I have an Orion isolated dc to dc charger with 12 volt input coming from my AGM engine battery and output going to a 12 volt lithium house battery. I‘m adding another isolated lithium house battery and I’d like to charge them both simultaneously from the dc to dc charger. Would the Argofet battery isolator be a correct solution? The product description states it will work off one dc charger, but I don’t see any documentation with a dc charger included?
What do you mean by isolated for the second lithium?
The lithium batteries are identical and from same manufacture. They‘re on a sailboat and both are connected to a DC Parallel panel where they can be combined or separated to feed the house circuit. The desire to keep them separated is that we’ll be blue water sailing (1,000 miles off shore) and we’d like to always have one fully charged house battery ready to go while recharging the other or both at the same time.
Whatever the Argofet battery isolator is doing, it probably isn't doing what you want/need for an 'optimal' solution, assuming I am understanding your proposed setup properly...
Looking at the spec/description the unit appears to behave like 3 'ideal' diodes, which is a cool concept and a product I didn't know existed, that will likely be useful.
In a situation where your goal is to supply a maximum voltage, from a current limited source, and let the batteries internal BMS handle charge cutoff I see no reason why this wouldn't work, although differing pack size and SOC will cause the larger, and or, more depleted pack to grab most of the available charge current. Additionally the maximum charging current would have to be set to the maximum current of the smallest pack to ensure that when it was the only pack charging that it wasn't being stressed.
If you are trying to control the charging algorithm of both/all packs, to optimize the battery life, you need two chargers.
I am running a pack of Ultramax Lithium batteries and asked Ultramax to comment on using a constant voltage current limited supply for charging, as opposed to anything intelligent.
They said that most of their chargers did exactly that, being set to the max bulk voltage, and that the internal BMS would stop the charge, pulsing occasionally, once the battery was full.
I would recommend asking the battery manufacturer to comment, as not all BMS's are created equal, before making a decision and then consider your system performance goals IF the strategy is a possibility.
