[jevonmorris]

Hey I have seen on the internet guys saying they are using multiple chargers (so each battey has its own charger) on motorcycles (6 ) and in cars (28). My questions is how exactly is this wired? It did not seem they were breaking the series.
If I have (4 )12 volt batteries in series and I wanted to use (4) 12 volt chargers would'nt I have to disconnect the series so I would not create a short? The positive from the charger to the positive of the battery, which is inturn connected to the negative of the next battery. Someone please clarify this for me.
Thanks

[mk4gti]

Was using 6 12v chargers in a 72v system. chargers are not in series, they work independently from one another. Not all chargers support this, however. I was using duracell 12v, 12A chargers and it was charging my 12 batteries in 8 hours.

[GizmoEV]

You don't have to break the battery string but you need to use isolated chargers.

[Duxuk]

I added an extra battery to my 48V scooter which I charge with a 12V Ctek charger whilst charging 4 batteries with the OE 48V charger. I do turn off the circuit breaker whilst charging but it make no apparent difference.

Everything seems fine.

[jevonmorris]

Ok I now realize that It can be done with isolated chargers. Does anyone know how to find out if a charge is isolated or not? I have not really seen anything in the info online or on the boxes in the stores that says if a particular charger is isolated or not.
Thanks

[dougingraham]

Originally Posted by jevonmorris

Ok I now realize that It can be done with isolated chargers. Does anyone know how to find out if a charge is isolated or not? I have not really seen anything in the info online or on the boxes in the stores that says if a particular charger is isolated or not.
Thanks

Lets see. Plug a charger into a GFI protected outlet. Connect the negative output to the wiring ground wire. If the GFI pops it isn't isolated. Repeat for the positive output.

If you have two of the chargers you can plug them in and then measure for DC voltage between the positive output on one unit and the negative output on the next one. If they are isolated you wont see any voltage, DC or AC. If you hook them together and they aren't isolated you will see sparks and most likely blow a breaker somewhere.

Ive never seen a 12V automotive battery charger that wasn't isolated. That doesn't mean they don't exist, I just have never seen one. And if I was a manufacturer I wouldn't sell one that wasn't isolated.

[PStechPaul]

A less dramatic way to check for isolation is to connect the (+) of one to the (-) of the other, using a small 12V lamp. If it lights, they're not isolated. But in that case (which would be unusual and dangerous), you could use several isolation transformers.

The problem with reading voltages using a modern DMM is that they have very high input resistance and can pick up voltages due to capacitance and normal leakage resistances and even inductive coupling.

As an addendum:

If the chargers are not isolated they will share a common connection to AC neutral. So there will be 12VDC from the positive output of one to the negative of the other.

You still need to be careful. If the chargers do not have polarized plugs, it's possible to have 120VAC between the outputs of the chargers. So you might use a neon indicator first.