Suggestions for a niche 12v rechargeable battery pack

After a 12v rechargeable battery pack that can be recharged off a 12v line from my aux battery and left hardwired in.

Any suggestions - the ones I've seen recharge off mains and I need one designed to recharge off a 12v source.

Are you talking leisure battery, split charge, or something to be charged from cigarette lighter etc ?

freelance said:

Are you talking leisure battery, split charge, or something to be charged from cigarette lighter etc ?

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Got an aux battery off a split charge this feeds to a aux fuse box. I'm after a 12v battery pack that can be hard wired to this fuse box and then will charge when ever the aux circuit is live

Is this the sort of thing you are after, can charge of cig socket.

https://www.ebay.co.uk/itm/Car-Jump...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

Suaoki G7 Jump starter. (You'll have to Google that because either this pc or LZ has started refusing to show the link I'm pasting).

I've had one of these for a year and it's done everything I've asked of it. Starts ordinary cars as well as a normal battery. Started a Transit a bit slowly, but it did it. I bought mainly to use as a portable power supply for electronics and it has been superb. After sales is excellent. I thought mine had a fault and they swapped it by return. In hindsight I don't think there was anything wrong with it! (Odd switching itself off turns out to be protection).

Having said all of that, I'm not sure that it's what you're looking for if you want it hard wired in as a second/third vehicle battery. The 12V permanent is the normal electronics-type 12V plug that you'd find on a power brick for your external hard drive/router etc.. and not good enough for larger currents. It also limits current through that connector to about one Amp afair. The other connector (the one for battery boosting) needs (I belive) the electronics in the supplied jump leads to work it, so prolly no use in your application.

My need for a portable supply has now has now escalated to needing a bit more than an amp, so I'm now going for a straightforward Lithium motorcycle starter battery. Gives me sturdier contact/connections even if it is slightly more of a nuisance to hook up/recharge.

https://www.alpha-batteries.co.uk/brands/relion-batteries/?ab_ah=477

That’s for the input but I probably didn’t explain it well enough.

Don’t need a jump starter, need a 12v battery pack that will run a small low amp tracker and the battery pack can be hard wired to the aux circuit so it’ll charge when ever I run the vehicle and will have power when ever I don’t.

Got you. You need some sort of circuit system that will charge your battery yet keep it isolated from the rest of the car's system. Then decide on the most effective chemistry.

I'd do the former with an ignition sensing relay switching a feed from main battery +ve. You also need to know how many amps your tracker consumes, and then decide how many hours you want to run for to arrive at the battery capacity. The next choice is a bit less simple. A lead/acid is cheap, but will be ruined by being run flat. Lithiums like the one above don't really care how they're discharged, but they are three times the price.

payydg said:

That’s for the input but I probably didn’t explain it well enough.

Don’t need a jump starter, need a 12v battery pack that will run a small low amp tracker and the battery pack can be hard wired to the aux circuit so it’ll charge when ever I run the vehicle and will have power when ever I don’t.

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Cant ya use a 12v battery off a moped or a bike? Then some clever wiring

bankz5152 said:

Cant ya use a 12v battery off a moped or a bike? Then some clever wiring

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I don’t recon the tracker uses that much power so a lithium one will do I think. Just not sure on the charging wiring.

boguing said:

Got you. You need some sort of circuit system that will charge your battery yet keep it isolated from the rest of the car's system. Then decide on the most effective chemistry.

I'd do the former with an ignition sensing relay switching a feed from main battery +ve. You also need to know how many amps your tracker consumes, and then decide how many hours you want to run for to arrive at the battery capacity. The next choice is a bit less simple. A lead/acid is cheap, but will be ruined by being run flat. Lithiums like the one above don't really care how they're discharged, but they are three times the price.

Click to expand...

I guess my question is can a simple rechargeable lithium battery pack be charged of a car 12v battery or do I need some sort of transform to create the right charging voltage?

Charging usually requires a voltage higher than the battery itself can supply eg. 14.3 ..14.8v as chucked out from the alternator when the engine is on.
Run a relay operated and fused additional wire from the Alternator to your ancillary battery perhaps?