Can I Jump Start A Car?

[Cold-E-Commuter]

Just courious if any has tried to jump start a car with their e-bike. I know there are a lot of great minds here and wondered what the math might entail to do so. My set up is a Ping 48V15Ah battery and I am running a DC-DC convertor for a headlight and wonder if it would be possible to pull from this to start a car.
http://www.thunderstruck-ev.com/index.php?dispatch=products.view&product_id=81
I know in the RC world than people charge batteries from their car. Can we give the love back when we have drained their batteries?

 

[vanilla ice]

I've jumped my car from a single lipo pack.. With the ping/DCDC you could slowly charge your car's starter bat back up to 12v if its really low. That may or may not be enough depending on the car and condition of the starter bat.

 

[Doctorbass]

I had no prob with only 4 A123 cells ( 300grams total ) on my integra at -20 celsius!

Here is the proof:

[youtube]qcvmvrmTMMk[/youtube]

Doc

 

[Cold-E-Commuter]

DocBass, I have seen this video, very cool. I was wondering more about pulling the 12V from the DC/DC convertor and how long it might take. It has a limit of 10A output. This would be the only way I could do so off the Ping pack, thru the convertor.

 

[Cold-E-Commuter]

Actually, I guess I should have named this "Could I Jump Start A Car". I am in process of a rewire of my entire bike with a new battery box and was wondering if it would be possible so that I can wire things in the proper way. The off chance that this might be needed has happened 2 times but I have not done so because I do not know how hard my batteries would be hit. I have been using SLA's up to about a week ago and now have the Ping. I know the C rate needed to jump a car from the DC-DC convertor (15Ah Ping vs 10Ah convertor) should in theroy not hurt the battery. The main question is time frame. I am guessing that it depends on the car more than my setup.

 

[dogman dan]

Put a 20 amp fuse between the DC converter and the battery, and you can't pull more than the battery could handle. But to my dogbrain, isn't 10 amps of 12v pretty small compared to the 20 amps of 48v your controller puts out? So it wouldn't be a problem, the converter will only put out so much and no more.

From my experience with a 6 amp charger, most cars would start after 30 min on that DC converters 10 amps of charging. A full charge would take longer, but 30 min of 10 amps will usually warm up a battery some, and get the electrons flowing. In hot weather though, it might not work as fast. But often in cool weather, just a short charge warms up the battery just enough to crank the car.

If you put a couple extra leads on your batttery, you could pull 12v straight from 3s ping, and start a car right up. But it would unbalace the battery pretty bad. You'd then need a 12v charger to bring those cells back up.

A jump pack, or lawnmower pack is the best use I could think of for the remains of a Vpower or ping pack gone bad.

 

[vanilla ice]

My experience matches with DM.. maybe half an hour to an hour charge will do it. It really depends on the condition of your starter battery, more time if its hammered. Or its really far gone, you could charge it all week and it wouldn't help! Keep in mind a real charger puts out like 14 volts, not 12.

 

[chroot]

You will need lot ampere to meet your vehicle's requirement normal start motor. Like my Jeep will need
minimum 650 ampere cold start.

 

[tostino]

Not completely related, but I used my Meanwell powersupply to jumpstart my car. It's not even a 12v version (configured for 29v), but since it's cc/cv, it worked just fine.

 

[tostino]

Not completely related, but I used my Meanwell powersupply to jumpstart my car. It's not even a 12v version (configured for 29v), but since it's cc/cv, it worked just fine.

 

[dogman dan]

Some confusion I guess, between jumping a weak battery, and starting the car on nothing but the lifepo4.

For sure, ping cells would get pretty stressed starting a car by themselves. But attached to a discharged but still relatively good lead battery, the ping cells would only need to recharge the battery some, not provide all 650 amps. If the lead battery was dead enough, you might have an amp surge that trips the bms. If you tapped the pack bypassing the bms, something to limit amps to 20 would be best for a ping cell. Btw, if your jeep would fail to start with a 450 cca battery, you either have something wrong with your engine, or a really BIG one.

And finally, 4s lifepo4 would be about 14 volts, not 12.

