On Monday, April 2, 2018 at 10:51:03 PM UTC-7, wrote:
On Monday, April 2, 2018 at 11:14:19 AM UTC-6, john firth wrote:
Recently I tested two 12v SLA s which had been in use
sequentially for some years usually recharged before going
going flat, or at least within one day.
Both were run down to 10.5 v with a 10 ohm load and then recharged to 14v,

The Yuasa 7 AH bought 2005 was good for about 2.5 AH
the UB 1280 8AH 6 years old good for 2AH.
On this showing the Yuasa look like the better battery.
Both were used as panel supplies running at .5 A load.

Any opinions on competing SLA batteries?

John F

Just for reference, 4.5 hrs on Duracell 9AH to drop to 10.5V. This is running everything including PF and TX. No more than 2 seasons use. I buy one every season from local high volume outlet (Around 25 bucks). Will occasionally use a smaller tail battery as well.
The biggest determinant of longevity is the charger. I have been using SLA for decades for soaring and other applications and for some reason I have been having a hard time finding good chargers lately. Used the PowerSonic chargers for years (No longer made) but sold these with my last ship. Have fried more than one battery when the charger did not detect peak and shut of (Or float) before the battery got hot. I have never measured it but this always results in a noticeable reduction in capacity.
3 years max (With the right charger) sounds about right. We are only talking 20 some odd bucks.

BTW if an SLA battery charger does not switch to float, the first thing to suspect is the battery is faulty, a cell shorted or partially shorted... and then the charger being in bulk charge mode across the other cells for a long time will tend to evaporate out the small amount of electrolyte in the battery and kill it pretty fast. If it's happening in multiple batteries then obviously suspect the charger.

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To everybody/more generally: using missized SLA/VRLA chargers can cause problem, the charger needs to be an SLA/VRLA charger, and should say the battery capacity they are designed for, ...or use around C/5 to C/10 bulk charge charge current (where C is the battery capacity in A.h). Too large a charger can damage the battery, too low a charger may never get to float mode and might fry the charger. Some chargers have temp sensors... you want them and the battery near each other and well ventilated. Solar chargers might put a surface charge on the battery but not actually much charge capacity. it's important to hammer the nail in with the right screwdriver :-)