Battery Wiring Question

[Tx Jim]

12v to 12v series is 24v.

Take two batteries and parallel them. Now you have one 12v battery. A large one with 4 posts. The terminals you use will be at the ends (of battery 2) with 12v DC between them. You can then connect the + of battery two to the - of battery 3 (series) and the leftover terminals are going to give you 24v DC.

I was not entertaining your extreme method of trying to utilize three 12 volt batteries on a 24 volt system OR what the advantage would be BUT If the batteries on each side of a 24 volt system ARE NOT close to equal in amperes even if there was no smoke one will have difficulty in getting the batteries to charge correctly by means of the implements alternator or generator. Batteries utilized in a 24 volt system are similar to a chain and are only as good as the weakest link.

 

[rutwad]

Well I was brought into this situation only recently. Several months back I bought 3 12 volt batteries to replace the ones taken out (not by me). I brought them home and placed them back in the battery tray of the lift. My dad is struggling with medical problems and last week was his first attempt to hook the batteries up and requested my help. He said it was a 24 volt system. I never thought 3 12 volt batteries seemed right so I told him let me look online before we hook them up wrong. Turns out it is a 24v system and I know 3 12v batteries came out of it. I told him the previous owner may have changed something because it didn't seem right to me. But it has worked for years and I was trying to figure out how it may have been hooked up.
I hooked it up as 24v and it works. However I did not hook the charger up. It is putting out 36v. Even if I swap to 4 6 volt batteries I still wouldn't know how to hook the charger back.

 

[rutwad]

I'm trying to reply using my phone. I will get to my computer shortly. Thanks for the input and your patience

 

[CobyRupert]

Seems like others have said you have a 24v machine that uses 4-12v batteries, (2 in parallel that are in series with the other two). But you only run 3 batteries (2 in parallel in series with 1).
I believe a 24v charger should put out around 28-29 volts. Sort of like a 12v charger puts out 12-14 volts. So what is a 36vt charger and where did it come from? (Why wouldn't a "36v charger" (for 3-12v in series) would put out about 41v? -Doesn't matter, you have what you have. )
Seems like instead of charging at 29 volts you've been charging at 36v without incident?

 

[CobyRupert]

Or put another way: most Info I find says 2.45 volts per cell is a healthy max. charge voltage (= 14.7v for a six cell 12v battery, and 29.4v for 12 cells (a 24v system) connected in series. Having more batteries connected in parallel doesn't change this).
Can you charge with 36v (3 volts per cell)? I guess you have been. But it probably causes a shorter battery life. This is where the chemistry inside the battery and the metal reactions get over my head.

 

[TomSeller]

I was not entertaining your extreme method of trying to utilize three 12 volt batteries on a 24 volt system OR what the advantage would be BUT If the batteries on each side of a 24 volt system ARE NOT close to equal in amperes even if there was no smoke one will have difficulty in getting the batteries to charge correctly by means of the implements alternator or generator. Batteries utilized in a 24 volt system are similar to a chain and are only as good as the weakest link.

I had not thought of the unusual configuration of wiring the third battery in parallel of one of the two in series either. Technically it is 24V but makes no sense to me and I would not do it.

 

[Xfaxman]

When you run the batteries down on a hard start (or leaving something on) the single battery will completely discharge long before the parallel batteries because all current runs through the single battery while only half runs through each parallel battery.


When the single battery is discharged fully, the parallel batteries will then force current through it backwards. I think that can happen (been a long time since I studied the chemistry of lead-acid batteries) and it can't be good.

You should be able to look at the cables and see how they were connected.

I agree that two in parallel, in series with with one is not good. :thumbdown:

I had not thought of the unusual configuration of wiring the third battery in parallel of one of the two in series either. Technically it is 24V but makes no sense to me and I would not do it.

I brought that up in post #8.

 

[TomSeller]

I brought that up in post #8.

But the original post said

"2 in series and the other parallel"

That says to me the "parallel battery" is parallel to the 2 in series.

 

[Xfaxman]

But the original post said

"2 in series and the other parallel"

That says to me the "parallel battery" is parallel to the 2 in series.

Well I thought he would be smart enough not to do that! :shocked: That would put 24 volts on a 12 volt battery.

I took it to mean "2 in series and the other parallel with one of the ones in series". Which dosen't have any advantage over 2 in series.

 

[CobyRupert]

But the original post said "2 in series and the other parallel" That says to me the "parallel battery" is parallel to the 2 in series.

That wouldn't be good.