Hi everyone.

Hopefully you can help me. I am trying to find a circuit diagram for a custom adjustable voltage regulator for high power automotive alternators. I have a small electric car with a 60 volt battery pack. It consists of 10 6 volt 225 amp golf cart batteries.

I need to be able to build a small self-contained gas powered charging system for when I have to travel beyond its 15 miles each way distance limitation. I want to be able to build an external adjustable regulator I can attach to automotive alternators. I would need it adjustable from 48 volts to 90 volts DC. It would need to be able to handle 400 or even better 500 amps.

My goal is to us a small internal combustion engine running of wood gas to charge my pack or maybe even supplement the energy available to feed the electric motor. I first will try it on some surplus 12v 100amp alternators I already have. If I can get some data from them. I plan on purchasing a 24 volt 400 amp alternator which are oil cooled. Maybe even two if it does what I hope it can do. I know the amps will diminish as the voltage goes up. With a 24 volt 400 amp starting point, I believe I will be able to end up with something close to a 63 volt 200amp DC power generation capacity.

I know that it would take somewhere around 31hp at peak to power the alternator. I have most of the trailer and such worked out. But my ability to design circuits is very limited. I can follow instructions and basic schematics fine. Hopefully someone on here might know of a schematic of a variable external voltage regulator for automotive alternator. Or even better yet know of, or draw up a schematic of the variable voltage comparator circuit for this purpose.

Any help will be greatly appreciated. I will be sharing everything I learn from this build with the web and my college electric vehicle building club.

Thanks in Advance

Raz

 

Are you asking for a single VR for the big alternator, a single VR for several 100A alternators connected in series, or several individual VR, one each for each 100A alternator?

 

I think,,he just try to buildup 63v 400amp regulator system on his 12v 100amps alternator..but he just cover up only 200amps 63v with his knowledge..and so he want some advice from seniors of dis forum to get dis 63v 400/500 amps regulator system...If he can't do anything,,,then he will buy 24v 400amps alternator..

----------------Lizard(suvo)

 

It's going to take a 25 or so horsepower motor to spin that alternator to get 400 amps out of it.

edit: Let's look at the numbers 400a* 63v = 25,200 watts
If memory serves me, 1 hp = 746 watts
25,200/746 = 38 hp, and that's assuming 100% efficency, which we know isn't going to happen.

 

So you want to pull an engine, alternator and fuel supply along on a trailer behind your "electric" car, so that you can charge the batteries?

What a ridiculous waste of resources! Criminal, IMHO.

Get a 10HP motorcycle and be done with it!

 

Yes and no to all of the above. I have a very small 1980 Commuta Car. It has a maximum and I do mean maximum distance of 40 miles. But to take it to that distance would have my pack depleted to below 15%.

I do understand that it would take 25 or a few more hp from an internal combustion engine. I have shopped and these can be found with weight less than 90lbs. I would like to be able to drive multiple 100amp or 150amp alternators at the same time using one adjustable regulator. This would be the least expensive way of getting the amps I am seeking. This setup would also be of the most benefit to the EV diy community. As it would be scale-able to any voltage and or amperage size with in reason. I know a lot of 36v, 48v, and 72v home built all electric vehicle owners who could use an inexpensive system like this.

I know that adding around 200 or 300 at max extra pounds could diminish to speed and reduce distance. This would be a trade off for being able to make longer trips away and back. The college I attend is 22 miles each way with a couple of short hills. They do not have any charging system there yet for us to use.

I can weld a very lightweight aluminum trailer frame to hold the system and make a low co-efficient of drag abs enclosure with ventilation. My hope is that if I can speed charge my pack or maybe even supplement it for the trips back from college.

If a multiple inexpensive alternator regulator is not easily designed and constructed by the general home build community. Them a single unit to change the voltage of an 24v 400amp bus alternator would be my next hope.
I hope to be able to keep the costs down and have the end result easily affordable by many who might want or need the charging or supplement system.

Thanks for all your responses hopefully I have answered all your questions.

 

I hope I don't offend you, but you give me the distinct impression that you don't really know how an automotive alternator works.

