Draw power from one of two batteries in series

[seemtorecall]

This might be an odd question, but I was wondering if you have two 12v sla batteries in series to supply 24v for one part in for example a preamp, and have another part that needs just 12v, could you with no problem draw 12v from just one of batteries
even though it is connected in series with another?

 

[Pano]

Yes, you can. Just remember that the battery with the largest draw will run down first.
Do you charge them in series, or in parallel?

 

[seemtorecall]

Thanks for the reply Pano, I charge them in series with a standard 24v charger, so I guess I need to make it so the 12v part is disconnected from the one battery when charging right?

 

[gmphadte]

Not necessary to disconnect if the 14.X volts is not damaging your load(12v part). However charging may differ for the individual batteries.

Gajanan Phadte

 

[sofaspud]

However charging may differ for the individual batteries.

If the 24V supplies a preamp, and the 12V supplies a power amp, the discharge will be significantly different between the two batteries. If recharged in series, the current required by the more-discharged battery will have to pass through the less-discharged battery. That is probably a situation to be avoided, as the charge current will continue well past the full-charge point of the one battery.
I would definitely do some research on the possible effects. Maybe a switching circuit or bipolar charge circuit could provide a workable solution.

 

[seemtorecall]

Sofaspud I hear you, as long as I stick to powering things like a relay or any part that draws a very low curren I shouldn't be in trouble connecting the part directly to one of the batteries in a series (given that the part can take the 14.x charge current as well).

 

[seemtorecall]

If the 24V supplies a preamp, and the 12V supplies a power amp, the discharge will be significantly different between the two batteries. If recharged in series, the current required by the more-discharged battery will have to pass through the less-discharged battery. That is probably a situation to be avoided, as the charge current will continue well past the full-charge point of the one battery.
I would definitely do some research on the possible effects. Maybe a switching circuit or bipolar charge circuit could provide a workable solution.

After reading about a bit, as you said it gets a bit more complicated, as it seems this tiny imbalance that will happen between the batteries will not be corrected when charging them in series, and so the difference between the batteries will only grow larger and eventually become a real problem over time and could result in overcharging...