Charging multiple 12V batteries

[rigi36]

Hi.

I have a tray of 10 x 12V 7Ah batteries connected in parallel.

They are these I think: http://www.amazon.co.uk/Yuasa-NP7-12-le ... roduct_top

I am looking for a mains battery charger to charge the whole lot in one go.

What would you recommend?

Thanks.

[Richard]

Not usually a good idea to charge multiple batteries together without some form of individual current sharing (if in parallel) or individual voltage regulation (if in series). Probably better to use the correct charger and just do each one separately.

[piratepaul]

They will be OK in parallel, thats a 70 Ah 12V battery, a large car battery... À bigish battery charger ... Depends how fast you need to charge them... 10 amp car charger may be.

[Richard]

Don't forget to allow for fault conditions. One of the batteries could develop an internal short in one of its cells, and then that would unbalance a set of batteries in parallel without some form of individual current sharing.

[piratepaul]

What you say is true Richard,but as long as they are all the same they will give no probs, the weakest one will drain the rest, but that diference should be mV if the charger raises the voltage by a few more mV the will all charge, as long as they are charged regularly ...no probs.

[Richard]

It’s not quite bas easy as that. Battery charging is a rather complex matter, and batteries should be treated with respect in view of their very low internal resistance and their ability to source very large currents (100s of amps in the case of vehicle batteries). Battery characteristics which can be normally ignored in general use may become of importance when they are paralled. Such matters as the ambient and internal temperatures, state of charge, manufacturer, age, and type of construction will all have an effect on terminal voltage.

If two or more batteries are to be charged in parallel, then the least that should be included is an individual current distributing resistor in the feed to each battery, and probably a series diode as well to guard against internal shorts or the connection of a completely discharged battery among an array of more fully charged ones.

[piratepaul]

Don't forget the safety goggles ,protective footware and lucky rabbits foot and of course fire extinguisher... an expensive gas detector a must..
It will be fine, a 10 A charger will not put out 100's of amps, they will all charge at less than 1 A each.
Swallowed the text book Rick.

Tar&stuff.

[Richard]

I no longer have the slightest wish to contribute to this thread. You have completely misunderstood the points I have been making - so you charge your batteries as you think fit.