I'm currently fine tuning our charging system for our 800 A-hr AGM
bank: a Magnum Energy MagnaSine 2800 inverter/charger (125A charger), a Balmar
190A dual-output alternator
with a Balmar
MaxCharge MC-612 regulator
, and an Iota DLS-75/IQ4 charger. The chargers are driven by either a Westerbeke
7.6 BTD genset, or 2 x 30A/125V shorepower connections.
I haven't run the engine alternator
simultaneously with any of the chargers. But I can say that while bulk charging - with almost identical charging profiles - I've seen the Magnum's battery monitor
register as much as 179 Amps going into the battery bank. Without detailed testing, I can't confirm (but I do expect) that if the bank was discharged more deeply, I'd see the full output of both chargers when in bulk mode - 200A.
Since the two chargers aren't synchronized, I shut down one once either goes into the absorption phase. Since absorption is voltage-limited (14.5-14.9V @ 77°F/25°C for our Fullriver 6V AGM
bank) and typically the currents are less than 75A, I usually just shut off the Magnum charger. And it appears that the Iota charger, with its PWM charging technology, can actually maintain a higher current
output into the battery bank for a longer period, reducing the time it takes to get the SOC to 100%.
Of course, all that's moot when you're on the hook and don't want to run the genset for hours to ensure a full charge. And we do have a wind generator
(SWWP Air Breeze Marine), but it typically goes into regulation early in the absorption phase.
One problem I have seen (and I'm starting to work with Magnum Energy's tech support on this), is that when on shorepower, unless the charging voltages of the MagnaSine and the Iota DLs are matched, the MagnaSine will actually switch to invert mode (stopping charging), even though the AC input is still well within spec for a 125V/30A service
. What's got me scratching my head
is that the MagnaSine is running off one 125V/30A shorepower service
, and the Iota is running off the other
I've got it tweaked to where it doesn't happen anymore, the the problem seems to a bit more pronounced when running off the genset (which also has two 30A service legs).
I know this has wandered off topic a bit, but my main point is that when a bank is depleted enough, charging from two unsychronized charging sources is one way to quickly get the bank through the bulk charging phase.