Back from the DEAD! Lithium Batteries!

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hey everybody today I'm going to show

you how you can easily bring a dead

power tool battery back to life when

your charger won't bring it back to a

full charge and says it's defective now

a lot of times especially with lithium

packs the Chargers are very sensitive

about the low voltage of the pack and if

it drops below a certain threshold it's

gonna tell you it's defective

even though you can revive it fairly

easily now in this case I have a 20 volt

max lithium pack that's on a porter

cable drill and when I pull it on the

trigger you'll see that it does work

that means that the battery pack is not

completely dead but when I take this

pack and I put it on this charger a red

light starts flashing telling me it's


that means that the voltage of the pack

is below the threshold set by the

manufacturer and as far as they're

concerned the pack is defective now many

times if you get a brand new tool out of

the box or let's say you leave something

on it they might have a power draw such

as an LED light it will drain these down

below that threshold and you would have

to spend 50 or 100 bucks to replace it

so what I want to do in this video is

show you how you can revive these your

charger will accept them and bring them

back to a full charge and you will save

yourself a lot of money unlike older

NiCad battery packs which might have a

similar size weight and feel to today's

lithium units the cells inside are going

to be completely different with the

older NiCad packs even if you drop them

down to completely discharge normally

you could charge them back up fairly

easily but the new lithium packs when

they drop down below a certain voltage

the cells can corrupt that can cause

them to overheat short-circuit catch on

fire even explode so if you do try to

charge one of these back up make sure

you're not indoors specifically in your

house and your garage or near anything

flammable it's best to do this out your

driveway or even a parking lot to

minimize the risk to you or anything

around you to show you what's going on

with this battery pack we'll pop it on

the charger and take a look at the

battery status indicator light now you

can see a solid green

would mean it's fully charged a blinking

green light would mean it is charging

and then a rapidly flashing red light

means the battery pack is defective now

the reason it thinks this battery pack

is defective is because the overall

voltage has dropped below the safe range

of the charger and it will not apply any

power but when we take the same battery

pack we plug it on our drill and then

pulling on the trigger

you can see that there is power still in

the pack so that means that we should be

able to charge this back up and revive

it using a digital multimeter we can

check the voltage of the defective pack

taking our positive lead and attaching

that to the positive terminal taking our

negative lead and attaching that to the

negative terminal it's going to show a

pack voltage of thirteen point nine

volts we need to bring that up in order

for the charger to think that this is a

good pack and then it would apply power

to fully charge it to bring the voltage

up in our defective pack we will want to

use another battery that does have the

same voltage specifically an eighteen

volt battery and a 20 volt battery are

going to be the exact same except for a

marketing term describing them with the

20 volt max describing the voltage

without any load being applied and the

18 volt battery describing the voltage

when a load is being applied as you can

see with the digital multimeter

connected to the Milwaukee m18 battery

its voltage without a load is coming in

at over 20 volts so what we'll do is

connect the two of these and just like

connecting jumper cables in your car

when you would have a good battery and a

dead battery you connect the positive

terminal to the positive terminal and

the negative terminal to the negative

terminal that means that the two battery

packs will eventually equalize and then

they will have the exact same voltage

because that voltage will be above the

range which is going to be the low range

on our charger when we plug that battery

back into the charger since it will be

above the cutoff it will start charging

it now the one thing you want to keep in

mind if you are going to do this you do

want to match up your battery packs with

the identical voltages because if we

tried to equalize it with let's say a 12

volt pack this does not have

amount of voltage we need in order to

bring our pack back to a usable level if

we connect these two there's a good

chance that both battery packs could end

up being damaged the gauge and length of

the wire is going to be important and if

you notice the two leads that I've

already made I've used a 12 gauge wire

and I have a fairly short length this

means that it won't overheat on me

and it can carry the power with no

issues and if you've noticed I've taken

some ring terminals and soldered them on

the end of these wires but you could

easily crimp these on the same way and

have an equally effective connection the

reason I went with a ring terminal it's

completely flat and it's going to be the

same width as the terminals on the

bottom of the drill that plugs into the

battery pack that means using the same

exact ports I'll have great surface

contact but more importantly I'm not

going to accidentally damage something

if I had use alligator clips with a thin

gauge wire although it would connect the

two it would not be effective at

carrying that load and these could

overheat on me or the alligator clips

could actually damage the batteries by

going this route and taking a little bit

of extra time to make these connectors

I'm not going to damage either battery

in the process to connect the two

batteries I'm going to take my two leads

and I'll connect one to the two positive

terminals I'll connect the other to the

two negative terminals this is going to

allow them to synchronize as far as the

power levels and I'll let them sit for

roughly five to ten minutes after that

time I'm going to unplug it will take a

reading of both batteries as far as the

voltage and then we'll see if the Porter

Cable will charge on that charger

okay it's been just over five minutes

I'm going to go ahead and remove the

leads one at a time and now we'll go

ahead and take a voltage reading on each

battery pack first we'll take a look at

the m18 and with it originally it was

roughly at twenty point four volts now

connecting those leads we can see that

it's roughly at 19 volts meaning that

some of the energy in this battery pack

did transfer over to the porter table

when we switch the two we'll go ahead

and see exactly how much transferred so

now taking those same leads and plugging

it in the porter cable we'll know

exactly how much power did transfer over

now we're at over 16 volts and this

started out at under 14 now we'll go

ahead and pop this on the charger and

see if it's gonna charge when we

initially plugged the battery pack in

this charger the LED light was blinking

very fast and it was red that did

indicate that the battery pack was

defective but now that we've charged it

up off the m18 when we click it into

place you're gonna see a slow blinking

green light that means it's above the

range it's applying power charging the

pack and then when it is a solid green

light it means that the pack is gonna be

fully charged so once the battery pack

has fully charged just pop it off the

charger put it back on your tool and you

can get right back to work now this was

effective because it did not drop below

the threshold of actually corrupting the

cells inside the battery if that had

happened it could have short-circuited

it could have damaged the other battery

caught on fire or even exploded you

never want to do this indoors around

anything flammable if you're gonna take

the risk of trying to charge a lithium

pack back up after your charger will not

charge it make sure you're outside so if

there is a problem you're not going to

run into more problems because of that

specifically you don't want to hurt

yourself or burn your garage or your

house down so when you're working with a

lithium pack if your charger is not

going to charge it and you don't feel

comfortable doing this turn it back into

the manufacturer or send it out for

recycling it's a lot cheaper to go ahead

and just buy a battery pack then risking

burning your house down in order to save

a few dollars

now in this case we were able to save

roughly 50 to $100 by reviving this pack

and now we have maximum power meaning we

can get back to work and we don't have

to go to the store and buy a replacement

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