. Quite the contrary, the range and charge time of an EV depends on many factors such as the size/weight of the vehicle and what components you used when you converted it. I only get 35 miles per charge because my Jeep is pretty big, heavy, and has the aerodynamics of a rolling brick (I mean all this in a kind way regarding my Jeep). Whereas a small, efficient car EV conversion can pretty easily achieve 50-60 miles per charge with a similar setup and lead acid batteries. Similarily, I can charge in 2 hours because I have (and am limited by) a 30-amp battery charger. Had I bought the 50-amp model, I could be charging in about an hour. Another tactic for faster charging includes using multiple chargers wired in parallel... which can give you 30-45 minute recharge times or lower (assuming you have the grid conenctions to feed multiple chargers). At any rate, I'd like to encourage everyone to check out the EVAlbum at http://www.evalbum.com/ . It is a photo album and database where you can check out the specs of many different EVs. It doesn't get close to being a comprehensive listing, but includes quite a few vehicles nonetheless, and allows you to get a feel of the different capabilities (range, top speed, etc) of different EVs.

Point taken, but they're still largely out of the reach of most hobbyists. The support systems necessary to operate them efficiently are also considerably more complex, from what I understand (and I may be off-base on this, so please correct me if I am).

If they are out of reach it is because of their price, not avaliability. They are being used in some conversions now. For example, check out this Honda CRX conversion here: http://www.metricmind.com/ac_honda/main.htm . As for support systems, it depends on the specific application. At the very minimum, batteries like Li-Ion and Li-Poly should have some sort of battery monitoring system. Though, such a system can describe a wide variety of equipment with varying levels of complexity, intelligence, cost, and availability. One system that will be available soon to help solve the delemma of finding a good BMS system is the one being developed by http://www.metricmind.com/

Compared to fuel costs across the same time period for the same distance travelled, how do they compare when the up-front cost of the batteries are figured in?

I'll get back to you on this when I get some time to dig up those calculations...

- While they may claim it's cleaner to relocate emissions to the power station, what happens when there are literally tens of thousands (or, as could hypothetically be the case in this part of the country, millions) of EVs plugged in and charging at any given time? We've already got power shortages and rolling blackouts here, -snip- At best, it's a zero-gain proposition.

I disagree about it being a zero-gain proposition because you *are* gaining several important things. First, you are reducing overall pollution when driving electric. This is not a claim, it is a fact. I'd rather not get into the whys here and now, because quite honestly this topic requires _much_ more time to discuss. Also, we can become more energy-independent, not only as a country, but as individuals (if you generate your own power via solar or wind). It should be obvious how important this is because we depend so much on transportation to get on with our daily lives. And I don't think the power shortage concern will be as big of a problem as you think. It's not like millions of EVs are suddenly going to start sucking power from the grid tomorrow. So saying that today's power grid cannot handle the millions of EVs of tommorrow is a bit silly. Any change of this proportion happening this quickly would be problematic and very unlikely at that.

Also, I don't see how it's any harder to control emissions on private vehicles - they're tested periodically, the same as the plants are;

Yes, but how many people cheat and get away with it? For example, someone who has gutted the catalytic converter to get more power. They'll get away with it until inspections, unless they cheat again by temporarily installing a good cat. converter so they can pass the inspections only to go reinstall the gutted cat. afterwards. So much for reducing pollution. Many people do this. Even worse, many areas still don't have emissions testing.

- By moving the pollution source out of the cities, all you're doing is pushing it out into the country. People do live there too. Nobody wants to be downwind from the problem in either case, but all this is doing is getting it out of the urban backyard and into the rural one.

I was not trying to suggest that polluting the rural areas is the right thing to do! I think we should be using clean energy sources and do away with it all together. But if we have to be making this pollution somewhere, make it away from as many people as possible. That means get it off of the streets and out of the cities where most people live and breath and where the air quality is worst.

Not trying to knock what you've accomplished, but like I say I'm still skeptical as to the overall benefits of EVs. Out of curiosity, have you looked into regenerative braking systems or storage battery flywheels?

