Using a jump pack overnight - consequences?

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henni

henni

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Is there anything to be aware of leaving a jump pack connected to a car battery overnight ?

Clearly, the intended purpose of any modern jump pack is to briefly connect it, start the car and disconnect.

What negative issue may result to the car battery if left connected for 24 hours?

For the sake of analysis, let's assume the car battery is fine but car is driven only 1 or 2 days a week and then only for very short duration (20 minutes). Clearly, not enough time to fully compensate for a slow discharge due to on-board electronics. In case it matters, the car has an AGM battery and the jump pack has a Lithium battery. Let's also assume that no practical way exists to use an electrical connection/trickle charger (ie. airport parking, condo parking)

The jump pack (source) would slowly equalize voltages to the car (destination) battery.

I would expect that the jump pack would be Ok to recharge under this scenario but would something unforeseen occur to the car battery if this was done repeatedly?
 
As long as thé Li-ion jump starter has over-discharge protection, I don't see a problem. Li-ion batteries are not tolerant of over discharge.
 
Lithiums are also not damaged in any way from being at a low charge -10 % or so (unlike lead acid batteries).
You dont need to keep them topped up. Each charge/discharge cycle does take away from their 1000-2000 cycle life.
 
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Solar is not available at the destination.

Question is not to "fix this issue" - the question is about "negative consequences" ?
 
I see what you're asking. It would be cool is they had a low amp slow charge mode, but these jump packs are designed for high amps. I would think they would quickly peter out as there are only so many amp hours available in the lithium ion batteries. Damage; I doubt it.
 
Negative to either battery? None.

The only negativity I have is that it's a pretty dirty hack, which, if successful, will encourage the operator to do other dirty hacks. But that's none of my business.

The ideal would be to give the battery a 14.5 volt source that actually charges it. Mixing 12.7 with 12.5 volts isn't going to do much to the lesser battery.

PS my F150 only goes to the dump once a week, and runs for maybe 15 minutes. I throw a charger on it every 6 months or so to desulfate it and/but the battery acts 80-plus percent full.
 
I'm going to be the one to ask the stupid question-why? If you left the fully charged jump box in the car, but not connected, you could charge it on the day or two you use the car, and then it would be ready when you needed it. I kind of use my Clore JNC-660 this way-it stays in the (warm) house to be fully ready if needed for a winter jump, and I charge it off the car/truck lighter plug if I'm going somewhere to use it it to power the trailer winch and/or jump something. This concept has worked well for the 3+ years I've had it.
 
it will put shallow cycles on your jump pack while providing no benefit.
big waste of time.
invest in a small solar panel.
you have to get the voltage up to fully charge.
my agm charger holds at 14.7v till the current drops to under 500ma.
a 5w unregulated will do this.
or get close.
you have enough parasitic loads in a modern vehicle that overcharge with a 5w panel is not possible.
use an isolation diode and a fuse of course.
 
This is what I was thinking.

The potential negative consequence is you end up with a flat battery and a non-working jump pack, the worst of both worlds.

Keep the jump pack separate and charged.

Since the battery is AGM, even in a condo, you could remove it from the vehicle bring it in the condo and charge it there. Doesn't work for the airport, but does work for when left at home for long stretches.

Instead of connecting the jump pack, why not disconnect the battery to eliminate the parasitic drains going on.

Sure, you'll have to actually use a key to open the door when you return to the vehicle as your keyless entry will not work. But the state of the battery should pretty much be the same as when you left it.

Originally Posted by bullwinkle
I'm going to be the one to ask the stupid question-why? If you left the fully charged jump box in the car, but not connected, you could charge it on the day or two you use the car, and then it would be ready when you needed it. I kind of use my Clore JNC-660 this way-it stays in the (warm) house to be fully ready if needed for a winter jump, and I charge it off the car/truck lighter plug if I'm going somewhere to use it it to power the trailer winch and/or jump something. This concept has worked well for the 3+ years I've had it.
 
Originally Posted by javacontour

The potential negative consequence is you end up with a flat battery and a non-working jump pack, the worst of both worlds.
Keep the jump pack separate and charged.


Exactly. You won't be disappointed doing this.
 
Originally Posted by DrDanger
Lithiums are also not damaged in any way from being at a low charge -10 % or so (unlike lead acid batteries).
You dont need to keep them topped up. Each charge/discharge cycle does take away from their 1000-2000 cycle life.


Hi,
that's not true, is it?
Only protected Lithium cells are protected. Lead Acid would be likewise protected if protection was provided. Comparing protected calls vs unprotected cells is no measure of life.
Cheers,
Iain.
PS. No I would not leave A Lithium battery pack connected to a Lead acid battery. I would leave a lead-acid battery connected to a lead-acid battery overnight or longer.
 
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IMO, leaving a lithium jumper box connected is asking for trouble.
Just install an automatic battery disconnect like the PriorityStart. What this device does is disconnect the battery from the vehicle when the voltage gets too low, but not so low that the vehicle won't start after reconnection. If the vehicle is being driven enough to keep the battery charged up, you will never know that it is even on the vehicle.
 
Are you sure the jump-pack is not timing out?

If not, what is the jump-pack putting out for voltage?

I would not leave the jump-pack connected for an extended period of time.
 
The batteries in those jump packs are really small. They make big claims, but they can't actually source the high current values for any appreciable time. They will get hot and explode.

Thus they should have over discharge and a contactor of some sort (or power electronic switch perhaps), that cuts it out after a short time.

IOW, it won't maintain your battery.

If you're underground, and have no access to grid power, an option that will marginally work is to get a group 29 deep cycle battery, a maintenance charger with ring terminals and quick disconnects, and some cheap 10ga booster cables.

Charge the deep cycle battery at home, using the ring terminal quick disconnect. When parking the car (with as full a battery as possible), connect the booster battery in parallel with the booster cables. The two batteries will quickly equalize in voltage, and then you'll notionally have double or more energy. While batteries do self discharge, this rate can be pretty low, especially if the car is in a cool place. Parasitic loads do more of a job on the battery, but by having all that extra energy, at really low discharge rates, the man battery in the car will stay at a much higher state of charge for much longer.

It's no replacement for a maintenance charger on the battery, but it does allow you to keep the voltage higher for a very long time.
 
I think I'd rather own a pump jack than a jump pack.
smile.gif
 
No a jump pack is not a charging device, you need a maintainer/smart trickle charger. They are cheap and very good for the money vs even a few year ago.
You can hook up a jump pack to a battery for an hour or two prior to starting if the battery is really dead but overnight is too long and asking for issues.
 
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