Trouble searching.... DC to DC charger for larger battery banks
- Thread starter javajoe79
- Start date
DiploStrat
Expedition Leader
???
With the usual caveat to be sure that you really need a DC to DC charger ...
My 40A REDARC works well with my 600Ah battery bank and Sterling Power has models up to 100A.
In the end, the highest output is going to be a direct connection to a 200A+ alternator, again, assuming the correct voltages, no Euro low voltage weirdness, etc.
With the usual caveat to be sure that you really need a DC to DC charger ...
My 40A REDARC works well with my 600Ah battery bank and Sterling Power has models up to 100A.
In the end, the highest output is going to be a direct connection to a 200A+ alternator, again, assuming the correct voltages, no Euro low voltage weirdness, etc.
javajoe79
Fabricator
I guess I'm not good at google. I did look at the 40a Redard and it said it's for up to 200ah banks. I will have 425ah house batteries with solar. I wonder why they rate them at 200ah if they can work on much more than that. I also don't know enough to know why the battery bank size would matter. Is it just because a huge battery bank would take forever to charge?
javajoe79
Fabricator
It is my understanding that it is the best approach to maintaining different battery banks using only DC power.
DaveInDenver
Middle Income Semi-Redneck
I think you may be perhaps reading it wrong. Redarc recommends the 40A BCDC1240D specifically for banks over 200 A-hr and the smaller BCDC1225D 25 A for for those under.
https://www.redarc.com.au/dual-input-40a-in-vehicle-dc-battery-charger
"As a guide, the BCDC1240D is used for battery bank sizes over 200AH. For smaller batteries of 75-200AH REDARC recommends the BCDC1225D."
The charger's instantaneous current capacity is independent of the bank size. You could use a 5 A charger with a 1000 A-hr bank in theory if you gave it enough time to charge. But there's a practical matter that you need a charger large enough to bulk charge a battery in a way that prolongs its life and does so in the few hours of sunlight you might have each day.
There's no reason you can't use a 40 A charger with a 400 or 600 or whatever amp-hour bank, depends on the depth of discharge and time you routinely have. You're probably not going to hurt it, it'll shut down if you exceed the duty cycle and over heat it pushing it too hard.
https://www.redarc.com.au/dual-input-40a-in-vehicle-dc-battery-charger
"As a guide, the BCDC1240D is used for battery bank sizes over 200AH. For smaller batteries of 75-200AH REDARC recommends the BCDC1225D."
The charger's instantaneous current capacity is independent of the bank size. You could use a 5 A charger with a 1000 A-hr bank in theory if you gave it enough time to charge. But there's a practical matter that you need a charger large enough to bulk charge a battery in a way that prolongs its life and does so in the few hours of sunlight you might have each day.
There's no reason you can't use a 40 A charger with a 400 or 600 or whatever amp-hour bank, depends on the depth of discharge and time you routinely have. You're probably not going to hurt it, it'll shut down if you exceed the duty cycle and over heat it pushing it too hard.
Joe917
Explorer
What will your batteries accept? How much solar will you have? What will your loads be?
Our Magnum puts out 125 amps, too much for our 470AH lead acid bank, so we dial back the max amperage.
Our Stirling B2B puts out 40 amps, great for bulk charging while driving if necessary.
630 Watts of solar take care of full charging most of the time making the other two chargers back-ups.
Point being, your set up is a mix of charging sources, no one stop solution. Unless you go lithium you will not be using the full power of your charger most of the time.
Our Magnum puts out 125 amps, too much for our 470AH lead acid bank, so we dial back the max amperage.
Our Stirling B2B puts out 40 amps, great for bulk charging while driving if necessary.
630 Watts of solar take care of full charging most of the time making the other two chargers back-ups.
Point being, your set up is a mix of charging sources, no one stop solution. Unless you go lithium you will not be using the full power of your charger most of the time.
Only necessary for GEL.
NP for AGM or FLA no matter what the maker says.
But of course higher than CAR's self-regulating anyway, just saying. . .
DaveInDenver
Middle Income Semi-Redneck
He didn't say he was using AGM house batteries. You have to be aware of charging voltage and current with AGM if you don't monitor charging temperature. If you overheat and burp gas it's impossible to put the genie back in the bottle. With flooded you can check gravity and add water if you overheat them.
The benefit to a DC-DC charger is that voltage drop on the supply side becomes unimportant. It's transferring power. So long as you don't exceed the safe limit for the wires you could be down a couple of volts at the end of the supply and be drawing significantly higher current. It'll still be supply 40A over the intended voltage profile to the battery under charge.
The benefit to a DC-DC charger is that voltage drop on the supply side becomes unimportant. It's transferring power. So long as you don't exceed the safe limit for the wires you could be down a couple of volts at the end of the supply and be drawing significantly higher current. It'll still be supply 40A over the intended voltage profile to the battery under charge.
Joe917
Explorer
Our batteries will accept the whole 125 amps in bulk. The Rolls Surette Tech told me to keep the max charge rate to 45 amps per string to maximize battery life. I'll go with the battery manufacturer's advice.