I understand... and I also realize that I may not fully convince you or anyone else of the benefits of driving electric. But I'm trying my best . As for regen, yes I've looked into it. The short answer is that it is hard to implement safely on DC drive systems, and isn't commonly used with them. AC drive systems, on the other hand, almost always include regen braking because it is very easy to achieve regen with these systems.

Hope that all makes sense and answers your questions. I'll be out of town for awhile, so sorry to those whose posts I didn't have time to address tonight... be back soon

-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[XJNick2]

Hi again,

I don't mean to perpetuate this thread if you guys have lost interest in it but...

How about a booster trailor for longer trips?

Yes, things to this effect have been done to extend range. Different methods include towing a trailer full of batteries, towing a trailer with a small engine/generator combo on board, installing a small engine/generator combo on the vehicle, etc. All of these methods will work, but each has its advantages and disadvantages depending on the vehicle you're trying to power.

throw a little geo metro 1.0L on the trailor with a generator?? I know it defeats the purpose a hair but those metro motors can go 40-50 mpg pushing the whole metro...bet they could do better just spinning a generator, would that work?

Yes, it would... and in several different configurations as noted above. You would effectively be making your EV into a "plug-in" Hybrid Electric Vehicle. While this means you are no longer driving a zero-emission vehicle, such a setup still has many benefits over driving a traditional Internal Combustion Engine powered vehicle. For one, you'd still be able to go shorter distances _without_ burning any fuel. Then once your batteries begin to run low, flip on the engine/generator combo and enjoy longer range. The only downside to such a setup is that it adds more parts to the car and thus adds some complexity to the otherwise simple Electric drive system.

As a side note, most people who use engine/generator systems as range extenders burn alternative fuels in the engines, such as propane, natural gas, or biodiesel. The reasons why are obvious

-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[XJNick2]

Hi,

The 35 mile range would actually work for me on most occasions, I only live 6 miles or so from work (depending on the route taken). It would be worthless in other occasions, but that's a reason to have a fuel powered vehicle too.

Exactly... if the range of an EV can't meet all you're needs and you have two cars anyways, why not own one fuel-powered vehicle and one Electric Vehicle. You can use the EV for commuting, errands, etc... and the fuel-powered vehicle for long trips. IMO, this could be a win-win situation for most people.

if you start with an old beater type vehicle thats fairly light, then put a motor like what Nick is using in it it would be a shocker at a stoplight and probably get better run time than the Cherokee too.

True, the lighter and more aerodynamic the vehicle is, the better your range will be with a given electric drive setup. My Jeep is one of the worst examples of an efficient vehicle, and so with my Lead-acid batteries I am more limited in range than most EV owners.

I'm also kinda curious about transmissions, I see that nick has kept the french tranny in his, how often do people who do this kinda thing use either some kind of auto trans or just lock a manual trans in one gear (again like AC Propultions does)

Funny you mention my french tranny, because I actually just got _rid_ of it. My Jeep has just over 411,000 miles on it, and the Peugeot BA10/5 finally began to die a slow but steady death. As of last week, the Peugeot and old transfer-case are gone, and I've installed a nice new AX-15 and matching NP-231 in my Cherokee.

As for transmissions and EVs... in general most people retain the transmissions in their EV conversions. However, you don't use all the gears and don't shift nearly as often. Why? Because unlike an Internal Combustion Engine, DC electric motors are most efficient at their max speed (in my case 5000 rpms). This means that to maximize range, you want to drive the car with the motor spinning as _fast_ as possible (i.e. the exact opposite of how you drive an internal combustion engine vehicle). For example, I never use 4th or 5th gear in my Jeep. 1st gear gets me up to 30mph, 2nd gear to 55mph, and 3rd gear for everything faster. This means that going from 0-55 mph, I only shift gears once, which is really nice! With that said, people who drive lighter weight EVs usually never use 1st gear. They'll often use only 2nd and 3rd or in some cases lock the transmission only in 2nd or 3rd gear and never need to shift.

Also, as you mention, there are EVs out there that use no transmission and are direct drive motor to differential. While this can be done on both DC and AC drive systems, it isn't done with DC systems that much because DC motors usually top out around 5000-7000 RPM and require very large controllers to provide decent power in a single-ratio setup. AC motors, on the other hand, are usually rated from 7000-11000 RPM, have a torque/HP curve that makes them a better for use a direct drive setup, and are all around more efficient.

