Fuse inside Battery

I have a battery which doesn t have a voltage reading (0V) but is displayed at the Switch and at an external lipo-charger as full charged. I discovered that the cell has 4V and the fuse on the intern battery controller board is blown. Does someone know the rating of this fuse. It s an smd 1206 fuse with the letter ‘M’ on it.

I have no idea what the original fuse value is, I suppose you could connect one to a bench PSU and starting at a 2A current limit, increase it a couple of hundred mA at a time and see at what point it blows which will give you a pretty good indication of the value.

Alternatively, afaik the current never goes beyond 2A so a 3A fuse should be more than adequate as they’re really intended as last stop fail safe.

Although, saying all that, I don’t know what the peak draw is by the console itself… this would have to be measured and taken into account, for example if the console pulls 4A out the battery (I have no idea)

Looking at the BQ datasheet it has the max current listed at 4.5A… so maybe a 5A fuse would be more appropriate.