Ni-Cad Battery Maintenance

[Up And Down]

I have a few questions about ni-cad battery maintenance. I own some Snap-On cordless stuff...CT6850 1/2 inch impact (18v), CT4410A 3/8 drive impact (14.4v), and both the 1/4 and 3/8 drive cordless ratchets (12v). All of them have the ni-cad battery packs. Being that I am not a pro auto mechanic and use them for at home exclusively, they get used very little. I would like to know the bext way to store and maintain the batteries, which are very expensive. Should they be charged fully and then stored? Drain and then stored? Stored on the tools or off? If it is on the tools, should the switch on the impacts be in the middle "off" position? Is there any kind of drain and recharge sequence on the chargers or anything like that to help keep the batteries in the best shape? Any input on this subject will be appreciated as these batteries are pricey and I would like to maintain them as best I can.

 

[wafrederick]

I am a member of the Handyman Club of America and their magazine,Handy did an article on power tool batteries a few years agne thing that was said in the article was to remove the battery from the tool when not in use.The batteries last longer this way and I do this.There is something you do not ever do and will kill the batteries.Taping the trigger down is a huge no no,reverses the battery cells and kills them.If a battery gets low,put it in the charger asap.

 

[route246]

Never leave them in a charger that is unplugged, ever. A charger has internal resistance when not plugged in and will also reverse the cells, making them unable to hold a charge.

 

[Up And Down]

Thanks for the replies so far. Anyone else have anything to add? I was hoping for a certain routine that guys follow to keep these rarely used and very expensive batteries in top condition and get maximum performance and lifetime out of them.

 

[wafrederick]

Keep them out of cold conditions too.If you want a copy of the article I mentioned,let me know and I will mail a copy of it.

 

[Lhorn]

I have the Craftsman c3 with NICAD batteries. Can you just leave a battery on a plugged in charger so it's ready to go or should you take then off the charger soon after they're fully charged?

 

[Daniel Kinder]

Thought this would help.

http://reviews.ebay.com/Rechargeable-Battery-Care-and-Maintenance-Guide_W0QQugidZ10000000001229809

 

[cdseven95]

So run them completely out before recharging?

 

[djb2]

I have the Craftsman c3 with NICAD batteries. Can you just leave a battery on a plugged in charger so it's ready to go or should you take then off the charger soon after they're fully charged?

Almost every piece of advice here is partially wrong.

The answer for the charger is "it depends".

A great charger will maximize the service life a battery left connected.

Few chargers are great. Most sorta ****. Some **** hard. They will just keep charging the battery, overheating it. So the general advice to remove the battery is safest.

Most chargers won't discharge the battery when unplugged. Most, but not all. I've had one that allowed a 20mA reverse current -- enough to drain the battery in a day or so.

Very few tools will discharge the battery when not in use. Not even slightly. There isn't a reason to remove a rechargeable battery.

Normal cold generally doesn't damage standard NiCad batteries. It will reduce their available supply capability, but if you don't use a heavy current draw that's not a problem.

 

[route246]

Do not do this under any circumstances. It will wear out NiCads.

I have the Craftsman c3 with NICAD batteries. Can you just leave a battery on a plugged in charger so it's ready to go or should you take then off the charger soon after they're fully charged?

I didn't read the article but the best approach is to run them down until they get weak. Don't run them dead because eventually the weaker cells will get reverse charged and then you're f&cked. NiCads are basically 1.2V batteries that are lashed together in series to provide the correct voltage and in parallel if they need more capacity. The problem is that they tend to get weak a slightly different times and then you end up with reversed cells and the problem keeps getting worse and worse. There are no chargers out there that know how to handle NiCads. NiMH are better because they prefer being trickle charged and also prefer not to be fully charged for maximum lifespan. LiIon batteries all have logic in them to prevent overcharging and overcurrent.

So run them completely out before recharging?

There are no chargers that I know of that can effectively manage NiCads. You are basically on your own. There is no feedback mechanism, no logic on-board and the so-called "memory effect" is often caused by weak cells getting weaker.

Almost every piece of advice here is partially wrong.

The answer for the charger is "it depends".

A great charger will maximize the service life a battery left connected.

