Using EV (car) batteries to store power on playa

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worldjoe
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Using EV (car) batteries to store power on playa

Post by worldjoe » Mon Nov 27, 2017 5:11 pm

I currently have two 12V 65AH deep cycle batteries. And two 100W panels each with their own charge controller. I'm trying to upgrade my setup to achieve Solar without buying more stuff.

I realized:
I have 18 solar panels on the roof of my house.
I have a plugin electric hybrid car (Ford Fusion Energi) which has a gas engine AND can drive for up to 18 miles on electricity - which means a bank of Lithium Ion batteries in the trunk.

I'm wondering if anyone has used the battery bank in an electric vehicle for off grid storage. I don't know anyway to retrieve power from the battery bank, it doesn't have any obvious outputs.

Storing power from the solar panels to the vehicle is also non obvious. The car came with a 110V AC plug. So perhaps it's as simple as converting the solar energy into AC then using that plug. It looks like the battery is 310.8V, 26AH (Info here: http://www.diyelectriccar.com/forums/sh ... 72058.html )

Joseph Elwell.

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Token
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Re: Using EV (car) batteries to store power on playa

Post by Token » Mon Nov 27, 2017 10:38 pm

There are two batteries in your car;

A small regular 12V lead-acid battery. This is used to crank the ICE and run the instrument cluster, lights and whatnot.

A Lithium based 7-8 KWh driving battery. That is the 300+V monster that runs the motor and wheels.

The standard ICE engine has a generator that charges the Li drive battery when it needs it.

The small regular battery is powered by a DC-DC converter from the Li drive battery.

Phew, that was complicated.

To turn your car into a generator, connect a small inverter (1000W or less) to the 12V battery, put the car in run mode, turn off all the lights, fans, climate control, radio, nav, etc.

Use the inverter.

Your car will start the engine every now and again to charge the main Li drive battery when needed.

Not the most efficient use but works in a crisis situation.

As for charging with solar ... yeah... 200W of solar panels at 15-18V DC to charge a 8000Wh battery running 300V+ ... not really worth the bother. Would take 80 hours of optimal solar charging after all the voltage conversions from 12V DC to 120V AC to 310V DC . . .

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Popeye
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Re: Using EV (car) batteries to store power on playa

Post by Popeye » Tue Nov 28, 2017 12:02 pm

Token: Sounds like that would work fairly well for a bucket cooler, a few led's and some personal music. I don't think you would need a deep cycle battery as the li bat would keep the 12V from dropping to low.
Just thinking here but is the 12V bat small? Say about the size of a 4 wheeler bat? Maybe designed to start the engine and be "refilled" by the li with minimum ampacity of the dc-dc converter? If so increasing the 12V bat size would reduce the number of engine starts.
There aren't any of these where I live and I haven't had a chance to look at one.
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torrey.smith
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Re: Using EV (car) batteries to store power on playa

Post by torrey.smith » Tue Nov 28, 2017 3:01 pm

My campmate stayed in his Prius with the engine off and the AC on quite a bit this year.

A Tesla would be much better :mrgreen:
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Re: Using EV (car) batteries to store power on playa

Post by krly » Tue Nov 28, 2017 3:02 pm

Actually, it is efficient. The last test I saw showed a Prius ,used as a generator with an inverter (as posted above) was more efficient than a Honda 2k generator (gas used per watt).

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Re: Using EV (car) batteries to store power on playa

Post by BBadger » Tue Nov 28, 2017 4:01 pm

You should only use the generator (car or standalone) to do the bulk charging on your battery (up to 80%), where they can provide all the current they can to charge up the battery. After that, the absorption and float charge stages use less and less current, wasting the power provided by the generators.

You can let your solar panels do the remaining 20%, or just don't bother.
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Token
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Re: Using EV (car) batteries to store power on playa

Post by Token » Wed Nov 29, 2017 8:37 am

Or use the built in inverter in the dash ;) it is rather small tho usually 100 to 300 W for cell and laptop use etc.

The generator is efficient.

