I'd have thought this could be done simply by just having a switch to charge
one or the other of them. Don't like the idea of having a charging battery
in the passenger compartment withou ventilation.

The lighter is not going to sink the sort of current you need to charge it
really, and yes you could current limit this by a simple circuit (Look in
many of them old Bibani Books!)

I'm sure little modules exist for this nowadays.

Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"David" wrote in message
...
I am getting to the point where it seems a cunning plan isn't.

We have a caravan with a leisure battery.

We also have a spare leisure battery which gives us the option to carry it
for extra capacity and possibly use it with an inverter to power some low
demand 240v devices.

It is a few years old and doesn't match the new one in the caravan so just
linking the two together may not be the best option.

I thought I might be able to trickle charge it from a 12v socket in the
car for the times when we will not have an Electrical Hook Up (EHU)
available over night.

However, although there are DC-DC chargers these seem to start around £70
which is not far off the price of just buying another leisure battery and
fitting it to the caravan.

Does anyone know of a cheap but effective DC-DC charger?

To make it easy to use it needs to work off a cigar lighter socket; I know
I would probably get far superior charging by fitting a charge controller
to the output of the car alternator to feed the battery but this looks to
be in the £200+ price range.

Just looking for a cheap and simple way to use the spare battery without
any major electrical surgery to the car or caravan.

Cheers


Dave R



--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus