# How do I test a rechargeable battery?



## Larryh86GT (Feb 2, 2013)

I have a number of Firestorm 24V cordless tools. Can someone tell me how to test my batteries ?


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## oberkc (Dec 3, 2009)

If it is easy to open your battery pack, perhaps you could probe voltage for each cell. I assume nominal voltage should be around 1.2V. Maybe there is one or more cells that is obviously bad.

Have you checked the voltage of the entire pack? 

Are the batteries old enough to not be surprised by a failure?


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## Larryh86GT (Feb 2, 2013)

oberkc said:


> Have you checked the voltage of the entire pack?
> 
> Are the batteries old enough to not be surprised by a failure?


How do I check the voltage of the entire pack?


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## del schisler (Aug 22, 2010)

Larryh86GT said:


> How do I check the voltage of the entire pack?
> 
> The batteries are getting old.


if you have a volt meter set to at least 30 volt or 50 volt don't know the scall on the meter , now with the leed's red and black, i beleve the spade to the bigest part of the battery is postive and the spade to the smallest part of the battery is neg, not touch the leed's to these spades and red the voltage, now the the needle goes to the left on the meter reverse the leed's, this voltage is with out a load on it so it will not tell you much, it is like a surface charge, you need to be set up with item's to do this , it's been a while sence i measured battery's , as far as repairing the charger, take it to a repair place, or replace it , if you can't measure battery voltage , i don't belive you should tackle the charger my 2 cent's, been in repair for 50 yrs leve someting to the pro's


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## oberkc (Dec 3, 2009)

> The batteries are getting old.


Perhaps, then, it is time for new ones. They don't last forever. While you might be able to identify and replace a bad cell, it is likely that the other cells are near the end of their life as well. Have you noticed that the batteries required more frequent charging as of late?



> if you can't measure battery voltage , i don't belive you should tackle the charger


I agree. 

Learning to read voltages is a useful skill for the DIY person. Do a web search on AC and DC voltages and learn the difference. Search on electrical resistance (Ohms) and learn how to use such measurements for troubleshooting. Pick up a volt meter and learn to use one. They are quite handy (even essential) for basic house electrical and electronics troubleshooting and repair.


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## Larryh86GT (Feb 2, 2013)

oberkc said:


> Perhaps, then, it is time for new ones. They don't last forever.


Asking someone to walk me through the steps testing a battery. Replacement 24V chargers are a lot cheaper to replace - I'm not too concerned with that.


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## joecaption (Nov 30, 2011)

A dead or defective battery would have nothing to do with the chargers dying.
Could be as simple as dirty or weak contacts where the battery makes contact with the charger.


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## oberkc (Dec 3, 2009)

> thus my asking someone to walk me through the steps testing a battery.


The steps of testing a battery, whether an individual cell, or a complete pack, are simple. Take your volt meter and probe the contacts. That is the easy part.

-can you get your pack apart without destroying it?
-can you find a source for replacement cells, exact size.
-can you solder?

My limited experience with such things is that while this can be done, success is not guaranteed. Then, you may find that another cell goes bad a month later. Unless you do this a lot, you would have to place a pretty low premium on your time to make this worth it.

Unfortunately, I cannot help with your specific packs. Only you can look at them and determine whether you think you can get them apart successfully. Once open, inspect the cells...do you think you have the skill to remove and replace a cell, once a bad one is identified. 

For me, if I have an old pack and it is showing signs of failure, and I have gotten good use out of it, I replace the whole pack. 

I don't mean to discourage trying...just suggesting that it is not a simple task, and has a high likelihood of failure.

Also, in case you were not aware, there are aftermarket replacement packs that can save a little money.


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## Larryh86GT (Feb 2, 2013)

oberkc said:


> The steps of testing a battery, whether an individual cell, or a complete pack, are simple. Take your volt meter and probe the contacts. That is the easy part.
> 
> -can you get your pack apart without destroying it?
> -can you find a source for replacement cells, exact size.
> ...


I just want to do a test to determine if a battery as a whole is still good.


