Battery World

Cruising Cruze · Guru

Battery World

Happywanderer · The Master

John, how much was supposed to be going into the battery? Still trying to understand these things.
Sounds like they sorted it all out good for you. Marj

Cruising Cruze · Guru

all depending of what type of battery Marj

normal AGM 14.4 volts it tells me in the booklet

and when full 13.3

Hope this will help you

John

dorian · Guru

Measure the charging voltage of your engine's alternator. It's typically around 14.1V to 14.4V or so, with temperature compensation. Your solar panel regulator should be smarter than that, ie it should trickle charge when the battery is full.

Happywanderer · The Master

Oh I see. It was reading higher than it should.

GaryKelly · Guru

Speaking of regulators, mine shows about 14.5 volts. When I'm on the road and using the AGM on a daily basis, how do I tell when it's "half full". If it were like a petrol gauge it would show 7.25 volts but that's not the case is it. I've heard that when the regulator shows about 12 volts, the battery is down to about 50% capacity, and needs charging without further use. Is that right?

Loki · Senior Member

GaryKelly asked:-

"I've heard that when the regulator shows about 12 volts, the battery is down to about 50% capacity, and needs charging without further use. Is that right? "

Yes, that is what I understand. I try not to let my AGM's get below 12V, which is about 1/2 charge, even tho the indicator on my regulator still show Green (rather than yellow for part discharge). While AGM's can take a hefty discharge without major damage, to get the maximum life out of them it is best to keep them above half charge.

hako · Guru

Slightly off-topic but I bought an 80watt folding panel off Ebay for $155 delivered - when I went to use it I found that the regulator was not working properly and cutting out at 13.2 volts instead of 14.4.
So I rang the supplier and he said straight off it sounds like a dud regulator and said he'd mail a new heavy duty regulator up that day. Two days later we had the new regulator that normally retail for over $50. Didn't want the old one back either. I thought that was pretty good as he believed what I said with no arguement and rectified the problem in a flash.

dorian · Guru

I found this lecture on lead-acid batteries:
http://ecee.colorado.edu/~ecen4517/materials/Battery.pdf

Page 26 has a graph which shows how voltage varies with electrolyte concentration.

Page 12 states that the voltages in the fully charged and completely discharged states are 12.7V and 11.7V, respectively.

Page 23 shows how depth of discharge influences battery life. At 10% discharge the battery survives 5000 cycles, while at 50% it lasts for 1000. At 100% discharge it lasts about 350 cycles. In terms of Ah delivered, ISTM that there is no difference between 10% and 50% -- both result in a figure which is equivalent to 500 complete discharges. At 100% it reduces to 350. Or am I misreading the data?

Page 26 has a graph of charge and float voltages versus temperature for an AGM battery. Higher temperatures require reduced voltages.

At 0C the charge voltage is 15.0V, at 20C it is 14.4V, and at 50C it is 13.8V. Between 20C and 50C the voltage drops by 0.2V per 10degC.

The float voltage is 13.2V at 25C and about 12.7V at 50C. At 0C it is about 14.0V.

-- Edited by dorian on Saturday 21st of September 2013 05:38:54 AM

bloomoon · Veteran Member

I won,t go into details, but I had terrible service from battery world Maroochydore. Wrote a complaint and no reply. Maybe it wasn,t my week !!