Hi From the Desert

[jerrywc]

Hello Friends,
I have been living in my bus for about 15 years. This is where I am now for the winter.

I have 8 200 AH 12 volt AGM batteries for 1600 AH. 1580 watts solar, 3000 watt 12 volt ProSine sine wave inverter/120amp charger, 2 outback MX60 charge controllers. My first set of bus batteries were Trojon L-16's, they lasted about 12 years before they started dying, I replaced them with 200 amp 12 volt AGM's.
I'm now thinking about Lithium batteries. Besides all the obvious reasons, I would save over 800 lbs..
I've spent most of the last 25 years living with lead acid batteries an solar panels boondocking mostly on the beach in Mexico. So for me, it's a new way of thinking.
My plan is for 16 280 AH LiFePO4 cells with BMS.
I need to decide the best way to layout the cells for 12 volts or do I even have a choice. Input from my solar panels are about 50 volts.
Also, The right BMS for the job. This is a little bit foggy.
Thanks for all the info here and thanks to Will for the videos.
Jerry Campbell

 

[snoobler]

Welcome to the forum!

8 * 200Ah * 12V = 19,200Wh, half of which is usable = 9600Wh

16*280Ah*3.2V = 14,366Wh, 80% of which is usable = 11,469Wh

So a 19% improvement in usable capacity. Somewhere around 500# weight savings.

It seems you're locked into 12V since you have a 12V inverter, so you'd have 4X 4S batteries, each with its own BMS (overkillsolar). That would allow for redundancy should a battery have an issue and up to 400A/4800W discharge. Also, order 1-2 extra cells to avoid any issues with the original shipment and to have spare cells in the future.

Download the PDF concerning top balancing from the Resources section. Digest it and plan to do this. Also plan to test the cells either individually or as 12V batteries using your existing system to load them and measure their capacity.

Assuming 18 cells as spares and 4 BMS, looking at about $2500.

 

[HRTKD]

That's a sweet setup Jerry! My DIY LiFePO4 batteries replaced my Trojan T-105's.

I agree with using the Overkill Solar 4s 120 amp BMS. I'm using two of them.

The only downside to LiFePO4 in an RV is that they don't like to be charged below 32° F. If you're always down south, then it's not really a concern.

 

[jerrywc]

Thank You for your comments, I appreciate the info.
That clears things up a bit.
I live in my bus so 32deg is not probable.
Jerry