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Duffy
06-27-2008, 11:57 AM
I have suspected for a while that battery life is shortened if the battery is left on the charger. I just talked to the Ryobi tech, who "doesnt recommend that the battery be left on the charger." He could give no reason why. I have no "battery protocol discipline" and just leave them on the charger until I need a charged one. I suggested that I put my charger on a timer and he agreed that this would be a good idea. This was prompted, by the way, when I paid $129.00 for a single Li-ion battery and "special charger."
Anyone suggest a simple 60- to 90-minute timer that I can plug my charger into? PULEEZ dont recommend an "elctronic wonder with X daily functions and Y on-off intervals." I just want to slap a battery in the charger and hit a GO button. Duffy

Quetico Bob
06-27-2008, 12:24 PM
Think any inexpensive timer such as the ones you use for lamps would work, just don't install the start pin and set time 2 hours from the off. But I'm wondering if this would have the reverse effect by slowly draining the battery when it's not connected.
Cheers, Bob

pcarpenter
06-27-2008, 12:57 PM
Hmmm...I dunno. I would find someone with more specific knowledge of the internals and relative "intelligence" of your charger than "the Ryobi tech". I have a Dewalt 14.4 v drill and impact driver. The drill is over 11 years old and the original batteries are not great....but still going. They are traditional NiCd's which are perhaps the most problematic battery construction as compared to some others available today. Their charger rapid charges and then does an occasional "keep warm" (my term not theirs) to keep it charged. They do recommend keeping them in the charger, and I have a hard time arguing with 10 years of use--even if the original batteries have very limited life now.

If you cycle such a charger off and on, I found that it tries to go into "full charge" mode...at least for a little bit until it figures out the battery is fully charged. I would think that regular power cycling could be self-defeating in a case such as this.

Paul

rotate
06-27-2008, 01:06 PM
If you have an intelligent charger, and except for the very low-end cordless tools, most are now intelligent, I would leave it pugged in. It should go into a trigger charger mode and this should not cause harm.

If you don't use your cordless for weeks at a time, then it may actually be better to leave it uncharged until the time that you need it.

kendall
06-27-2008, 01:53 PM
agree, my chargers go into maintenance mode and just keeps them in tune.
The batteries reange between 12 and 5 years old and still work fine.

I have a LOT of cordless tools, mostly porter cable 19.2v, with a dozen batteries and 4 chargers for the PCs alone. Only reason I've had for replacing batteries has been when I physically break them.

With nicads I've noticed that if you routinely remove the battery after use and put it back on the charger it shortens the life, I only recharge when the battery is dead, and my batteries have lasted.

Ken.

Dunc
06-28-2008, 10:18 AM
I have 5 NiCads for assorted DeWalt (DW) 18 volters. I am a DIYer, not a pro, and queried DW how to deal with the charge it, use it a bit and then recharge or not (realising that several weeks may pass until the battery pack is used again).

DW states that the best is to charge all batteries (preferably leaving connected to the "intelligent charger" -their terminology - to allow the charges to be equalized in each cell of the battery) at one point in time and use each in turn until it shows an *initial* drop in performance. Running it to the point of exhaustion is not recommended. While, in theory, it can be re-charged at that time I believe that a cool-down period won't hurt before it is plugged into the charger. At this point, I have about 43 months on the oldest battery & still going strong.

Fwiw, the pros on the Fine Homebuilding forum (hope mentioning this is ok) have been known to open the battery case & replace the cells instead of buying a new battery. There are businesses that offer this service or the cells can be bought and soldered by a diy'er)

GKman
06-28-2008, 10:45 AM
Instructions with my Mikita Ni-MH.

1. Charge when performance decreases.
2. Don't charge when already charged.
3. Charge every 6 months.

These batteries seem to have full power until the last few revolutions of a drill.

I let the battery cool before charging in case the charge sensors sense heat in the battery package.

I date the batterers after charging to comply with 3.

Ni-MH's didn't grow up with lead acids or Ni-Cads, they weren't pen pals or go to camp together. They don't speak the same language or date the same girls.

Duffy
06-28-2008, 07:17 PM
Thanks for the advice guys. I dont suppose that I go more than a day or two, (or three,) without using a cordless something-or-other. I have a 9.6V Makita, a 14.4V Mastrcraft, (Canadian Tire,) and an 18V Ryobi. I am the first to admit that these are NOT top-of-the-line tools, but I dont make a living with them, and they seem to suit my needs. I threw away a Milwaulkee 12V drill when I was told $79.00 for one new battery! Dammit there are only a few companies making battery cells, and there CANT reasonably be THAT big a difference in either quality or value. Duffy

clutch
06-28-2008, 08:59 PM
What I've always wanted to know is how these chargers act if the garage is unheated and the temps go to -20F with battery in place.

CLutch

darryl
06-29-2008, 03:06 AM
It won't be easy to find out if the charger drains the battery when the battery is in and the power cord pulled or power disconnected, but there were some brands and models where this did happen. Unless the instructions explicictly state that the battery can be left in while the charger is unplugged, I'd be taking the safe route and pulling the battery after full charge. My old boss used to leave a battery in the charger while the light switch in the shop would also kill power to the charger. Those batteries were shot after 2 yrs.

