NiCad charging

[420TEE]

I should know this but don't. One of my NiCad powered tools tells me to run the battery pack all the way down till the tool stops before recharging. Elsewhere I have read to never fully discharge a NiCad pack or it may reverse polarity. Then there is the elecrtic toothbrush and other things that spend their life in a charger base. What is the corect way to handle them? Running the boat packs down wouldn't be easy. Maybe a bleed resistor across the contacts? :confused:

[Hoghappy]

http://www.rcgroups.com/forums/showthread.php?t=706332


Captain Slick

[Umi_Ryuzuki]

You want to avoid running the batteries down flat.
Typically with tools, you run till the drill or saw ceases to function under load.
The tool will still run, but not if you actually try to do work. So the batteries are
not completely flat.

Same goes for your model batteries.
A nice discharger is usually inexpensive. I built one out of four automotive light bulbs.
And use a Deans black box II to regulate the low voltage limit.
I have seen other resistor type dischargers at the hobby shop.

Here is a pdf on Nicad Memory
http://www.aeroelectric.com/articles/Ni-Cd_Memory.pdf

[420TEE]

Neither the batts nor their package indicate NiCd or NiMH on them. They're V.MAX superduty, 2400 MAH. They have disposal symbols for both types on them. Also the charger I got with them from MACK Products, DuraTrax Intellapeak twin pulse charger says it charges both types, so what do I have?
Umi, your light bulb discharger is what, 4 taillight bulbs in series? Do you check the voltages occaisonally or does the lamp brightness indicate something? The batt packs say to discharge to no less than 5.4v. Also I would have no idea what or where to find a Deans black box. Tower doesn't show one and I don't have a LHS to ask. I think I'll go back to my old way of boat building. Stick a bunch of C batts all over inside and when the boat runs slow, throw them away and put in new ones. Helps with ballast also. ;)

[Kmot]

In the old days, the knowledge at the time was to not run your nicads down too low because that could lead to reverse polarity.

That was the dark ages. This is the 21st Century.

Run your nicads all the way flat. Stone flat is just fine. They will not reverse polarity. There is even equipment you can buy that do a total discharge of a nicad cell and you leave it connected to keep the cell totally discharged.

The reason you need to discharge nicads before recharging is the nicad only phenomenon of developing "memory". Memory develops in a nicad cell if it is continually run down to a certain leverl and then recharged. For example, you have a 1500 mAh battery and you continually discharge 500 mAh out of it and then recharge it. After a while, that battery will devlop a memory that it is a 500 mAh battery! So one day you need to run it a full 1500 mAh but when it has used only 500 mAh boom! It drops dead. Because of the memory. Fully discharging a nicad before recharging it prevents this. It is commonly refered to as "cycling your nicads".

NiMh batteries do not have this problem. Lead Acid batteries do not have this problem. LiPo batteries do not have this problem.

As for a convenient discharger, hooking up a whole bunch od tail light bulbs and soldering them together is a PITA and not necessary. Just get a single HEADLIGHT and wire a connector to it and use that to discharge you battery pack. When the light filament goes completely dark, your battery is discharged. Store your nicads flat, with no voltage in them. Do not store other battery types flat, however. Only nicads.

The technology and methods of 30 years ago are absolutely not the correct way of doing things today!

[Umi_Ryuzuki]

I am surprised that Tower didn't turn up something.
I bought my "black box" from Tower Hobbies.

Maybe Deans discontinued the item. It was designed to read the battery voltage and turn off the connection when the battery reached the low level limit. I wired up the tail lights in parallel. That increases the Amperage draw.

You can look at the other Dischargers on Tower Hobbies.
They used to sell a light bulb discharger also. Must be antiquated technology these days. :rolleyes:

[ernest2]

i also have a dumb question (if not dangerous). can i use nicd or nimh chager to charge SLA? :confused:

[420TEE]

At risk of starting something, I still don't have an answer as to what my 2400 MAH V.MAX batts are, Mh or Cd. I also have two directly opposite opinions regarding discharge. One is go dead flat, the other says don't go dead flat. :confused: :confused: :confused:

[Kmot]

At risk of starting something, I still don't have an answer as to what my 2400 MAH V.MAX batts are
Why not contact the maker?

[Hoghappy]

They wouldn't look like this would they? They are 2400's

Captain Slick

[420TEE]

Cap, Nope. They're 6 cell packs, nominal 7.2v.

