Since I switched my house batteries to Battle Born LiFePo4 batteries, I had to remove my combiner, which kept my chassis battery topped off from my solar panels. This means that the chassis battery discharges slowly due to parasitic draws on it. I guess I could just disconnect it when I am not using the coach for a while, but I'm thinking a solar battery maintainer would be a better bet.

In researching the options, I see they come in sizes anywhere from a few watts to 20+ watts with MPPT controllers etc. Prices vary accordingly. The question is, how many watts should I be looking at in order to keep the battery topped off? Any recommendations would be appreciated.

Carl S. wrote on Sat, 06 August 2022 12:41

Since I switched my house batteries to Battle Born LiFePo4 batteries, I had to remove my combiner, which kept my chassis battery topped off from my solar panels. This means that the chassis battery discharges slowly due to parasitic draws on it. I guess I could just disconnect it when I am not using the coach for a while, but I'm thinking a solar battery maintainer would be a better bet.

In researching the options, I see they come in sizes anywhere from a few watts to 20+ watts with MPPT controllers etc. Prices vary accordingly. The question is, how many watts should I be looking at in order to keep the battery topped off? Any recommendations would be appreciated.

Carl,
To keep a battery like our main engine starting battery alive with the typical parasitic loads takes something like 3 watts. I used to do this for one of my cars. VW did this for the cars in holding lots and that is where the panel I got came from. It worked great until I got the space in the barn cleared. (I'll let you guess what happened there.)
Matt

G'day Carl.
We switched over to lithium batteries about 18 months ago. We already had a Victron Multiplus which has an option to monitor and charge a second battery (chassis)up to 8 amps and also has an option for maintaining Lithium batteries.
Our solar panel controller is a cheapish chinese one, but allowed us to lower the voltage charge rate to suit the lithium batteries.

For added peace of mind we also installed a Victron battery monitor, which has a battery cut-out. Both the monitor and the Multiplus has Bluetooth capability so you can monitor both units and receive alarms on your mobile phone.
It took a couple of camping trips, having to lower the solar controller charge voltage again, but all works well now. I'm still contemplating changing the solar controller to Victron as well.