Battery powered trickle charger

[mgv8]

Hi All
My car and bike are stored in a garage with no power. I would like to keep them charged up so save the batteries. What I am looking for is a battery power changer (not a booster) that I can change at home and then leave with the bike or car for a few weeks keeping them topped up. Then bring home and repeat.
All I can find are either mains changers or boosters. Am I missing something?

[Scrump]

A big car battery (with a “go handle”), keep it connected with some jump leads and the external battery will trickle charge the battery in the vehicle.

Or take the car and bike batteries home with you to keep charged.

[alabbasi]

You're not missing anything. A booster will charge a battery @ 3amps if you don't crank it, but it will not keep it topped up for weeks on end.

Either disconnect the batteries or get a solar powered charger that will charge the battery at 0.5amps or so.

[RizzoTheRat]

Another vote for solar if you have somewhere you can place one. Over lockdowns my car sometimes went several months without being used, so I bought a small solar charger that sits on the dash and plugs in via the OBD socket. Seemed to do the job and I never had any trouble with the car battery.

https://www.amazon.co.uk/Aa-Automobile-Association...

If I had a garage with no power I'd be tempted to use a solar panel to trickle charge a spare 12v and then use that to power some LED lights and occasionally connect it the car/bike battery to charge them.

[Polly Grigora]

Portable car battery chargers are built for this job
https://bestreviews.com/automotive/batteries/best-...

[mgv8]

Polly Grigora said:

Portable car battery chargers are built for this job
https://bestreviews.com/automotive/batteries/best-...

All the above either needs mains power or are just boost starters. None are battery-powered changers.

To the post below about solar power. I did give it a go but it's underground and the small light there is, was not enough.

[alabbasi]

mgv8 said:

To the post below about solar power

[Polly Grigora]

mgv8 said:

Polly Grigora said:

Portable car battery chargers are built for this job
https://bestreviews.com/automotive/batteries/best-...

All the above either needs mains power or are just boost starters. None are battery-powered changers.

To the post below about solar power. I did give it a go but it's underground and the small light there is, was not enough.

Sorry about that, should have studied more before posting

[bongtom]

Make sure the battery is new and check for leakage (pretty simple to do Google it) I forget what’s acceptable. Then get a simple 3V solar and that’ll keep it trickle charged, unless your battery is crap or you’ve got leakage.

[bongtom]

anonymous said:

[redacted]

Not normally no.

I am assuming the hand warmers only work when the ignition is on.
Batteries do not like to be drained and left, it screws up the plates as you in effect have distilled water instead of acid. As I mentioned you need to check the drain on the battery as there might be a short.

[RizzoTheRat]

anonymous said:

[redacted]

If it had started ok and it just conked out rather than you stalling it and not being able to restart, it might be a problem with the charging system I had a regulator/rectifier fail and knacker the battery. Easy to check if you have a multimeter. You should have about 13 volts with the engine running a but above tickover, and then as you increase the RPM it should rise but not go above 15v

[Polly Grigora]

Good project for someone

If a battery powered battery charger doesn't exist, design one, not difficult is it?

Decent sized battery, small inverter and a step-down transformer to give 3 Amps @ 14 volts

[finishing touch]

Both of these chargers require 12v DC input (mains transformer or car battery) and will charge almost anything
from a couple of AAA's to a lead/acid car battery. Obviously within reason. Both sort the voltage and you set the charge rate,
from a few mili-amps to 5A.

I used to use them for days out with RC model planes charging stuff in the back of the estate car.

Still use the Prodigy to charge the Suttol as that has a relatively small Bosch lead acid (70amp/hour) and if I forget, it auto switches off.

Goes without saying that you can't fully charge the 3.2 Merc from the MX5 but you can do the reverse.