I have a Multiplus 12-3000-120, about 2 years old, installed on a sailboat. In general, it's a great inverter. I especially like being able to limit incoming power, as I often use a 15A shore power connection.
My issue is getting the thing to charge. Classic chargers go through a three step process -- Bulk, Absorption, and finally Float. Classic chargers aren't very smart, so they simply start off in Bulk. Even my SmartSolar appears to.
The problem is that the inverter tries to out think itself. If I connect to shore power with my 800Ah AGM bank down 150Ah (about 80% SOC), it goes to float. Even at float, I'm putting in 30A into the battery! If I start my engine, my alternators go to Absorption, and put 120 to 150A into the battery. This is very frustrating when I have an opportunity to get shore power for an hour or two and want to charge them at Absorption voltage (and rate!).
The problem was even worse when I had "Storage" enabled -- sometimes I'd connect to shore power at 90-95% SOC, and it would go to "storage" and never even get charged! I've disabled that, which has helped a lot, but I really would like to have it work -- when on shore power for weeks at a time, it makes a lot of sense.
I could enable the option to automatically initiate Absorption daily, but that is not really appropriate for extended time on shore power.
A serious problem with the smart algorithm is that the inverter has ZERO awareness of the battery. It has no idea of the battery capacity, so it doesn't know tail currents. It has no idea of battery SOC, so it will happily go to float with a battery down 20%. It has no awareness of other loads, so it can't tell if the 20A it is putting out is charge current or load current. A fixed charge routine is "dumber" but given the lack of input data, it is the "smartest" solution!
Is there any way to dumb this down a little? Force it to always go to Absorption for an hour every time shore power is connected? And if you could make "Storage" a little more logical, I'd love to reenable it.
My issue is getting the thing to charge. Classic chargers go through a three step process -- Bulk, Absorption, and finally Float. Classic chargers aren't very smart, so they simply start off in Bulk. Even my SmartSolar appears to.
The problem is that the inverter tries to out think itself. If I connect to shore power with my 800Ah AGM bank down 150Ah (about 80% SOC), it goes to float. Even at float, I'm putting in 30A into the battery! If I start my engine, my alternators go to Absorption, and put 120 to 150A into the battery. This is very frustrating when I have an opportunity to get shore power for an hour or two and want to charge them at Absorption voltage (and rate!).
The problem was even worse when I had "Storage" enabled -- sometimes I'd connect to shore power at 90-95% SOC, and it would go to "storage" and never even get charged! I've disabled that, which has helped a lot, but I really would like to have it work -- when on shore power for weeks at a time, it makes a lot of sense.
I could enable the option to automatically initiate Absorption daily, but that is not really appropriate for extended time on shore power.
A serious problem with the smart algorithm is that the inverter has ZERO awareness of the battery. It has no idea of the battery capacity, so it doesn't know tail currents. It has no idea of battery SOC, so it will happily go to float with a battery down 20%. It has no awareness of other loads, so it can't tell if the 20A it is putting out is charge current or load current. A fixed charge routine is "dumber" but given the lack of input data, it is the "smartest" solution!
Is there any way to dumb this down a little? Force it to always go to Absorption for an hour every time shore power is connected? And if you could make "Storage" a little more logical, I'd love to reenable it.
