Battery charging practices

[Tom Henderson2]

Greetings and Happy Holidays to all.

Santa brougnt me a new DeWalt 9.6V drill -- cute little thing. And since my ancient Makita 9.6V driver/drill is on its last legs, the timing is excellent.

But I have a question for you folks.... do you leave one battery in the charger at all times, even if it may be weeks before you think you will use it again?

My usage is sporadic; I might use it daily for a few days, and then not touch it for a couple months. Seems like the old Makita battery (I only had one) was often dead when I wanted it.

Reading the DeWalt literature that came with the drill, it looks like the charger is smart enough not to overcharge a battery that was left in the charger. It would be nice to always have a fresh battery available when I need it.

With the older NiCd batteries and dumbo chargers, it was a no-no to leave a battery on charge for months at a time. But now I'm wondering if the newer battery chemistry combined with smarter chargers has eliminated that risk.

So I'm just wondering what y'all do. I'll probably just leave a battery in the charger unless somebody has had bad experience doing that.

As always, thanks in advance for all the help.

-Tom H.
Ventura, CA

[Bob Genovesi]

Hi Tom,

You're correct, the older units did require the user to monitor the charging otherwise the batteries would over charge. Another nice feature they came with was a memory that severely limited their lifespan and use time.

Todays chargers and batteries have built in security that monitor the charge levels and more importantly have no memory, according to the manufacturer.

I always leave a battery in the charger so I can use it when I need it and swap them out when the charge level gets low.

[Jim Mims]

I have two of them. When I was shopping for a drill, I liked it's balance of size and power.
Mine is about 5 years old and works great, I have 3 batteries and find that if I leave one battery in the charger, it does not have a charge when I get ready to use it.
So, I make sure to take the battery out when the light goes off. Perhaps my charger is older technology and the newer ones are better at monitoring the battery?

I have a lot of electronic equipment (my wife calles them "gadgets") that use rechargeable Lithium Ion batteries. The shelf life on them is fantastic. I've taken over a 1000 pictures in the last 6 months with my dSLR and it still shows a full charge.

Now there are battery powered tool lines that use Li Ion and I'd like to see some long term reviews, to find out if they have the shelf life that'll allow me to move away from Ni Cads.

- Jim

[Al Willits]

I've got the Dewalt 14v drill and if I leave the battery in when I come to use it it seems a little warm, which would lead me to believe it charges continually, or as needed, I don't know which, so I pull the battery when its charged.
I was going to ask Dewalt what they recommended but haven't got around to it yet.

Al

[Jim Becker]

I used to leave a battery in the charger, but have lately stopped doing that in favor of unplugging the chargers during the week to save energy. I just top them off every few weeks once the shop is warm on the weekend. The Festool 12v batteries last a long time anyway as do the newly rebuilt DeWalt 14.4 batteries for my secondary drill/driver.

[Greg Sznajdruk]

I posted this on another form that was asking to show your jigs.

This is not a jig, but if you have a bunch of batteries for your screw gun to charge this may be of interest.

I bought two of these mechanical timers ( digital could be ok) Plug timer B into timer A. Recharge units are pluged into timer B.

Set timer A to be on for 10 hours, my B timer is set to 4 hours.

Timer A at 10 hours 24/10= 2.4 days
So every 2 1/2 days my batteries are charged for 4 hours.

If you set timer A at 5 hours your batteries will be charged every 5 days or so.

Timer A set to 5 hours 24/5 = 4.8 days

The upshot is that my batteries are ready to go when they are needed.

Greg

[Tom Henderson2]

I bought two of these mechanical timers ( digital could be ok) Plug timer B into timer A. Recharge units are pluged into timer B.

Set timer A to be on for 10 hours, my B timer is set to 4 hours.

Timer A at 10 hours 24/10= 2.4 days
So every 2 1/2 days my batteries are charged for 4 hours.

If you set timer A at 5 hours your batteries will be charged every 5 days or so.

Timer A set to 5 hours 24/5 = 4.8 days

Greg

Hi Greg-

Very neat idea! I had never thought about compounding timers.... thanks for the thought.

And thanks to everybody for taking the time to respond.

-Tom H.

[John Bartley]

These DeWalt 9.6v drills are GREAT!! I used them in my small engine shop for years and I have three left out of the five I've bought over the years. I've always made it a practice to run them right to the bottom, charge them up and then take the battery out of the charger. Doing that and using four batteries on two drills five days a week, I've had batteries last as long as three years. That's pretty good for the work I was making them do (screwing, drilling, lots of clutched driving work). The new batteries and chargers may be different, but I will continue to charge them and then remove them after they show "charged". It can't hurt.

edit : that's just my preference, and is not to say that the approach that some one else uses isn't better (or more correct), it;s just what works for me :).

cheers eh?

[Rick Christopherson]

Even the battery chargers that are designed to maintain a battery after it is charged are not intended to store the battery. It is intended that it will maintain a battery for a few days so you don't have to worry about it, but it is not something I would leave connected for longer than that. I also wouldn't keep topping off a stored battery every week. The battery has not self discharged enough to be topped off in just 7 days, so this too will result in an overcharge. If a battery is being stored, just top it off no more than once a month.

[Greg Sznajdruk]

Even the battery chargers that are designed to maintain a battery after it is charged are not intended to store the battery. It is intended that it will maintain a battery for a few days so you don't have to worry about it, but it is not something I would leave connected for longer than that. I also wouldn't keep topping off a stored battery every week. The battery has not self discharged enough to be topped off in just 7 days, so this too will result in an overcharge. If a battery is being stored, just top it off no more than once a month.

Ok so to automatically charge once a month you would need three timers.
A & B set to 10 hours and C set to 4 hour and it would recharge the batteries every 24 days or so. The math is giving me a headache.

