using NimH batteries for Canon motor drive MA

[reynold]

<p>I bought a Canon motor drive MA in which the vendor has replaced the NiCd batteries with a NimH battery pack. What I need is to be able to re-charge the pack. Can anyone advise me on what charger to buy to re-charge the pack?<br>

Can a charger for an NiCd battery pack work for an NimH pack? After all, the output is the same --electricity?? One suggestion was to use the Canon charger that came with the MA drive -- assuming I can find one.<br>

I hope I don't, but I may have to open up the battery pack to replace the batteries. Can anyone explain how to do it? I'm a little wary because I tried to open up an old power winder and broke a wire!</p>

<p>Thanks for any help!</p>

<p>Reynold</p>

 

[howard_m]

<p>so you're saying that the original Ni-Cd pack has been replaced by the 'Battery Pack MA' that has removable battery cells and there are NiMHs in there now?</p>

<p>The issue w/ using a NiCd charger on NiMH cells is that when charging is complete, the output voltage of NiCds 'dips' slightly which tells the charger that the cycle is over. NiMHs display MUCH less 'dip' and NiCd chargers usually dont detect it. That can lead to overcharging the batteries and damaging them eventually. If you can put the battery charger on a timer, then that would be a win once you determine approx how long you need to charge them. If you can remove the NiMH cells, then get a decent multi-cell charger. Also note that NiMHs self-discharge fairly quickly (exception being the new Eneloop type).</p>

[reynold]

<p>Thanks Howard.<br>

My understanding is that there are 2 versions of the power pack: one with removable AAs [takes 12 cells] and an Ni-CD version that is "non-removable". The model I bought was the Ni-Cd version, but the previous owner had the Ni-Cd pack replaced with an NiMH pack, and he used the original Canon Ni-Cd charger. At least that is what he told me.<br>

I found out from the web that the Ni-CD model takes 12 N cells and it requires a [third-party] charger that can put out 16.8 volts at 95mA. Charging takes 10 hours.<br>

It's nigh impossible to find a working Canon MA charger so I would be looking for a third-party Ni-MH charger with the above requisites AND that can plug into my pack.<br>

Ideally I find a charger which plugs into the pack. However, at some time in the future I will have to open up the pack to replace the batteries, but to do so I need to know how to open it up. I am trying to teach myself how to service the A series, but progressing [?] at a snail's pace.</p>

[howard_m]

<p>I do a lot of Radio Controlled stuff and we use chargers that you simply 'dial in' the desired number of cells and the charge rate and battery chemistry. The more immediate problem is finding the mating connector to that which is on the pack.</p>

<p>Such a low current tells me that the original was probably some really simple charger circuit and it always just slow charged (1/10th the cells capacity) the drive unit and probably just had an internal timer. More modern chargers would essentially 'listen' for that voltage dip I mentioned in my first response and shut off when it saw that.</p>

[awahlster]

<p>Using batteries not designed for the MA battery pack is asking for trouble. The NiMH pack will not stall out at the end of the roll and either cause the motor drive to be damaged or the film can tear off the spool.</p>

<p>This problem as been known and discussed on forums for close to 15 years now. Do so at your own risk.</p>

<p> </p>

[reynold]

<p>Looking straight down at the location of the pins there is a larger receptacle [hole] and a smaller one. The larger hole according to the manual is the "mounting socket for Charger".<br>

I downloaded a photo from the FD Canon site but I don't know how to post a photo using its URL. Here is the link to the site: <br>

https://www.google.ca/search?q=canon+motor+drive+ma+service+manual<br>

There are a whole series of photos but one shows the connector pins and receptacle.<br>

If I have to buy a charger I would be happy to buy a newer one if they are not too expensive, but I need to know what to buy and where to go. I live in Vancouver Canada. <br>

There is still a chance that the vendor did send me the original charger and I misplaced it.</p>

<p>R</p>

 

[reynold]

<p>Hi Mark,<br>

I didn't find too many discussions re Ni-MH as a replacement for the NICD and what I did find seemed positive. Besides the drive I bought already has the NiMH batteries in them. If what you say is true then I am caught between a rock and a hard place. Besides, I thought NICD are now obsolete[?].<br>

Reynold</p>

[reynold]

<p>Hi Howard,<br>

I'm happy to say that I FOUND the Canon charger! Thanks to the vendor who suggested that he had sent it I went back to my mess and found the charger under some other equipment. Still, it would be good to know if there are any 3rd party chargers that could replace the Canon one.<br>

Another issue arises. See the comment from Mark. I'll ask the original user but I hope there are other people out there who have made the change to NiMH and could comment. Any thoughts on this?</p>

[alan_swartz]

