1 Solar panel--2 Seperate batteries

Hi,

If one is for the chassis you could use a trik-l-start.

TOMMY47 wrote:
Thanks for the input again. Since the batteries are different types, ages, capacities, different locations, different purposes, it seems the simplest though not cheapest (but not too expensive) solution is to get another panel and controller.

TOMMY47 wrote:
Thanks for the input again. Since the batteries are different types, ages, capacities, different locations, different purposes, it seems the simplest though not cheapest (but not too expensive) solution is to get another panel and controller.

I would think the simplest solution would be to install a battery master disconnect switch like 69 avion, myself, and Canadianrainbirds have suggested. Of course, one can't have too much solar. ;)

Canadian Rainbirds wrote:
With 20 feet between batteries and only one 100 Watt panel and controller I would be tempted to charge the batteries one at a time. Install a battery switch at the output of the controller and run two sets of wires to the batteries. Charge one to say 80% then the other, then back to the first.

Trying to charge both at once would essentially put both your batteries in parallel. 20 feet is a long run for parallel batteries unless they are not providing much current.

OR as others have said one of the special controllers designed to charge two banks. Best, but more expensive.

I have a 250 watt panel and that is basically what I did. I just hooked the solar MPPT controller output to the common(+) side of my battery switch. I can choose Battery 1, Battery 2, or Both. I usually just leave it on "Both" since it seems to work fine that way.

Thanks for the input again. Since the batteries are different types, ages, capacities, different locations, different purposes, it seems the simplest though not cheapest (but not too expensive) solution is to get another panel and controller.

Hi Pianotuna,

Here's your original post:

pianotuna wrote:
Hi,

If you are careful to have exactly the same length of wire from the charge controller to each battery it will be ok.

This is what confused me:

- If the batteries were paralleled, there wouldn't be a need for an additional charge wire as the single charge wire would be charging both batteries.
- If they weren't paralleled, the additional wire would now parallel batteries that are probably of different age and capacity. Potentially high battery currents would be carried by what is usually a 20 or 30 amp wire.
- If the batteries were paralleled, the two wires you recommended from the controller to each battery would be in parallel with the existing battery wiring. Any large battery currents would be shared across what is probably a large wire and the small charge wires, through the charge controller terminal.

pianotuna wrote:
Plus the Peukert effect would benefit the overall capacity if they are wired in a balanced manner.

It depends on how high the battery currents are that you expect. For very high battery currents, any additional reserve capacity gained by paralleling the two batteries to counter the Peukert effect would likely be offset by the coup de fouet effect. ;)
Bruce

If you are planning to use the one 100 watt panel while camping: I would tie the two batteries together, and wire the panel directly to the batteries (no controller). Watch the voltage and if it rises above 15 volts disconnect the panel.

If you are planning to leave the system alone (ie. storing the RV), tie the two batteries together and use one controller.

With one 100 watt panel, anything more than this is over-engineering a simple system.

Regards,
Doug

bdosborn wrote:
Take a look at the Susnsaver Duo



Sunsaver Duo

Bruce

X2...

Hi Bruce,

But if they are conjoined in a balanced manner, then, electrically speaking, they are in parallel, so why would they be at different states of charge?

Plus the Peukert effect would benefit the overall capacity if they are wired in a balanced manner.

bdosborn wrote:

pianotuna wrote:
Since they would be defacto wired in parallel how would they get to different charge levels?

Because the OP said they were separate batteries.

Bruce

I have a 100 watt solar panel. I want to use this 1 panel to charge 2 separate batteries in different locations.

Have you done a power budget? Are you charging or just maintaining these 2 batteries?
Do you need more than 100W?? If so then add a second panel and controller.
If 100W is enough then just get a Morningstar SunSaver Duo and call it a day.
-Mark

With 20 feet between batteries and only one 100 Watt panel and controller I would be tempted to charge the batteries one at a time. Install a battery switch at the output of the controller and run two sets of wires to the batteries. Charge one to say 80% then the other, then back to the first.

Trying to charge both at once would essentially put both your batteries in parallel. 20 feet is a long run for parallel batteries unless they are not providing much current.

OR as others have said one of the special controllers designed to charge two banks. Best, but more expensive.