[RE-wrenches] discharging Rolls batteries

[Hugh]

Hi wrenches,

I have been selling and using a few sets of Rolls 4000 series S530 
batteries lately.

I have downloaded the Solar Battery manual from www.rollsbattery.com

It's very interesting.  At 17 degrees C you need to charge at 14.4 
volts.  At 16 degrees it's 15 volts.  Hmm, Ok I get the idea.  I am 
certainly learning to compensate my temperatures this winter.

I did a search in the document for the word 'discharge'.  I am 
cutting off at just below nominal voltage and starting my generator. 
I do not get much capacity.  A customer has suggested that a lot of 
the discharge capacity is to be had at 11.5 volts (he has a 12v 
system obviously).  Hmm.  Sounds a bit harsh.  But what voltage 
should I be considering to be 50% discharged, and time to start the 
genny?  And in a hard frost, the same voltage?

No mention of discharge in the solar battery manual.  Any ideas anyone?

Please don't tell me to buy an amphour meter (or worse still to sell 
them).  Those things are way too confusing to calibrate.   I can tell 
you that I am not getting many amphours out of my batteries in these 
low temperatures before the voltage per cell drops below 2.

What do I tell my customers about the end-of-discharge voltage for 
sustainable cycling of their Rolls batteries?  And is it temp 
compensated?

thanks
-- 
Hugh Piggott

Scoraig Wind Electric
Scotland
http://www.scoraigwind.co.uk