Charging a 300V+ battery from 18V panels is not efficient if you go dc - ac - dc — i e using the stock 120V ac charging cable. Might not even work if that source is to power the thermal management, which may fire up the A/C to cool the battery during charging.

My Chevy does that when charging in summer.

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Re: Using EV (car) batteries to store power on playa

Post by Token » Wed Nov 29, 2017 8:43 am

Popeye wrote:Token: Sounds like that would work fairly well for a bucket cooler, a few led's and some personal music. I don't think you would need a deep cycle battery as the li bat would keep the 12V from dropping to low.
Just thinking here but is the 12V bat small? Say about the size of a 4 wheeler bat? Maybe designed to start the engine and be "refilled" by the li with minimum ampacity of the dc-dc converter? If so increasing the 12V bat size would reduce the number of engine starts.
There aren't any of these where I live and I haven't had a chance to look at one.
I have a different EV and mine has a typical 35 - 55 sized Pb battery.

The key is the dc-dc converter used in the car — the rated current would need to be discovered in order to size the load correctly.

On a Prius, someone hacked it and found a 100A unit, hence the Prius is good for a 1000W 12V inverter.

Would need to hack the specific Ford to find out before going forward with anything more than the dash inverter.

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Re: Using EV (car) batteries to store power on playa

Post by worldjoe » Thu Nov 30, 2017 2:10 pm

I wasn't planning on driving the Ford Fusion Energi to Burning Man. But that is an option I will consider.

I was kind of hoping I could pull the lithium ion battery out of the vehicle and use it for energy storage to power an Air Conditioner running off of it. And solar to supplement power needs. I found instructions on how to remove the battery, but nothing about how to charge it (other than with the AC charging plug) or how I might connect an inverter directly to it.

I'm starting to like the idea of using the Ford as a giant generator. I will try out connecting an inverter to the 12V battery and see if leaving the car on will allow the 12V to slowly drain the lithium ion battery bank (with occasional engine starts).
Thanks,
Joseph Elwell.

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Re: Using EV (car) batteries to store power on playa

Post by maladroit » Thu Nov 30, 2017 3:00 pm

300 volt battery will kill you. Go get a couple deep cycle batteries and hook them up to your solar panels if you're not bringing the whole car.

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Re: Using EV (car) batteries to store power on playa

Post by Captain Goddammit » Thu Nov 30, 2017 9:39 pm

A Honda generator works GREAT and is a hell of a lot smaller and lighter.
What you’re proposing is gonna be a lot more expensive and a lot less practical.
An inverter large enough to run an A/C will draw hundreds of amps at 12Vdc.
You can’t run it straight off the car’s battery.
And it’ll weigh a whole bunch.

It’s possible but I think it’s got way more negatives than positives. No pun intended...
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Re: Using EV (car) batteries to store power on playa

Post by BBadger » Thu Nov 30, 2017 11:50 pm

That Ford Fusion Energi battery pack only has a 7.6kWh capacity. If your AC unit consumed as little as 500W of power, even with 100% efficient conversion that would only last you about 15 hours. That's about 2 gallons of fuel on a generator in eco mode.

You'd probably be better off just powering a nice array of evap coolers instead if you're going for battery power.
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Re: Using EV (car) batteries to store power on playa

Post by maladroit » Sat Dec 02, 2017 10:17 pm

That's actually a pretty impressive runtime for battery-operated AC. I can understand the attractiveness of the idea, it's just dangerous and won't work.

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Re: Using EV (car) batteries to store power on playa

Post by BBadger » Sun Dec 03, 2017 3:20 am

Yeah, one 12V, 125AH lead acid battery only yields 3 hours. So it's about five of those.
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Re: Using EV (car) batteries to store power on playa

Post by Jackass » Sun Dec 03, 2017 4:11 pm

Don't forget, F-ing around with an electric vehicle's battery system when you're not exactly sure of what you are doing, may possibly lead to a lethal dose of juice. Don't fuck around, it'll get really hot really quick...

*As mentioned above
Sooner or later, it will get real strange...

