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Model 4416B battery replacement (NiCad to NiMH)


My 4416B rechargeable batteries need replacement. According to your 4416B instruction manual, 9V 110mAh NiCad batteries are necessary for it. But these batteries are getting harder to find as NiMH batteries are the preferred replacement these days. I have found NiMH batteries, 8.4V 250mAh, to be available. Can these batteries be used in the 4416B Isotron conditioner without any problem? If so, will they charge correctly?


You are correct in that it can be very difficult to get NiCad batteries to replace those in legacy model 4416B Isotron conditioners. The good news is the charge characteristics for NiCad and NiMH is very similar. The current production models are supplied with NiMH batteries.

Note: Do NOT connect a FAST or SMART charger to the 4416B as it will cause internal damage. Only use the supplied power supply.

The power supply/charger (110VAC or 230 VAC to 12 VDC regulated linear adaptor) supplied with, both legacy and new, Model 4416B units is suitable for either type of battery. In fact the 4416B is supplied with an external 12V power supply, with a current limit, as opposed to a charger. Charging of the battery, whether it is NiCad or NiMH, is accomplished by circuitry internal to the 4416B. The external power supply provides the option of charging and using the unit at the same time.

There will be a slightly longer charge time for the NiMH batteries, but the discharge time will be very similar. Per IM4416B, a fully charged unit can operate for approximately 8 hours.

٭Current production 4416B units utilize 3 rechargeable Nickel Metal Hydride(NiMH) batteries.

See photographs below for battery replacement sequence.

Figure 1: shows the 4416B outside cover removal. Cover screws are underneath rubber pads at each corner of case.

Figure 1

Figure 2: Internal 4416B exposed showing battery pack alignment in unit.

Figure 2

Figure 3: Battery pack removed from 4416B and ready for individual battery removal from battery pack pcb and subsequent replacement with new batteries.

Figure 3

Internal 4416B exposed showing battery pack alignment in unit.