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Discussion Starter · #1 ·
I've got an opportunity to showcase EV's in an unusual forum in two years, but I need some advice about how to get it done. I own the Electro-Willys, a 1952 Willys military Jeep that has a LA 144vdc pack and a WarP11 motor. In 2012 the Military Vehicle Preservation Association (MVPA) is hosting a convoy up the Alaska Highway from Dawson BC to Anchorage AK to commemorate the construction of that highway during WW2. I made that trip with a Jeep many many years ago. I'd like to do it with my Electro-Willys. I've had several members of the MVPA encourage me to look into it.

So here are some of my challenges:
1. What size generator do I need to power my EV with a trailer at a top speed of 50 mph? Continuous service?

2. How do I convert the typical generator output from 120/240VAC to something like 120-160 VDC?

3. I'm thinking that the generator will be in the trailer, and that I'll use 2/0 welding cable to bring the power to a contactor then to the controller. The generator contactor would be parrallel to the pack contactor. Only one contactor could be closed at one time, so the controller would receive power either from the pack or the generator, but not both. Does this sound reasonable? problems?

4. Are there other configurations that would be more efficient or more effective?

5. Would it be better to have the generator feed about 170VDC into the pack, and use the pack as a buffer between the generator and controller?

I've got a little over a year to design and build this long-distance-configuration. I'd like to take some 100-1000 mile test runs before I run it to Alaska. Maybe push it to failure to see where my weak points are. I'm looking for all the help I can find to make this a reality.
 

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Before you do anything else you need to determine just how much power you use driving at the expected speed, and maybe a little bit more... There's a huge difference in price (and size) between a 10kW and 25kW generator.

I would only consider propane or diesel powered units.

If you are really savvy you might be able to build your own with a small diesel engine (Kohler makes some that I have heard are pretty good) driving an induction generator but operating these beasts can be tricky. Still, your pack voltage is just right to simply rectify the output of the IG and apply it directly to the pack. IG's operate as a quasi constant current source and are totally safe from short circuits so they make great battery chargers.
 

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If it were me I would be tempted to run a 240VAC generator to the Jeep and then convert to 144VDC.
The cables can then be a little smaller, with the higher voltage, and you will also have an AC generator for the times when you all stop and someone needs to do running repairs with some power tools.
:)

Also depending on long you run and how long you coast or stop you may only need enough to keep the pack topped up.
 

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Mike,

Good to see you back on the site. How is the Jeep performing? You should, by now know how many watts per mile the Jeep uses. From that you should have no problem figuring how big a generator set you will need.

Arn't there military generator trailers? Maybe you could find something surplus.

Rrectification of A/C is such a standardized thing that it will probably be the easiest part.

Another thought is one of those home emergency power generator sets mounted on a trailer of your own construction, you may even have one since you live out in the country. The come preconfigured for propane, a fuel you should be able to find with some frequency. Fuel use specs. for those gen sets is available so figuring storage on the trailer will be simple. I suppose that these sets are available with Diesel power as well.

Something that will run your home should run your Jeep with a little electronic wizardry added in. Either driveing through the batteries or directly. Myself I would try a through the battery system to even out the little ups and downs of power needs.

I have heard of load sensitive gen sets, but that was just in passing

Another way would be to rent one of those home APU units on a trailer. I've seen them advetised.

Just ramblin on,
Jim
 

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Discussion Starter · #6 · (Edited)
Tesseract, you are right, I need to methodically evaluate my power needs. I'm thinking that I'll load one of my jeep trailers with about 500 lbs of something and start driving. I may set up a video camera to monitor my speed, amps, volts, rpm. I don't know about building an induction generator. The reference you gave showed making a small AC unit, but of course, I need DC.

Woodsmith, I'm thinking along the same lines you are. One of my challenges is the equipment to convert 240VAC to 144VDC. I'm not sure what I need, and definitely do not know how to build it - but not afraid to try. I'm thinking that with a 144VDC rolling power pack, I'd make a great portable welder! :D

David, I'm not sure the cost of renting wouldn't be more than the cost to buy a good used generator, by the time I get done testing, then spending 1-2 months on the road to Alaska and back.

Jimdear, Thanks, and the Jeep is running well - mostly. Still have a few circuit "challenges" that I'm playing with. To run this EV on a generator, I think I'm more concerned with my W/mph than W/mile. And I have not added the weight of a trailer to any of my tests so far. I need to do that to see what my total loaded weight will do to performance.

