Charge controller loss?

[1stmate]

Hi folks-
A quick question.

What would be the anticipated loss of power through a charge controller with ~1a in off a 15w panel?
IOW, how many milliamps should be arriving @ the battery?

Thanks in advance...

[12vman]

Idunno.. Mebby 2-3 hundred mills used by the controller to do its thing..

Some controllers have a mininum current/voltage input rating. Why would you use a controller with such a small panel? A blocking diode would be fine and you would only lose 7/10ths of a volt..
~Don

[1stmate]

Glad to hear from you Don-
It is suggested that anyhing over 5w should use a controller, that's why I got one. But here's my problems...
I have metered the panel @ 24.8v max @ 830 ma. The unit is supposed to be 15w 1a output, but 24.8v @ 830 ma comes out to be 20.6 watts. ANYway, when I connect the charge controller & measure the output at the battery side, I’m getting 23.5v @ 8.12ma!
I called Northern, & they referred me to Sunforce. The fellow there wasn’t sure of the output amperage specification, but thought I should return the unit for replacement.

Here are my concerns:
1) The 23.5v output to the battery seems extreme to me, even though the instructions indicate the controller should reduce the panel voltage by 5-10% (my reduction was 5%). 23.5v is well over the “gassing” voltage of the cells. Is the high voltage the problem I think it is?
2) What should I expect on the battery side of the controller given the 830ma going in? I’ve read specs on other controllers that indicate a +/-4ma internal power usage. That’s not so bad, but losing 99% of the power produced is unacceptable!

What'cha think?

[12vman]

What you read with your volt meter on the panel with no load is common. Most 12 volt panels have an open circuit voltage reading much higher than the operating voltage..

Check out the specs of this 1.5 watt panel..

http://www.harborfreight.com/manuals/44000-44999/44768.pdf

Most charge controllers need to "See" the (a) battery before they'll start to operate. If you just connected the panel without a battery connected, the controller doesn't know what to do. The controller gets its operating power from the battery, not the panel. Did you have it connected to a battery when you made your voltage readings?

[1stmate]

NO.
I'm just a maroon. :P
Since the original post, I've been educated on the correct way to read the output, & now the whole thing looks MUCH better!
Thanks for your time anyway Don...

[12vman]

Trial and error.. The best wat to learn.. ;D
~Don