Charging batteries with a DC-DC converter

[john61ct]

I would then just put in heavier wires, no voltage conversion needed.

If at all possible, eliminate the dedicated thruster batts, add that AH capacity to a consolidated House bank, much more overall capacity via Peukert, shallower cycling, longer lifetime overall better value for money spent.

Not telling you (specifically) what to do of course but from a general design POV...

[Adrian Chen]

Originally Posted by john61ct

I would then just put in heavier wires, no voltage conversion needed.

If at all possible, eliminate the dedicated thruster batts, add that AH capacity to a consolidated House bank, much more overall capacity via Peukert, shallower cycling, longer lifetime overall better value for money spent.

Not telling you (specifically) what to do of course but from a general design POV...

Sure you could do that, unfortunately the builder had selected 12v thrusters, and put in the local banks, even so to get decent performance these are wired with double 120mm sq cables with around 610amps draw (when props are clean) and voltage at 11.3v they work well, cable run I guess is 1.5m. Not sure what cable would be needed to consolidate the bank....

Best would have been 24v thrusters (or 48v) then much easier but that wasn't what they did.

Still in consolation, at least if I have run down the domestics, the thrusters still work well!

[magentawave]

Originally Posted by mikedefieslife

Was looking at the Victron Orion range of DC to DC converters, and noticed they mentioned battery charging as a potential use. This wasn't why I was looking, but it did get me thinking. Anyway;

As I understand it, the 12v DC-DC converter can output a voltage up to 25% higher than the input voltage. Theoretically then you could charge an AGM battery from a 12v FLA, however since it's not a charger, it doesn't have charging curves or profiles, nor a temp sensor, or cut in/out.

Is an AGM going to be happy being supplied with a constant/fixed voltage, and what is there to stop over-charging?

There's a guy on a survival forum that made his own gas powered DC battery charger very inexpensively to charge his batteries on days when there's not enough sun for his solar panels.
My home made battery charger for my battery bank, when my solar won't do the job. - Survivalist Forum
and
My homemade battery bank, what do you think? (Pictures) - Survivalist Forum