lml@lancaironline.net Mailing List Archive

Marv built a simple rig to do exactly that with my Battery Tender and dual battery system. I bought a cheap plug-in light timer. That drives a simple relay. The battery tender feeds the common ground and the hot input for the relay. For 12 hours the Battery Tender looks at one battery, then for 12 hours the other. It's all stuck in a small plastic case, and we use a three-prong non-reversible plug. The case, relay, and plug were about $5 at our local surplus outlet, and the timer was about $12. The work was more expensive than the parts.

Ted Noel

----- Original Message -----

From: Jim Scales

To: lml@lancaironline.net

Sent: Monday, January 07, 2008 12:29 AM

Subject: [LML] Battery tender

I want to install wiring to my batteries so that a Battery Tender can keep them topped and ready during cold weather.

I have a dual battery 12-volt system with the batteries charged by one alternator through an isolator. There is a master toggle that allows me to choose one or the other to be the battery used by the plane at any particular time. The system works very well.

I want to be able to keep both batteries topped without having to change the tender from one to the other.

It would seem that hooking the tender to the center pole (alternator input post) of the isolator along with the common ground would accomplish this purpose. However, I do not pretend to have even a rudimentary understanding of the electrical system, so I would like some input from the list members as to what would be the proper wiring plan.

Thanks,

Jim Scales