Battery box in car charging.

Stewart · Senior Member

Battery box in car charging.

Peter_n_Margaret · Guru

Theoretically, if you don't pop the fuse. A cig socket is generally only good for 10A and it may get warm at that.
Cheers,
Peter

Stewart · Senior Member

Thanks Peter. A portable dcdc charger would be good but I guess they would use too much power. Cheers Stewart

PeterD · Guru

Stewart, It does not matter whether you use a "portable dcdc charger" or not. A cigarette lighter socket will not carry enough current to charge a battery quickly. Install a dedicated circuit with an Anderson plug/socket connection for your battery charging. Connect the positive cable (via a fuse) to the positive terminal of the starting battery. Connect the negative cable to the bolt where the negative lead to your battery also terminates (and not the battery terminal end.)

-- Edited by PeterD on Monday 13th of December 2021 04:04:37 PM

Peter_n_Margaret · Guru

Stewart wrote:
Thanks Peter. A portable dcdc charger would be good but I guess they would use too much power. Cheers Stewart

A DC-DC charger connected direct to the crank battery (with alligator clips if you like, not via the cig socket?) won't use any more power than it is set to use until the battery is charged, and it matters not how much it uses anyhow as the alternator can produce much more than you need.

As far as charging from the cig socket, go for it. How long it takes will depend on how flat it is and what does it matter matter how long it takes anyhow?

Exactly where is this battery that you want to charge?

Cheers,

Peter

Stewart · Senior Member

Hi Peter it is a battery box that I have sitting behind the back seat next to the waeco fridge. Used for when I need some extra power if the van battery has been run down due to lack of sun. Or if parking for a while (lunch or shopping) and running portable fridge. Usually I just charge it with a solar blanket. At the moment I am home and not using fridge at all , so I was thinking I could keep battery box topped up this way. Cheers Stewart

Peter_n_Margaret · Guru

If it is an AGM, you could safely just disconnect everything from it for 6 months or more without an issue.
The cig plug would keep it topped up if that is what you preferred.
Cheers,
Peter

dabbler · Guru

I have an Aux battery bank in the tub of the ute and have fused cable run from cranking to tub where it's terminated with an Anderson plug. The dcdc charger alternator input is also terminated with an Anderson. It's always connected but still effectively transportable and can be connected/disconnected simply. Fir your setup, a dcdc could be anywhere as long as any cabling to/from isn't prone to excessive vibration and could be fitted to most battery boxes.

oldbloke · Guru

Sounds like your need is not great.

I would just try it and suck it and see.

A DC-DC charger is not needed for all models. My Triton works fine without one.

If you don't need a DC-DC charger then just running a fairly heavy cable (60 or 80 amp) from starter battery to the 80ah batt will work. Best to have a fuse.

The various options are mainly about speed of charge/efficiency.

-- Edited by oldbloke on Thursday 16th of December 2021 09:04:25 AM

Peter_n_Margaret · Guru

oldbloke wrote:

If you don't need a DC-DC charger then just running a fairly heavy cable (60 or 80 amp) from starter battery to the 80ah batt will work. Best to have a fuse.

The OP is only needs a trickle, so even a light cable will be fine, but the advice to include fuses is essential. Put one at each end of the cable, near each battery.

Cheers,

Peter

Aus-Kiwi · Guru

Imo if your running some wire / cable ? You just need to go that little further and connect to main battery with decent wire size, fuse . You need as much volts you can . Any voltage drop will reduce charging !!

Peter_n_Margaret · Guru

Aus-Kiwi wrote:
Imo if your running some wire / cable ? You just need to go that little further and connect to main battery with decent wire size, fuse . You need as much volts you can . Any voltage drop will reduce charging !!

The OP is not charging the battery, he is maintaining it.

Half an amp will do that.

Cheers,

Peter

Stewart · Senior Member

Thanks for all the replies. It certainly gives me some ideas. I will try it but will probably end up with a fused cable from battery and maybe another dcdc charger. Thanks Stewart. Ps can't do much at present due to Covid spreading and medical issues.