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Re: Using EV (car) batteries to store power on playa

Post by BBadger » Sun Dec 03, 2017 6:05 pm

Especially those Lithium-Ion batteries. They might even explode if abused.
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Re: Using EV (car) batteries to store power on playa

Post by maladroit » Mon Dec 04, 2017 8:40 pm

Would you say pulling the battery out of the car, dragging it out to a hot desert full of corrosive dust, and running heavy loads after being wired up somehow by a neophyte counts as abuse?

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Re: Using EV (car) batteries to store power on playa

Post by Captain Goddammit » Tue Dec 05, 2017 1:40 am

Oh what the hell its Burning Man. It’s called dangerous art. That’s a good thing, right?
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Re: Using EV (car) batteries to store power on playa

Post by worldjoe » Tue Dec 05, 2017 6:09 pm

Captain Goddammit wrote:A Honda generator works GREAT and is a hell of a lot smaller and lighter.
What you’re proposing is gonna be a lot more expensive and a lot less practical.
Not solving for practical. Not sure how free (I already own the car and solar panels) is more expensive than buying a generator.
BBadger wrote:You'd probably be better off just powering a nice array of evap coolers instead if you're going for battery power.
I built the Figjam bucket cooler, as did a friend of mine. At near 0 humidity neither of us could get temperatures to drop more than 10 to 15 degrees and never could I get an enclosed space to drop at all - it was only useful as a spot cooler for me. I've gone back and forth trying to replicate Figjam's design, suffice to say it is not well documented which is why so many people are chastised for not "sticking to the original design". In particular, the Home Depot buckets are not the same dimensions in every region. Even the most well regarded swamp coolers on Amazon don't get the 30 degree drops that are shown in the chart people like to share. YMMV
maladroit wrote:300 volt battery will kill you. Go get a couple deep cycle batteries and hook them up to your solar panels if you're not bringing the whole car.
First post mentioned I already have a couple of deep cycle batteries.

Sparr showed that solar AC can work on playa. I'm perfectly happy to buy a honda generator, but if I can get solar AC working with the equipment I already have I'd prefer that. I had planned on bringing 2 vehicles to the playa, so bringing the Ford 15 hours would probably be more than enough. I'm not looking for 8 hour a day AC.

I love the idea of using the Ford, in idle, as a generator. Apparently people have been doing this with their Prius for a decade, they cap out at 1000Watts. Not sure how much wattage I can get out of my Ford. I found a document that states, "The 2013 Ford CMAX Energi utilizes an air-cooled standalone 2kW DC/DC Converter, as shown in Figure 4-15 below. The DC/DC converter is rated at about 145A at an output voltage of 14V. " I've read the Prius DC Converter is rated for 100A at 12V.

A 5000btu window AC draws 4Amps and only needs 500Watts. I will try this setup at home, when it gets hotter. It's freezing today!
Joseph Elwell.

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Token
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Re: Using EV (car) batteries to store power on playa

Post by Token » Tue Dec 05, 2017 9:07 pm

"The 2013 Ford CMAX Energi utilizes an air-cooled standalone 2kW DC/DC Converter
There you have it!

Look for a quality 12V inverter that will fit under the 2KW and 145A then drive a nice sine wave. Connect using thick cables capable of running the high current to the Pb battery.

Check the specs on any A/C unit for the locked rotor current so you can size the startup power surge and you are set.

I’d use the solar panels and deep cycle Pb setup for other stuff and not try to charge the Li battery.

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Re: Using EV (car) batteries to store power on playa

Post by Zubeneschamali » Wed Dec 06, 2017 12:32 pm

Bought my last EU2000 off a CL post. It was still wrapped in plastic in the box - never had gas in it. Asking $800 sold $550.

Tell me anywhere you can get that bang for the buck and have bulletproof power for 9 days.

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Re: Using EV (car) batteries to store power on playa

Post by Captain Goddammit » Thu Dec 07, 2017 6:26 am

Your setup won’t be free because there are still expensive parts between the car and some solar panels and being able to run an air conditioner.

