Ampere control issues in a scr battery charger

[unelco]

SIR,

I have a problem my scr battery charging please help me.i used charging circut attach this mail.my problem is ,battery charging voltage setting is ok but ampear control is not properiy working .I tried this circut 24v ups, sett battery charging voltage no load condition 28v,it is ok
then i connect the charger to battery and sett ampear 6amp .then i discharge the battery voltage ie 22v(charger off condition) and retry the charging the charging current is more higher 15a .no limitation this time ,what is the problam please help me.I use copper shunt current limit.

 

[BradtheRad]

Your schematic does not show up in your post, if you attached the image.

I'm not familiar with methods using an SCR to charge a battery.

Are you using an SCR to conduct current continually, unobstructed, until the battery is charged to an equal volt level as your charging source? Then current no longer flows and the scr turns off? This sounds like conventional use of an scr.

Or are you using the scr to pulse current, or to restrict current? This requires careful attention as to what volt levels you apply to its pins, and at what moments in time.

Not knowing what detection circuit you are using...

But it may detect differently with a 24v battery in the loop, as compared to no battery.

By the way, a 28 V charging source will send only a limited amount of current into a 24 V battery. This is because the net voltage in the loop is 4 V. To obtain 15A charge rate you cannot have greater than 1/3 ohm total loop resistance.