Disconnect dead battery from circuit

Thread Starter

bignick270

Joined Mar 25, 2009
36
How can I disconnect a dead rechargeable battery from a circuit to prevent leakage current from completely draining the battery therefore damaging it? It would be great to find a solution that would have a minimum increase in operating current and a minimum voltage drop from the battery supply.
 

SgtWookie

Joined Jul 17, 2007
22,220
Well, two AA batteries put out too little voltage to control a MOSFET gate.

BJT's and relays would require too much current.

Probably best to just use a simple switch to disconnect the batteries.
 

Thread Starter

bignick270

Joined Mar 25, 2009
36
The device is enclosed in a case and it can not be easily opened for controling a switch and it is not pratical to have a switch on the outside of the case.
 

t06afre

Joined May 11, 2009
5,934
I may be wrong here. But the some N fet from International rectifier seams to have a very precise Gate Threshold Voltage fixed at 0.7 volt. As some examples IRF7401, IRF7402,IRL3103,IRL3402,IRL3502. Maybe you can use one battery to control the V gate/source voltage
 

SgtWookie

Joined Jul 17, 2007
22,220
OK, so cut a small piece from a plastic milk jug, and insert it between the terminals of the two batteries. That will prevent any current flow from occurring.
 
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