Car starter (dead battery) Lithium battery power bank

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Lynx_Arc

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I think they used to make a gadget that plugs into a cigarette lighter to keep memory alive during a battery swap but with some of today's cars shutting off the lighter socket for some reason it may not work without some work.
 

turbodog

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I have this one on order. Looks like security triangular screws holding it together.

1634252266715.png
 

BVH

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I use one of these. Just a raw, 4S LiFeP04 chemistry RC hobby battery to jump start V-8's with no issues at all. The extra Volt makes a huge difference in actual starter motor speed. No circuitry, no caps, nothing but the raw battery.


Here's a link to an earlier post on this: https://www.candlepowerforums.com/threads/li-ion-to-jump-start-a-car.117527/post-5170941


The thing about LPF, is that there is practically no self discharge so you can leave them topped up without damaging the cells. No so true for lithium Ion or Polymer. Number of charge cycles is at least twice, up to 4 times as many before capacity loss.

A few years ago, I tried some microstart brand units. After a year, they swelled so I opened them up. They would add the cells In-Series AND in-Parallel and give a completely false battery capacity figure.
 
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turbodog

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Device just came in. When connected to battery it shows the car's voltage level.

Press on/off to turn on and begin charging. Takes around 2-5 mins depending on voltage level.

Can put in bypass mode, which is basically a forced 'on' setting for jumping w/o car's battery present. It's also useful for diesel glow plugs.

They DO warn against using bypass, cranking, and then removing device... saying it could fry your ECU/etc.

Overall a good looking unit.
 

Lawman VII XIV

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I've got a Li-Ion jumppack "rated" for small diesel and small 8cyl ICEs. My battery is in good shape, but I incurred a drain over a few days and when it was time to start the solenoid clicked a couple of time and stopped.

The jumpstarter was connected to the terminals, waited for 30seconds to soak in some wonderfulness, and the car started right up. The starter never spun so fest – ever. Later the battery went on a charger/tender.

Everytime a lead-acid battery goes dead, it looses some capacity. And if not maintained, it's harder for a jumpstarter to do it's magic. I had no recommendation to go on so I chose one that had decent reviews at Amazon and was said to start a car with a bigger engine than mine and pressed BUY.

It's pretty much a roll of the dice. Amazon has had plenty of fake reviews so I just bought something that seem good and looked good promising myself I'd return it if it didn't work. It
did.

Taking care of the battery is half the battle, and cleaning the top of the battery and making sure the terminals and connectors are clean and tight goes a long way towards good battery health, as does not killing it.
 

lumen aeternum

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I wonder if you could make a dongle that would take several 18V power tool batteries and reduce it to 14v. Or the larger 40v power packs. Probably inefficient, but the batteries are always available around the house.

IIRC a Chinese 40v that fits Ryobi was about $60. Buy a couple more & keep them in the trunk, swapped in the usual rotation for your power tools.
 

Lynx_Arc

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I wonder if you could make a dongle that would take several 18V power tool batteries and reduce it to 14v. Or the larger 40v power packs. Probably inefficient, but the batteries are always available around the house.

IIRC a Chinese 40v that fits Ryobi was about $60. Buy a couple more & keep them in the trunk, swapped in the usual rotation for your power tools.

I don't blindly recommend this but is interesting for sure.
 

lumen aeternum

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I don't blindly recommend this but is interesting for sure.
Just using the battery at 18v? How many amps can that battery push out? What was the ambient temperature?
45 deg, 4 cyl car.
Wonder if those battery packs have a load detection circuit that pushes like a battery charger into the car battery?
Say he's done it 25 times without ruining the battery pack.
 
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lumen aeternum

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Worse: using a wall wart on a long extension cord as a charger. "Its warm, so I know its hooked up."
Hey, he's got a Crown Vic Police Interceptor.
Fittingly when he starts it up, there are sirens in the background.
 

Lynx_Arc

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Just using the battery at 18v? How many amps can that battery push out? What was the ambient temperature?
45 deg, 4 cyl car.
Wonder if those battery packs have a load detection circuit that pushes like a battery charger into the car battery?
Say he's done it 25 times without ruining the battery pack.
I'm really not sure how many amps but a 5A dewalt battery pack likely has 2500-2600mah 18650s in it that may be able to put out 10-20A and in 2 stacks of parallel sets of 5 batteries that means from 20-40A or so. If you couple a possible 40A charging and starting rate and a car battery that isn't totally 100% dead it makes sense to me as I have a car charger with a 50A starting boost setting that I've used several times over the years to help start a completely dead battery (no solenoid noise at all) but it took a lot longer to start the car with a large V6 vs that example with a 4 cylinder which takes considerably less current most likely.

