Wiring two 6V batteries in series when you have solar panel

**Bailey'sMom** · 05-27-2018, 05:51 PM

Hi All

I have been reading old threads and I have downloaded Bill's diagram on battery set up. I hate working with electrical anything. I need to replace my batteries and I would like information on several things.

I have attached a PDF with pictures of my current set up. (Camper is not open right now, took these last year). My batteries are in the storage compartment under the back bed.

1. How is wiring different when you have a solar panel in addition to two 6V batteries in series? Can someone update Bill's diagram to include solar?

2. How do I turn off the solar power when swapping out batteries? (I'm assuming that would still send electricity thru and could zap me if I don't shut it off before swapping out batteries.)

3. How do I add a cut off switch into this equation? Can someone add this to the diagram? Suggestions for a good cutoff switch?

Thanks in advance.

BrucePerens · 05-27-2018, 09:18 PM

Just replace the 12 volt battery in the schematic with this.
Make sure the batteries are identical type and age.

**Bill** · 05-28-2018, 07:37 AM

Sara -

You treat the pair of 6-volt batteries as if it were a single 12-volt battery. There is no difference.

The solar input is connected to the black positive (+) wire and the white (-) wire. When you are changing out the batteries, there is no need to turn anything off. Just remove the connections from the old batteries, take the old batteries out, put in the new battery(s), and make the connections just as you removed them.

By the way, 12 volts is a very low voltage. You cannot get a shock from 12 volts. I think that the National Electrical Code, which is very conservative, says that anything under 50 volts is "shock safe". The only thing to be careful of is that you do not inadvertently create a short circuit across the battery terminals. The way this usually happens is by dropping a screwdriver or wrench so that it contacts both battery posts simultaneously. But you can grab both posts in your hands and feel absolutely nothing. Try it, just as a demonstration and a feel-good convincer.

As for a cutoff switch, you first choose a switch, and a place to mount it. Then you cut the black wire, and attach the cut ends to the two terminals of the switch. Done. There is a bit more to it mechanically, but electrically that is all there is. There has been a lot of discussion here on the forum about cutoff switches. I've done my own, a bit simpler I thought, but I don't think I posted about it.

Perhaps the attached diagram will help. With the cutoff switch in the location shown, the battery is cut off from everything when the switch is turned off. As an option, the cutoff switch can be located at the "X", which leaves the solar system connected to the battery, but cuts the battery off from everything else. Your choice.

Let us know how it goes. And feel free to PM me with any questions. As you know, I am good at L-O-N-G explanations.

Bill

Craigrrr · 05-28-2018, 08:01 AM

One other thing when hooking up solar and batteries is to connect the battery to the charge controller first then connect the wires from the solar panels to the charge controller

Padgett · 05-28-2018, 08:12 AM

Thought I had posted this long time ago & should be in archives...

BrucePerens · 05-28-2018, 11:34 AM

You won't get a shock from 12V, but if your ring goes across battery power, it welds itself to the connection and turns red hot, and when you pull away your finger flesh comes off of the bone like a glove. Really horrid. I can't forget the pictures. Take jewellery off before working on 12V.

**Bailey'sMom** · 05-28-2018, 11:59 AM

Quote:

Originally Posted by Bill

Sara -

You treat the pair of 6-volt batteries as if it were a single 12-volt battery. There is no difference.

The solar input is connected to the black positive (+) wire and the white (-) wire. When you are changing out the batteries, there is no need to turn anything off. Just remove the connections from the old batteries, take the old batteries out, put in the new battery(s), and make the connections just as you removed them.

By the way, 12 volts is a very low voltage. You cannot get a shock from 12 volts. I think that the National Electrical Code, which is very conservative, says that anything under 50 volts is "shock safe". The only thing to be careful of is that you do not inadvertently create a short circuit across the battery terminals. The way this usually happens is by dropping a screwdriver or wrench so that it contacts both battery posts simultaneously. But you can grab both posts in your hands and feel absolutely nothing. Try it, just as a demonstration and a feel-good convincer.

As for a cutoff switch, you first choose a switch, and a place to mount it. Then you cut the black wire, and attach the cut ends to the two terminals of the switch. Done. There is a bit more to it mechanically, but electrically that is all there is. There has been a lot of discussion here on the forum about cutoff switches. I've done my own, a bit simpler I thought, but I don't think I posted about it.

Perhaps the attached diagram will help. With the cutoff switch in the location shown, the battery is cut off from everything when the switch is turned off. As an option, the cutoff switch can be located at the "X", which leaves the solar system connected to the battery, but cuts the battery off from everything else. Your choice.

Let us know how it goes. And feel free to PM me with any questions. As you know, I am good at L-O-N-G explanations.

Bill

Thanks Bill!

So what I labeled as #6 in my picture is probably the 30amp fuse, right?

**Bill** · 05-28-2018, 08:00 PM

Quote:

Originally Posted by Bailey'sMom

Thanks Bill!

So what I labeled as #6 in my picture is probably the 30amp fuse, right?

Sorry, I didn't even see the extra pictures in your post. Now that I do, you are right, item 6 is what I called the fuse. In your case, though, the 30-amp fuse has been replaced with a 30-amp circuit breaker, probably self-resetting. This is a good change.

Bill

Padgett · 05-30-2018, 08:10 AM

Do not try with a Mercedes or Chrysler: always remove the negative battery cable first both for safety and not to confuse the computers (plural). Modern systems have some residual power and if you pull the positive first it will trigger a number of "low voltage" and CANBUS errors.

**Bailey'sMom** · 06-02-2018, 10:47 AM

Quote:

Originally Posted by Bill

Sorry, I didn't even see the extra pictures in your post. Now that I do, you are right, item 6 is what I called the fuse. In your case, though, the 30-amp fuse has been replaced with a 30-amp circuit breaker, probably self-resetting. This is a good change.

Bill

Bill - would you please look at the pictures again. Why do I have 2 wires attached to the positive post? In my image (attached) I labeled them 1a and 2a. What would the second one be for?

I am trying to compare mine to yours and label as clearly as I can. What confuses me is that I have the same number of wires attached to the negative post as you show in your diagram, one is the ground and the other negative.

So why do I have the same number of wires attached to the negative post, but an extra wire attached to the positive post?

The 2 positive wires connect to the 30 amp circuit breaker and come out the other side. I don't know where they go to.

Thanks in advance. Once I get this all straight in my head, I will write up the connecting batteries for dummies version.