[Ham-Computers] Parallel gelcel batteries

[Jim Brampton]

I work with lighting unit. Many times I find that there are  2 8AH 
batteries in parallel. The units that have failed usually have terminal 
corrosion and wire damage. A friend wires car size batteries in parallel 
for use in his boat and has not had unusual failures.

Would the batteries have to be always connected together or could they 
be separately charged with diodes and only connected together when they 
have to handle load. With 8AH batteries I doubt that the load is greater 
than 4 amps per battery.

Would a low value resistor allow for differences in battery state of 
charge without lowering the system voltage.

On friend boat the charging comes from engine alternators and when a set 
of batteries other than the main  engine battery needs charging the 
extra batteries are fed voltage from the main  battery to the extra 
batteries with a relay. The wiring from the main batteries to the extra 
batteries is 14 gauge and via a relay that is ignition  circuit powered. 
The main batteries for starting are not dragged down when the engines 
are off. This is not a perfect system but has functioned for several 
years with small modifications as the number of batteries has grown with 
the addition of accessories and the addition of  a 110 volt generator.

only a thought. Because the batteries that you are using are small 
capacity compared to large Marine or RV batteries I believe that it will 
work/. With multiple batteries you can get them charged sooner because 
you will have greater heat dissipation  with the smaller batteries. The 
batteries will eventually  fail. Periodic testing and charging to full 
will help the condition of the batteries.

Jim VE3 JIW

Ronald KA4INM Youvan wrote:

>> I would like to put six 12V 8Ah in parallel for power.
>> I am thinking of float charging them
>
>
>> and using a series resistor to limit the current from the
>> charger in case the batteries are flat.
>> Would this system work or do I have to isolate each battery
>> with diodes on the charge side and/or on the load side?
>
>
>   Put a fuse in the positive terminal of each gel cell.
> The little fuses used in cars work fine and usually can
> be soldered in.