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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Repairing NiCd battery packs
I have a nice 14.4V Dustbuster where the battery pack is pretty much
unsable right now. It's a nice vac. I bought a new 18V one with a removable battery, but it doesn't seem to work as well. I took the 14.4V battery pack apart. It contains 12 sub-C size cells. 4 show 0V, while the rest are showing about 1V (it's not fully charged.) Has anyone had any luck in replacing individual cells? There are no markings on the batteries, so I have no idea what their capacity is. These are chained together with short metal strips that are spot-welded to the batteries. How easy/hard would it be to solder to them, and will it damage the batteries if I try? I have found direct replacement packs at some sites, but at $30+, I wonder if it's worth it. It's as much as a new vac, but then the new vacs seem to be pretty crappy. -- If there is a no_junk in my address, please REMOVE it before replying! All junk mail senders will be prosecuted to the fullest extent of the law!! http://home.comcast.net/~andyross |
#2
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Repairing NiCd battery packs
In article ,
Andrew Rossmann wrote: How easy/hard would it be to solder to them, and will it damage the batteries if I try? If you scratch the areas to be soldered with sandpaper and *use liquid flux* then you can readily solder the batteries without damaging them. |
#3
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Repairing NiCd battery packs
The problem with replacing /individual/ cells is that, even if they're
exactly the same cell used in the original battery pack, the new cells will have higher capacity, increasing the chance of cell reversal. You really should replace all the cells. My experience with Black & Decker's OEM battery packs -- if you can find them -- is that they hold up well. I wouldn't purchase a third-party battery pack, unless the supplier offers an iron-clad guarantee. You might consider putting together a battery pack of 2500mAh or 2700mAh AA NiMH cells. You'll get higher capacity, though the battery will take longer to reach full charge. |
#4
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Repairing NiCd battery packs
"Andrew Rossmann" Has anyone had any luck in replacing individual cells? ** Best to replace the lot. There are no markings on the batteries, so I have no idea what their capacity is. ** See above. These are chained together with short metal strips that are spot-welded to the batteries. How easy/hard would it be to solder to them, and will it damage the batteries if I try? ** Try to get cells that have tags fitted to them. These are very easy to solder with any decent soldering iron and flux cored solder ( not lead free) as used for electronic work. ..... Phil |
#5
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Repairing NiCd battery packs
Smitty Two wrote:
In article , Andrew Rossmann wrote: How easy/hard would it be to solder to them, and will it damage the batteries if I try? If you scratch the areas to be soldered with sandpaper and *use liquid flux* then you can readily solder the batteries without damaging them. If cells with solder tabs and the bulge caused by the solder and wire still fit in the space, that's the way to go. Be aware that QUALITY cells will cost more than the cost of a battery pack. Dustbusters are sold on PRICE. That means low quality batteries and chargers with zero control that overcharge/degrade the cells. If you don't do something about the charger, your new cells won't last any longer than the old ones did. People tell you that you can safely solder on cells. That ain't the case. Yes, if you're very experienced at soldering on batteries, you may be able to do it most of the time without serious degradation. If this is your first attempt, expect to ruin at least some of them. If you must solder on 'em, do it with them discharged, so when you melt the separator and create an internal short, there's less energy to fuel the explosion. Wear eye protection, and make sure the kids are outa the house. They're not lithium, so making sure your fire insurance is paid up is a secondary issue. I can hear the villagers lighting the torches to come after me to tell me how stupid I am...that you CAN solder on batteries. I even did it for a number of years. I am fortunate that I got old enough to require glasses before the first one exploded in my face. Otherwise, you'd be reading this in braille. There's a reason they weld the tabs. Ignore that at your peril. People who have to ask "how hard it is" should NOT be soldering on batteries...even if some "newsgroup expert" says THEY can. |
#6
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Repairing NiCd battery packs
"mike" If cells with solder tabs and the bulge caused by the solder and wire still fit in the space, that's the way to go. ** There is a simple way to join ( un-tagged) cells very neatly, tip to base, that uses just a few centimetres of 1.5 mm dia solid copper wire. Here it is: The copper wire ends are first tinned and one end soldered to the *side of the tip* of one cell and then the other end soldered the outer edge of the base of another. A quick twist and the two are perfectly connected in series with no increase in overall length. People tell you that you can safely solder on cells. That ain't the case. Yes, if you're very experienced at soldering on batteries, you may be able to do it most of the time without serious degradation. If this is your first attempt, expect to ruin at least some of them. ** This is just not true. There's a reason they weld the tabs. ** It's quick, cheap and nasty. Most spot welded joints have so much resistance the joint gets VERY HOT when packs are subjected to a fast discharge - ie when used on RC models involved in racing etc. People who have to ask "how hard it is" should NOT be soldering on batteries...even if some "newsgroup expert" says THEY can. ** You need a good soldering iron - preferably a modern, variable temp station and iron rated at 50 watts with a large tip size fitted and full setting ( ie 450C) on the temp dial. Then one works quickly and purposefully with ordinary, rosin cored 60/40 solder. The nickel plated surfaces of fresh Ni-Cd or NiMH cells usually tin so quickly - it fair makes your head spin. ...... Phil |
#7
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Repairing NiCd battery packs
"Phil Allison" wrote in message ... "Andrew Rossmann" Has anyone had any luck in replacing individual cells? ** Best to replace the lot. There are no markings on the batteries, so I have no idea what their capacity is. ** See above. These are chained together with short metal strips that are spot-welded to the batteries. How easy/hard would it be to solder to them, and will it damage the batteries if I try? ** Try to get cells that have tags fitted to them. These are very easy to solder with any decent soldering iron and flux cored solder ( not lead free) as used for electronic work. I do it that way. Flux and quick tin tab and cell. I use a 250 watt Wen gun type. With high wattage the quicker it will solder with less heat expanse on the cell. WW .... Phil |
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