WTB (or borrow?) Pentax Power Pack M

Bump, just in case someone has one to sell. Thanks, Kris.

Another bump.

Kris, I now understand what your after. It's the CHARGE pack M.

So one suggestion, buy this 24v DC wall cube link and from Maplin, buy an LM317T and have some one make this link for you. It's got to be connected mid cable between the wall cube and the NiCad pack, i.e. in series. So the leads will need changing for the Pentax plugged lead.

The current needs to be set @ 10mA as the NiCads in the pack are 100mA Hr cells. The value of R in the circuit would be 125 Ohms, so a 120+4.7 ohm would do or a 100+22 ohm is close enough. Maplin also sell small ABS project boxes so it will look tidy.

IF the LED is used as per the circuit, then it's current (via series resistor) will need to be taken into account. Better still is to use an LED in series that will handle 10mA and it proves that charge current is flowing. Also add a 1N4001 diode in series with the output to act as a blocking diode so that the pack can't "feed" the regulator circuit if the mains is off.

Very simple way of solving your requirement.

Best regards

I nave just acquired a Charge Pack M but I am afraid it is a 110V US plug one. US E-Bay acquisition along with Motordrive LX and Power Pack M.

I suspect the batteries are dead in the power pack, the NiCds wont have lasted this long, so I plan to use the info here: http://users.tpg.com.au/distudio/pentax_nicd_pack/ to rebuild the battery packs. I have found 1/3AA NiMH cells seem to be relatively readily available (Farnell stock tagged ones IIRC), the 1/3AF NiCds less so. With the lack of a UK charger I was planning on butchering a power lead to attach to a 3rd party charger. Modern chargers are much smarter than the old constant current OEM devices. However I need to get hold of a second lead having just got one from LennyBloke on here. (For which many thanks .)

Anyway, my thinking is why not just buy a multi cell NiMH/NiCd battery charger? The Power Pack M has 12 x 1.2 volt cells at 110mAH each (14.4 V and 1320mA) which seems well within the range of devices such as the two at the top of this page: http://www.strikalite.co.uk/prodcat_type/10/ALL/0/Battery_Chargers.html (other websites and chargers are available).

They claim to charge "... 2.4volts up to 14.4volts (2-12 cells) worth of Ni-Cad / NiMH batteries so it will do anything from 700mAh up to 5000mAh cells."

This would also give you additional flexibility should you come to replace the batteries in the Power Pack M with higher capacity ones, 1/3AF NiCd (225mAH) or 1/3AA NiMH (280mAH), at some point in the future.

These chargers look like they come with a Tamiya style 2 pin connector (available from Maplins and the like) which could easily be attached to a cut off Pentax M power lead making absolutely sure you get the right two wires connected with the correct polarity obviously!

Mike 8-{>

If Kris uses the original pack (providing the NiCads are OK), 11mA is a "safe" charge rate.

If the pack is rebuilt with new cells then the C/10 rate still applies so 23mA and 28mA respectively. If you charge at a higher rate and forget to disconnect or don't use an automatic type charger, you will heat up the pack.

By the way,(14.4 V and 1320mA) is not correct, the capacity of same type series cells remains the same as a single cell so you get 12 x cell voltage at 110mAHr.
Also, fully charged NiCads typically sit at 1.35v so you have a full charge voltage of around 16.2 volts (not an issue).

Whatever Nicads are used, they can be fast charged although this application does not warrant that. In all cases, charging above the C/10 rate would require an auto cut off charger, preferably with delta V detection.

It's much easier and safer to charge overnight and not worry about cell/pack damage.

If you want the latest technology, five of these




wired in series with these




easily fit the battery case and can be safely charged with a LiPo auto charger. They never self discharge.

As for the 11mA charger:




The LM317T is shown wired as viewed from the front of the device.

Best regards

I stand corrected and defer to you greater knowledge. I wonder if either of these would be a better device for charging if considering your suggested future upgrade?

http://alshobbies.com/shop/lookupstock.php?pc=5355 or perhaps this http://www.gliders.uk.com/prodinfo.asp?number=FS-LX60BP

I assume the lowest charge current of 100mmA is probably too high still but they would appear to be smart enough to detect when the pack is charged ( the delta V detection you mention) so should not suffer with regard to your observations of being left on all night. Both will also charge LiPo packs and can also discharge packs which could be useful?

Is this something you have done yourself out of interest?

