Agilent U1252B Damage from Recharge with Rotary Switch Movement

[Wing47]

Just pulled my DOM 2011.05 Agilent U1252B off the shelf after about 1.5 years unused and found the Original Battery discharged. No Surprise there. Removed the leads. Grabbed the recharge kit and plugged it in to the main and then into the meter. The looked at the rotary switch and realized I had moved it to ohms position while messing with the leads. Quickly moved it back to the Off/CHG position.  Test cycle posted and then reported battery error. Did test twice more and figured after several years it was best to just chuck it and get a replacement.

While I was reading the manual to get battery specs I noticed a HUGE WARNING to have switch on CHG before connecting charger and NOT MOVE IT while charger is connected. 

As an amateur I figured I would ask you all: What if any damage may have been done by this? 

I could just proceed as if nothing happened and wait for a failure to appear, but I'd rather intercept the damage, make repairs and maybe save some part of this $$$$ gear. 

I tried reaching Agilent but no path seems open without a contract or fee.

Thanks.

[saturation]

Put a fresh 9v battery in it, even if non-rechargeable, and power up.   If it works, perform the basic operation tests at minimum, as specified in the manual, and if you have the gear, do performance tests.  These tests insure all is well with the DMM.  Its less likely the DMM has been damaged but without a schematic, you never know.  The charge terminals are on the low amps terminal that will engage when the rotary knob is set to it, which is past the ohms setting, and likely will blow a fuse if it were set here during charging.

Chances are the NiMH battery needs to be cycled as its been deep discharged. 

A simple way to restart the 9V NiMH is apply 8Vdc 40mA for 1 minute and then charge it in the DMM or use an external 9V NiMH charger instead.   If the battery doesn't charge or fails the self test repeat 8V 40mA procedure for up to 5 minutes.  If it fails, the battery is likely dead.  If the battery charges up cycle it: charge full then discharge to 7V, 3 times.

While Agilent likely would have designed shut down circuitry if the battery provided <= 7Vdc, the battery could also be permanently damaged as 9V NiMH are made of series 1.2V cells that could suffer polarity reversal if overdischarged. 

[Wing47]

Saturation, Thanks for the clear explanation and advise.  I have installed a std 9v and it did power-up and pass SLFt.  Appears normal. I'll do some more testing to confirm, but this is a great start!  The original rechargeable unit is now 3 years old, so I'll use it for hacking, but I'll get a new one for the meter if my usage warrants, otherwise I'll keep throwing in a fresh 9v, and removing it when not in use.  Thanks again!