'ryobi tech' sounds like a guy who doesn't really know the facts and was just spouting off, like so many so-called techs and specialists seem to do. I would bet that for every 10 cordless tool dealers or repair places, you'd be hard pressed to find 1 that could give you the information you need. Unless you're willing to be a test monkey, you'd be better off forgetting about putting a timer on the chargers. Better would be a timer that sounds off to alert you that it's time to remove the battery from the charger. Just my opinion-

ptjw7uk
06-29-2008, 07:12 AM
I would go for a timer especially for NiCd as they will definately have a shorter life if overcharged. These cells have an excess of electrolyte to accomadate an amount of over charging if this is depleted then the cell will slowly loose capacity over time.
I built a charger for a couple of my NiCd batteries which required a 5 hour charge and was not in the habit of remembering that I had left them on charge and with another 2 drills(both the same) I found the batteries smoking just in time to avert a fire. These were supposed to turn of the cgarge after 1 hour but didnt still both imes I got more back than I paid and invested the money in a more reputable make(not sure what that is)
The timer I used was an elecromechanical timer with an electric motor and gears that could go upto 24 hours not sure of the make except that it was of German origin and quite reliable even if old.
The whole problem of one shot timers has always bothered me in that in this world of electronics they are not very prevalent.

Peter

Your Old Dog
06-29-2008, 07:23 AM
I haven't read the entire thread so someone may have said this.

You should not leave the drill battery on the charger all the time. If you feel even the slightest warmth to the battery case you are cooking off your battery. You should have two batteries and ONLY charge when they need it. What's the difference if you own 2 batteries and they last 10 years (as in my Bosch drill) or you own one battery and it last 1 or 2 years?

I do leave my ATV, lawn mower and medical equipment batteries on the charger constantly but they are "battery tenders". They sample the battery voltage ever hour for a second. If the voltage slips a certain amount they will gently bring it back up to voltage and shut off. Napa auto parts sells them for $32.00 and they work fantastic and batteries seem to last forever because they never cook off.

We had 3 batteries assigned to each of our 22 TV news cameras used damn near round the clock and they lasted easily for 5 years by simply running them down before charging.

jdunmyer
06-30-2008, 04:45 PM
I bought one of those 12-hour wind-up timers that are used for whole-house fans and wired it to a charger outlet. Spin the knob to set it for a few hours and walk away. Have seen other stories about batteries catching fire when left in the charger and want no part of that.

COMP
07-02-2008, 07:36 AM
I bought one of those 12-hour wind-up timers that are used for whole-house fans and wired it to a charger outlet. Spin the knob to set it for a few hours and walk away. Have seen other stories about batteries catching fire when left in the charger and want no part of that.
where you get it ??

jdunmyer
07-02-2008, 09:29 PM
Comp,
I bought one of those timers at the local hardware store, but they had to special order it, as their in-stock units went to only 1 hour. Had to go to the Internet for the second one, as the h/w store could only get digital units after that first one, and the ones they got in were all faulty. Plus, too complicated in their operation for what I wanted. I don't remember where I ordered it from, just did a search. Actually, I'd almost bet that the big-box home improvement stores would have them, for whole-house fans. The ones I have are exactly like that installed in my house for that purpose.

The first one I installed wasn't for the battery charger(s), but for my cartridge case cleaner. I load the machine, twist the knob to "2 hours" or so, then leave, not having to listen to the thing run, nor forgetting it for many hours.

lwalker
07-02-2008, 10:55 PM
The problem is that no-one can tell you how smart the charger is. It's recommended for NiMH that it not be charged for longer than 18 hours, but trickle charging at extremely low rates is allowed for longer than that. Simple chargers just feed current at a set rate for a fixed time then shut off.

A good charger will detect if the battery is warm and let it cool before charging. In fact, temperature rise is the recommended method of charge termination of NiMH batteries (when full charge is reached, the battery temperature increases rapidly); for NiCd, the voltage can be monitored and used to decide when to stop charging.

A better charger (I have never seen these in consumer equipment) will properly discharge a charged battery to a certain point, then let it cool off before recharging it and then enter a "maintenance mode" where it is trickle charged.

darryl
07-03-2008, 01:40 AM
Sure you can use a timer, but if the point is to save the battery before it cooks and explodes, or ends up with a short lifetime- wouldn't you be better off with a proper charger instead? In my opinion, any fast charger that relies on a human to provide the appropriate end to the charge cycle is dangerous and should not be used. The manufacturer should be scalded in hydride electrlyte for selling such a product to the people, along with those responsible for such a product receiving approval in the first place.

I'll agree that disconnecting power to the charger (via a timer) is much better than just leaving it alone and finding the battery cooking hot and ready to give birth, but it doesn't really solve the problem if you're looking to have the battery give the longest possible service life.

