Help with two 12 volt batteries (parallel)?

[Bellbear]

So I originally thought I was gonna need to replace my batteries but I charged them and they seem to be holding a charge. I can't remember how they were wired before I took them out (I know, I know). Obviously the ground goes to negative on one battery and the power of camper goes to the positive of other battery. Then there was a small red wire. Does that go from positive on one of the batteries to negative on other battery?

 

[CougarCouple]

Hello bellbear
Do a search on wiring batteries in parallel, or series
This is one I found https://www.batterystuff.com/kb/articles/battery-articles/battery-bank-tutorial.html

You said a smaller wire that sound strange as the load carrying wires are normally the same guage if your not sure you might want to seek a rv repair center to ask for assistance.it could be very dangerous to short the battery terminals.Hope this helps.

Russ

 

[Bellbear]

Thanks Russ. As in small, the red wire is the same gauge but not long in length. Not sure if that goes pos to neg

 

[klahanie]

No. between batteries should be pos to pos. neg to neg.
So there should have been 2 short wires plus the pos and neg wires to camper system

 

[klahanie]

are you sure both batteries are 12v ? each battery should have 6 cell caps if 12v

well you charged them so would know ...

 

[Bellbear]

I just bought this hallmark and owner says they are 12 volt BUT... they only have 3 cell caps. Does that change the wiring if 6 volts instead of 12 ?

 

[Bellbear]

And I assumed cause the batteries were so big that they were 12 volt

 

[klahanie]

I just bought this hallmark and owner says they are 12 volt BUT... they only have 3 cell caps. Does that change the wiring if 6 volts instead of 12 ?

yup.
it matters, per link from Russ

2x 6v should be like this...

so no missing parts
all is well

but how did you charge them ? charger have auto select for charge voltage ?

 

[pvstoy]

Take a picture and show us what you have. Use a volt meter and see what the voltage is on each battery. If 12 volt wire in parallel. If 6 volt wire in series.

 

[Bellbear]

No auto select, just a basic charger

 

[Bellbear]

When I pulled batteries out. Cells were nearly empty and after I filled them and put basic charger (8 amp ?) It charged to full charge in about 45 minutes

 

[Bellbear]

Can I text a picture to someone on my charger setup and battery. I have not be able to download pics from smart phone to WTW. Says pics to big...urg!!

 

[klahanie]

OK, well maybe a 12v (nominal output) charger will charge a 6v battery, IDK.

If you pulled the caps and there were only 3 cells on each battery then my money is on them being 6v batts and would use the 2nd diagram I posted.

 

[Optimistic Paranoid]

Ordinary battery acid is actually 1/3 concentrated sulfuric acid diluted with 2/3 distilled water. Only the water is lost through evaporation etc. which is why you only add distilled water to batteries. If your cells were dry, that means the liquid in the bottom of the cells was CONCENTRATED sulfuric acid, which will eat away at the lead plates given time. Best case scenario, you've drastically shortened the life of your batteries, worst case scenario you've destroyed them.

Do NOT use a 12 volt charger on a 6 volt battery!

But if you have the two 6 volt batteries wired together in series (a wire between the positive of one and the negative of the other, per the SECOND diagram) You can treat the two of them as one 12 volt battery.

 

[Bellbear]

It's a 2amp charger

 

[Wandering Sagebrush]

As Optomistic Paranoid said, do not, repeat... do not use a 12 VDC charger on a 6 VDC battery. If you have the battery pair wired in series, you can safely use a 12 VDC charger on the pair if you connect it across the series wired pair. The diagram in an earlier post shows the connection points that OP mentioned.

 

[Mighty Dodge Ram]

Late to the discussion but you need to try and find some identifying info on the battery that indicates 6 or 12 volt. But considering your comments about the battery being larger in size (especially taller?), having only 3 caps, and being able to fill/refresh the cells...I’ll bet you have two 6-volt batteries wired in series to give you 12 volts total. That system, when operating normally, will provide you with a bunch of amp hours to use in your camper!

 

[klahanie]

Bellbear,

Re the charger:
by way of explanation, I only brought up the charging voltage because at that time the single battery voltage was in question yet the batteries seemed to be have been successfully re charged with a home charger. That brought to my mind the older, automotive chargers I am most familiar with that were either 6v or 12v nominal output. Or some units could do both, but one voltage needed to be selected to use. Sorry if this muddied the waters.

Your charger should be marked with it's output voltage (label?)

And I should have specifically asked or followed up on how exactly you had charged the batts - singly or connected together (if connected, how).

Re the battery voltage.
I should have mentioned that, from what I have gathered, in a camper with 2 batteries, using a 2 x 6v format is commonplace, even to be expected and, some have said, generally better than a 2 x 12v format.

Although you may not remember the exact wiring, you may remember if each battery post had only 1 wire connected to it ?

Everything but the thread title (which prompted me to chime in) suggests the batteries are 6v. Which would mean they should be wired in series as show in my 2nd post. The previous owner may have meant the camper system is 12v, incl the "battery bank" as opposed to the individual batteries.

If in doubt about the battery condition/usable service life, an auto service or battery shop should be able to test them.

 

[Bellbear]

So batteries back in camper
Reading 11.5 vintage
2.8 current

 

[Bellbear]

And it keeps going up. Green light says good but looks like it can be better