Alec Cameron wrote in a message to Bryan Fullerton:
 AC> Hi Bryan
 AC> On (08 Nov 96) Bryan Fullerton wrote to All...
 BF> ............................................. and I need to add another
 BF> one to run the accessories on like fridge etc. This battery 
 BF> needs to be good holding a charge for a long time and being 
 BF> able to recharge again and again.. also been interested in 
 BF> perhaps collecting some to hook together  and hook up to a big 
 BF> inverter for when the power goes out.. could still run a few 
 BF> lights etc..(G) in either of these applications which type or 
 BF> style of battery is best?
 AC> For your extra battery which needs to be recharged again and 
 AC> again, I assume that you expect it to be considerably run down 
 AC> prior to many of these recharges. In which case an automobile 
 AC> battery would not be the best- these are not designed to run 
 AC> flat/ recharge/ flat/ recharge, but to remain almost fully 
 AC> charged throughout the working life.
 AC> I suggest that you get a battery as supplied for wheelchairs. 
 AC> These are "deep cycle" and made to run flat without injury. 
 AC> Much dearer that auto batteries, but with long life and good 
 AC> performance.
They do perform better than typical "wet" batteries,  but the price!  I'd be 
tempted to go with a deep-cycle "wet" battery (and have a couple of them 
here) although gels are nice,  too...
 AC> "Holding a charge for a long time" is not to be assumed. Lead 
 AC> acid batteries, discharge while standing idle. I have seen a 
 AC> figure of one percent per day. 
One thing I can add to that is that this depends a lot on the temperature.  
Which is why all those people who came into that store I was running and said 
how they'd taken the battery out of their garden tractor and put it in the 
warm(er) cellar all got the same look from me...   :-)
 AC> On that basis, and idle battery needs to be charged say once 
 AC> monthly, to keep it healthy. A PV panel on your vehicle roof 
 AC> could keep it healthy 'tho neglected, for very long periods.
Yes.  Once a month is what I usually ended up telling people.
 AC> A historic rail train down here, has solar panels on the roof 
 AC> for just that purpose- the big 24v batteries under each car 
 AC> cost a lot and must not be allowed to become diseased thru 
 AC> neglect. The train runs for tourist hire. 
Sounds like a good use for a train roof to me,  they sure don't seem to do 
much else with them!
 AC> ... FLASH! Energiser bunny arrested, charged with battery.
Couldn't resist that one,  eh?   :-)
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