(More images below.)
I constructed a Gel Battery Charger for the 12 ah gel battery that is fitted in my Solar Power Supply. I will be using the charger to keep the 12 ah battery topped up when it is overcast and rainy. Here are some “useless” basic information which will hopefully help to keep the battery in good condition for a few years. I am no expert in batteries and do not claim that the information is reliable. I have been asked why do I want to build a gel battery charger? Just use a normal lead acid battery charger. Sure a lead acid battery charger will charge the gel battery but will shorten the life of the gel battery substantially. As batteries are no cheap commodity these days, I wanted a long life expectancy for all my batteries.
Here is the specs of the 12v (12 ah/10 hr) gel battery fitted in my DIY Solar Power Supply:
Type: Gel Battery
Cycle Use: 14.5 – 14.9 Volt
Standby Use: 13.5 – 13.8 Volt
Charge Current = 3.6 Amps Maximum
Float Level = 13.6 Volt
Peak charging voltage for Gel Batteries is 14.1 or 14.4 volts. Exceeding this voltage in Gel Battery can cause bubbles in the electrolyte gel and will result in permanent damage to the battery.
The size or capacity of the charger also plays and important role. In gel batteries several manufacturers indicate that the capacity of the charger must be 25% of the battery capacity. (ah = amp hour capacity)
So for the following two batteries one would need a charger of the following capacity.
100 ah Gel Battery = 25 Amp charger or less.
12 ah Gel Battery = 3 Amp charger or less.
Now whether the above will contribute to the life expectancy of my Solar Power Supply battery needs to be seen. I will keep record of the battery and see how it performs.
UPDATE 6 Nov. 2021: I have two of these gel batteries. Both are still going very strong. The one in the image above was manufactured on 2 May 2017. It still takes a full load an performs like the day I bought it. This shows that if you look after any battery, you should get your money back in return.
Once again this is not the Alpha and Omega of charging gel batteries but hopefully in following the above guidelines the battery will last much longer.
Compiled by:
Johan ZS1I, Mossel Bay
25 October 2019
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