Yippee! Lipo saved us on the way back home

[supi7]

We pulled into a rest area on the way back, had to park in the truck zone with the trailer. I left the parking lights on so the trucks pulling in could see us, and tilted the seat back to get some z's.

After 5 hours of nap time, the battery in the van was dead; with no jumper cables and anyone around awake to help we were stuck.

I remembered one of our customers told me a story last year about jumping his VW with our 4S lipo, so I pulled out a 6S pack out of my Twist 60, cut off the Ultra plug and jump started that bad boy. Whoo what a relief.

So if you are ever at the field and you drain your car battery with a charger, let lipo return a favor.

Dan
TrueRC

[Yellowspider]

LOL, Done that several times. Even back in the days of Nicads I did it once or twice. There are actually products out there that you can keep in the glove box. It does the same thing through your lighter socket. But now since I fly a whole bunch more. I put a regular car battery in the bed of my truck wired to the alternator with a on off switch. I turn it on the day before flying to charge up then use this to recharge my batteries for the planes. Leave it on for another day or so and then turn the switch off. Left my lights on one time over night. No problem just turned the switch and varoooom just like a jump.
Now got a question for ya. Remember that 456MB airliner I bought from you at NEAT? Do you still have the motors? I need to know the diamiter.
Thanks
Yellowspider
Dave R.

[antslake]

Careful with applying too much voltage to your cars electrical system. You can easily fry the components. I wouldn't go higher than 4s.

[Tommy D]

Originally Posted by Yellowspider

It does the same thing through your lighter socket.

Back in the 80's I purchased such a tool to keep the ESC/SBEC/Whatever charged if you had to remove the vehicles battery. It had a huge warning decal regarding setting off the cars air bag!

Tommy D

[Yellowspider]

Originally Posted by antslake

Careful with applying too much voltage to your cars electrical system. You can easily fry the components. I wouldn't go higher than 4s.

I am an auto tech by trade since 1976. 12 volts 24 or 36 volts would never hurt the starting system on the car. When you jump a car through the battery or the lighter socket it does not go through the computer. Now if you applied more than 12 volts through the connector under the dash for the computer (used for testing the computer and running emission tests) you could fry something. The computer in all cars I know anyway only run on 5 volt referance. We also have a little box with a motorcycle battery inside that we plug into this connector when changing a battery in a car. This is called Keep alive. In most late model cars you have to keep the system live. If you do not. You will lose your radio programing and have to reset the hidden code to access the radio again and on some cars if theyt are not kept alive they will not restart once power has been taken away and restored.
I never in my life heard of anything that could blow off and airbag indirectly. (through the lighter socket) If you apply any voltage directly to the airbag it will blow. We have set off airbags out of junk cars just for kicks from a 9 volt battery and two 10 foot pieces of wire. Rumor has it they will blow on as little as 1.5 volts. WARNING if youever try this stay away as the bag jump like 6 feet in the air. (we did it out of the car in the parking lot of course)
Yellowspider

[Tom Hunt]

I have jumped many a car/truck/van on a 3s-3700 25C lipo. Most times, a "healthy" dead battery (pun intended) just needs a little extra "oomf" to get it to start an engine.

Tom

[Tram]

Sign me up as one of the guys who "done it too."

[gravityKills]

me to, 3s 2200 mAh for a minute or two is enough. There is no risk of overvoltage, since a LiPo tops at 12.6 V, but a 12s Pb pack during charging can go up to 14 V or so.

I wouldn't start the car with the LiPo connected, though (risk of overcurrent for the LiPo)

[feda]

I did that too with a 3S2200mAh 20C pack. When I tried it, I didn't know the battery was capable of starting my car. It was a nice surprise to me.

[gravityKills]

Originally Posted by feda

I did that too with a 3S2200mAh 20C pack. When I tried it, I didn't know the battery was capable of starting my car. It was a nice surprise to me.

Yes, but as said: Don't start while the LiPo is connected.
An average car battery (75 Ah) is rated at 600! amperes. For a 2200 20C pack for example, it's only 44 amps, give or take some. There is risk to damage the Lipo.
But it's still good to bring an empty car battery back to 12 volts.