-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[old_man]

Being an EE, I had to scratch my head about charging times. 2 hours at 50 amps at 12v is 1200 watt hours. 1 hp = 746 wats. Given 100 percent efficiency, that give you 1hp for roughly 1.5 hours. Either the voltage or the current needs to be seriously increased to give you the storage capacity you need. Given the fact that most homes are limited to a 100amp service, Your max charge rate could be 100a x 2 phases x 120v = roughly 24kwh or 30hp/hour. Given an average cost of $.08/kwh then a full charge for two hours would run you around $4. Or the equivelent of 1.5 gallons of gas at todays rates here. 1.5gallons in a Civic can get you 75 miles.

I go through all of that to show that a 2 hour charge from a typical home is pushing the limits and thinking that electricity is cheaper than gas is a falicy promoted by some groups. The costs per unit energy are fairly close. If the electric vehicle has less power than the gas vehicle, you will get more miles, but a smaller gas engine would have the same effect.

I have a buddy that has a hybrid vehicle he commutes 65 miles each way with every day. He averages about 60 mpg. The gain is through peak operation of a gas engine and temporarily storing the energy.

 

[XJNick2]

Hi,

Being an EE, I had to scratch my head about charging times. 2 hours at 50 amps at 12v is 1200 watt hours. 1 hp = 746 wats. Given 100 percent efficiency, that give you 1hp for roughly 1.5 hours.

The problem is you started out with the wrongt numbers. I do *not* charge at 50 Amps *nor* at 12 Volts. My charger is rated at 30 Amps input, and I'm charging a 160-Volt nominal battery pack which has a finish charge voltage of 194 Volts. With that said, you cannot simply say that 2*160*30 = 9600 Watt-hours is the total amount of power I'm dumping into my batteries because both the voltage and current are always *changing* during a charge cycle. This should be familiar to you if you've ever worked with batteries because it describes a basic 2-step Constant Current/ Constant Voltage (CC/CV) charge cycle. The easiest way I know of to measure the power going into my battery pack is to use a kilowatt-hour meter... and I do.

The kilowatt-hour meter installed in my garage tells me that an average charge cycle consumes 15 kWh of electricity for me having driven 20 miles. That equates to about 750 watt-hours per mile on the AC (charger input side). Multiplying 750 watt-hours by the approx. efficiency of the charger and batteries respectively yields 750*.9*.8 = 541 watt-hours consumed in the DC system per mile driven. You can take the math from here.

Given the fact that most homes are limited to a 100amp service, Your max charge rate could be 100a x 2 phases x 120v = roughly 24kwh or 30hp/hour.

Maybe it has to do with where we live, but I've never seen a house limited to 100 Amps/phase. Around here, most houses have a mains breaker rating of 200 Amps/phase, giving you 200-Amp @ 240-Volt service. 240*200= 48,000 watts which implies you can pull a maximum of 48 kiloWatts from the grid.

I go through all of that to show that a 2 hour charge from a typical home is pushing the limits

Sorry, I disagree... and this argument is pretty subjective. The main problem is you have to define a typical charge. As I say, a typical charge for me, with my setup consumes around 12-15 kWh in a little over 2 hours and my charger can never pull more than 7.2 kW (30*240) instantaneously from my house and thus the grid. Pushing the limits? I'd say not seeing as how a typical appliance like a home hot water heater easily pulls 7.6 kW.

and thinking that electricity is cheaper than gas is a falicy promoted by some groups.

You're right. Grid electricity used to power an Electric Vehicle is often not cheaper then the equivilant energy in gasoline. However, EVs make far better use of the energy (electric drive systems are much more efficient) than a gasoline/Internal Combustion Engine powered vehicle does. This is why an EV is still cheaper to operate than a gasoline-powered vehicle.