I've been watching some surplus military diesel 10K gen sets and they are running about $2,000. Not bad if they are in good shape. I saw a generator trailer with a 15Kw sell for $4k. If I can make a 10k work, then I can simply load that into my military jeep trailer with room to spare. The military 10k is 2.5' x 2.5' x 4' and about 500 lbs. My trailer bed is 3.5' x 5.5', and it has a 900 lb capacity on road. So I'd also have room for tool boxes, and a 20 gallon aux fuel tank (mini-drum). And once I've completed this oddessy, I can take it on the road to EV conventions or car shows.

The military 10k is rated at 10k at 80% load, and is designed to operate at that load for up to 8 hours on one tank of diesel. The vehicle convoy I'd be part of has a typical speed of 40 mph and has a 10-15 minute stop every 1 to 1.5 hours. They plan to make about 2-300 miles per day with an 8 hour driving day. So what I'd be asking the gen to support should be well within the design requirements of a 10k, as long as I don't need more than that level of power on a sustained basis. For short bursts, or long hills, I could switch back to battery power. Once upon a while ago, I remember doing a rough calculation that told me that I could run my jeep at 60mph all day long using a 10k generator. But I don't think I calculated the weight of a trailer, generator, fuel, tools in that. I've got some experimenting to do.

I'd like to upgrade my Logi 1000 controller to a water cooled Netgain or Soliton. With this payload, and occasionally pulling long grades on the Alaska highway, I want a durable controller that can handle lots of heat. In fact I may want two, just in case. That part of British Columbia, the Yukon Territories, and central Alaska are not your typical EV communities. So replacement parts would be a long time coming on a little brown truck.
 

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http://www.evconsultinginc.com/articles/hybridizing_dc_system.html

I dont know if that link helps, just trying to contribute and help...

Looks like you could keep your EV setup the same, no need for switching back in forth from genset current to battery current...

Per the link, you could just run the genset into your onboard charger(s) and have them charge the packs as normal..charging while discharging...

This may require you to upgrade your charger to something that can push more amps in your batteries. I am not sure if you can use dual chargers..all dpeends on what maximum charge amps your batteries can take...

I read online somewhere that this trek you are discussing is 4000 miles, is that true?
 

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Discussion Starter · #9 · (Edited)
Thanks Bowser330, your link gave me a good lead to investigate. The EV consulting site recommended a Zivan NG5 charger as a good on board charger to take the 240VAC and feed the pack while the pack was powering the motor. I've got a Zivan 1500 charger, that uses 120VAC, I wonder if it is capable of continuous charging with the pack in use? I'll have to ask the manufacturer. I know that my 1500 will probably not be able to keep up with my power needs while on the move, but if it can come even close, then it may be able to catch up and top off the batteries while we're on breaks. That would also mean that I could probably get by with a slightly smaller generator - maybe a 5kW instead of a 10kW. That would save cost and weight.

Does anyone out there know if a Zivan 1500 can charge while the pack is discharging? I didn't get a manual with my charger from the knuckleheads that installed it. Now I wish I had one.

I did a quick check of the mileage and it's about 2400 miles from Seattle to Anchorage. And the average convoy speed will only be 30 mph, not 40. And they expect to make between 100 and 200 miles per day. So it's slower and longer than I remembered. That works in my favor for finding a powerplant. That military 5kW is looking better and better, but I still need to do some experimenting with a loaded trailer to check my electrical loads. I don't think the WarP11 will have any problem pulling the load. I just need to be able to feed it enough power.
 

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Discussion Starter · #10 ·
I've got another question, if i'm driving down the road at say 30 mph and the voltmeter reads 140v and the ammeter reads 120 amps, how would a Zivan NG5 144-30 possibly keep up with my power drain from the batteries? The Zivan takes in 240VAC and produces 144vdc at 30amps. It would seem to me that if I am using 120 amps, but only inputing 30 amps, then I'm not going to refill the pack at all, just extend my range by some small amount.

What did I miss? or miscalculate?
 

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I've got another question, if i'm driving down the road at say 30 mph and the voltmeter reads 140v and the ammeter reads 120 amps, how would a Zivan NG5 144-30 possibly keep up with my power drain from the batteries? The Zivan takes in 240VAC and produces 144vdc at 30amps. It would seem to me that if I am using 120 amps, but only inputing 30 amps, then I'm not going to refill the pack at all, just extend my range by some small amount.

What did I miss? or miscalculate?
You didn't, and you're absolutely right. You will need to size your charger/generator to at least match, if not exceed, your driving load. But do bear in mind that while you are freewheeling, slowing, or stopped (IE, not loading the drive system) you will be charging your cells, thereby extending your range.

