The list went thru a "good battery/bad battery" discussion maybe a year or
two ago - check the archives.

I had trouble keeping sealed lead acid, recombinant gas Concorde batteries
alive (RG25) in my LNC2 - three in about four years - though I went to an
adjustable voltage regulator to be able to set the correct alternator output
voltage per their tech gurus. No explanation, no ideas either. Too bad we
can't get Hawker batteries here in the states.

Dan,

 

Interesting.  It appears that not all Sealed Lead Acid (SLA) batteries are the same.  That also goes for the safer Absorbed Glass Mat (AGM or no free liquid) batteries that many of us use.  There are two very important considerations with these types of batteries:

 

1. The voltage regulator should deliver 14.5 (+ or - .2) VDC to properly maintain such batteries.  AGM batteries favor the high side of that range.

 

2. Recharging such batteries is a challenge.  If you use a regular automotive charger and leave it on long enough the charging voltage can rise above 15 VDC - ultimately leading to destruction of the battery.  Trickle chargers can retain too high a residual voltage and diminish battery quality if active for a long period of time because of gassing.  There are devices available (B&C, Battery Tender) that maintains a float voltage that keeps the SLA battery safely topped up over a long period of time.

 

SLA/AMG batteries lose their capacity if left unused (uncharged) over a long period of time.  I have found these sites to provide interesting reading material:

 

 

It is illuminating to read topics such as:

 

	Overview Information on VRLA Batteries - 1603KB
	Precautions for Handling VRLA Batteries - 538KB
	VRLA Charge Methods - 508KB

One notes that the specs for the 12 VDC 28 AH SLA battery is interesting reading:

 

 

Other interesting reading about Battery Tender can be seen at:

 

 

Especially the FAQs:

 

 

If you use B&C products and are interested in their battery maintainer, review:

 

 

I use 3 Battery Tender Jrs.

 

1. Hangar - To recharge or maintain my SLA aircraft battery after electronic testing, etc. via the pig-tail connector located in my glove box.  Of course the pig tail can be connected to my electric jacket liner for those really cold winter flights. 

 

2. Shed -To keep my Deere tractor battery ready-to-go.  This is necessary because of irregular use of the tractor (grass, leaves, snow blowing, etc)

 

3. Garage - To keep my SLA motorcycle battery in tip-top shape over periods of disuse such as during snowy icy road conditions and periods of extreme cold.