Most(> 90%) automotive alternators have 3 phase Y or Δ stators and the three phases are rectified using diodes pressed into a heatsink.
Voltage control is by varying the rotor (electromagnet) field strength using a voltage regulator. The rotor current is typically 3A to 4A.
In your case at 63V the rotor current is still likely to be only about 3 or 4 amp beyond that you would tend to reach saturation.

The stator output current will not be directly controlled by the voltage regulator but will be a function of the rotor field strength, the speed of rotation, the stator size, the ability of the rectifier to handle your peak current, and of course the ability of the batteries to take the current at a particular voltage difference between the alternator output and the battery nominal voltage.

You need to check all the other parameters first, cooling of the rectifier being especially important - you will need to dissipate nearly 650 WATT at peak output!!!!
After that the voltage regulator is the easy bit.
I will first need to know your rotor current and an approximate idea of it's inductance.
We will then copy the CAV 440 Voltage regulator (24V) circuit, using discreets and modify it for 63V but It is ultra simple and reliable and is adjustable in steps using fixed voltage reference resistors. I would not use a potentiometer - they are a pain in the arse and could easily cause accidental overcharging.

 

Wow, what an amazingly ugly mode of transport.

Google images, 1980 Comuta car:
https://www.google.com/search?q=1980+Comuta&tbm=isch


Why go through all this bother to make it into what will basically be an internal combustion powered vehicle.... except with additional energy-wasting conversion and storage steps, that will make it even more inefficient than a normal engine-powered vehicle?

Just buy an, um, normal car? A motorbike?

 

No you did not ruffle my feelings. I actually understand how an automotive alternator works quite well. I just have a really hard time designing things. I understand that the field output is relational to the current fed to excite the rotor (armature). I understand that a voltage divider circuit is used in a comparator circuit to regulate the current fed to the rotor. This is accomplished sometimes in a pwm type fashion. But not a true pwm design, as the original external regulators were just relays switching on and off to adjust the voltage and current to to rotor.

I do not have the alternator to attach this to. If that is needed I will need to make a trip to the local pick N Pull. I was hoping that a semi-universal design could be put together. This would allow a lot of home EV builders to make the basic circuit if they had one to work with. If I need the reading off of the alternator like you mentioned I will have to wait until next weekend for the chance to get one at an auto dismantler. I know the amps are fixed by the winding's in the alternator.

 

I already own several two wheel vehicles, including 750, 650 275 motorcycles, 125, 90, 70 scooters, mopeds etc. This is for different purposes, so please no haters. I do not intend to use the generation system all the time just when I have to travel beyond the battery packs 50% occasionally. The system should be able to be kept within the weight of a large passenger with very little drag.

 

Cork_ie is there a way to pm in this forum?

 

Cork_ie is there a way to pm in this forum?

I really don't know.

 

FYI, the complete owners manual, with wiring diagrams:

http://www.hightechscience.org/ComutaCar.pdf

 

Thanks for the link to the Owners, Service Manual and Wiring Diagram.

 

So you want to pull an engine, alternator and fuel supply along on a trailer behind your "electric" car, so that you can charge the batteries?

What a ridiculous waste of resources! Criminal, IMHO.

I'm on board with the trail-behind charging generator. I've considered it before and I think its a good idea. I've actually considered building an electric car with a very small battery bank or maybe instead, a very large capacitor bank, and a small generator to keep it charged.

Reason being, the generator could be kept running in it's power band where it is most efficient, whereas an automotive engine is generally not running in its power band, leading to it's crappy efficiency.

I believe an efficient ICE, running in its power band can get close to 30% efficient. I've read that it only takes maybe 15-20hp to keep a full sized sedan at highway speed on a flat road. So slap a 30hp generator on the back of an EV to keep the batteries topped up, and you're still burning gas, but much less than all those v8's banging away at nothing at the stoplight next to you.

This is just an idea I've thrown around; I have no idea if its accurate and I have not even come close to testing it, but it sound plausible to me. What say you?

 

I also understand that about engines running in their sweet spot. The system I am thinking of would be very light, when added to the vehicle would extend the range and usefulness of the vehicle. I of course with this car would not replace my 1988 Daihatsu charade and its 48mpg. I would make it possible to travel where it can not now and make it sometime to the next charging outlet. With this light a vehicle it would only take on the average a 140 amp replacement to keep the pack from discharging. But most importantly to me I would be able to increase its percentage of use from around 20% to over 65% with this. Even if I had to use it to make the last 10 miles, I can always plug in at the other end to replenish my pack.