Few chargers are great. Most sorta ****. Some **** hard. They will just keep charging the battery, overheating it. So the general advice to remove the battery is safest.

Most chargers won't discharge the battery when unplugged. Most, but not all. I've had one that allowed a 20mA reverse current -- enough to drain the battery in a day or so.

Very few tools will discharge the battery when not in use. Not even slightly. There isn't a reason to remove a rechargeable battery.

Normal cold generally doesn't damage standard NiCad batteries. It will reduce their available supply capability, but if you don't use a heavy current draw that's not a problem.

 

[MrMark]

In the directions for my impact, Bosch says to store the batteries at 40-50 percent charge for long term. I've read similar to this elsewhere. This is a black art and there is a dearth of consistent good information on this topic.

On thing for sure is that batteries like to be used.

 

[ajchien]

Check out:

http://batteryuniversity.com/

It takes about all kinds of rechargeable batteries and their best care.

 

[MrMark]

Link says store at 40 percent. Good luck figuring that state of charge.

 

[wafrederick]

Running them down will reverse the battery cells and kill them

 

[honcho]

I second http://batteryuniversity.com/

Solid, factual battery information unlike most of the misinformation that usually mixes up information specific to each rechargeable technology (nicad, nimh, lithium based, and lead-acid are the big four of portable rechargeable devices) One approach definitely does NOT fit all.

NiCad is actually a pretty good technology for storage and infrequent use but all rechargeable batteries deteriorate. Use and monitoring is the best way to make sure they'll work when you need them.

Unlike Lithium-Ion batteries, Nicad do not deteriorate in storage as much as Li-Ion batteries. I have 10 year old Nicads that work reasonably well whereas beyond three years most Lithium based rechargeables are worthless.

However, happy note is that NiCad and Nickel Metal Hydride battery packs can generally be rebuilt for a reasonable cost. I am not aware of any commercial companies that rebuild Lithium batteries due to concerns over liability.

 

[paris_tj]

Also Ni-cads develop a memory and to keep that from happening they need to be fully cycled some. For example if you run one until it is 50% dead and then charge it will start to remember that, and actual go dead at 50% charger. If you cycle them occasionally from full charger to 100% dead or close it will help keep them from developing memory. This is only for Ni-cads, Nimh, and others are different. This is from my R/C car days of running Nicads. I can only assume it would be similar if not the same since it is the same batteries.

 

[Warrenator]

To test and rebuild a NiCad battery pack, basically disassemble it, (you may have to clip the metal straps and resolder with new overlapping straps when you are done) once you have the cells detatched from each other you can deep discharge, recharge, and test them as INDIVIDUAL CELLS. A D-Cell battery charger works well for this, with adapters. (Adapters don't have to be fancy, I've been known to use little wires with ol' copper pennies soldered on the ends and a rubber band) Also I use a flashlight lamp to discharge a cell overnight, you can run a stopwatch to see how long it lasts. You can usually identify one bad cell and just replace that one. Also the trick of connecting the battery to a car battery for just a moment to burn off the "whiskers" that grow inside and short out a NiCad cell works much better if you treat an individual cell. You can buy new cells online, or take two battery packs and scavenge cells to make one good one.

If you charge them as a PACK, the weak cells will cause incomplete charging, if you discharge them as a PACK, as the individual cells get discharged, the other batteries that are still good will cause the current to flow in reverse through the bad cell.

When you are using your tool, and suddenly it loses half it's power and is running like really slow, you are reversing a cell, don't keep using it when it is that low. It is good for a NiCad to fully discharge when it is a CELL, bad to discharge it as a PACK. Storing them in a partial state of charge is fine, the cells are not damaged by self discharge, and the self discharge rate of NiCads is very low, unlike NiMh batteries.

I used to spend a lot of time messing with these NiCads. (Can you tell?) Now I just use NiMh packs.

 

[tooth]

I've been using dewalt 18v nicad batteries with the dewalt charger that has automatic battery tuning. It also works with my black and decker batteries that are 14v. It revived those nicad batteries - they were only lasting 5 minutes.

I'd say you're better using the tools frequently if you want the batteries to last long.