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## oberkc (Dec 3, 2009)

> I just want to do a test to determine if a battery as a whole is still good as I don't intend to open it up to inspect or attempt to repair the cells inside.


Measure, then, the voltage of the entire pack. I assume that the batteries are NiCd, but you should confirm this. I assume that this is a 20-cell pack. If I remember correctly, a discharged cell is around 1.1V. A full cell is over 1.2 Volts. The full pack, then should be at least 22 volts...higher if charged. If you see less than this, I would take this as a strong indication that you have a bad cell or more. 

Unfortunately, this is only a gross test of one type of failure mode and not indicative of capacity. You can have full-voltage cells and still be near the end of life. A Voltage test is only an indication of a completely failed cell, at best. To measure capacity, I assume one has to apply a known load and measure time until discharged.

Still, measuring voltage is simple and quick enough that it is worth doing even if not conclusive.


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## woodworkbykirk (Sep 25, 2011)

a bad battey cell wont do anything to a charger. most chargers will have a specific blinking pattern on the led light that will tell you if have a defective battery.. 

a bad battery wont make the charger go bad,, however if you have a defective charger it can effect hte battery

the best way to get a battery tested is to simply go into a tool service center that deals in that brand of tool, they have the gear for just this


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## Larryh86GT (Feb 2, 2013)

woodworkbykirk said:


> a bad battey cell wont do anything to a charger. most chargers will have a specific blinking pattern on the led light that will tell you if have a defective battery..
> 
> a bad battery wont make the charger go bad,, however if you have a defective charger it can effect hte battery
> 
> the best way to get a battery tested is to simply go into a tool service center that deals in that brand of tool, they have the gear for just this


If my charger had a blinking pattern that told me the battery was defective I would not have started this thread. 

I prefer not to deal with shops if I can avoid it.


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## woodworkbykirk (Sep 25, 2011)

getting a repair shop to check a battery is free, all they have to do is put it on a tester.. now mind your talking about a cheap cordless tool, just replace the whole thing


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## Larryh86GT (Feb 2, 2013)

woodworkbykirk said:


> now mind your talking about a cheap cordless tool, just replace the whole thing


Thanks for your suggestion but I'll just keep my set running.


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## wkearney99 (Apr 8, 2009)

It's entirely possible a cell within the pack is bad (or more than one). Search on repairing those packs. It can be done. One such example:
http://www.handymanclub.com/connect/forums/aft/37148/afpg/2

The hard part about repairing battery packs is sometimes the cells have tabs welded to them, not just soldered. And there's not always enough room to do a repair without welding on new tabs. Trouble is the sort of spot welder that's necessary is usually a lot more expensive than new battery packs. So unless you're doing a lot of them, repeatedly, it's not very cost effective. That and you can ruin cells by overheating them if you attempt to solder them, some can even explode as a result. That and welded connections tend to be more secure and won't break as easily.


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## del schisler (Aug 22, 2010)

Larryh86GT said:


> If my charger had a blinking pattern that told me the battery was defective I would not have started this thread.
> 
> For sure a defective charger can effect the battery. Seeing as my 2 chargers are defective and no longer charge my batteries the batteries are going to stay dead.
> 
> As far as testing the battery by simply taking it to a shop I was under the impression this was a DIY forum but I guess I was mistaken. Perhaps it should be renamed. I prefer not to deal with shops if I can avoid it.


a couple fellow's have told you about testing a battery, even me, just measureing the voltage doesnt realy tell you much, the battery say's 24volt now if you measure it it may read 25volt now that doesn't mean that it is better that probly is just a surface charge, now put a load on the battery and it may go down to 23volt or lower which doesn't mean the battery is bad, but you have to be able to measure the battery's with a load on it , that is why it is better to take it to a shop that does this kind of busisness, this doesn't mean that this site has to be renamed ? just leasten to the pro's here that know what they know, i guess if you know you wouldn't be here, listen to what has been said, now that is a diyer with good information no more on this my 2 cents


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## ddawg16 (Aug 15, 2011)

That battery back most likely has between 16 to 20 batteries in it....wired in series.