 

Have you considered making improvements to what you have, instead of this? A lot of more efficient technology has hit the market since 1980. I'm assuming the car has lead acid batteries? Filling the same space with LiFePo4 batteries would probably double or more your range.

I just read up on the "controller" for this car (pg 12a of the link DMahalko provided). no regen braking, and the a decent chunk of voltage is burned off in a resistor to control speed. You can do much better than this. An ETEK motor or motoenergy ME0708, with appropriate switching controller, will give you regen braking, much improved efficiency, and pantswetting performance (comparatively, with your current 3.5HP wound motor).

I think you can get the range you want, plus a very generous unexpected improvement in performance, for cheaper and easier than this tagalong generatalternatortank attachment.

 

My Commuta already has a 350 amp Altrax controller. Unfortunately I do not have thefive or six thousand dollars to go LiPo with the pack or purchase an expensive motor upgrade. I purchased my little ugly car for five hundred dollars with current registration in California. If I can make an inexpensive external voltage regulator that I can use on one or multiple alternators. I already have an 25hp motor out of a riding yard tractor( glorified riding mower) which weighs less than one hundred pounds. With adding one or two alternators, a very small fuel tank and the thirty eight pound aluminum trailer. I will be under the second passenger weight and hopefully only have to go three to four hundred dollars out of pocket.

I am on a very tight budget being a full time college student. I know there are much nicer and smarter ways to accomplish the same result but not in my financial capacity. I can go to my local PickNPull auto dismantler and get used alternator for nineteen dollars each, no matter what they come off of. My idea is to find one or two larger ones hopefully around one fifty or two hundred amps and build the regulators for them. This will be a test bed I will be sharing with the one community. If it is beneficial I plus everyone out there will win. If it is not successful then I will only have spend a very small amount to make a gas powered charging station. Who knows maybe I could leave the gas powered charging station parked at my college to allow me to make the return trip home without running my packs rate of charge below forty five percent.

I was looking on Ebay and there are external regulators for twelve volt systems that work on many different models and manufacturers. I was hoping that a regulator that would be able to be set for higher voltages maybe through different components or switching between different components. Could be designed and built open source. I know several other members of my colleges Electric Vehicle Club have been anticipating the outcome of this project.

Thanks again for all the feedback, ideas, opinions, and your time and attention to this.

 

I see.

if you put all your batteries in series, could you reach 170V?

Where i'm going with this is, you could just rectify the output of an ordinary 120VAC backup generator. 170V is well above your 63V need, but I'm pretty sure you can set the needed 37% limit in your altrax controller.

I know it's a stretch, but I'm not having any eurekas right now. I don't think you can put alternators in series, as I believe (possibly mistakenly) that they utilize case/chassis ground. you might be able to pull the ground out to isolate it but not sure.

Barring all that, I'm intrigued by cork_ie's proposal. Are you able to test the amps and inductance to get him the figures he needs?

 

QuickCharge Corporation Series charger
120v input, 64v @ 20 amps output, 1280 watts, $437:
http://02a27d4.netsolstores.com/onboardchargerslarge253540amp.aspx

main page:
http://www.quickcharge.com/On%20Board%20Chargers.htm

Intended for permanent installation on floor scrubbers, forklifts, etc.
Can have device lockout so it cannot run while charging, but is optional only.



1500 watt 120v portable generator, Amazon search:
http://www.amazon.com/s/ref=nb_sb_noss?field-keywords=1500+watt+generator

2000 watt 120v portable generator, Amazon search:
http://www.amazon.com/s/ref=nb_sb_noss?field-keywords=2000+watt+generator



Also, multi-bank isolated-ground chargers:
http://quickcharge.com/multi bank chargers.htm

With the isolated ground, you could charge two 6v batteries in series from each bank output.


Oh, but this does not have the exciting hackery of DIY scrapyarding and trying to build a custom mounting frame with a serpentine belt across 5 alternators that you hope doesn't explode apart going down the highway. Bummer.