Naughty

I have an Akai EWI 5000, that is an electronic wind instrument.   It has an internal lithium ion battery that needs to be charged from time to time.   But the device has a design fault, in that if the battery gets too flat, it decides that the battery is dud and refuses to charge it.   Perhaps it's a safety consideration, I wouldn't know, but it's annoying, and replacement batteries aren't cheap (About €40 for a single-cell LiPo about the size of an AA).

I put my EWI on to charge last night, but when I came down this morning, there were several red lights on it, flashing.  This is not normally a good sign.   The lights went out when I disconnected the charger, but then I couldn't turn the EWI on.   I don't know what actually went wrong; it could be that I didn't plug the charger in properly, but the battery measured 2.7 volts this morning instead of the 3.7 that it should have, if it had been fully charged.

Clearly, in order to get a better idea of what's wrong, charging the battery is the first step.  But the battery is too flat to charge inside the EWI, and in any case, the charging system seems to have gone wrong.  What to do?  It has to be borne in mind that LiPo batteries have lithium compounds in them, and tend to catch fire or explode if maltreated.

I tried various Heath Robinson ideas, but it so happens that I have a charger for an 18V Black and Decker battery-powered strimmer that helpfully offers its metal charging connectors to the wide world.  I measured the voltages, and there's a pair of connectors offering 5 volts.  By inserting dressmaking pins into the little socket of the EWI battery, (making sure not to short it out) I found I could make a connection and start charging it.  But carefully; starting with a few seconds at a time, and making sure that nothing was getting hot.

The battery doesn't seem to be getting noticeably warm, and is adding about 0.05 volts every 15 minutes, so it's charging gently.   But don't try this at home folks.   This post does not present advice that you should follow.   As a separate project I will get myself a little power supply that will allow me to put, carefully, some charge into the battery when it is flat.