Two batteries, One solar panel?

[Tim Good]

There is another thread in this but I wanted to clarify something. If I have two batteries running throug a 1, 2 or both switch, and then I rig the 30w panel (via regulator and fuse)... What is the best way two ensure both batteries are charged whilst away from boat? I want to ensure both are done and not just the starter so I come back to two full batteries each visit.

I intend to simply clip the panel on each time I leave the boat in the cockpit and then stash it away when sailing.

Thoughts?

 

[Tropic Cat]

If keep your battery switch on "both", the solar panel will charge both.

 

[VicS]

Better than leaving the isolator on would be a regulator with two outputs...... one going directly to each battery.

A 30watt panel should have regulator any way.

 

[Tim Good]

Better than leaving the isolator on would be a regulator with two outputs...... one going directly to each battery.

A 30watt panel should have regulator any way.

Ok so either rig my current regulator after the switch and leave switch on both, or get a twin regulator and wire directly to each battery (allowing me to leave my switch off)?

Latter seems like a better option so i'll get myself to Maplin.

 

[Rigger Mortice]

Make sure that you don't inadvertently permanently connect the two batteries together through the panel/regulator circuit. If you do then the 1/2 switch won't really be doing much and the batteries will be connected together probably through fairly low current wiring.

 

[VicS]

Ok so either rig my current regulator after the switch and leave switch on both, or get a twin regulator and wire directly to each battery (allowing me to leave my switch off)?

Latter seems like a better option so i'll get myself to Maplin.

Maplin offer this one although you'll probably find something similar cheaper on eBay http://www.maplin.co.uk/dual-16a-solar-charge-regulator-266145#specification
it is however a simple on/off controller. Disconnects when the volts reach 14.4 and reconnects again when they fall to 13.4.

A better choice would be a pulse width modulated (PWM) regulator but AFAICS Maplin do not offer a dual channel PWM regulator. You will have to look else where for one of those.

 

[duncan99210]

This seems to offer a solution to charging both banks whilst keeping them isolated and it uses PWM. On ebay at http://www.ebay.co.uk/itm/20A-Solar...71200592410?pt=UK_Gadgets&hash=item3f24d0a21a

 

[Richard10002]

My engine starter battery only charges from the alternator. It uses so little power starting the engine, and is fully charged again so quickly, it doesn't need charging by the various other means.

My domestics charge from alternator, mains chargers x 2, 100W solar panel?

I have separate isolators for each bank, and a split charging relay means both get charged when the engine is running.

This way, there is no way the starter battery can be affected by the domestic battery, or by the switch being in the wrong position.

If it were me, I'd connect the solar directly to the domestic bank, (with a fuse of course). Then you don't need to worry about leaving the isolator turned on whilst away.

If, by some chance, the starter battery became flat, you can always get a jump from the domestics.

 

[cowpat]

Dual Batt' regulator

Maplin offer this one although you'll probably find something similar cheaper on eBay http://www.maplin.co.uk/dual-16a-solar-charge-regulator-266145#specification
it is however a simple on/off controller. Disconnects when the volts reach 14.4 and reconnects again when they fall to 13.4.

I fitted a 60w solar panel in 2010 using a simple toggle switch to switch it's imput between 2 batteries..... THEN I found the above controller and replaced the toggle switch with it. I would very much reccomend one AND both batteries will always stay charged and no need to worry about which batt' you left the panel on. The two existing battery circuits will remain independent. very simple wireing..Chris.

 

[rogerthebodger]

It is possible to charge two batteries from one solar panel by fitting two single battery regulators, one regulator for each battery with the output of the single solar panel paralleled to the two regulator inputs.

 

[GrahamM376]

It is possible to charge two batteries from one solar panel by fitting two single battery regulators, one regulator for each battery with the output of the single solar panel paralleled to the two regulator inputs.

Yes but, some regulators don't block backfeed as I found out so, I now use a split charge diode before the regulators which has solved the problem.