UPS and charger

[Islam Ghunym]

before I start pls don't ask me why do you want to do that....

anyway, I have SSD-UPS-650 Vision from TECH-COM, it has a 9 amp 12 V lead acid battery which is dead long time ago so I replaced it with a 300 amps 12V Gel deep cycle battery group which it can't charge so I plugged the batteries to external charger to charge them, but even if the UPS charger can't charge the batteries it is still trying to do it, so the negative wire linking the battery group to UPS is getting very hot not to mention the higher temperature of UPS with waste of power while trying to charge a big batteries...... now what I want to do is stoping the UPS from charging the batteries, is there anything I can do to stop UPS from trying to charge batteries?

[WereCatf]

12 minutes ago, Islam Ghunym said:

which it can't charge

Why can't it charge the new battery?

[Islam Ghunym]

24 minutes ago, WereCatf said:

Why can't it charge the new battery?

because it has a tiny transformer that can charge batteries with much lower capacities than 300 amps, it is simply designed for  something like 10 amps battery

[aezakmi]

do you have a schematic or a picture of the controller PCB?

[Islam Ghunym]

22 hours ago, aezakmi said:

do you have a schematic or a picture of the controller PCB?

what I want exactly is to stop the UPS from taking any load while it is being fed with AC power and start working as inverter once the power cut

 

as I said I can charge the batteries with external charger

[cole0622]

Is only the - wire getting hot? If your charging the battery(s) with an external charger then you could just unplug the ups from the wall, then it will run from the battery/charger. It sounds like your external charger is not delivering enough power therefore your ups is taking up the slack.