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When using the VU-AMS5fs device you can choose for normal (Alkaline) or rechargeable (NiMH) batteries.

We have chosen to sell the VU-AMS5fs device with rechargeable (NiMH) batteries as they have more capacity. Also when using them for hundreds of recordings they have less environmental and financial impact.

There are a few things to take into account when using rechargeable (NiMH) batteries:

  • You are advised to keep them in pairs so they age, i.e. lose their capacity, together (this is why we sometimes deliver two types of batteries like in the photo on the right)
  • The advice is to perform a few charge/discharge cycles when they're new to get them to the full capacity
  • At some point you may want to test their capacity to see if they should be replaced



By default all recent VU-AMS5fs devices where shipped with a Voltcraft BC-500 battery charger. This charger can also test the capacity of rechargeable batteries by doing a charge-discharge-charge cycle. You can do this by pushing the black button until 'TEST' appears in the display. This test can also be used to get new batteries to their full capacity or to revive batteries not used for a while.

The next day you will see something like 2.3Ah in the display. This means that the batteries (still) have a capacity of 2300mAh. Roughly speaking you will need a capacity of 2000mAh to do a 24 hour recording to be on the safe side.

Additionally, the charger displayed on the left will keep the batteries at their optimal capacity without damaging the batteries after they have been fully charged.