-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[bjoehandley]

Got another question Nick, regarding the Lithium batteries. I'm into RC hobbies with primarlily electric cars and trucks, running an increasing number Ni-MH cells and I'm interested in going to a 11.1v Li-Po's on a Mini-T with a 8000kv bl system. The thing that concerns me on Lithium batteries is the problems with over discharging them and killing them, over charging them and having fire issues, damaging the cell in a wrecK (the Mini-T currently has aluminum arms but I'm going to go back to plastic to disipate energy when it wrecks, and with something that small going 60mph, wrecks will be an issue I'll have to deal with) and catching fire, cell going bad and having fire issues, etc. Any thoughts?

 

[Lucas]

Just wanted to say that your conversion was amazing. Lots of tech in there. Kudos, man.

 

[XJNick2]

Hi,

Before I say anything, let me say that I'm not, nor do I claim to be an expert when it comes to advanced battery chemistries like Lithium Ion and Lithium Polymer... okay, disclaimer over...

Got another question Nick, regarding the Lithium batteries. I'm into RC hobbies with primarlily electric cars and trucks, running an increasing number Ni-MH cells and I'm interested in going to a 11.1v Li-Po's on a Mini-T with a 8000kv bl system.

I'm not quite following you here.... When you say Li-Po, you're referring to Lithium Polymer (Li-Poly) batteries, right? What is "8000kv bl system"? Is this the model number of a motor? If so, is bl referring to a brushless DC (BLDC) motor?

The thing that concerns me on Lithium batteries is the problems with over discharging them and killing them, over charging them and having fire issues, damaging the cell in a wrecK (the Mini-T currently has aluminum arms but I'm going to go back to plastic to disipate energy when it wrecks, and with something that small going 60mph, wrecks will be an issue I'll have to deal with) and catching fire, cell going bad and having fire issues, etc. Any thoughts?

These are all valid concerns that are (and should be thought of as) relevant regardless of what battery type used. However, these concerns become even more important when dealing with chemistries like Li-Ion and Li-Poly because these battery types are inherently less tolerant to abuse than say, Lead Acid batteries.

Now, theorhectically over discharging the batteries should not be a concern because you can prevent this by knowing when to stop use and/or by using instrumentation to alert you when it's time to stop and recharge. Overcharging should also be a non-issue assuming you are using a charger that is designed for use with the Li-** batteries. Such a charger should either be smart enough itself and/or make use of an external battery management system to safely charge the batteries with the proper charging algorithim. If you are not using such a charger then you should not be using Li-** batteries because you will destroy them in short order and/or have a big safety hazard on your hands.

Regarding fire issues: Yes, Li-** batteries could create a problematic situation if they ever catch fire. This is because they can create their own oxygen when they burn, meaning once ignited, a Li-** battery fire is self-sustaining and cannot be extinguished. But don't let this freak you out... getting something like this to occur would take a _lot_ of abuse. On the bright side, Li-** batteries are getting safer as new kinds of materials are being tested and used. For example, Valence Technologies (http://www.valence.com/) is using a different type of cathode material in their Li-Ion batteries that makes them much safer from risk of combustion. A closing thought on this matter is that it is hard to say for sure whether a certain brand of Li-** battery can be said to be "safe" or not, as the "safe-ness" of the battery depends largly on how it was designed and built. It also depends on the size and format of the battery, the application it's being used in, etc...

If you are really paranoid about the safety of such batteries, you might contact the manufacturer and see what information you can obtain from them (explain you're application and how you intent to use the batteries). Another option (though less desireable and potentially unsafe) would be to buy one or two of the batteries you intend to use and run tests on them yourself to see how they react to "unsafe conditions" like extreme overcharging, physical mutalation, etc... just be careful

Hope that helps,

-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[XJNick2]

Hi,

Just wanted to say that your conversion was amazing. Lots of tech in there. Kudos, man.

Thanks! Saying that I learned a lot from doing this EV conversion would be an understatement... as I learned more than I ever anticipated from this project. Even better, the result is real, it works, and it is _extremely_ useful in my everyday life!

In case anyone was wondering, I'm starting college next month as an Electrical Engineer major and plan to continue working with Electric Vehicles in the future. (Though, perhaps that was obvious?)

