Can current be limited from RV power converter (55amp) to BMS (Max chg 40amp)?

hpd611

New Member
Thank you for taking the time to read about my issue. I'll do my best to keep it short. I built a LiFePo4 battery, utilizing 4 120ah 3.2v cells, and an 80amp Daly smart BMS. I have learned, thanks to all of you, and completed the top balance charging and I have a pretty good history of experience with DC projects. Here is my oversight that I have a question about. My RV where I'm utilizing this battery has a 14.6 volt 55amp power converter (voltage adjustable). I didn't realize that this 80amp BMS will only charge at 40amps. This causes the BMS to understandably error out over and over. Is there a circuit, a way, or a device I can put inline to reduce the current to say 35 amps max reaching the BMS? I searched and couldn't find a post addressing this, so if I've missed it I apologize.

I am considering connecting two of these buck converters in parallel coming off of the power converter, then adjusting the voltage to stay at 14.6, but regulating the amps to between the 35 and 40 amps I need. Any thoughts?

Diymore 2pcs 20A 300W CC CV Step Down Module Adjustable DC 6-40V to 1.2-36V Voltage Regulator Buck Converter Constant Current Power Supply Module​

Amazon Link to Buck Converters

Thanks again for all of your help. As I learn more I will be sure to pass on the favor and good will that you've shown me here!
 
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ed209

New Member
It probably would work, but you might be better off with a PWM charge controller if you can adjust the voltage.

The better solution is to use a DC-DC charger meant for charging from an alternator. The newer ones have built-in isolators that will automatically stop charging, so you never have to manually disconnect.
 

hpd611

New Member
It probably would work, but you might be better off with a PWM charge controller if you can adjust the voltage.

The better solution is to use a DC-DC charger meant for charging from an alternator. The newer ones have built-in isolators that will automatically stop charging, so you never have to manually disconnect.
@ed209 Thanks a bunch for your reply. This is exactly the type of thing I was looking for. Obviously I know that I can buy a unit with smaller output, but I was hoping for a fix on the component level or close to that. I think I have it figured out, but will see how it goes. Thanks again for your time and thoughts!
 
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