As 5 x 3.7V is 18.5V would 4 packs at 14.8V be better? Or can the Motordrive LX (or MX as I think they mutually share the M power packs?) and associated control circuit handle 18.5V OK?

Mike 8-{>

PS apologies for kind of hijacking a Classifieds thread.

Wouldn't LiPo's be a bad idea in this instance Gary, were the
unit is not going to be used that often and they would be stored
almost 100% charged? Also the life of them is probably only 3-4 years.

I've some AA Cadnica's from about 10 years ago that still show full
capacity after quite long periods of storage and use in flashguns
and cameras.

It concerns me that nearly everything you buy now has Li-ion batteries
in it and replacements probably won't be available in 3 years time.

I've still got drills and a Bosch cordless hedge trimmer with Ni-Cads
still going strong after 10 years intermittent use.

A valid point Algi.

A few years back, I converted all my pistol drills to LiPo's. Due to me being away from the UK for extended periods I had thought that there would be an issue. Oddly enough, they are fine? I do leave them fully charged as well.

Using LiPo's in the LX pack is overkill. I doubt many people would use the packs enough to justify the cost of a decent LiPo charger.

On that note, I'm waiting for two tagged 16850 cells to arrive to fit a Chinese K7 grip.

Best regards

I can see your point but NiCd is no longer a viable, current, option.

In my case I want to refurbish my Power Pack M but with environmental concerns (and legislation I believe) for NiCd batteries they are becoming much harder to find too. In fact the batteries used in the pack, 1/3AF size, which, as far as I have found to date, are only available from Sanyo Cadnica are pretty much unobtainable. So we are already faced with the obsolescence problem you raise. With the rate at which compact power technology is being driven by the mobile electronics and car industries in 3 to 5 years there is bound to be something even smaller and more powerful around to replace whatever LiPo/Li-ion tech we are seeing now.

Fully charged NiCads "straight off charge" will show 1.5v so present an initial 18v level to the circuit.

I have used LiPo conversions in several bits of kit including my Maglite torches( a dummy plastic D cell-the type that takes an AA cell, is used for the lamp connection/contact). As you say, the correct charger is a must and the conversions must be done by some one comfortable with the work.

Kris should try his NiCads to see if they are OK. If changed to the newer-higher capacity cells, then a simple resistor change ( R=1.25/mA) would be all that is required. The LED I listed is good for a max of 30mA through it though I'd be more happy at 25mA max.

Best regards

That was my problem... I plugged a 110 one into an ordinary adaptor and fried the charger. That is why I am after a replacement. I'll pass on the various comments here someone more savvy than me for matters electronic and see if I can get something built.

Thanks everyone. K.

Hi Kris

Ahhh that would be a bad thing . You will have let the "magic smoke" out that is the secret power source of all electronics .

In that case hack the lead off the fritzed charger / wall wart (at the charger end) and attach it to the circuit above. Interestingly, looking at mine, the stated output is 18V and 25mA. Somewhat above 10mA. If you would like PM me a snail mail address and I'll build the voltage regulator circuit K10D described above for you, pop it in a little box if I can find one knocking around. I have all the parts, some vero board and a power socket for the input side. No cost to you. Should be able to have something for you in the post on Tuesday/Wednesday. You will just need to buy the Maplin PSU K10D mentioned and find someone to strip back your power lead salvaged from the burnt out 110V PSU and solder it on to the vero board. I'll fit some pins to make that bit straight forward. The only thing left to do is figure out which pin is which on the power lead. That shouldn't be too hard to track down. I have to strip my battery pack anyway as the cells are almost certainly shot. So will probably be able to figure it out in the course of doing that.
Mike 8-{>

Is this any use Kris CLICKY

Just a thought.

It is a good idea.

Only reason I didn't recommend some thing similar or your particular link is that its a one item, one job application and the unit you linked to is too shy on voltage for this application but useful for many others.

We need 24v to give us a headroom voltage as the nicads will hit 1.55 to 1.65v per cell when fully charged whilst still connected to the charger. So expected peak pack voltage will be 19v or a little over. Then add the 1.25v for the LM317, the .65v for the 1N4001 and the 1.7v for the LED and we approach 22v, hence the 24v wall cube.

Best regards

Dunno why I thought of this thread while being bitten to death by mosquitoes in a dodgy Romanian bar but I did. Knowing nothing about electronics I am still in possession of an LX motordrive but no power...

K.