Toyota Sunrader Solar charger

[Imatraveler]

Hi. I have a 1983 Toyota Sunrader with a Sure Power Systems 702 battery isolator. I would like to wire in a small trickle charger to maintain both battery banks when it is sitting. I’ve just replaced the lead acid deep cycle battery with 3, 12 volt, 100 ah Lifepo batteries. My question is, can I wire the Solar charger to the alternator post on the battery isolator? Thanks in advance, Jim.

 

[fratermus]

can I wire the Solar charger to the alternator post on the battery isolator?

The solar charge controller

* sends charge to the battery, and
* pulls power from the battery for the controller's own needs

I suspect the 2nd part won't work because the diodes in the isolator will prevent the controller from getting power from either battery to run itself.

I would like to wire in a small trickle charger to maintain both battery banks when it is sitting

I don't see a way to do that with the existing isolator. Are you determined to keep it?

The simplest solution is to tie the small solar system only to the starter battery.

A "trickle charge" panel wouldn't make much of a dent in 300Ah of Li and Li doesn't need to be trickle charged anyhow. If you are still committed to the idea of trickle charging both the cleanest solution might be to replace the isolator with a small DC-DC charger with integrated solar charge controller and starter battery maintenance. Ctek, or maybe a Renogy DCC30 (with the current turned down?). About $200. The least expensive solution would be a voltage-sensing relay, but I'd be concerned with how a 1983 Toyota alternator would cope with 300Ah of Li.

Hopefully onlookers will have better info or creative workarounds.

Digression: how much current is the 300Ah bank pulling through the isolator now? Do you know the amp rating of the existing alt? Is it OEM?