Kmot, I could do that but I figured with all the experience on this forum this was the quicker and cheaper way to go. In one of the articles people sent in response to my question I read somewhere, which I can't find now, NiCd's only go up to 1600 or 1800 MAH. Anything above must be NiMh. However on the batts themselves it states " Do not discharge to less than 5.4v" indicating NiCd, at least using older technology. Mine are 2400MAH. Gee, this stuff is so much fun. :(

[Umi_Ryuzuki]

Just to add to the fun,...

I have two 3000mah Nicad battery packs.
I bought them from Tower hobbies, and they were the largest I could buy
with out upgrading my charger.
Most batteries smaller than that are Nicad. Anything larger than that is certainly Nimh.

You could crack the shrink wrap open and have a look. Then re-shrink wrap the pack. ;)

[Ghost 2501]

last time i stripped a pack down,I used insulation tape to redo it :)

[Kmot]

I used to store my nicads in my airplane radios by charging them first and then putting them away. That was in the 70's. Knowledge has changed.

I now drain my nicads totally flat and leave them that way. I have nicad packs I use in cars and boats and some of them are several years old and I can charge them up again and they are as good as ever. This is also using a high quality peak detecting charger, however. YMMV. I am only explaining how I do it now, based on the latest knowledge I have read about.

I have several dischargers. Some are in the chargers and have a low rate of discharge. I also have a headlight I use. I also have a 10 bulb discharger, and an Integy 30 Amp discharger. On my nicads, I have used them all. NiMh's do not need to be discharged and the 'current' knowledge is to store them with a 500 mAh charge placed in them.

Kmot, I could do that but I figured with all the experience on this forum this was the quicker and cheaper way to go.

As far as I know, e-mail is still free. ;)

[steveciambrone]

i also have a dumb question (if not dangerous). can i use nicd or nimh chager to charge SLA? :confused:

No you cannot, you must use a charger that is designed for a SLA. If it states it is only for a NICAD or NIMH then it cannot be used for a SLA. That said some of the better chargers can do all three even Lipos. These are programable chargers. The different batteries use different charging control methods, the programable chargers can be set to accomidate the different charging methods.

Thanks
Steve

[420TEE]

Okay. Cut open a pack. Found cells enclosed in "plain brown wrappers",
cardboard tubes that require unsoldering the jumper strap on the end to remove. I have no intention of doing that. Looked up Team Orion batteries at Tower and found these are in fact NiCds. Why didn't I do that first? Never mind. Now to discharging them. How about a 30 ohm, 10 watt resistor? Also Kmot, when you speak of the latest technology I assime you mean the latest in thinking regarding discharging NiCds, not that the current batts are somehow different than older NiCds. So I should disregard the 5.4v minimum listed on the batts and assume they were printed a while ago and never updated. ;) Thanks for taking the time.

[420TEE]

One of the sites someone sent me, batteryuniversity.com is excellent. Most anything you want to know is explained in almost comprehensible English, even for us old geezers. :)

[Kmot]

420TEE: I do not have the references I had read bookmarked. I want you to understand that what I do with my nicads is my choice, based on what I have read and what I understand to be the best methods to use and what my equipment is. I have had great success with these methods on my nicads. YMMV. You need to make a decision based on all information you read. I cannot and will not say that my methods are the only way to go. ;)

[Greg_Vincent]

OK, here is another perspective/method.

I believe that "smart chargers" are able to compensate for the memory effect. The one that came with my 14.4v Ryobi drill has indicators for either a full charge or a "quick charge" to top off the battery. Doing this has not seemed to affect my battery life even after a couple of years of owning the drill. Using a smart charger (if available) seems a lot easier than religiously discharging a battery pack after each use.

Also, I have read that the memory effect is real, but that it is difficult to duplicate outside of a lab, since it requires regular recharging at exactly the same level of discharge, something that is unlikely under normal usage.

In my experience, what is more likely to damage a NiCd is recharging under hot conditions (or while the battery itself is still warm).

The only time I have done a "deep discharge" on a battery was when my son left the flashlight that came with the drill on overnight. When I first put the battery back on the charger, the yellow and green LEDs lit which signalled a potential problem. :eek: It finally took a charge after sitting a long time and is now working normally. Needless to say, he now plays with flashlights with regular batteries. :)

In my reading, the only time a complete charge/discharge cycle seems to be warranted is for the initial conditioning of the battery, to maximize run time.

