Charging main battery off leisure battery/solar panels

[gypo]

Can anyone help please,

Could I use this relay (TEC3M) in reverse i.e charging from my leisure batteries to my main battery so the excess power that my solar panels are at the moment dumping will trickle charge my crank battery?

I'm thinking I would probably need to fit a switch on the live between the relay and the crank battery for when the engine is running in case it tries to reverse charge?
here is the relay TEC3M http://www.justkampers.com/forum/viewto ... 5&t=184659
Thanks
G

[kevtherev]

Personally I would get a dual battery solar panel charge controller

http://www.ebay.co.uk/itm/Dual-battery- ... 0910730156" onclick="window.open(this.href);return false;

The controller senses any reverse charge and stops it automatically.

[gypo]

Trouble is I haven't long bought a mttp tracer controller and didn't want to be changing it just yet
Thanks for the reply
G

[California Dreamin]

If you were to use a 'SMART' voltage sensing relay between leisure and starter batteries, the increased 'charge' voltage coming from the solar panel controller would hold the leisure battery voltage above the 'switching' voltage of the relay. This would effectively connect the leisure and starter batteries together, charging both.

Just make sure your relay is 40 amps plus....some of the voltage sensing relays are only 25/30 amps which is marginal.

Martin

[Oldiebut goodie]

My solar charger is fitted 'back to front' compared to how most people fit theirs. Mine charges the starter battery and the leisure is charged by the voltage sensitive relay. I would rather have a flat leisure battery than a flat starter. I see no need to have it the other way round.

[California Dreamin]

My solar charger is fitted 'back to front' compared to how most people fit theirs. Mine charges the starter battery and the leisure is charged by the voltage sensitive relay. I would rather have a flat leisure battery than a flat starter. I see no need to have it the other way round.

??? doesn't the sensing relay connect under 'solar' power? most of these relays operate around 13 - 13.5 volts.

Martin

[Oldiebut goodie]

Yes, the same as running an engine to utilize the alternators output to charge the leisure by a split charge relay. Why just charge a leisure battery?

[gypo]

Thanks all for the replies, Good idea that charging the main battery off the solar panels with a split charge relay charging the leisure batteries,
If I stick with my original plan with the relay charging the main battery off the leisure/solar panels would I have to worry about the main battery trying to back charge when the engine/alternator is running? Would I need to fit a switch to isolate it when it is running?

Thanks again lads for the replies
G

[gypo]

Just come across this relay http://www.kiravans.co.uk/voltage-sensi ... rge-relays
The (TEC3M) is only 30A so not really fit for the job?
Thanks
G

[Oldiebut goodie]

Diodes in the panels and controller take care of the back feeding aspect so no worry there.
The only problem that I foresaw doing it my way is that the leisure battery could be connected via the relay whilst starting the engine, if you use a puny relay there is a chance that it could be burnt out by high current flowing before the relay cuts out due to battery voltage dropping. I am using a 100 Amp voltage sensing relay and that has survived for over 5 years with no ill effect.

E D I T - just looked at the one linked to above - 140A! They weren't around when I set mine up.

[gypo]

Diodes in the panels and controller take care of the back feeding aspect so no worry there.
The only problem that I foresaw doing it my way is that the leisure battery could be connected via the relay whilst starting the engine, if you use a puny relay there is a chance that it could be burnt out by high current flowing before the relay cuts out due to battery voltage dropping. I am using a 100 Amp voltage sensing relay and that has survived for over 5 years with no ill effect.

E D I T - just looked at the one linked to above - 140A! They weren't around when I set mine up.

Thanks for the info. Ill get the relay ordered up
G