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Author Topic: is a 6v92 capable of putting out 96 volts when driving?  (Read 4639 times)
happycamperbrat
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« on: September 29, 2010, 02:15:10 PM »

My alternator is only 24volts. I am thinking about a project but would need about 96 or more volts charging power from the engine. Is this possible without stressing my engine?
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TomC
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« Reply #1 on: September 29, 2010, 02:24:02 PM »

Voltage is not the problem-how many amps are you thinking of.  One horsepower equals 750 watts.  Give us a clue what you're thinking. 

The easiest is to use the big Delco 50DN 270amp at 27.2 volts (that's 7344 watts [27.2 volts when running]) to power a 4,000 watt inverter.  Remember, AC power requires the power source to be turning at exactly 1800rpm, or 3600rpm to create 60 cycles per second.  Variable speed on the bus engine can't do this-hence the inverter theory.  Good Luck, TomC
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« Reply #2 on: September 29, 2010, 02:25:13 PM »

The 24V alternator is capable of only 24-28VDC output. Might you be thinking about 96 Amps? If that's the case the alternator is capable of that output. If you are entertaining converting something ex-military that requires 96 volts (and in my mind clouded old age I can't imagine what) it might be 96 VAC but @ 400 HZ.

You've got me puzzled so I'll watch this thread to see how the mystery unfolds.

NCbob
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Jeremy
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« Reply #3 on: September 29, 2010, 02:41:05 PM »

I'm guessing that you're thinking of an electric-powered toad - electric vehicle motors often run at 96volts.

It's actually a nice idea which I've thought of myself in the past - especially as the toad can become a (very big) house battery bank for the bus. Bear in mind though that the 96v you generate to charge the toad isn't 'free', or even particularly cheap  - burning diesel to generate electricity isn't an efficient process.

Jeremy

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happycamperbrat
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« Reply #4 on: September 29, 2010, 02:55:14 PM »

BINGO!!!! And the winner is Jeremy!!! Step right up son and get a new bus for your insight!!!  Grin  Grin  Grin

But yes, that is what I am working on is an ev toad which will house my battery pack for the house system on the bus.

As far as the efficiency, my brother is supplying me with biodiesel so that helps.
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Jeremy
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« Reply #5 on: September 29, 2010, 03:09:00 PM »

Cool...please let us know all the gory details as the project progresses. I've spent a lot of time looking at websites of people who've built their own electric vehicles, and it's definitely do-able - although given the high initial cost of the motors and speed controllers, and the relatively short life of the batteries, it isn't necessarily economically viable. Compromises on both motors and batteries can be made though if performance (power and/or duration) isn't that important. I've not come across any viable alternative to the very pricey specialist speed controllers yet though.

Oh, and by the way - I have a UVA Fugitive (Beetle-based rail buggy) sitting in my back garden which has a 'future electric toad' label attached to it.


Jeremy

PS. Where do I pick up my new bus prize??
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Len Silva
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« Reply #6 on: September 29, 2010, 03:17:32 PM »

Your bus prize is sitting on the trailer, just awaiting your delivery instructions.
http://www.busconversions.com/bbs/index.php?topic=17594.0
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« Reply #7 on: September 29, 2010, 03:22:06 PM »

Your bus prize is sitting on the trailer, just awaiting your delivery instructions.
http://www.busconversions.com/bbs/index.php?topic=17594.0


Gee, thanks...

Jeremy


PS.

There's probably no need to worry about getting 96v from the bus's alternator....if you're towing your toad with it running on the road (rather than sitting on a trailer), it should be fairly straightforward to arrange it to charge it's own batteries as it's being pulled along (ie. it's motor acting as a dynamo). It'd be quite easy to overcharge the batteries like this though, so you'd need some kind of system to protect against that.


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Don4107
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« Reply #8 on: September 29, 2010, 03:27:44 PM »

If you EV has regenerative braking it could charge it's self whilst being towed.

Don't think I would want my house bank remote from the house.  
Don't think I would want to have to take the toad everywhere.
Don't think I would want to have the toad always hooked up when camped or stored.
Don't think it would be easy to up convert to 96V to power the toad then down convert to something usable by coach electronics.

We never learn unless someone tries.

Good luck
Don 4107
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happycamperbrat
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« Reply #9 on: September 29, 2010, 03:44:19 PM »

Okay guys, Im thinking (trouble comes now) that it might be possible and safe to have the ev toad carry the house batteries instead of the bus.

1) While driving down the road the alternator on the bus would run to the toad's charge controller and charge the batteries, at the same time I would run the battery's juice back to the bus' inverter.

2) Have a generator on the toad for emergency charging and boondocking.

3) When at a campground plug it into one of the RV house electrical outlets. My bus would be plugged into the campground site of course.

4) I only work about 10 miles from home and can charge while at work or home so this would also be my daily driver.

I dont know much of anything about electrical stuff and am probably going to end up hiring someone to help me with my bus electrical system, let alone all this. But this is my idea and dream. Im also open for options on solar power to make this work right.
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Tim Strommen
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« Reply #10 on: September 29, 2010, 04:30:40 PM »

Voltage is not the problem-how many amps are you thinking of.  One horsepower equals 750 watts.  Give us a clue what you're thinking. 