 

[liveforphysics]

I started my Civic with a 2.2Ah 3S LiPo pack that slips into your pocket like a pack of gum. At a later point I ended up having one of the tabs on that pack vaporize while trying to show a buddy it could start his car (supra). lol

If you've got a DC/DC on your bike outputting 14-15vdc, you don't need to start from the bike (starting from a DC/DC would be a bad idea). Just leave it on your battery for a few minutes to charge the battery, then disconnect the power and start the car.

 

[dogman dan]

Good advice. This thread got me thinking, A 3s 5 ah lipo and a cigarette lighter adapter would do the trick. Or maybe just some alligator clips. Hook to the battery, wait 30 min, remove and start the car. Could be a handy thing in the box with the air pump and tool kit.

What would be a good way to limit the amps flowing into the battery, so you don't vaporize a tab? Just a resistor? 20 amp household breaker?

 

[texaspyro]

If you are going to use it to charge a battery (vs start the car) you can use a resistor or lamp to limit the current.

I now carry 4S A123 packs for the job... wired with 10 ga wire... no vaporized tabs, less worry about fireworks. My packs have Deans connectors and I have a Deans to battery clip cable. I am using a 1P config. These people will build the pack with 10 ga for you at a reasonable price. They have 2P or will build what you want. Also forum member cell_man builds A123 packs for cheap.

http://cgi.ebay.com/4S1P-13-2V2300mah-A123-original-Battery-RC-Battery-/190444906119?pt=US_Batteries&hash=item2c5766a687#ht_4049wt_752

One thing you need to consider is the self-discharge of lithium cells (around 5% per month). You can just leave the pack sitting in the trunk for a couple of years before you need to use it. You need to regulalrly top off the charge. I plan on building the thing into a small box with a buck-boost charger circuit/cell monitor. It would be interesting to see if you could use a your weak battery to charge the pack then used the increased current ability of the A123/LiPO cells to start the car.

 

[Cold-E-Commuter]

Nice to see this post "got some people thinking." I assumed that there would be many people that have already tested this and had a tried and true way to use their bike batts to start cars. I might have to try pulling from the DC/DC convertor soon as my car has not been started in quite some time. I will take the advise and hook it up for a while and see what happens but not start the car with it hooked up. I have wired the DC/DC convertor inline on the bike after the shunt for the CA so I should be able to monitor the output. I decided to wire it this way so that I can measure total usage of the bike, controller and convertor. Otherwise I could have run the battery out by not knowing the usage of the convertor. Any thoughts on that one?

 

[dogman dan]

Makes sense to me, to measure all the output of the bike. You need to know that the motor, and whatever runs on the converter together don't exeed the continuos amps you want to pull from your ping. So you might want to ease off the throttle if your lights use a lot.

 

[Cold-E-Commuter]

Well, I still don't know about jump starting a car, but a can run a living room light. There was a power outage here the other night that lasted for a bit over an hour. I must admit that I have plenty of flashlights and candles for just such an occurance. But the thought was there! Can I run my TV off my bike? Can't miss season opener of House! With the bike having a 36-72V input to 12V output convertor, and also owning a 12V to 120V invertor (the kind you plug into a power output (cigarette lighter) from your car), I decided to find out. In the candle light night I added a connector to the invertor that can connect to the convertor. Once this was done, I tested it on a 3-way light. 50-100-150 watt bulb. No problem on the 50 watt. However, the breaker on the invertor tripped when switching to 100W position. I guess this can be attributed to the fact the convertor has a max 10A output (at 12V) thus resulting in a max of 120W. I don't know the power loss thru all of the connections, but apparenly it is greater than 20W. Then testing the TV and the answer is no. At least not with the current invertor and convertor set-up. Once power was back on I tested the TV with my Kill-O-Watt and it requires 86W to run but has a 165W peak at start up. Needless to say, I missed my show, but I did find out I can keep the light on if needed. Enjoy.

 

[magudaman]

From my experience it doesn't really take the Cold Cranking amp rating to turn a car over. When I've checked it out I've never seen more than 200 amps on my vehicles. Just FYI. There is also usually a trim voltage on DC-DC converters that could let you take a 12v up to say 13.8v, would be better for charging.

If I am not mistake mine was a green gallaxy one two with a slightly different design but same specs, no voltage adjust on those babies. Here was my review: http://visforvoltage.org/forum-topic/accessories/758-dc-dc-converter-20-60v-12v-10a-out-review