So, in other words, you size the Generator and Charger to meet your average load (to hold your vehicle at a certain speed, 55MPH for highway driving, for instance), letting the batteries soak up the excess during lean periods, and using the batteries to augment the generated power during heavy use periods.
 

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I've got another question, if i'm driving down the road at say 30 mph and the voltmeter reads 140v and the ammeter reads 120 amps, how would a Zivan NG5 144-30 possibly keep up with my power drain from the batteries? The Zivan takes in 240VAC and produces 144vdc at 30amps. It would seem to me that if I am using 120 amps, but only inputing 30 amps, then I'm not going to refill the pack at all, just extend my range by some small amount.

What did I miss? or miscalculate?
It wouldn't if you were drawing that continuously.
However, you may only be powering the motor part of the time, the rest of the time you are coasting on the level or down hill or to a stop. During these times the charger will be able to catch up a bit.

Also when you have stopped the charger can continue to charge if needed.
 

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It means you're using 16,800 watts, or 22.4hp to maintain 30mph. That translates to 560 watt-hours per mile (16800/30=560)... which is kinda high for 30mph. So you need a generator that can output at least 16,800 watts to be able to continuously drive at 30mph. But your reading is an instantaneous measurement. If you take several measurements over a level mile and find yourself averaging the same numbers, then there you go. But 22.4hp @ 30mph does seem high to me.

And no, the Zivan would not be able to charge the cells at that rate. Max would be 144vdc x 30amps = 4320 watts from the charger.

I've got another question, if i'm driving down the road at say 30 mph and the voltmeter reads 140v and the ammeter reads 120 amps, how would a Zivan NG5 144-30 possibly keep up with my power drain from the batteries? The Zivan takes in 240VAC and produces 144vdc at 30amps. It would seem to me that if I am using 120 amps, but only inputing 30 amps, then I'm not going to refill the pack at all, just extend my range by some small amount.

What did I miss? or miscalculate?
 

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Discussion Starter · #15 · (Edited)
Thanks everyone for helping me understand better the details I need to collect, and how to use them. I don't know that 120 amps at 30mph is my constant draw. I remember seeing that match up but I don't remember if I was climbing or on the level. Unfortunately where I live, not much is really level. And I still have not put a loaded trailer on back to see what a difference that would make. I did however find a trailer/generator combination that may work for me. Here's some photos.



This is a jeep-size trailer with a 5kW generator on it. This would be a perfect match to the Zivan NG5 144-30 since it needs 4400w to provide a full 30 amps. And since it's all military, it fits in with the theme of the convoy. The combination gen/trlr weighs in at about 1500 lbs. That would put a tax on my power needs. It also makes me realize just how much more efficient today's hybrids are compared to the rugged military equipment I'm working with.
 

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... I don't know about building an induction generator. The reference you gave showed making a small AC unit, but of course, I need DC.
S'alright, Mike. What I was basically saying is that the induction generator behaves a lot like a current source and since your pack voltage is 144VDC you could capacitively couple its output to a full-wave 3ph. rectifier to charge the batteries directly. Count on about 500-600W per nameplate hp of the original motor. So a 15hp induction motor should be good enough to produce 7.5kW to 9kW.

A better link on how to use an induction motor as a generator is here.

Finally, you can also do the same thing with a regular generator: capacitively couple the output to a full-wave (or bridge) rectifier and charge the batteries directly. No charger needed. The coupling capacitors limit the current and the maximum voltage reached should the pack reach full charge (with 240VAC full wave rectified or 120VAC bridge rectified) is ~165VDC, or a nearly ideal 13.75VDC per 12V battery.
 

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Maybe you can solve the problem with something like this:

http://www.jstraubel.com/EVpusher/EVpusher2.htm

A trailer pushing a car sounds ridiculous, and dangerous, and unreasonable...

I love it :)

aesthetically speaking I think your better off with that 5K though...
would it run biodiesel stock? I know they can run commercial diesel, so it seems like it should, but they are built to run JP8...
 

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A trailer pushing a car sounds ridiculous, and dangerous, and unreasonable...

I love it :)
That's why they are not legal in the UK.:D


aesthetically speaking I think your better off with that 5K though...
would it run biodiesel stock? I know they can run commercial diesel, so it seems like it should, but they are built to run JP8...
For a military Jeep a military trailer has to be the one to go for.
It would look authentic and quite reasonable to be towed along in the convoy.
I think a big red or yellow painted civvy gen set with Honda on the side would look wrong.;)
 
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