Battery charger over heating

[Aliyu Umar]

Hi all
I built the below circuit diagram wish i search from the net, the charger works ok but the Mosfet transistor dissipates a lot of heat even when the charging current is in mili-amperes, the cooler attached to it got extremely hot. Please is there any idea on how to run this charger cool. I will be grateful for any assistance. 

[indulis]

Where did you tie the "Adj" pin of the LM236-5 (D2)? It should be ties to the cathode if you wanted a 5V reference.

Are you relying on "T1 & R2" to make it constant current? Don't!

[Aliyu Umar]

Hi Indulis

Thank you for the reply, I used a 5.1v Zener for the reference diode.

My intention  is to charge SLA battery with 1.2A so I don't rely on T1 and R2 for the constant current.