Have two corded battery maintainers/trickle chargers, bought this one for when I travel and want to top off the battery.


Tests fine (up to 20v in bright direct sunlight) but when I attach to battery, the battery voltage measurement keeps decreasing. Not sure if the charger can't keep up with some (yet undiscovered) parasitic draw or I just bought the wrong item.

To clarify, my typical test procedure would be:

• Position solar charger for maximum sunlight capture via meter test (usually16v or more)
• Open trunk and attach clamps to battery terminals
• Close trunk gently to avoid pinching wires
• About 15 minutes or more later, open trunk and meter battery

Typical measurement would be 12.9v at start, 12.6v at test

Opinions?

 

Could it be that your trunk lights are staying on and overpowering the output of the charger? I use a trickle charger on my cars and have removed the fuse for the trunk lights to avoid that problem.

 

Thanks, I will check that. I know there is a way to trip the trunk latch such that the lights go out, but pulling the fuse will work too...