Is discrete charging of series connected batteries OK?

Question

Is discrete charging of series connected batteries OK?

mudcrab (Automotive)

(OP)

15 May 09 03:42

I have a 24v 'house' system made up of a pair of 12 volt Lead Acid Auto batteries. I have a multi output 12v Victron marine charger.
Is there any reason why I cannot/should not hookup each 12v battery to it's respective charge input and keep it all running? e.g. continue to use the 24v system.
To my mind this is should be a better solution than a 24v charger covering the pair as it allows for the individual battery condition to be monitored by the charger. Am I missing something? Cheers, Paul

MikeHalloran (Mechanical) · Answer 1 · 2009-05-15 07:55:25

Read the booklet that came with the charger.
What does it say?

Mike Halloran
Pembroke Pines, FL, USA

mudcrab (Automotive) · Answer 2 · 2009-05-15 15:31:46

Manuals and website make no comment on this situation. I have not found any information specific to this idea. Cheers

MikeHalloran (Mechanical) · Answer 3 · 2009-05-15 20:42:02

You could meet us halfway and tell us the model of the charger... so anyone already familiar with it might speak up, or one of the dedicated crazies might read up on it and offer an educated opinion.

Mike Halloran
Pembroke Pines, FL, USA

mudcrab (Automotive) · Answer 4 · 2009-05-16 01:19:57

Sure Mike,
Victron Centaur 12v 20A. Manual can be found at this address.
http://www.victronenergy.com/manuals-per-product/?productid=151
It is the older model.

Cheers Paul

MikeHalloran (Mechanical) · Answer 5 · 2009-05-16 12:40:23

Nope, you can't do what you want.  On page 6:
"                  The -DC is used common for all
three batteries.   "

You need a charger that has a + and a - for each battery, and that specifically states that the outputs are isolated from each other.

Mike Halloran
Pembroke Pines, FL, USA

mudcrab (Automotive) · Answer 6 · 2009-05-16 15:42:18

Thanks Mike,
I can see the problem now.
That explains why using two 12v chargers has worked fine on the 24v bank in the past but the Victron will not. FYI. I do not own the Victron but had the option if the system was workable so will not take up the option.
So here is the question I am still seeking a clarification on.

Is charging discretely, no common ground, a good idea or better or worse than charging as a 24v bank?

Cheers
Paul

MikeHalloran (Mechanical) · Answer 7 · 2009-05-16 21:07:36

The ideal would be to charge and monitor each individual cell.. well, it would be if you could replace them individually.

From the standpoint of detecting incipient failure of one battery early, two 12V chargers with isolated outputs make sense.

If that costs a lot of money, or you replace the batteries on a time basis anyway, then a single 24V charger makes sense.

Mike Halloran
Pembroke Pines, FL, USA

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Is discrete charging of series connected batteries OK?