advisability to turn off battery periodically

Won't "hurt" the battery, but will boil the electrolyte so you will need to constantly check and refill the water level. 13.6V will boil off water and if you fail to replenish it will boil the battery dry which is most likely what happened to your last battery.

If you are permanently setup and have zero intentions of ever moving the trailer you might consider just skipping a battery altogether as it is not needed in order for the WFCO converter to work. In this case the battery is more of a hassle and cost that isn't needed.

Modern converters do not need a battery to regulate and maintain 12V.

You will however be subject to having all 12V devices stop working whenever you have a commercial power outage, sort of like a sticks and bricks home..

If you might wish to move the trailer, of course you would need a battery to operate the emergency break away system..

You can of course disconnect the battery, but then you must remember to reconnect once every 3 to 6 months and allow the battery to fully recharge for a day.. Good chance you will eventually forget.

If you already have bought a replacement, you could see if they would take it back and get your money back if you do not plan to move it anytime soon..

Thanks. I am full-time living in the TT, and still wonder why when connected to shore power 100% of time, that it is good and/or I need to keep charging the battery. Since I am constantly using light, pump, etc., the WFCO will never go into storage mode, but will always stay in absorption mode.

My question is whether it is good for the battery to get hit with 13.6volts for endless months, or whether it is best to disconnect the battery as long as the battery is still well-charged.

Timeking wrote:
Had a cell die, and then the WFCO burned it to a crisp. Had to replace battery and the acid-laden case.

It seems there is little advantage (?) in keeping the battery charging ALL the time when connected to shore power. A fully charged battery measures 12.9 volts, yet the WFCO in 'absorption mode' is hitting the battery with 13.6 volts, as it was designed to do. Doesn't seem healthy to be continually running current through the battery, month after month after month, which I suspect can only increase gassing, and loss of water ... and bad cell and kablooey.

What might I be missing here?

When I turn the battery OFF, it does not get charging current.

The battery was shot and the issue was probably not the fault of the WFCO.

Either way the battery was bad. The WFCO did not kill it, turning the battery off would not save it.

Although the WFCO is notorious for not changing modes as expected. Might do better with replacing the converter.

Assuming you have the 8900 series I recommend the Boondocker MBA 45 amp

WFCO should actually be going into "storage" or "float" mode when no load draw has been present for a predefined period of time. Storage or float voltage is roughly 13.2V, not absorbtion which is higher than storage.

See HERE for WFCO stage voltages.

See page 7 HERE for more explanation..

A "bad" battery most likely will force the WFCO in staying in absorbsion mode especially in the case of a bad cell.

These converters measure voltage and current to determine what mode to go to and use a timer for each mode.

For detailed explanation you can go to WFCO Theory of Operation document HERE Page 2.

I quote "Float Mode-is third stage of converter operation. This mode is to provide a trickle charge to the battery. If converter observes no significant variations in current draw for approximately 44 continuous hours, it will drop the output of the converter from 13.6V to 13.2V..

..This lower voltage will keep the battery charged while the RV is not in use..

..A change in DC current will cause the converter to exit Float mode and return to default, or normal, Absorbtion Mode."


If you have things turned on like a fridge that may even be enough to wake up the converter and stay in absorbtion mode.. Turn everything off and wait 44 hrs and see if converter changes to storage.

Or as others have noted, too long or too light of wiring between converter and battery allows too much voltage drop which can cause WFCO converters to sort of hang up on switching stages. The fix to that is to replace existing wire from converter to battery with a heavier ga wire which reduces the voltage drop between them.

If you disconnect the battery, you will need to periodically remember to connect it and allow the battery to recharge for a day or so. That replenishes the "self discharge" that happens naturally with batteries.

Otherwise if you can determine and fix what is keeping the converter from going into storage you can just leave everything connected and the converter powered up 24/7.

You should be able to adjust the absorption mode voltage downward. With my old charger that was not possible and my batteries lasted 7 years when left hooked up at a constant 13.6 volts.

My opinion is to charge up, then disconnect for about a month and check them. And I don't mean the battery 'disconnect', I mean remove a cable.

I leave a car in the winter for 6 months with a disconnected battery and it starts right up.