Monday, 24 October 2016

Clansman Battery Not Charging? Try This...

When I was refurbishing my first PRC-350, I had a small problem, in that no matter what I did I just couldnt get any power from the battery cassette. Eventually, after a lot of head scratching, I discovered that something was causing a very bad voltage drop when on load. This was eventually found to be due to corrosion building up under the battery contacts. Removing them, cleaning them up, and in this case replacing a rusty washer, sorted the problem out.

Fast forward to today, and I am somewhat lumbered with a great stack of old PRC-349 batteries. I cant shift these, because no one wants to buy untested and potentially no use batteries, even when offered at under 50p a go!

So, ive started cycling them all to find which are usable. The first problem I had was making a reliable contact to the batteries, croc clips have a tendency to spring off! Here one of the spare PRC-349 chassis came in handy. Stripped of all other parts and connectors, save the battery terminals, this can be easily connected to the charger by, at present croc clips, but soon by its own dedicated pair of 4mm plugs. The battery then screws in and makes perfect contact just as if being fitted for use in a radio.

Chassis turned into charge adapter
One problem that ive been having though, is that some batteries that are showing decent terminal voltage when tested with a meter, fail when attached to the charger. The Accucel-8 reports 'connection break', suggesting that it thinks the battery isnt connected.

After a bit of thought, I realised that in order to check the presence of a battery, the charger must sense current flow to or from it. Now, as for the PRC-350 battery cassette mentioned above, if the terminals are dirty, perhaps the resulting volts drop over the added resistance is causing the problem?

So I took one of the batteries that this morning reported 'connection break', and cleaned the outer surface of the terminals. One connecting to the charger it still reported a fault. So, not just the mating surfaces! So, I removed the terminals

and cleaned away any corrosion and dirt on the fixed terminals of the battery casing, and the underside of the spring terminals

A very crudded up terminal
This time, when connecting to the charger, the battery was detected! It is now on the second of a pair of Discharge/Charge cycles, and so far showing every sign of being a good usable battery!

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