Battery Failure on a Mitsubishi Controller

[gearmachinist]

We have a very frustrating problem with battery failure on a M320LCV Mitsubishi control on a Citizen CNC Machine. I placed a new battery in the control and it lasted about a month when suddenly one morning after the machine was off about 4 days the control didn't come up. We thought that possibly we just got a bad battery so I purchased another new battery and it was off for just over a day when it died. I'm guessing at this point that we have developed some sort of problem where the control is draining the battery. Probably the most logical approach would be to have the control repaired and move on but for the sake of time and cost I was wondering if we could just purchase a small plug in DC transformer from Radio Shack and replace the battery? We could then plug this into a UPS system and possibly have a more reliable system than the battery has proven to be. Has anyone had experience with such an arrangement? Will this work or will I create other problems? Any advice or feedback would be appreciated.

Thank you,

Gary Jennings
Jennings Machine & Gear, Inc.

[Caprirs]

Are you using a new battery from Mitsubishi or did you improvise? The replacement battery must be nickel cadmium. Nickel metal hydride and lithium will damage the charging circuitry in the Mits control.

I think you can rig up a seperate charger but you have to figure out how to electrically isolate the RS transformer from the control when the machine's power is switched on. This is beyond my knowledge so I would call Mits and ask. Done incorrectly, when the machine is on, the Mits charging circuitry will try to "charge" the transformer and I have no idea what would happen to either the control or transformer.

[gridley51]

Nickel Metal Hydride is ok as a replacement for Nicad batteries as long as it is of a similar capacity.The charging system is similar for both types.This information was given to me by battery manufacturer G S Saft who used to make the Mits batteries.This is actually to be preferred as most of the world is moving away from cadmium.
I have a Siemens control which has the same problem.The batteries run down in a matter of days when the power is of.The fault is reckoned to be a diode on the memory board.

[onthebumper]

Hooking up a transfromer sounds like there is good potential to make things worse then make them better.

The battery usually gets drained do to the memory board but it could be another board as well. You can isolate which board it is with a few simple tests. Power down the control and pull out the battery and measure it. Measure it again in ten mintues (the memory should retain because of the capacitor on the memory board). This reading will give you a base line setting. Now plug the battery back in and check how much it drains in ten minutes. Start to disconnect the boards one at a time for ten minutes and see if there is a change or no change. This won't fix your problem but at least it will pinpoint where the problem is so that you do not have to have the whole control repaired.

[Captdave]

I’m using an aftermarket battery (3,000 MlAMP) on a T32 control that has a high draw on the MC-116 card (dead battery after 3-4 days) that I can’t isolate and not willing to pay Mit’s 1600.00 to overhaul. The only negative I see is when the control is first turned on the battery malfunction alarm comes on, clear it and good to go.

Been like that for all most 2 year now and haven’t lost anything even after being off for a month while on vacation.