Hi Devo.
I have a very simular battery as pictured in the first picture. The wharehouse tossed it because it was old and it wouldn't make it through it normal work piriod (thats what happens when you get old).
I got it free (very good price). It is 36 volts or it was. I cut some jumper bars and rewired it to 12 volt.
I found a few cells with low SG. At that time I was playing with DIY battery desulphators. That topic was very popular for a while here on the board.
My first desulphators were some what complex. They used a 10 amp 30 volt power supply, 2 TO-3 power transistors and a small 555 timer circut using opto photo couplers as trigers for the transistors. It also used a large 120,000 UF/ 50 volt cap.
The 555 circut would turn the input TO-3 on to charge the cap from the 30 volt supply. Then it would be turned off and the output TO-3 would be turned on to domp the 30 volts from the cap onto the battery. Pulse speed was addjustable at the 555 timer curcut. This all worked OK.
However a much simpler circut was presented here on the board and I've been using it ever since.
The circut is simple and works very well. I use this circut daily in several apllications.
1. on my E-car. 1 on my golf cart. 1 on my shop RE system, and 2 or 3 restoreing batteries at home and my store/shop.
Its simple but dangerus. 2 parts are needed. A large value motor run cap and a fullvave bridge rectifier/diode.
One side of 120 volts gose into the cap the output of the cap gose to one ac conection on the bridge. The other side of the 120 volts ac goes to the other ac conection on the bridge. The dc outputs of the diode go to the battery needing desulphation/pulse charging.
To avoid shock hazard from a direct conection to the ac line I use a suitable large isolation transformer.
I use a few of these chargers/desulphators direct on the ac line ( but I urge don't try this at home or anywhere for that matter).
This system has brought many batteries back to life and good SG for me.
I used it on the battery that looks just like yours and now that battery is the hart of my store RE system.
I'm now building a few of these charger/desulphators fo a few of my freinds.
I found a very cheap islation transformer. There was several things I needed to build these units.
Suitable metal housing, fan to keep the transformers and diodes cool, a heavy power cord and fuseing plus a big isolation transformer.
WALA old microwave ovens. I picked up a pile of used microwave at the used appliance store cheap (nice metal houseings), heavy cords, nice windy fans, 20 amp fuse holder and the best part a 1500 watt transformer.
Big problem with transformer though, primary 120 vac, secondary 2000 volts ac.
Problem solved. Since they were so cheap and plentyfull. I'm using 2 transformers per charger/desulphator. Thats right and it goes like this. 120 volts primary tranformer # 1, 2000 volts secondary of tranformer #1 to the 2000 volt secondary of transformer #2 and the very well isolated 120 volt output is taken from the primary of transformer #2.
These transformers do have some insertion losses so at about 6 amps load I'm see'ing about 100 vac out of this combo. But this is a good amount for charging/desulphation.
This system will work with a singel 2 volt cell all the way up to, well I'm using it to charge my 120 volt battery bank in my daily driver E-car (20 X 6 volt golf cart batteries).
BIG WARNING! Make all conection to battery first befor plugging in the pulse charger even if isolated. Open circut the pulse charger is developing 170 volts (don't touch) Once hooked to the battery it asumes battery voltage.
I use used motor run caps (not motor start). For ever 24 UF of cap 1 amp of charging current is passed. So I wire a group in perelell.
This system works so well for me, I'll keep building more and you gotta love the cheap price, easy to build and to top it off bring junk sulphated batteries back to life.
I even use this charging system on new batteries. I'm on my second year of new batteries in my daily driver E-truck and the SG is as good or better than when I put them in 2 years back.
JK TAS Jerry