[antslake]

Originally Posted by Yellowspider

I am an auto tech by trade since 1976. 12 volts 24 or 36 volts would never hurt the starting system on the car. When you jump a car through the battery or the lighter socket it does not go through the computer. Now if you applied more than 12 volts through the connector under the dash for the computer (used for testing the computer and running emission tests) you could fry something. The computer in all cars I know anyway only run on 5 volt referance. We also have a little box with a motorcycle battery inside that we plug into this connector when changing a battery in a car. This is called Keep alive. In most late model cars you have to keep the system live. If you do not. You will lose your radio programing and have to reset the hidden code to access the radio again and on some cars if theyt are not kept alive they will not restart once power has been taken away and restored.
I never in my life heard of anything that could blow off and airbag indirectly. (through the lighter socket) If you apply any voltage directly to the airbag it will blow. We have set off airbags out of junk cars just for kicks from a 9 volt battery and two 10 foot pieces of wire. Rumor has it they will blow on as little as 1.5 volts. WARNING if youever try this stay away as the bag jump like 6 feet in the air. (we did it out of the car in the parking lot of course)
Yellowspider

Well I can't agree with you. If the battery of the car has a problem with it, and for some reason doesn't suppress the voltage going to the computer (and all the electrical components), several parts in the electrical system will fry, possibly all of them. It happened on my 97 maxima, and on my Dad's 95 mariner 115hp outboard, also on my 81 Yamaha motorcycle. Over a thousand dollars later it is a lesson learned. I am a tech too, and a ham radio operator, I know a few things about electricity.

In the old days you could lift the cable off the battery and not worry, but now if you do that, it will fry, that is because the battery acts as a voltage regulator. Even hooking up the negative first when jumping can cause a short. You are supposed to hook up the negative last when jumping a car. You shouldn't even hook the negative cable to the battery on the dead car, you should hook it to ground.

http://www.carbuyingtips.com/jumpstart.htm

Formerly, especially in cold climates, some jump starts were done with two series-connected batteries to provide 24 volts to a 12 volt starting motor. However, such overvoltage can cause severe and expensive damage to the electronic systems on modern automobiles and should never be used.

http://en.wikipedia.org/wiki/Jump_start_%28vehicle%29

Voltage spikes are bad....

[gravityKills]

Originally Posted by antslake

.. Even hooking up the negative first when jumping can cause a short. You are supposed to hook up the negative last when jumping a car.

This is why:

If you slip and accidentally touch "something" with the cable you're holding, chances are 99 % that you'll touch ground.

It only matters for the 2nd cable - you can't have any current with a single cable.

Option A)
Connect ground first, then connect plus. While doing so
*slip* and accidentally touch ground with the wire you're holding
result: Short circuit, sparks, burnt fingers etc

Option B:
Connect plus first, then connect ground. While doing so
*slip* and touch ground
Result: Nothing

Option B is safer, that's the only reason. The electrons don't really care where you interrupt or close the circuit.

[Shpook]

Sorry to keep the thread off-topic, but anything over 15V can do some severe damage to the ECM/BCM/IPC and any other computerized components. Most automotive computers use both 12V and 5V, which is internally regulated by the ECM. When you have an over voltage situation, these regulators overheat and let out the magic smoke. GM's Quad-Driver system is a very popular example. Even if the computer doesn't go south, high and low voltages cause the 5V and 12V rails to sag or rise, throwing off readings from any sensors using the 5V line as a reference.

And airbags need power directly to both wires from the same source. You typically can't blow an airbag by shorting a wire...the airbag connectors have shorting bars to prevent this.

[Yellowspider]

You guys need to go back to school. The only way you would ever burn or shock yourself is is to short the battery. (lay a wrench from + to -. We have kids come from the local auto training center and they all think if they touch + and - they will get a shock.
If your frying cars boats motorcycles while jumping you my friend should not be fixing cars. That is just scarey.
I have a 2000 dodge and have jumped it several times with 4s and never fried anything. I have also jumped a friend Subaru with 4s and the only thing that has happened is the wires get hot on the lipo battery. These are not wasted batteries but batteries that have gone dead while flying and recharging. Just a quick tap of the key and they always start.
Yellowspider

[gravityKills]

Originally Posted by Yellowspider

...
I have a 2000 dodge and have jumped it several times with 4s and never fried anything.

if it's about american cars, remember that most of those are still running on steam power. Don't draw any conclusions about a modern car that contains semiconductor technology

PS
if someone finds out "the hard way" that your advice wasn't that great, the lesson will be very very expensive.