Quote Originally Posted by Corker View Post
Let's back up to your basic plan before solving the charger puzzle. Parallel hookups are not the best way to use your two batteries. As ReelMan points out, batteries charge and discharge at different rates--even a pair of identical batteries purchased at the same time.

It's true that hooking a pair of batteries in parallel lengthens your TM's running time but that's all you get. A two-battery parallel bank doesn't increase the TM's power. What you don't see happening (but will eventually learn from experience) is that the stronger of your two batteries will charge the weaker one. On the water, that means a bank will deliver less run time than the sum of the individual batteries.

A better plan is to hook your batteries to an A/B/Off switch. Start your day switched to the weaker of the two batteries and run it down to a safe voltage--a level that will not do permanent damage to the battery's plates, probably 12.00v. Then switch to your other (fully-charged) battery for the second half of the day. Doing it this way, you can squeeze every useable amp out of your batteries & protect them in the process.

Now, we come back to your original question. With an A/B/Off switch in place, two banks of your charger can be hooked to the batteries without concern. Should you choose an A/B/A+B/Off switch, you'll want to set the switch to any setting except A+B while you charge.
This is very good info. I had wondered if my run time would actually double or not. My initial thoughts were that I can usually make it all day on one battery. So, by adding the extra, it would be a sure bet. So, let's talk about maximizing!

I know that the extra battery can't deliver more power, but what happens when you start to lose to battery power? For instance, on days I pull cranks or when I'm facing a strong wind, I'll have to increase the speed setting to account for the draining battery as the day goes on. If it were in parallel, I would be carrying a higher voltage level over a longer period of time. Shouldn't that increase the overall run time? I've got no problem installing a switch or disconnect, or disconnecting the parallel connection. I'm just wanting the most effecient, and safe, way to this situation.