Vileda Ultramat Electro 4.8V 3600mAh Ni-MH Replacement Battery

Replaced the battery in my Vileda Ultramat Electro and the spin mop head is turning slower than before — what's wrong?

A fresh Ni-MH battery needs several full charge-discharge cycles before it reaches rated capacity — out of the box it will often run noticeably weaker than the original did in its prime. Leave it on the charger until the light indicates a full charge, run it until it cuts out, then charge it fully again and repeat that twice more. If the head speed still feels sluggish after conditioning, check the motor brush contacts inside the bucket unit for corrosion or debris, since the wet environment accelerates buildup there. Put a multimeter on the battery terminals at rest after a full charge — you want to see at least 5.5V for a 4.8V Ni-MH pack; anything below 5.2V points to a cell not accepting charge.

My Vileda Ultramat Electro battery charges fine but the mop head stops spinning mid-bucket and then starts again on its own — why does it keep cutting out?

This is a thermal cutoff triggering inside the motor housing, not a battery fault — the Ultramat's enclosed bucket design traps heat, and Ni-MH packs drop voltage sharply under load when warm, which trips the thermal protection. The replacement pack here has higher capacity than the original NiCd, so the motor controller may be seeing slightly different discharge curves and cutting out earlier than it used to. Let the unit cool for five minutes with the lid open and see if it restarts normally — if it does, the battery is fine and the issue is ventilation or duty cycle. Check that the impeller and outlet ports at the base of the bucket are clear of mop fibre, as blockage forces the motor to draw harder and heat builds faster.

The charger light on my Vileda Ultramat Electro went out like it was done but the battery is completely flat after one use — is the charger broken or is this the battery?

Original chargers for 4.8V NiCd packs use simple timer or delta-V detection, and when you swap in a higher-capacity Ni-MH cell the charger often terminates early because it misreads the voltage peak on the different chemistry. The battery is almost certainly not fully charged — it just looks that way to the charger. Charge the pack, then measure terminal voltage immediately off the charger: a properly topped 4.8V Ni-MH should read between 5.6V and 5.9V; if you're seeing 5.0V or below, the charger ended the cycle too soon. A 12–14 hour slow trickle charge via a Ni-MH compatible charger set to 200mA will bypass the detection problem and confirm whether the cells are healthy.