48v Lifepo4 pack charge 12v lead acid

[georgia088]

I read some places where this will work ok and others where it will not. Can I use a dc converter that converts my 48 nominal lifep04 battery pack to around 13.7v and connect that to a lead acid battery to maintain a charge. Will this work? I am sure that a charge controller is "better", but for a budget system will this work ok?

Thanks!

 

[sunshine_eggo]

Yes. I don't know that I've seen one at 13.7V, but there are a lot on Amazon for 13.8V, which is a typical GEL/AGM float value.

Fuse both sides.

Example (not an endorsement):

Amazon.com: uxcell Voltage Converter Regulator DC/DC DC 48V to DC 13.8V 30A 414W Power Buck Transformer Waterproof : Electronics

Buy uxcell Voltage Converter Regulator DC/DC DC 48V to DC 13.8V 30A 414W Power Buck Transformer Waterproof: Power Converters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[RvNaut]

I have a setup in my RV where I use a Victron 4812/30 converter connected to a 12v deep cycle to power the 12v side of my RV. I have it currently set to 12.9v, but am considering upping that to 13.3v

 

[sunshine_eggo]

I have a setup in my RV where I use a Victron 4812/30 converter connected to a 12v deep cycle to power the 12v side of my RV. I have it currently set to 12.9v, but am considering upping that to 13.3v

Lead acid batteries should be held at their published float voltage. 12.9 is definitely too low. The lowest float I've seen is 13.2V. Most are 13.5-13.8V.

 

[georgia088]

So, a 13.8 output from dc converter would be ok for a lead acid AND AGM battery? Or, would 13.8 begin to boil the water out of a lead acid battery?

Thanks for the input guys!

 

[sunshine_eggo]

So, a 13.8 output from dc converter would be ok for a lead acid AND AGM battery? Or, would 13.8 begin to boil the water out of a lead acid battery?

Thanks for the input guys!

AGM is lead acid.

I assume you mean flooded lead acid, FLA.

For FLA, a float of 13.8V would encourage accelerated electrolyte loss, but you should be checking and replenishing with distilled water regularly, so it's a mixed bag.

Best option is to float at the manufacturer's specification.

12.9V is below any manufacturer's specification.

 

[georgia088]

Thanks, Yes, I meant FLA. I am going to give it a shot. 13.8 output with an FLA battery and keep distilled water in it. Thanks

 

[HarryN]

A DC - DC converter is not a charger.

If you want to really properly "charge" the 12 volt battery, then you will need to use a true "multi step charger".

If you don't really care about the lifespan of the 12 volt battery, then you can just use a DC converter and the battery is essentially just a buffer.

For batteries that only cost $100 - 200 it might not be worth to chase down a true charger.

For a $500 each, 12 volt battery, then use a proper DC - DC charger.

 

[sunshine_eggo]

For a buffer battery or a battery that's lightly cycled, a 13.8V float is more than enough to maintain its health. In low utilization circumstances, it's arguably better for the battery vs. regular 2 hour absorption cycles following shallow discharges.

 

[wopachop]

Do you already have a car battery charger? For a super budget approach you could plug that into your inverter to charge your 12v.
I do that for a generator starting battery that rarely gets used. I don't leave it permanently hooked up.