<p>To be entirely specific (yet entirely obvious), the issue isn't that you <em>cannot use NiCd batteries</em> with the motor drive. The issue is that you <em>cannot use AA NiCd cells in the Battery Pack MA</em>, which is intended for alkalines or the then-dirt-common carbon-zinc cells. The problem arises when loading up a dozen NiCds in the AA form factor, which comprises a greater current source than the motor drive (or camera or film) was apparently designed to handle. Therefore, you supposedly arrive at the end of the film roll and the souped-up motor drive tears things up. It's all about horsepower.</p>

<p>The MA manual doesn't specify why you cannot use NiCds in the Battery Pack, it just says you cannot. The NiCd pack obviously came loaded with NiCds, which according to Reynold's post are a dozen N cells. N's are little. That suggests a lower current capacity, hence lower torque from the drive. Makes sense, too, because the NiCd Pack MA is a good bit physically smaller than the Battery Pack MA.</p>

<p>So what about NiMH cells in the Battery Pack MA? Depends on their current capacity and internal resistance. I don't know that answer. If they are similar to AA NiCd's in those parameters, don't risk it. If they're close to AA alkalines, they might work safely. Perhaps knowing the background of the situation, those of you better equipped than I to evaluate battery specifications can hazard an opinion.</p>

<p>If your Charger MA is actually working, you may still be able to find solder tab NiCd N cells. I successfully rebuilt the battery pack for my 1977-vintage TI scientific calculator by that route. All problems solved...it works properly and charges with its original charger.</p>

<p>Mouser lists N's without tabs, but I didn't find any with tabs in a quick search. A 2/3 AA cell is about 2mm larger in diameter. Perhaps there is room in the case to use those if they are electrically compatible. </p>

[reynold]

<p>Thanks Alan,<br>

It was in a post that I discovered that the NiCD pack took 12 N cells, which when fully charged produced 400 mAh. It also stated that N batteries were 30mm x 12 mm. So I am assuming that the NiMH pack is charged when it has 400mAh, and that it takes 10 hours to charge. The third-party charger had 16.8 volts and produced 95mA.<br>

You can gather from this reply that I am not technical, hence my reluctance to open up the pack. I'll wait till I hear from the vendor re specs before I charge the pack. However, let me understand what you wrote;<br>

1. There are AA alkaline cells [standard batteries we buy....]<br>

2. There are AA NiCD batteries that have the same size but different specs from standard alkaline<br>

3. There are NiCD batteries that are smaller in size than standard AAs with lower specs than AAs<br>

4. If my NimH pack has the specs of the NiCD pack then there should be no problems.<br>

I hope whoever created the NiMH pack [and the owner had it built by a battery store] created one that matched the NiCD pack's specs</p>

 

[peter_simpson1]

Just a comment on NiMH vs nicd. You'll be lucky to find nicd any more as they are being phased out due to the cadmium being a toxic heavy metal. NiMH cells are usually higher capacity and don't die as quickly when left idle.

 

You can usually just replace nicds with NiMH cells without any problems unless as pointed out above, you have a fast charger that is terminating on the specific voltage characteristic of a nicd. I'm using externally charged NiMH cells in my Nikon F4 with absolutely no problems. Just make sure you buy a quality brand cell.

[reynold]

<p>Thanks Peter.<br>

Heard from the original owner who had replaced the NiCD with the NiMH and he said that it had cause no problems with his two A1s, so I will assume that [he had it done professionally] whoever made the change knew what he was doing.<br>

The Canon MA charger has an output of 16.8V and 75mA. The charger states "each exhausted battery can be charged approximately in 5 hours" so I am assuming it's not a fast charger!</p>

[glen_h]

<p>NiMH aren't quite the same in overcharging as NiCd. As well as I know it, you don't want to continuously charge them at 0.1C. If it is 5 hours, it would be more than 0.1C.<br>

They might do better at 14mA, charge for 14 hours, but not much longer.<br>

<br />(0.1C means that the charge current is 0.1A times the capacity in Amp-hours. That charges NiCd in about 14 hours.)</p>

 

[reynold]

<p>Thanks Glen.<br>

I charged the battery pack for 7.5 hours. No calculation here, just panic. Unfortunately when I plugged the charger into the pack I didn't really observe the light. I thought it went <strong>red</strong>, but when I went back after 4.5 hours it was <strong>flashing red</strong>. I didn't know if this meant it was charging, or the charging was complete. So I left it for 3 more hours and then unplugged it because I was afraid of overcharging. I asked a friend who has such a Canon charger and he said that the light should go <strong>green</strong>. I know this is what happens with my G3, but I didn't know if the old MA charger would do the same.<br>

My friend thinks that with NimH, the batteries have a "memory" and will not fully re-charge until I run the batteries flat a few times. Next time I will be more observant when I start.<br>

Even if the battery pack is half charged that should be 30 rolls, which is a lot for me.</p>