Basically speaking starting a car with a dead battery right away can take the full starter current almost totally from the additional power source vs charging the car battery up so that the load of the starter is shared by the somewhat charged car battery and the jump starter. If the tool battery can do 50-60A or even a little more that would make things a little easier. The fact you hear the solenoid being energized for a short time attests the car battery does have some power to it such that charging it at a decently high current rate may be enough to suffice.
 

lumen aeternum

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How do you figure Peak Amps from the Ah rating of the batteries?
I see a Harbor Freight item with 12Ah claiming 450 peak amps, $90.
So in freezing cold weather, 450 peak reduces to ???
And a 6 cyl car probably needs ???

The Chinese knockoff 36V (40V max) 6Ah Ryobi batteries seem to be lasting; at $60 each I wonder if two in parallel might be sufficient. What exactly happens when you use a 36V source to jump a 14.5V battery? Does a 2020s era car have circuitry to avoid passing over-voltage to the electronics?

Or when you reduce the 36V to 12V? Golf cart converters seem to be current limited to 10A output.
 

lumen aeternum

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Another issue is making sure the charger in your trunk stays charged. Whether its Li ion or SLA, you want to connect it to a smart charger, connected to car power that is "on when running." Battery Tender makes lead acid units - but they do a cycle which might be messed up with short running times. I don't know of any smart Li ion chargers that could handle a battery pack, other than the Ryobit etc tool pack chargers (and nowadays only the expensive add-on ones, Ryobi at least seems to be packaging a non-smart charger with its battery sets & tools).
 

knucklegary

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The 1500A NOCO says 35 watt hours, so 35/12v = 2.92 A hrs. That's not many batteries in there.
It's hard to get a straight answer from Noco. So, to make easy on the messenger, i asked what is total battery mAh for 2500a Boost X.. Replied 5000.. a single 21700 wtf? I ordered a triangular shape security screw driver so I can take unit apart
 

Poppy

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A few things:
I bought a jumpstarter LiIon battery pack about a year ago. November 2020. I bought it to start my lawnmower, rather than to buy a replacement battery for the mower in the beginning of the winter. I had read that those small mower batteries don't handle winter cold very well and will only last a year or two.

During covid lockdown, my car sat for 10 weeks, and the battery was dead. It didn't hold a charge, and as is my policy, if the battery is more than 3 years old, and the first time it is slow cranking when it gets cold out, I replace it.

There used to be three diodes in an alternator. Now I think there are six. At any rate if one fails, it may cause a continual drain on your battery. My alternator tested good when I tested it, but a few days later my battery was dead despite the fact that I replaced it. I retested the alternator and it was bad. It is possible that my old battery was still OK and the issue was a failed diode in the alternator.

All this to say... I wouldn't try to use 40 volts to jump start my car. I don't know what the tolerance is for the alternator diodes, but why take a chance? If you back feed them too much voltage they may burn out. If out in the woods, I might take a chance by disconnecting the car battery, and use the tool battery to charge it directly. Feel it and if it is getting hot, stop, and let it cool, then continue. At least you won't damage the electronics, including the alternator.
 

Poppy

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It's hard to get a straight answer from Noco. So, to make easy on the messenger, i asked what is total battery mAh for 2500a Boost X.. Replied 5000.. a single 21700 wtf? I ordered a triangular shape security screw driver so I can take unit apart
I took my LiIon jumpstarter apart, because that's what I do! I also was very much surprised that the battery was only something like 3500 mah. I don't recall the voltage. But it was one of those flat cells, not a few 18650's in series or parallel. I guess it is of a chemistry that allows it to put out high amperage, and drain itself quickly.

If I get bored, I'll pull mine apart again.

Edit: Please see my post below... because this one is wrong.
The battery is more like...
12V 40C 7500 mAh LiPo battery
 
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Poppy

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I took my Type S 12V Jump Starter apart.
It also claims to be a 8000 mAh portable power bank.

I opened it up to find...
niTWcZA2E7_zcVY6cR0EnzCJu_=w837-h789-no?authuser=0.jpg

4BX-yUUjFeKODS6UCLkPVqbOW=w1119-h789-no?authuser=0.jpg


google pointed me to:
high discharge rate lipo 606080 12V 40C 7500mah lithium ion battery for car jump starter
 

Lynx_Arc

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I took my Type S 12V Jump Starter apart.
It also claims to be a 8000 mAh portable power bank.

I opened it up to find...
View attachment 18963
View attachment 18964

google pointed me to:
high discharge rate lipo 606080 12V 40C 7500mah lithium ion battery for car jump starter
If the specs are right then likely the manufacturer is within 10% of ratings which often I see they proclaim in the small print somewhere, but who knows as you can make a label easy enough to say anything you want to.
 

BVH

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29.6 Watt Hours divided by 11.1 (3S nominal Volts) = 2.666 Amp Hours. It does not appear to be anywhere near 7500 mah. I have found that many add the number of cells in Serial and also add the number of cells in Parallel when the pack is only 1P. It looks like that's what they have done here.

You can also look up the dimensions of any 3S/8000 mAh rc hobby Lipo and see that it is 3 times larger than what's in these micro jumpstarters. But, none-the-less, they do, in fact, have the power to start vehicle engines. That's what it's all about.
 
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