Battery Power

At 23:10 23 September 2012, Tom Gardner wrote:
Mike McCarron wrote:
Help!

I have carefully measured my current draw in my glider at .8 amp. l
would
like to know if there is any reasonable explanation for why a 9 amp
hour
battery goes from 13 volts open circuit fully charged to 11.6 volts in
4
hours.

Short answer: 9AH is the nominal capacity, the actual capacity
depends on temperature, discharge rate and battery age..

Long answer: have a look at the graphs in, for example,




Could not find the graphs. Brand new battery and very reliable battery
charger.

On 9/23/2012 4:32 PM, Mike McCarron wrote:
At 23:10 23 September 2012, Tom Gardner wrote:
Mike McCarron wrote:
Help!

I have carefully measured my current draw in my glider at .8 amp. l
would
like to know if there is any reasonable explanation for why a 9 amp
hour
battery goes from 13 volts open circuit fully charged to 11.6 volts in
4
hours.

Short answer: 9AH is the nominal capacity, the actual capacity
depends on temperature, discharge rate and battery age..


Could not find the graphs. Brand new battery and very reliable battery
charger.

Fully charge the battery, then do a discharge test at about 0.8 amps.
Even a new battery can be defective, so I always do a discharge test on
new batteries before using them in the glider.

It could also be the charger. Have you tested it's charging ability
recently?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)