Solar Panel

[directentire]

I have 100 watts solar panel with two batteries. Batteries are connected to selector switch 1/2/both/off. Can I use a controller that can only be connected to one battery? connect the positive lead to battery one and the negative lead to battery two. At times one battery will be discharged more than the other. The photo does not have solar cables connected.

6C7A8730-7192-47DB-A5C

 

[I2C]

Are the 2 batteries habitation ones or one habitation and the other the vehicle one?

You’re picture tastes me too a boat forum so assuming they’re both habitation batteries then yes you can, plenty of guides on the internet on how to connect them.

 

[autorouter]

Can I use a controller that can only be connected to one battery?

Yes, it's possible. Solar controllers don't like being disconnected from the battery when there is solar power coming in from the panels. So switching the solar controller between the batteries is not a good idea.

You could connect it to the pos and neg of one of the batteries, and not the other one. The first battery would charge up, and when connected together the second battery would take a burst of charge from the charged battery, and they would equalise.

If the solar controller was connected to one battery, and the selector switch was set for 'both' batteries, then both would charge from the solar.

connect the positive lead to battery one and the negative lead to battery two.

Not a good idea. The solar would charge both batteries if 'both' was selected, but otherwise the solar controller would be disconnected from the batteries, possibly causing problems.

 

[sonar]

So if you were unable to select one battery or two would you still be able to have one battery live the other battery neg.
assuming it was a single controller with two batterys

 

[autorouter]

So if you were unable to select one battery or two would you still be able to have one battery live the other battery neg.
assuming it was a single controller with two batterys

Yes, if the two batteries were connected together by links (pos to pos, neg to neg) then that's the recommended way to do it - it equalises the (very small) voltage drop differences so both batteries are charged exactly equally.

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[sonar]

Yes, if the two batteries were connected together by links (pos to pos, neg to neg) then that's the recommended way to do it - it equalises the (very small) voltage drop differences so both batteries are charged exactly equally.

Thank you so the OP could if they so wished charge two batteries on a single outlet from the controller in the habitation and use the other side the second charger to charge the cab battery.

 

[stevec]

From the picture you sent it looks like both positive terminals are connected together by the thinner red wire on the right. Also seems the two negatives are also connected so effectively both batteries are wired in parallel thereby negating the action of the switch. Would others agree? Also the lower positive wire has been quite hot a some time. Maybe check the connection at that terminal. It may need a clean.

 

[gus-lopez]

 

[Eggs]

From the picture you sent it looks like both positive terminals are connected together by the thinner red wire on the right. Also seems the two negatives are also connected so effectively both batteries are wired in parallel thereby negating the action of the switch. Would others agree? Also the lower positive wire has been quite hot a some time. Maybe check the connection at that terminal. It may need a clean.

I'd cut that crimp off and shorten the cable.

 

[pappajohn]

Why bother with a selector switch in the first place..
It isn't needed and just complicates thing.
You won't get any more power using one battery and then the other.

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[cyberyacht]

A useful idea is to fit a switchable fuse between the solar panels and the controller. That way you can isolate the panels if you want to safely fiddle with the battery connections.