In most cases, when a battery pack goes bad...it's just one or two cells....but because they are in series....it affects the whole battery.

You have to take it apart and measure the individual cells. One problem though...in most cases, the interconnecting tabs on those are spot welded to the battery.

For reference, a freshly charged NiCad battery will have about 1.4 volts on it....once it gets below 1.1 or 1 volt....it's done....really done....time to recharge.

If you measure the voltage while charging....if it does not come back up to about 1.4 volts quickly....then that battery is done.

Yea, there are some hacks where you can zap them with a high current to burn off a short (it's finger short inside the battery can...commonly caused by being left on a charger and/or not being used much). But that is a hit and miss....and typically does not last long.


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## woodworkbykirk (Sep 25, 2011)

the reason i say to just replace the kit is because if your having problems with it now youll be fighting with the tool from now on. no matter what the tool is corded or cordless they never come back from the repair center the same. i spent my early apprenticeship years dealing with that as my tool budget was limited. now i dont bother with that sorta nonsense. time is money. either take it to a shop to get sorted out properly or replace it


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## oberkc (Dec 3, 2009)

> As far as testing the battery by simply taking it to a shop I was under the impression this was a DIY forum but I guess I was mistaken. Perhaps it should be renamed. I prefer not to deal with shops if I can avoid it.


I suspect the responses you are seeing here is an indication that repairing one of these packs is, simply, not a commonly-performed DIY project. While a voltage check is within the abilities of many, it can be inconclusive. Furthermore, even if you can identify a failed cell, those cells are packed in pretty tights and replacing one in such a way as to be able to pack them back into the original housing can be problemmatic, assuming that you were able to get it open without destroying it. I, for one, don't even try this any more.

Yes, battery tools are expensive. I continue to select corded tools in many cases, for this reason.

BTW...last I checked, ridgid tools at HD still have a lifetime guarantee, including batteries. It was sure nice taking a failed set to the local repair center and walking out two minutes later with a couple of fresh packs.


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## ddawg16 (Aug 15, 2011)

> As far as testing the battery by simply taking it to a shop I was under the impression this was a DIY forum but I guess I was mistaken. Perhaps it should be renamed. I prefer not to deal with shops if I can avoid it.


This is DIY....you can DIY the battery to the shop.

As noted above, repairing one of those battery packs requires special tools. Do you have a spot welder? Do you have access to replacement batteries with tabs on them?

When it comes to DIY....one does it for 2 reasons....to save money or they just enjoy it. If your doing it because you enjoy it....then you don't mind spending more than a new pack would cost....after all, it's not about saving money....it's about "I did it"...

In your case....it's obviously to save money. So save some money and buy a new one or take it to a shop.


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## Larryh86GT (Feb 2, 2013)

I just want to do a test to determine if a battery as a whole is still good as I don't intend to open it up to inspect or attempt to repair the cells inside. This was a simple request on how to test batteries and a couple kind folks have tried to give that information and to those I thank you.


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## wkearney99 (Apr 8, 2009)

The point about the spot welder is the KEY to the solution. They're non-trivial devices. They're expensive and pretty much good for just that purpose. So it's a balancing act of 'how many times will you use it' against 'the cost of a whole new pack'. Unless you make a side business out of repairing batteries (which would be problematic to insure due to risks) then it's kinda hard to justify the expense. I'm all for clever tools, but that's a hard one to justify.

Whether or not your generation had any advantages over another is dubious, at best. Least we look to closely at the trash disposal and lack of recycling policies that led to disasters those in later generations are stuck cleaning up...


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## Larryh86GT (Feb 2, 2013)

I think you guys are right and you have convinced me that it would be too hard to repair the batteries and I have decided not to get a spot welder. :thumbsup:


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## pblum81 (Aug 14, 2012)

*Battery soldering*

Batteries conduct current through contact by conductive mat'l from where it's produced to where it is needed. Think about plugging in your TV or lamp. There's only a friction connection conducting 12 or 15 amps and 110V.The current only flows when activated (switched on)Why would you need to solder when there are cells with mechanical connections available. After all no welders were used when wiring your house.


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