The easiest is to use the big Delco 50DN 270amp at 27.2 volts (that's 7344 watts [27.2 volts when running]) to power a 4,000 watt inverter.  Remember, AC power requires the power source to be turning at exactly 1800rpm, or 3600rpm to create 60 cycles per second.  Variable speed on the bus engine can't do this-hence the inverter theory.  Good Luck, TomC

Tom is right, the power is what you need to figure out.  What kind of EV are you thinking?  If your EV is a home-brew, you may have better luck using an isolated charger to each battery.  This is what I'm looking to do for my house/chassis banks.  A single 28.8VDC alternator powering a ultracapacitor-attached "bus".  Step-down regulators attached to that "bus" will charge each of the 2V house batteries independantly, plus charge the 12V chassis batteries independantly.  Shore power would be rectified and stepped down to 28.8VDC right at the connection panel.  Similar to an airplane, I'll end up with 4 choices for powering each load: Chassis-A, Chassis-B, House, and Shore - simple control logic will allow DC load circuits to switch to different power supplies as conditions and availability change, shed loads as power is used up, and retain emergency operation of critical systems while in-use.  AC appliances will each have their own properly sized/wave-form inverter as close to the point of load as possible (usually modified into the device enclosure).

The size of the bank is what determines your alternator need - I am staring down the barrel of a C.E Niehoff N1701 (910A @ 28.8VDC or roughly 25kW) they make them big, they just cost more...  A big part of my engine HP boost project is going into covering the load of the huge alternator (not making it go up hills faster...)

Once you have the power available, you can build a step-up or "boost" controller which will convert 28.8VDC to 96VDC (charging if this is lead-acid will probably require 115VDC...) - but remember that power is Volts x Amps.  28.8 volts at 100 amps is 2.88kW, that only works out to 30Amps of charging at 96VDC (before you account for loss in the conversion).

-T
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« Reply #11 on: September 29, 2010, 04:56:34 PM »

Tim I know you were speaking english  Shocked I also know your heart is in the right place, but I didnt understand hardly a word you said.

Jeremy could you expand on how the toad would recharge the batteries by not being on a trailor? I intend on pulling it 4 down. Most of the stuff I have read about regenerative braking (which wouldnt work with it being 4 down anyway) is not good, the stuff I have read says that for the weight of the system against the little bit of power that is recouped it isnt really worth it.
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« Reply #12 on: September 29, 2010, 05:41:50 PM »

Charging the toad's batteries by towing it behind the bus is quite simple in principle:- when toad is being driven under it's own power, it's electric motor is converting electricity from the batteries into the rotational movement of the wheels; but this process will work almost as well in reverse - in other words, if the toad's wheels are being turned by an outside force (ie., it's being towed along by the bus), the electric motor then acts as a dynamo to produce electricity, which charges the batteries.

This isn't quite the same as regenerative braking, which is when you use the braking action (ie. actually using the brake pedal, not simply letting the car coast) to generate electricity to charge the batteries. Regenerative braking is technically quite a complex thing to arrange as you have to use electronics to alter the charging 'load' to match the amount of braking force required - and naturally there are all sorts of safety features and back-ups built into the system to make sure the brake system works perfectly every time (not even Toyota get this bit right...).

So a simple charge-as-you-tow system would be fairly straightforward, but proper regenerative braking - as you say - isn't easy or cheap


Jeremy
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« Reply #13 on: September 29, 2010, 05:53:08 PM »

Jeremy I love you!!! Really?!! The motor creates energy while the wheels are turning even when the engine is off?! That is better yet!! Are there certain types of electric motors that would do that, or is that the way they are geared? I had no idea!
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Tim Strommen
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« Reply #14 on: September 29, 2010, 07:14:30 PM »

Tim I know you were speaking english  Shocked I also know your heart is in the right place, but I didnt understand hardly a word you said...

 Grin  - Let's start with what EV you are thinking...  Tesla Roadster or a home-built EV?


...in other words, if the toad's wheels are being turned by an outside force (ie., it's being towed along by the bus), the electric motor then acts as a dynamo to produce electricity, which charges the batteries.  This isn't quite the same as regenerative braking, which is when you use the braking action (ie. actually using the brake pedal, not simply letting the car coast) to generate electricity to charge the batteries...
...So a simple charge-as-you-tow system would be fairly straightforward, but proper regenerative braking - as you say - isn't easy or cheap

I'm going to go out on a limb and say (especially if it's a manufactured EV) unless the vehicle came with an existing regen braking system, don't bother with this approach (the motor controller would need to be built to handle it or it won't happen) - note that the same system will be charging the batteries as regen braking, but you won't be pushing the pedal.  Also remember - in order to impart spinning energy into the EV's wheels a force has to act against it (i.e. your bus pulling).  This extra load may take you from 25MHP up an incline down to 5MPH, and it won't work while you're waiting at a traffic light (no-spin, no-charge).  By having the wheels attached to the motor draggin against the bus, the EV might also have issues on wet pavement - typically you want your trailer/toad tires to free-wheel until you aply the brakes (which raises another interesting concept - how would you control the brakes on your EV?).

I'd venture a guess, it will be far less complicated/dangerous if you run a big fat cable from the bus to the EV and charge it directly.  The jist of what I was saying above is that you don't necissarily need to create 96V at the alternator to have 96V on the EV - this can be done with some fairly comon hardware, and more than one way. The big question is, how much power do you need to charge the EV?  Even if you don't have the answer directly, many of us here on the board can probably do research on the side if we know more about the EV you are looking at towing...

Best,

-T
« Last Edit: September 29, 2010, 07:27:40 PM by Tim Strommen » Logged

Fremont, CA
1984 Gillig Phantom 40/102
DD 6V92TA (MUI, 275HP) - Allison HT740
Conversion Progress: 10% (9-years invested, 30 to go Smiley)
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