I bring a 5000btu A/C as an emergency spare. I’ve tried it on playa, in a relatively small RV (truck camper) and it’s inadequate when it’s really hot. That’s why no campers ever come with such weak units.
Depending on what you want to cool, I’d strongly recommend a bigger unit. The low power draw of the little ones is attractive while designing the power, but, nuthin’ in, nuthin’ out.

Remember that 4 amp number is at 120VAC, it’ll be 40 amps at 12VAC.
And it’ll take a lot more than that to start the thing.
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Re: Using EV (car) batteries to store power on playa

Post by Token » Thu Dec 07, 2017 9:03 am

Or you can build a monkey hut for your EV, recline the seat and run the A/C already built into the car for naps and whatnot.

Now that would be the cheapest route.

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Re: Using EV (car) batteries to store power on playa

Post by worldjoe » Thu Dec 07, 2017 1:54 pm

Captain Goddammit wrote: I bring a 5000btu A/C as an emergency spare. I’ve tried it on playa, in a relatively small RV (truck camper) and it’s inadequate when it’s really hot. That’s why no campers ever come with such weak units.
Depending on what you want to cool, I’d strongly recommend a bigger unit. The low power draw of the little ones is attractive while designing the power, but, nuthin’ in, nuthin’ out.

Remember that 4 amp number is at 120VAC, it’ll be 40 amps at 12VAC.
And it’ll take a lot more than that to start the thing.
Thanks for this, you are probably right, I will need to test out an A/C in the desert this summer. To make sure I have adequate BTU for the space.
Token wrote:Or you can build a monkey hut for your EV, recline the seat and run the A/C already built into the car for naps and whatnot.
Now we are getting into the heart of the problem - which is really cooling. I have built a Monkey Hut for my poptop van. Which is where I'll be sleeping and trying to run A/C too. The A/C unit in the van is insufficient even when driving. When idle, the A/C is extremely weak. I found a way to increase my idle, which will give the A/C more power, but given that it is weak even when driving, I think it is underpowered for the space - especially with the top popped up which nearly doubles the space it would need to cool.

The A/C in the EV is sufficient though, even when idling. I'm used to camping in extreme weather, so this is all for fun/backup. I may very well end up with a generator just for simplicity.
Thanks,
Joseph Elwell.

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Jas
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Re: Using EV (car) batteries to store power on playa

Post by Jas » Fri Apr 06, 2018 5:06 pm

worldjoe wrote:I currently have two 12V 65AH deep cycle batteries. And two 100W panels each with their own charge controller. I'm trying to upgrade my setup to achieve Solar without buying more stuff.
Side question: I'm thinking of establishing a similar setup-- what are you running off of it currently? My goal is a mini fridge (first priority) and possibly a swamp cooler (second priority).

So I don't crush myself financially, I'd likely start with just one 100W panel, and two 12v deep cycle batteries and rotate them out (depending on what I'm running)

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Re: Using EV (car) batteries to store power on playa

Post by worldjoe » Thu May 03, 2018 12:30 am

Jas wrote:
worldjoe wrote:I currently have two 12V 65AH deep cycle batteries. And two 100W panels each with their own charge controller. I'm trying to upgrade my setup to achieve Solar without buying more stuff.
Side question: I'm thinking of establishing a similar setup-- what are you running off of it currently? My goal is a mini fridge (first priority) and possibly a swamp cooler (second priority).

So I don't crush myself financially, I'd likely start with just one 100W panel, and two 12v deep cycle batteries and rotate them out (depending on what I'm running)
I've never been to the burn. But I an power my engel fridge and the swamp cooler indefinitely with just the one battery and 100W panel - at least in the San Diego deserts.
Joseph Elwell.

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Re: Using EV (car) batteries to store power on playa

Post by Jas » Sun May 06, 2018 12:53 pm

worldjoe how do you like your engel? Was thinking of getting one, but to use in more of a fridge capacity... I'd rather not jerry rig the thermostat like I've heard can be done (I've read through how to do so, seems complicated), but rather keep my perishable foods at the top of the freezer in hopes they don't freeze as quickly.

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