PV Gap

Wayne Said:

Using a trickle charger for car battery - can you drive with it while connected?

We Answered:

YES AND NO :) What kind of batteries?

Flooded batteries self discharge at 10% for the first day, and 10% every 30 days thereafter. Overcharging results in water loss, simply add water during maintenance cycle, no big deal. A TRICKLE CHARGER IS GOOD HERE.
http://www.rv-batteries.com/services.php

AGM batteries self discharge at 2% for the first day, and 2% every 30 days thereafter. Overcharging these batteries is really bad, you can't add water. So an unregulated trickle charger is bad in this scenario.
http://www.rv-batteries.com/services.php

HOW DOES IT WORK?
First off, your trickle charger (probably at 13.1v), will be less than the voltage of the alternator (14.4v). The alternator will actually charge the battery, when the car is driving, the trickle charger will hardly be noticed. The solar panel, with a lower voltage will not affect the system much.

Second, the amperage from the trickle charger normally isn't sufficient to blow any fuses. However, if you have a few of the tiny ones in your system, you should watch for this.

RESULT:
No blown up batteries....batteries resist a charge when they are full. However if you charge a battery that is already full, the electrolyte boils off.

CAVEATS:
The solar panel, may have a diode, if not DO ADD ONE. If you don't have a diode (one way door for electricity) between the panel and vehicle electrical system, you can blow it up. The high output from the alternator driving power through the solar panel isn't good.
Bright side, they are only $20.
http://www.bdbatteries.com/diodes.php

car battery said:

Great Charger. More information from Leoch International, http://www.leoch.com