-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[bjoehandley]

What I was refering to on the RC BL system (it is dc) as a KV, 1 KV is 1,000rpm per volt, so on my Mini-T's 8000KV bl system running a 11.1v Li-Po it should turn about 88,800 rpm :scared: I've been hearing stories of rc airplanes that have crashed and damaged the pack and have shorted out causing a fire, sometimes destroying the aircraft (I've seen a pic of an electric heli that looked like a rpg hit it, leaving shrapnel imbedded in the drywall of his hobby room, the hobbiest's vehicle (there's a pick somewhere of a Lexus SUV that is completely burned up because of this!) The problem is such that it's recomended to get an ammo box or something comparable to store them. Some of the over discharging problems have been taken care of by building in a chip (like what's in a cell phone) to prevent from happening, over charging is something that the user needs to be actively monitering while charging. If I go this way on that Mini-T, I'm going to get a Li-Po specific charger that's DC only so I can just stick it on a battery in the middle of the driveway away from anything flammable (hard to do with 2 Jeeps with more than 180K on them though.)

 

[bjoehandley]

Got another question, what's the cost on some of the motor controllers used?

 

[XJNick2]

I've been hearing stories of rc airplanes that have crashed and damaged the pack and have shorted out causing a fire, sometimes destroying the aircraft (I've seen a pic of an electric heli that looked like a rpg hit it, leaving shrapnel imbedded in the drywall of his hobby room, the hobbiest's vehicle (there's a pick somewhere of a Lexus SUV that is completely burned up because of this!)

I could believe this, especially if they were using older LI-** cells. As I say, the manufacturers seem to be paying a lot more attention now to how their batteries take abuse, and in general it seems that Li-** batteries are becomming much safer.

Some of the over discharging problems have been taken care of by building in a chip (like what's in a cell phone) to prevent from happening, over charging is something that the user needs to be actively monitering while charging.

Right, you're describing a Battery Management System (BMS). However, any decent BMS will protect the batteries from over discharge *and* over charge. Or, if the BMS is designed such that it can only protect against over-discharge, then it becomes the responsibility of the charger to not fry the cells... and most modern chargers are smart enough to take proper care of the batteries (assuming you use a charger specifically made for the battery chemistry you are using).

-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[XJNick2]

Hi,

Got another question, what's the cost on some of the motor controllers used?

For what application? Assuming you are talking about controllers for on-road EV use, here are some of the controllers that are avaliable and (most of) their prices:

DC Controllers (for Series-wound DC motors):

Curtis PMC 1221C-7401 (72-120 volt, 400 amp) $995
Curtis PMC 1231C-8601 (96-144 volt, 500 amp) $1424
Cafe Electric Zilla 1K-LV (72-156 volt, 1000 amp) $1975
Cafe Electric Zilla 1K-HV (72-300 volt, 1000 amp) $2550
Cafe Electric Zilla 1K-EHV (72-348 volt, 1000 amp) $2850
Cafe Electric Zilla 2K-LV (72-156 volt, 2000 amp) $3300
Cafe Electric Zilla 2K-HV (72-300 volt, 2000 amp) $4450
Cafe Electric Zilla 2K-EHV (72-348 volt, 2000 amp) $4900

AC Inverters (for 3-Phase AC induction motors):

Siemens Simovert (110-350 volt, 100kW) $(?)
Siemens Simotion (110-350 volt, 100kW) $(?)
Siemens Elfa Dual (110-650 volt, 240kW) $(?)
MES-DEA TIM-600 (80-400 volt, 100kW) $4297
MES-DEA TIM-400 (80-400 volt, ? kW) $3887

What you discover is that, in general, you can get a lot more raw power cheaper by using a DC drive instead of an AC drive...

Hope that helps,
-Nick
http://Go.DriveEV.com/
1988 Jeep Cherokee 4x4 EV

 

[bjoehandley]

Thanks Nick, if I ever win the Lotto, I'll have to try and through one of those together.

 

[sandman]

I know people have asked questions similar to the one I'm about to ask, but I don't completely understand why it wouldn't work.
I know it's useless to have a pulley attached to the motor to turn the alternator (since the motor doesn't idle) but wouldn't a small seperate motor that constantly runs with a pulley/similar system (that multiplies the rpms) connected to an alternator or two work?

Thanks in advance for any replies.

Nick, awesome site and jeep. I've been looking at it now for a week. Good work man.