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Jump starting with LiFePO4

hardtop

hardtop

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Sep 13, 2020
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Las Vegas, NV
I was shopping for a jump starter battery for my LR4 so that if the starter battery died, I would have a way out. But it dawned on me that I could physically connect my DIY LiFePO4 to the starter battery via custom Anderson jumper cables.

I don't want to break my battery pack and I'm not very technical in this area. If my starter battery died and I tried to jump it with the DIY pack, would that cause a problem and would it supply the juice? The cells are 4x EVE LF304 grade A with a JK 200A BMS and 12V.

9b0bee3.jpg
 
Should work if your jumper cables are long enough to keep the current below the 200 amp BMS overcurrent shut down. You don’t need to supply the cold cranking amps, you just need to put a few amp hours into your starter battery and let it pick up the load.
 
It sounds like I may have a problem, 200 AMP doesn't sound like much power either. The jump starters do 400 AMP but they advertise like 1,500 peak amps. These are my cables, not very long by design.

HDNN0KG.jpg
 
I could use 100' of 12AWG cord for my generator too. I already have 75', then I could stash my generator 175' away and won't hear much of it from that distance lol.
 
Use a 5s, give her the beans, send the starter into high speed!
 
hardtop said:
I just want to start it and not break it lol.
Click to expand...
Funny thing about that. When I was a teenager we had a little 80's Diesel Nissan pickup. The glow plug controller kept burning out, then killing glow plugs. It had low compression too.
My dad got fed up, and put a second battery and series/parallel relay from a Galion motor grader in. The starter would run on 24v.
It worked for years that way.

One summer in the middle of wheat harvest, the clutch throwout bearing went out. That starter had enough juice to start the truck when it was warm, in 1st gear, with a 250 gallon fuel trailer behind it. :eek:
 
Back in the day a 12v car can really get a 6v spinning, but modern day electronics I wouldn’t push over 16v.
 
Since the BMS has a current limit of 200A and the starter would draw more then that (550 CCA), it seemed like I couldn't use the pack. But I'm wondering now if I bypass the BMS and tried to jump start, would I damage the Lifepo4 battery?
 
Me, I would bypass the BMS (proceed at your own risk.)
I have a tiny LiFePO4 jumpstarter from Harbor Freight, rated for 400A. That's probably 20C.

For your 304 Ah, about 1.33C

I wouldn't be worried.

There's a thread here where somebody experimented quite a bit, I think to start a tractor.
Here you go:

diysolarforum.com

Experiments with $40 'starter' lifepo4 for engine cranking

Recently I needed to replace an FLA battery in my little 600cc diesel Kubota tractor. I could have done the ~$34 thing and just bought another U1 riding mower battery from Walmart, but i wanted to turn it into an experiment instead. When i looked at lifepo4 options to use as an engine-cranking...
diysolarforum.com diysolarforum.com

Assumption is the abuse shortens life, but likely good for hundreds of starts.
 
How about one of these it's not cheep but it's blue 💙 and color coordination half the game.
Not the devices intended purpose but puts out up to 15 volts and at a solid 30a should raise SOC of the FLA starting batt. Enough to get you rolling in 10-15 min. Just add some fancy quick connector plugs an on board interface and some custom warning labels. So many possibilities.
And it's Blue! 🥰
71cS0wlOu2L._AC_SL1500_.jpg
Sorry about got distracted by a phone call
 
Last edited:
Bananaman321 said:
How about one of these it's not cheep but it's blue 💙 and color coordination half the game.
Not the devices intended purpose but puts out up to 15 volts and at a solid 30a should raise SOC of the FLA starting batt. Enough to get you rolling in 10-15 min. Just add some fancy quick connector plugs an on board interface and some custom warning labels. So many possibilities.
And it's Blue! 🥰
Click to expand...
One of what?
 
hardtop said:
I was shopping for a jump starter battery for my LR4 so that if the starter battery died, I would have a way out. But it dawned on me that I could physically connect my DIY LiFePO4 to the starter battery via custom Anderson jumper cables.

I don't want to break my battery pack and I'm not very technical in this area. If my starter battery died and I tried to jump it with the DIY pack, would that cause a problem and would it supply the juice? The cells are 4x EVE LF304 grade A with a JK 200A BMS and 12V.
Click to expand...
Back in the day, this would not have been an issue. If you had a stick shift, you could always push start the car with a friend. 😁 😁
 
Supervstech said:
Heh... little known secret, mercedes autoatics can be push started...
Click to expand...
You can push start nearly any old automatic if you are on tall enough of a hill.... you have to sping the torque converter at something like 30mph to get enough power to the motor
 
robbob2112 said:
You can push start nearly any old automatic if you are on tall enough of a hill.... you have to sping the torque converter at something like 30mph to get enough power to the motor
Click to expand...
Not really.
Most manufacturers omit the rear pump, so no way to get fluid pressure to spin up the TC.
OLD fords could, some mopar, and mercedes autos...
But yeah, need a HILL to get enough speed to spin it up to start pressure.
 
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