# clamping the battery voltage with zener diode?

I want to do an experiment with a battery I have. I have 200AH 6v lead acid battery and I want to charge it with maximum current the battery can take in bulk stage, then in float or acp. stages, I want to reduce the current, but clamped the voltage applied to the battery. so I decided to use a zener diode parallel with the battery (let say also the power supply I have is the only has Constant current mode). this way I can charge the battery with max current in bulk stage and in next stages with voltage clamped to zener diode voltage (let say voltage of zener diode is 6.8V) and then I reduce the current with the voltage being constant. so I am looking into the specification of this zenar diode. since I am working with high current, I don't know how to choose the right 6.8V zenar diode? .

• You have a 6V battery, and you want to clamp its voltage to 6.8V? Why? Why not just not apply more than 6.8V to the battery? Also I imagine the nominal voltage of a 6V battery is around 6.9V. – Bort Apr 24 at 18:37
• What is a high current? 5A? So, when the zener has to clamp, it has to dissipate 6.8V•5A = 34W (assuming it clamps still at 6.8V, but which likely will be an even higher clamping voltage). I think you'd better pick a more efficient way of charging. – Huisman Apr 24 at 19:28
• I'm afraid this is an XY problem. The actual problem is that you only have power supply which only has constant current mode. So, the solution would be charge it with power supply which also has constant voltage mode. – Unknown123 Apr 25 at 0:32