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Author Topic:   Handheld VHF battery repair

ratherwhalering posted 11-05-2005 07:04 PM ET (US)
I have an older Standard Horizon HX250 that I had left in the trickle charger for upwards of 12 months. Needless to say, that pretty much killed that battery. It would not hold a charge for very long, and even then it was at 1/4 of its capacity. I found that the replacement battery was upwards of $100.00 and back ordered. I did a search on this site re: replacement batteries, and I came across a thread in which Chuck Triblet identified the cause of the problem, and a potential solution. The solution involves using 10 gauge wire to connect the + and - terminals and essentially short out the battery. This is a dangerous method of 'repair' because there is a very real probability that the battery will explode. I donned some heavy leather gloves and safety glasses, then hid behind a nice pine tree, while reaching around either side of the tree and connecting the terminals (not the charging contacts) with the 10-gauge wire.
Well, the wire heated up something fierce, and the negative terminal initially sparked like it was hit with an arc welder, but I persisted for a few minutes until the battery was drained. Fortunately it did not explode.
After that little experiment, it now holds a full charge, and is acting quite normally. I gave it a full charge, then a full drain, and now it has a full charge again. I don't know if this is necessary, but I remember reading that rechargeable NiCad batteries can have some sort of 'charge memory,' and it is good practice to allow them to fully drain from time to time.
In any case, thank you Chuck for saving me $100.00 (plus shipping.) I have tried to find the thread that describes the problem and the solution, to no avail.
This is my backup VHF, and my only concern is that it will not hold a charge due to my recent 'repair'. Of course I will no longer leave it sitting in the trickle charger for extended periods, but I'm wondering if there are any long term detrimental effects from this procedure.
Chuck Tribolet posted 11-06-2005 08:29 AM ET (US)
You zapped those dendrites pretty good. I probably wouldn't
have drained it all the way so as to avoid reverse polarizing
the weakest battery.
The dendrites are whisker-like crystals that short out the
battery. You've blown them like fuses and there are now little
gaps in them. Operatative word is little as they can grow
back and bridge the gap.

Chuck
ratherwhalering posted 11-06-2005 10:20 AM ET (US)
Ahh, I see. So it is only necessary to zap the dendrites, and I don't need to completely short out the battery before I accomplish this. I will be much more careful with my charge times. Thanks again, Chuck!
jimh posted 11-06-2005 02:09 PM ET (US)
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Author	Topic: Handheld VHF battery repair
ratherwhalering	posted 11-05-2005 07:04 PM ET (US) I have an older Standard Horizon HX250 that I had left in the trickle charger for upwards of 12 months. Needless to say, that pretty much killed that battery. It would not hold a charge for very long, and even then it was at 1/4 of its capacity. I found that the replacement battery was upwards of $100.00 and back ordered. I did a search on this site re: replacement batteries, and I came across a thread in which Chuck Triblet identified the cause of the problem, and a potential solution. The solution involves using 10 gauge wire to connect the + and - terminals and essentially short out the battery. This is a dangerous method of 'repair' because there is a very real probability that the battery will explode. I donned some heavy leather gloves and safety glasses, then hid behind a nice pine tree, while reaching around either side of the tree and connecting the terminals (not the charging contacts) with the 10-gauge wire. Well, the wire heated up something fierce, and the negative terminal initially sparked like it was hit with an arc welder, but I persisted for a few minutes until the battery was drained. Fortunately it did not explode. After that little experiment, it now holds a full charge, and is acting quite normally. I gave it a full charge, then a full drain, and now it has a full charge again. I don't know if this is necessary, but I remember reading that rechargeable NiCad batteries can have some sort of 'charge memory,' and it is good practice to allow them to fully drain from time to time. In any case, thank you Chuck for saving me $100.00 (plus shipping.) I have tried to find the thread that describes the problem and the solution, to no avail. This is my backup VHF, and my only concern is that it will not hold a charge due to my recent 'repair'. Of course I will no longer leave it sitting in the trickle charger for extended periods, but I'm wondering if there are any long term detrimental effects from this procedure.
Chuck Tribolet	posted 11-06-2005 08:29 AM ET (US) You zapped those dendrites pretty good. I probably wouldn't have drained it all the way so as to avoid reverse polarizing the weakest battery. The dendrites are whisker-like crystals that short out the battery. You've blown them like fuses and there are now little gaps in them. Operatative word is little as they can grow back and bridge the gap. Chuck
ratherwhalering	posted 11-06-2005 10:20 AM ET (US) Ahh, I see. So it is only necessary to zap the dendrites, and I don't need to completely short out the battery before I accomplish this. I will be much more careful with my charge times. Thanks again, Chuck!
jimh	posted 11-06-2005 02:09 PM ET (US) [Moved]