Thanks for the info, I had already run across most of that. Unfortunately, at my electronics skill level the amount of effort would hardly justify the result. It would probably work but look like a dangerous mess of solder. :-)
LOL! Sounds like our local electronics stores. A fully charged 12v battery should read around 13.5 on the meter. The charger has to put out more than that to properly charge the battery. For a 7aH battery, a 750 MaH charger sounds right. Dr.1 Driver "There's a Hun in the sun!"
I did some reading and gel cells like a constant voltage charge. I recently worked on an old Ace CVC charger that needed a new transformer. It charges at a constant 14.2 volts and 400 ma. As the battery becomes charged, the current drops to about 10ma. It can be left on indefinitely at that rate.
John VB
Sure, it may drop to 14VDC and put 300mA into the battery, but in the end the correct answer is DON'T use one it will ruin the battery in the end. An unregulated wall wart is not a proper charger.
Jim
Check the charger!!! Some are AC output and need a bridge rectifier.
A fully charged battery being supplied with 14v will draw very little current. A battery is like a capacitor. As it charges, if the voltage remains the same, the current drops. No matter what the supply is capable of, Ohm's law still applies.
These type wall warts are supplied for, and have been used for charging and sustaining gell cells for over 25 years that I am aware of.
Yep, and they have been drying them out for 25yrs too. Ohms law might have something to do with it were you shoving 100's of amps into the battery, after all that is going to be the only way that the internal resistance of the cells are going to offer any appreciable voltage drop due to ohms law. What is happening with a charger has more to do with the difference in potentials. You can shove more than 10mA into a 12VDC (nominal) battery by applying 14VDC to it.
Jim
Look at this:
Morris
Those are usually designed for RV batteries and other high capacity things. Their float charge may be higher than a small gell cell can tolerate.
I can see that your mind is made up on this. I guess I won't let my 10 year old gell cell read these posts because it may find out that it shouldn't have been charged like that and give up on me! ;^)
It has nothing to do with an opinion or anything like that. Just in the last 6 months I have been the engineer on 4 products that have on board Lead Acid charge circuits. How many lead acid chargers have you designed? Do you actually know what occurs when an electrolyte cell is charged and discharged? The only real way to treat a "gel- cell" or lead acid battery is to apply the proper temperature compensated CC to CV charge. PERIOD. Anything has just been luck on your part not science.
Jim
With ALL the variations mentioned here, would anyone be interested in reading the section on "The care and feeding of 12v Lead Acid Batteries" at the clinic?
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