[Brooks]

Alternatives: 1) if it ain't broke, don't fix it strategy - recharge your NiCds whenever you like. Don't bother to discharge between charge sessions until you notice a drop in battery capacity. According to the paper cited by Umi, most (80%) crystalized NiCd batteries can be rejuvenated by discharge when necessary. My info says the discharge should not proceed to lower than 0.9v/cell.

2) Get a fancy German charger from Dave at Radical RC strategy - the Orbit Microlader has a "Reflex" charge setting - this will breakup crystalization on each charge session (by pulsing charge with micro discharges during the charging session). Unfortunately for the pocketbook, the Microlader is expensive, and their cheaper Pocketlader model does not have the reflex setting (I asked the Germans if they could add it and they said no, buy the expensive version :-). My Microlader has served me well for NiCd's, NiMH's, and Lipo's.

[420TEE]

Thanks for everyones help. Apparently that which I thought was a pretty straight forward question seems to have no answer, or many answers. I guess it's " you pays yer money, you takes yer chances." :)

[frankg]

:) 420TEE- Thought I would clear up your questions on what type of battery you have ,aka (“ORIAN V-MAX 2400 mha. NI-CADS”). As far as the charger you said you have , the twin pulse Intellacharger, it is one of the better chargers on the market to charge either NI-CADs or NI-MH batteries. It is a peak detecting charger which will peak charge two batteries at the same time than trip out to a trickle charge. The good thing about a peak detecting charger is that it will give you a full charge in your battery pack with out having to guess whether or not you have timed it right with one of the timer chargers. As for the difference between the NI-CAD and NI-MH batteries, first with the introduction of the NI-MH batteries which our environmentally friendly over the NI-CADs (which are being faded out) . Second is the fact that the NI-MH batteries can be manufactured to produce a much higher capacity of stored amperage in the same size package. Third NI-CAD batteries can be charged at both fast and trickle charge where as the NI-MH batteries are for only fast charge format. As far as the high discharge rate of the batteries NI-CADs were thought to have the edge in the total , but it is hard to call since so many speed records have been broken with the newer NI-MH batteries. As far as the choice in batteries, I have been using both with no problems and have found the with the introduction of the newer NI-MH batteries the price of the NI-CADs has dropped. As for LI-PO batteries, I still do not know that much about them and they have been shown to be potentially dangerous if given the same kind of treatment we give our NI-CADs and NI-MH batteries. :)

[Ghost 2501]

well My nicads get charged on a slow charge about every few weeks, to ensure they are ready for use, even if they havent been used, seem to be ok, however soon they will be going in for a full drain and re cycle.

[420TEE]

Thanks frankg--- How's the Lyman? :cool:

[Kmot]

Third NI-CAD batteries can be charged at both fast and trickle charge where as the NI-MH batteries are for only fast charge format.
I would like to dispute this.

NiMh batteries can be slow charged as well. In fact, it is recommended to balance your NiMh packs from time to time using a 0.5A charge rate. This brings the NiMh pack to full charge and equalizes all the cells that sometimes get out of whack due to fast charging.

[Brooks]

I asked Dave Thacker of Radical RC, my battery guy, how to tell the difference between unlabled NiMH and NiCd cells. Here's what he wrote back:

"Due to recycling treaties signed around the world, if the battery does not have retail printing on it (fancy colorful printing that shows the chemistry and capacity) then it will be dark green if it is NiMH and Lime Green if it is NiCad. Many Nicads are also yellow and white. But nearly every dark green cell I've ever seen is NiMH."

http://radicalrc.secure-mall.com/shop/

[Hoghappy]

...brown? :p

Captain Slick

[tim slocum]

I found this at www.mackproductsrc.com , go to the link and read the description.

[Hoghappy]

...I slow discharge my batteries by leaving the transmitter on till they die. I don't use nicads in the boats, so no need for the extras.

Captain Slick

[420TEE]

Any idea what the value of that resistor is? (I don't mean $4.75)

[tim slocum]

I thought one of the questions raised was do you or do you not totally discharge NiCd's.I just thought the description with the posted product answered some questions being discussed.

[mfr02]

The simplest discharger, should you really need one, is an auto bulb fed by a battery connector. Glows steadily fainter as the battery discharges, just a question of learning when to stop.
I have heard of people having problems with smart chargers and deep discharged batteries - it seems that when presented with a deep discharged battery, the charger can be fooled into believing that no battery is connected, get bored, and switch itself off to save you the bother.