Splitting up the batteries and charging

Vintage465 wrote:
Gordon Three and Drew,
I've noticed when the heater is running on a cold evening, then we have a couple lights on and turn on the water, the lights dim and the heater fan slows. This would leave the heater alone when we mess with other 12v draws. Also, on a real cold night, say 20-30 degrees and the heater cycles through out the night and pulls the battery down to say 40%, I will wake up to nice bright lights and easy running pump. Really that's the whole idea.

Based on what you describe, something is wrong beyond the size of the battery bank. Nothing you describe should overwhelm a charged bank to the point that the batteries dim.

One possibility is your current bank is near the end of it's life. If you are regularly pulling it down to 40% (or more), that's hard on the batteries.

Another possibility is bad wiring or connections. Under light loads it's OK but when pushed a little bit, the corrosion on a bad connection limits the amps that can flow and you see diming as the various loads compete for the limited amps.

A single house battery bank is generally best. Google the peurket effect. A single large bank can absorb more power more quickly and will allow greater overall discharge compared to two smaller banks of equal overall size. The exception would be if this is a MH and you want to keep the engine starting battery independent, so you can always start the motor.

First step would be to check the batteries.
Next would be to pull the connections apart clean them and put them back together.

One catch particularly if you have been hard on the current batteries is if the new ones are in any way connected, the old ones will try to constantly pull power off the new ones. It's best to install battery banks at the same time.