Directly driving 36v golf cart with 12v genny

Ideas, advice, tips, and tricks regarding the building and creation of mutant vehicles in Black Rock City
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Captain Goddammit
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Re: Directly driving 36v golf cart with 12v genny

Post by Captain Goddammit » Tue Mar 15, 2016 6:51 am

No, the 20-amp comment didn't confuse us. It showed that you're confused!
Real world playa altitude EU2000 output is a little over 10 amps, at a very tightly regulated 120VAC (not 110 VAC).
I don't know where you've gotten the idea that automotive battery chargers over 6 amps are at all uncommon.
Sears sells a nice one for $150 that does 2 amp trickle, 15 or 50 amp fast charge and a claimed 250 amp "starting" surge.
They are commonly available in a wide array of power levels.

You've got to remember that a 6-amp, almost uselessly-wimpy charger isn't always putting a full 6 amps into the battery bank, and that hooking up a few in parallel will reduce each one's charge rate.

Trickle charging isn't what you want for running an MV. You've got to maintain a charge rate that keeps up with your average consumption. If you try to trickle charge your MV you'll be parked an awful lot, waiting for it to charge. You've only got that one week out there, you want a rapid charge rate.

Knowing your technical info is good but you also need to put down the textbook, go to BRC and bust out the gear and see what really happens.

You're giving advise that will have an MV parked an awful lot rather than doing what it should be doing, running over darkwads and scaring babies.
GreyCoyote: "At this rate it wont be long before he is Admiral Fukkit."
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ygmir
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Re: Directly driving 36v golf cart with 12v genny

Post by ygmir » Tue Mar 15, 2016 7:16 am

Captain Goddammit wrote:No, the 20-amp comment didn't confuse us. It showed that you're confused!
Real world playa altitude EU2000 output is a little over 10 amps, at a very tightly regulated 120VAC (not 110 VAC).
I don't know where you've gotten the idea that automotive battery chargers over 6 amps are at all uncommon.
Sears sells a nice one for $150 that does 2 amp trickle, 15 or 50 amp fast charge and a claimed 250 amp "starting" surge.
They are commonly available in a wide array of power levels.

You've got to remember that a 6-amp, almost uselessly-wimpy charger isn't always putting a full 6 amps into the battery bank, and that hooking up a few in parallel will reduce each one's charge rate.

Trickle charging isn't what you want for running an MV. You've got to maintain a charge rate that keeps up with your average consumption. If you try to trickle charge your MV you'll be parked an awful lot, waiting for it to charge. You've only got that one week out there, you want a rapid charge rate.

Knowing your technical info is good but you also need to put down the textbook, go to BRC and bust out the gear and see what really happens.

You're giving advise that will have an MV parked an awful lot rather than doing what it should be doing, running over darkwads and scaring babies.

sticky note!!
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mudpuppy000
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Re: Directly driving 36v golf cart with 12v genny

Post by mudpuppy000 » Tue Mar 15, 2016 9:47 am

Hmmm kinda late, but why not 3 generators in series? 3x12=36v, 30 amps. I have no idea if you can hook up generators like that and not have them explode, but it works for batteries. Actually that's probably the way your batteries are hooked up in the golf cart to begin with.

Colonel Monk
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Re: Directly driving 36v golf cart with 12v genny

Post by Colonel Monk » Sun May 01, 2016 7:46 am

I have an EV I use on playa, and have had pretty good luck with it. Haven't had any major issues due to dust, though I'd def recommend that you would disassemble that motor and clean the dust out of it after each burn.

One thing I don't believe was mentioned was how the gearing effects the load to your power source. Given that an actual MV top speed is 5 mph, a really easy way not to utilize the max current draw of your golf cart motor @ 55 amps is to gear it pretty low, so that at 5 mph you're running in the top say 25% of the motor's theoretical max rpm. That might sound counter-intuitive but the more torque the motor must produce at low rpm the more power it's going to draw.

This is similar to the reason that your playa RV's AC unit at startup might max out your genny and trip the breaker, but if you turn off everything else and get it running, you can then turn some things back on. Start up torque is much higher under a load.

It's a bit more complicated than that, if you don't repurpose a motor and buy a new one instead you can look at power curves for the motor, and the mfr might actually be able to tell you what RPM is the most efficient.

I ran my motor off 24v and it was a permanent magnet motor, and runs of a PWM motor controller. The voltage to the motor is much lower than the battery voltage, unless I have the pedal to the metal. On 4 12v batteries it runs all night long, so then I have all day long to recharge it. It's also worth saying, that knowing the RPM per volt my motor would spin, I ended up with a 7:1 reduction gear which took two sets of sprockets and chains to accomplish in the space I had available. Had I just done a single chain and two sprockets I would not have had enough reduction, and with the load of my vehicle that probably would have led to burning out the motor, or less range, or both.

Yeah, gas motors are easier and a hell of a lot cheaper.

Still, EV has some charm. Can drive crazy slow with no noise which can make for a neat experience on deep playa - well at least in the old days when it was a bit more calm and dark out there.

I have thought about trying the hybrid too - big batteries are expensive. But like the man said, you can't have a charger on your batts where the amps are exceeding the max charge rate for your particular batteries. For many deep-cycle lead acid batteries, 10-13% of the C/20 Capacity (this is how most are rated)

So if you had 3-12V batteries in series, and they were 85 amp-hour batteries, you'd have an overall capacity of 85 amp-hours @ 36v. 13% is 11.05 AMPS so a 10 amp charger would be appropriate, for longest life.

You'd be losing ground with that however, meaning though you're putting power in you'd also be losing it potentially faster than you're putting it in...... And I think this is why it makes doing a hybrid without complex computer controls more difficult.

Reason is, you *could* have a charger supply with much higher output that could run flat out to supply your motor when at top speed, but at lower speeds or when not moving, you'd have to turn it down to avoid overcharging.

It is possible that a multistage charger would work - the voltage drop running full out with smaller batteries could kick it into the higher charge rate while running the motor, and perhaps it would drop when you are stopped. But that is all a major what if.

Yeah, gas motors are easier and a hell of a lot cheaper.

But if you really want to try it there are some other ideas. BTW there are MVs on playa that do what you're describing, but I do not know what motors they are using to run them off a genny. Could very well be using AC motors (because your generator is AC) and variable speed control. No batteries.

I suspect that some have done this because they are already running genny to provide power for lights and sound, and depending on the vehicle using multiple drive motors you can also get steering - it's like a hydrostatic drive but it's electric.

Good Luck
dust.

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Captain Goddammit
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Re: Directly driving 36v golf cart with 12v genny

Post by Captain Goddammit » Sun May 01, 2016 9:16 am

Another BRC-specific logistic consideration for vehicles is lighting. Mutant Vehicles need to be "radically illuminated". Generally speaking, using LEDs, that translates to at least 20 amps worth at 12 volts. Probably more. Mine is a lot more. It's hard to sustain hundreds of watts of lighting draw on top of the motor draw without a pretty big battery bank and a lot of stuck-at-camp charging time. That makes gas power or at least an onboard gas generator a whole lot more attractive.
GreyCoyote: "At this rate it wont be long before he is Admiral Fukkit."
Delle: Singularly we may be dysfunctional misfits, but together we're magic.

Autodoctortx
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Re: Directly driving 36v golf cart with 12v genny

Post by Autodoctortx » Wed May 11, 2016 6:57 am

Here is your solution look in eBay

It is a 36volt dc generator we used one last year at burning man it worked like a dream it puts our 70amps dc it is the scariest version of the generator you have. Also it was commissioned from Honda by a telecom company and never used they are selling for about 500 dollars new in the box

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