In general, I've found that a charger which has both voltage and temperature sensing will do the job, and is safe to leave the battery in for longer than the charge cycle. I can't guarantee that this is always the case, as I have had some contrary experiences. I know the NMH batteries are more finicky to charge than nicads, and the same probably goes for lipos, etc, so any charger that doesn't deal with these types properly shouldn't be used at all.

All of the chargers I'm currently using are 'smart enough', meaning that they all terminate the charge at somewhere near the appropriate time. I can come back an hour after the charge is supposed to be completed and find a fully charged battery and charger that are both cool. I have no problem leaving the battery in and the charger plugged in if that's the case. I agree with what YOD has alluded to, that if you feel any heat at all (after the charge cycle has completed and an hour or so has passed after that) that the charger is not doing the battery any good. I doubt that you'd be 'helping' the battery to much of an extent by using a timer on such a charger, just giving your home a better chance of not burning down due to a battery charging issue. That is of course more important than whether the battery dies early in it's life.

NickH
07-03-2008, 08:29 AM
I have several cheap but functional battery powered tools which have dumb chargers and have to be gharged for 2, 4 or 8 hours, after leaving one or two overnight when I forgot to unplug I bought a 24 hour mechanical charger.

Take the charger apart and rewire the power to the clock motor to feed from live output instead of live input. Wind it round to your set time period, the motor switches on with the charger feed, once the timer switches off the motor stops running - now you have a one shot timer capable of half an hour to 23 and a half hours for very little money, :D
Regards,
Nick

jdunmyer
07-03-2008, 09:22 AM
Darryl,
You're no doubt correct that "the answer" is to only use "proper" chargers. The problem is that you don't really have a way of knowing whether the charger has the proper circuitry, and cheaper cordless tools are probably the worst offenders in that regard. The timer prevents problems from such units.

Besides, it helps you in "going Green", because it eliminates that parasitic load from the charger. Don't you want to make Laurie David happy? ;-)

Duffy
07-03-2008, 10:15 AM
I guess this Ryobi "One plus" charger, which charges both NiCd and Li-ion batteries, is a "smart charger." I had a mad rush of blood to the head and took the temperature of the NiCd battery that has been sitting on the unit for a couple of days. It read 78 F which is a few degrees above ambient. So my NEW protocol will be to charge my batteries when they need it and remove them from the charger in an hour or as soon as I think of it after that. Definitely NOT leave them parked on the charger till "the next time." Thanks for all of the advice. Duffy

darryl
07-04-2008, 06:17 AM
I've 'gone green' enough times in my life. Now I'm starting to pay attention to what I eat :)

I'm starting to feel a bit like a battery and charger system myself. I don't hold a charge the way I used to, and I'm becoming more acutely aware that my charger IS on a timer! Once it times out, times up :)

Evan
07-04-2008, 08:27 AM
A better charger (I have never seen these in consumer equipment) will properly discharge a charged battery to a certain point, then let it cool off before recharging it and then enter a "maintenance mode" where it is trickle charged.


I recently purchased a new "intelligent" charger for the VRLA batteries in my e-bike project. It charges both for cyclic or float use and provides the correct maintenance charge rate at 13.8 volts for standby use. It also charges deep cycle flooded and starting batteries and has a desulfation routine where it charges to 14.5 volts. If it can't attain that voltage it discharges to 12.7 and then tries again until it can. It has settable charge rates of 2, 10 and 15 amps and cost $70.

Swarf&Sparks
07-04-2008, 08:37 AM
That's gotta be cheaper than building it :)
That use delta V/T Evan?

COMP
07-04-2008, 08:57 AM
Comp,
I bought one of those timers at the local hardware store, but they had to special order it, as their in-stock units went to only 1 hour. Had to go to the Internet for the second one, as the h/w store could only get digital units after that first one, and the ones they got in were all faulty. Plus, too complicated in their operation for what I wanted. I don't remember where I ordered it from, just did a search. Actually, I'd almost bet that the big-box home improvement stores would have them, for whole-house fans. The ones I have are exactly like that installed in my house for that purpose.

The first one I installed wasn't for the battery charger(s), but for my cartridge case cleaner. I load the machine, twist the knob to "2 hours" or so, then leave, not having to listen to the thing run, nor forgetting it for many hours.

thanks,,, i'd like to have up to 12 hours on one,,,,could use it for slow charger on cars :D

Evan
07-04-2008, 08:58 AM
That use delta V/T Evan?

As far as I can tell by monitoring it with a meter it does. I was going to build one but when these went on sale I figured it wasn't worth the effort. It also displays both charge percentage and voltage plus because it is a switch mode supply it weighs very little so I can afford to throw it in the trunk on the bike.

Swarf&Sparks
07-04-2008, 09:07 AM
Nice solution.
I'm still looking at building one cos the hub motors are 36 V.
Guess I'll stack 2 old 24V E-I transformers I've got in the junk box and use a PIC to look after things. Thanks for that pointer to the cheap MOSfets :)
(I'll keep the glassfets for that guitar amp front end I'm gonna build one o these days)