Bob Y. replied:

Phil, just come off the Exide site(www.exide.com.au) and the only info I noted for recharging was "fully discharged auto battery using 10 amp charger, will take 8 - 10 hours @ 80*F to reach full charge."

I'm not really up to speed with theory of these black boxes, but to check charge you would need a hygrometer, to read specific gravity. With no load voltage @ 12.93 feel it wouldn't be too far off full chg. Those Arlec chargers aren't much better than trickle chargers, so you could give it a fair run, without damage.

Just forget the lowest voltage, for long life, but am sure it was mentioned here before. Ozi mentioned it a number of times. Think some people use a percentage, say 10% drop. Hooroo...

Eric replied:

Phil.
Your battery has a capacity of 70 amp hours. so if it is completely flat it will take 70 hours at 1 amp to charge it. Simple. If you charge at 2 amps then 35 hours, etc, The maximum voltage you should charge at is 14.8v any higher and you will start to damage the battery. the minimum voltage is not a big issue it is the time the voltage is low is the problem, ie. if you flatten it charge it a.s.a.p. A battery left flat will sulfate the plates making it very dificult to charge. 12.6v is the normal voltage under load. The voltage is not a good indication of charge, mental arithmatic, how much load how many hours? is the best way. Eric.

Rod replied:

There's an easy way to calculate how much charge is left in your lead acid battery. Easy yes, accurate may be no.

See the table at :

http://continuouswave.com/whaler/reference/chargeBattery.html

Note that you will need to disconnect the battery from load and charger and leave stand before taking voltages. Ideally you leave them for 2 days but that is rarely practical. If you monitor the voltage accross the battery terminals and disconnect the charger, you will notice the voltage drop off with time. Eventually the decline willl slow to a trickle.

Phil P replied:

Thanks for the replies - got the answers I needed !
Regards
Phil P