Community Forums

manowell · 01-22-2019, 09:34 AM

This my be so hard it would be ridiculous to try to do it, but if I had a string of two deep cycle flooded lead acid batteries and a string of two LiFePo4, I can see how easy it would be to run off both.

Is there a device in retail existence today that would let me run down the former to 50% SOC while running the latter down to 80% SOC? And then charging the former at the charge rate it can take and the latter at the much higher charge rate it can take?

This is mostly an exercise for me, not saying I'm about to go to it.

The obvious attractiveness to me is that I've already got two deep cycle lead acid in a place that would be very problematic (dimensions) to put LiFePo4, and I have a good place to add the latter to an interior compartment that would be more temperature stable. But not room for four there, and not wanting to spend for four.

Itinerant1 · 01-23-2019, 03:05 AM

When or if the time comes push all the chips in and just get lfp and ditch the lead.
I have seen threads on forums that will keep a lead battery for starting the engine and lfp for house loads but not like how you ask. Never paid to much attention to that set up seeing it's not needed in a 5th wheel. Weight lose of a large battery bank is more important, my 500ah of lfp is 143#. I would think a comparable amount of usable "AH" lead/ agm would be 400-500#. In a class A you might not be to worried about that.

C.Martin · 01-23-2019, 06:08 AM

Just having to have two separate converters for the different charge parameters basically negate any advantages you could create. I see way more pitfalls than advantages. I know it’s not always possible,,,but this is one area where the K.I.S.S. principle is a good thing. Keep It Simple...

If you wait...

https://ieeexplore.ieee.org/document/7937853

twinboat · 01-23-2019, 08:32 AM

You could cobble something together with 2 auto generator start controls and a few solenoids. Set each AGS for your target voltage.

When one AGS sees low volts, it signals one solenoid to open and the other to close thru small relays. The second AGS could sense the second battery banks low volts and start the generator.

Charging can switch it back to battery A, with a battery combiner, voltage sensing relay, set at 13.4 + volts.

Then you need an automatic charger for each bank, to charge them both back up.

Not off the shelf, but a fun project.

**CountryFit** · 01-23-2019, 06:09 PM

Agree with Charlie, better stay KISS. Between FLP and flooded, choose one and make use of it.

manowell · 01-24-2019, 08:12 AM

Quote:

Originally Posted by C.Martin

Just having to have two separate converters for the different charge parameters basically negate any advantages you could create. I see way more pitfalls than advantages.

Basically confirms what I was guessing. Not what I want, but It Is What It Is.