Balmar Duo Charge Questions

[TxCoastSailor]

I use a Duo Charge to charge my starter battery from the house bank. Currently have it programmed to 'Gel' since the starter battery is a gel. Seems to work OK but I am about to change the starter battery to an AGM and may want to modify the 'lower' and 'upper' voltage limits.

Problem is that these terms are never defined in the manual. My assumption is that the starter battery is charged when the house battery is above the 'lower' voltage AND the starter battery is below the 'upper' voltage. Otherwise the charger shuts down and isolates the starter battery from the house battery.

Am I correct? Does anyone know for sure?

Contacted Balmar with this question by no reply. Their documentation is poor and they don't seem to care about customer service. Maybe time to find another solution.

[TxCoastSailor]

Well I did at least get an automated reply from Balmar technical support. We will see if they actually provide any useful information.

[Bycrick]

I usually had good luck with Balmar support, although sometimes it wasn’t as easy as I might have wished. Maybe COVID problems now. But I’ve heard that Victron is recently selling a DC-DC charger that appeared at a very superficial glance, to do much the same as the DuoCharge. It might be worth a look.

[TxCoastSailor]

Well I stand corrected about Balmar support. They actually called me.

My assumptions about how the Duo Charge works were confirmed.

I did learn something I hadn't realized before and that is that the Duo Charge can only step down voltage, it cannot step up. So the starter battery voltage will always be a bit lower than the voltage on the house bank. So if both banks are AGM it seems like the starter battery will always be a bit under charged.

[Stu Jackson]

Originally Posted by TxCoastSailor

>>>>>>>>>>>>>> So if both banks are AGM it seems like the starter battery will always be a bit under charged.

Not necessarily. A start bank rarely gets depleted more than 1-3 ash per start. Just because the V is a tad lower just means it will take longer to replenish what you take out. Not an issue, 'cuz the charging V is still way above the resting V.