Self Servicing The Fisher Impulse?

[bklein]

If I remove the faceplate will the batteries pull out from the case? They aren’t glued in are they?

[Carolina]

58 minutes ago, bklein said:

If I remove the faceplate will the batteries pull out from the case? They aren’t glued in are they?

Shake it. There is your answer.

[bklein]

I hear/feel nothing but may be because of the puffing cells.

[Carolina]

5 hours ago, bklein said:

I hear/feel nothing but may be because of the puffing cells.

They are loose.

[bklein]

After doing a few charge/discharge cycles the case bulge went away!  I haven't gotten to the inside of the case yet.  I did drill out the front panel screws using a piece of brass tubing in a drill.  I would think this drilling would have provided any inside pressure an escape.  I don't get what could occur to cause the bulge and then eliminate it.

From these charge/discharge cycles it looks like the factory pack is holding 2000-2100mA.  I would think that would last more than an hour - maybe 3 hours if the detector uses 700mA(?).  I've read several different specs on this.  Do you have any data on below:

1) nominal current requirements

2) minimum-maximum design voltage range

3) stock battery specs 

Pjrough, you made a statement that the AQ's lower voltage is 10V.  Joe, you published a factory battery charge/discharge chart that gave ~14.3V fully discharged, ~17.5V fully charged.  Usual discharge spec on NiMH is 1.1 or 1.2V per cell.  If 11 cells that's 12.1-13.2V per pack.  I was using 1.1V per cell cutout and at that voltage the charger stopped and read the pack voltage at 12.87V.

So I am left wondering if maybe the factory charger is not as good as my RC charger and there may be more life to this pack than I was led to believe.

[Carolina]

4 hours ago, bklein said:

After doing a few charge/discharge cycles the case bulge went away!  I haven't gotten to the inside of the case yet.  I did drill out the front panel screws using a piece of brass tubing in a drill.  I would think this drilling would have provided any inside pressure an escape.  I don't get what could occur to cause the bulge and then eliminate it.

From these charge/discharge cycles it looks like the factory pack is holding 2000-2100mA.  I would think that would last more than an hour - maybe 3 hours if the detector uses 700mA(?).  I've read several different specs on this.  Do you have any data on below:

1) nominal current requirements

2) minimum-maximum design voltage range

3) stock battery specs 

Pjrough, you made a statement that the AQ's lower voltage is 10V.  Joe, you published a factory battery charge/discharge chart that gave ~14.3V fully discharged, ~17.5V fully charged.  Usual discharge spec on NiMH is 1.1 or 1.2V per cell.  If 11 cells that's 12.1-13.2V per pack.  I was using 1.1V per cell cutout and at that voltage the charger stopped and read the pack voltage at 12.87V.

So I am left wondering if maybe the factory charger is not as good as my RC charger and there may be more life to this pack than I was led to believe.

This will be the last I respond to this thread. Your pack was over charged and one of the 11 (1.5) volt batteries likely exploaded. This resulted in the case bulge. Drilling out the screws gave the air tight case a vent. You likely ruined the battery with your charger. Ole Beechnut is correct. I will show you one last time, a properly charged stock battery with the supplied charger from Fisher. 17.4 volts.

[bklein]

I used the correct charger. I had two chargers, one for the AQ battery and one for the OBN battery and they were well marked and I charged both batteries simultaneously. Tenergy charger for the OBN and the AQ charger looks just like yours.  Oh well, I’ll try using it this weekend and see how long it goes. 

[PimentoUK]

I think the fully-charged voltage of 17.4V indicates that the battery is a 12-cell pack. Trickle-charged NiMH's typically settle at 1.40V per cell, a tiny bit more sometimes. 12 cells at 1.45V each would give the 17.4V observed.
It also seems slightly more likely from a packaging viewpoint - 12 cells is four sticks of 3 cells, or three sticks of 4 cells.

[bklein]

I asked Alexandre and he thinks the stock pack is 12 cells. 
I got 3hrs out of the stock pack today with no bulging after charge or use today.  I’m holding off on cutting it open for now and will continue using it and charging with my RC charger.

[Geotech]

Yes, 12 cells.