Greg

[Lee Schierer]

I posted this on another form that was asking to show your jigs.

This is not a jig, but if you have a bunch of batteries for your screw gun to charge this may be of interest.

I bought two of these mechanical timers ( digital could be ok) Plug timer B into timer A. Recharge units are pluged into timer B.

Set timer A to be on for 10 hours, my B timer is set to 4 hours.

Timer A at 10 hours 24/10= 2.4 days
So every 2 1/2 days my batteries are charged for 4 hours.

If you set timer A at 5 hours your batteries will be charged every 5 days or so.

Timer A set to 5 hours 24/5 = 4.8 days

The upshot is that my batteries are ready to go when they are needed.

Greg
That's a neat idea, but the math is not correct as I understand the timer settings. Assuming the settings are timer A= 10 hours on/14 hours off and timer B = 4 hours on and 20 hours off and all times start at midnight and the on periods are the last hours of each 24.
On the first day the charger will not run, but timer B will advance 10 of the 20 hours of off time, leaving 10 hours.
The second day timer B will advance 10 hours leaving zero off hours remaining.
The thrid day timer B will start and run for 4 hours. Timer B will also advance 6 hours of off time leaving 14 off hours.
On day five timer B advances 10 hours leaving 4 off hours.
On day six after timer B will advance the 4 off hours left from the previous day run the charger for 4 hours and advance 2 more off hours.
On day seven Timer B will advance 10 hours leaving 8 off hours.
On day eight Timer B will advance the 8 off hours and run the charger for 2 hours.
On day nine Timer B will run the charger for 2 hours and advance 8 hours of off time leaving 12 hours of off time.

This sequence continues so the charger actually runs on day 3, 5, 7,8,10,12

So while you can make the charger run every few days, calculating the time when it will run is more complex that it would first appear.

If you set timer A to be on one hour and off 23 and set timer B to be on for one hour and off for 2 hours then the charger could be made to run every third day for one hour. Since most chargers will charge a battery in about 1 hour this should be more than enough time to keep a battery at full charge. Setting timer B to 3 hours off and one on would run the charger every fourth day The settings of timer B have to be a factor of 24 to work out to even days. Otherwise you end up with more random charging times.

[Steve Clardy]

I always try to remove batteries after a charge.

[chris yount]

I started removing them from my charger after i had 2 dewalt 18v batteries that wouldn't take a charge after about a year of leaving them in the charger between uses.I had those rebuilt about 2 years ago and no problems after i started removing after the charge cycle.I try to let them run down fairly low between charges too.

[Howie French]

I always remove after a full charge. I have all my chargers (3) plugged into 1 power strip. After charging I turnoff the power strip.


Howie

[glenn bradley]

The manual or the website tech support is your best source for this info as it varies by battery, charger and manufacturer. I just had some batts rebuilt for my DeWalt 9.6 drill because i love it so much. You may find it becomes a favorite. I like my Makita 9.6 better (balance) and had those batts rebuilt too.

[Greg Sznajdruk]

Lee:

You’re a better man than me. Told you the math was giving me a headache.

Originally I started to write an Excel spread sheet to do the calculation. Until it occurred to me that this wasn’t as simple I thought. After 2 hours I called it quits. But there me someone out there who would undertake this challenge.

Greg

[Lee Schierer]

Lee:

You’re a better man than me. Told you the math was giving me a headache.

Originally I started to write an Excel spread sheet to do the calculation. Until it occurred to me that this wasn’t as simple I thought. After 2 hours I called it quits. But there me someone out there who would undertake this challenge.

Greg

Wow, I thought I was bad. I also started out in excel trying to do it with a formula and gave up after about an hour and just did the calculations in my head and recorded the results in the spreadsheet, but because both timers run together when they are on I couldn't figure it out. Probably some of the calculus that I learned 30 years ago would have helped. I'll see if my math professor son in law can figure it out. :D

[Greg Sznajdruk]

Wow, I thought I was bad. I also started out in excel trying to do it with a formula and gave up after about an hour and just did the calculations in my head and recorded the results in the spreadsheet, but because both timers run together when they are on I couldn't figure it out. Probably some of the calculus that I learned 30 years ago would have helped. I'll see if my math professor son in law can figure it out. :D

Lee:

I suspect that a math professor is probably what is required.

Let me know if he comes up with a formula. Execel doesn’t appear to be able to do algebra or maybe calculus is what is required to crack this nut.

Greg

[Larry James]

The manual or the website tech support is your best source for this info as it varies by battery, charger and manufacturer. I just had some batts rebuilt for my DeWalt 9.6 drill because i love it so much. You may find it becomes a favorite. I like my Makita 9.6 better (balance) and had those batts rebuilt too.

I usually charge my batteries and remove them from the charger and unplug the charger. I agree, read the manual - with newer batteries and charger technology a lot has change since I bought my 9.6 volt Makita around 1990.

I recently bought a new (rebuilt?) 9.6 volt battery at a Menards store for $32.00 and the drilll works good as new. Added bonus is a newer Makita charger that is about 3 years old will charge that 9.6 volt battery. The old Makita just keeps on going, and going, and going, ...

Larry

[Andrew Williams]

I remove the battery when fully charged and unplug the charger and blow out the vents with compressed air just in case flammable wood-dust has accumulated in the transformer.

The only rechargeable batteries that I leave plugged in are laptops and cell phones.

[Jason Abel]

Do not leave them in the charger at all times....unless you don't like your house/shop that much. The newer chargers are not much different from the chargers made a few years ago. They still continue to charge at a low rate even if the battery is full. This is both bad for the battery and unsafe as it could potentially cause a fire should the battery rupture and start to leak and drip into the charger. I've heard of too many incidents to ignore it as a possibility.

Jason
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