One pair of batteries both Series and parallel, possible?

[eabyrd]

Is it possible to wire a single pair of batteries first in parallel to one set of bus-bars for charging from a 12-volt charger, while connecting them in series to a 2nd pair of busbars (or directly) to a 24-volt inverter? Somehow I think that as soon as I series the batteries I will cause magic smoke to escape, or worse. I'm seeking confirmation, and if you're feeling generous, the why of it

 

[MisterSandals]

So you want to hook all the positive and negative wires together? Make a video and call the fire department if you try.

 

[severin20]

Do I understand you correctly? You have 4 batteries. You connect the batteries in parallel in sets of 2. One set of 2 have a 12v charger on it.

Now you want to connect the two sets in series so that you can connect your 24v inverter?

I dont know if your charger will freak out, but the wiring for the batteries to 24v for your inverter sounds good.

 

[pollenface]

I thought about doing it with diodes and charge each battery with separate controllers again shielded with diodes. Never actually done it though.

 

[G8trwood]

Separate leads for each battery going to a multi bank charger is how my boat trolling setup is. 36v config but each battery is charged separately. Who knows if it is correct....

 

[Bob B]

Separate leads for each battery going to a multi bank charger is how my boat trolling setup is. 36v config but each battery is charged separately. Who knows if it is correct....

Yep .... That's the way almost all fresh water boats charge their batteries.

I have a 24V trolling motor and a multi-bank charger for individual 12V batteries .... wired in series to supply the trolling motor.

 

[time2roll]

No on the dual wiring. Get a 24v charger.

 

[Diysolar123]

well...if your question is can you charge a "subsection" of a battery pack...
yes you can charge a "subsection" of a multi-battery pack but you need to be really really careful that you have a completely isolated battery charger.

consider this scenario:
you have 8 lifepo4 "battery cells" connected in series; so each cell is 3.2v and the total voltage is 8*3.2 = 25.6

now if you have a isolated 3.2v battery charger, you can connect it to any of the cells and it will, well, charge THAT cell; no problem; I do it all the time when testing cells or seeing how a BMS may respond to different cell conditions.
a few things to consider:
1) if you have a BMS it may be unhappy if it is trying to "balance" your battery pack via the balance leads when you are trying to charge a single cell because your BMS thinks it knows everything about what is going into and out of your battery and you would be going around that.
2) if your battery charger does NOT have a floating negative terminal you can definitely cause a short in the system if not careful; lots of battery chargers connect the ground to the negative terminal so I would consider NON-floating to be the normal type of charger.

 

[MisterSandals]

well...if your question is can you charge a "subsection" of a battery pack...
yes you can charge a "subsection" of a multi-battery pack

I read it as connecting 2 batteries is parallel to one bus bar and connecting them in series at the same time to a second bus bar...

a single pair of batteries first in parallel to one set of bus-bars for charging from a 12-volt charger, while connecting them in series to a 2nd pair of busbars

This essentially connects all 4 terminals of the 2 batteries together. (Bad)

 

[Diysolar123]

I read it as connecting 2 batteries is parallel to one bus bar and connecting them in series at the same time to a second bus bar...

This essentially connects all 4 terminals of the 2 batteries together. (Bad)

well if THATS the ops plan, yea...thats just everything shorted together hehe
If bus 1 was ONLY connecting to a single cell at a time for isolated charging it would be fine but you definitely cannot just "connect everything" together, well, you can but it will be a bit noisy...