Electronics geeks, I need your help.

[paul ron]

I have an old Sunpak 611 in great working condition. It fires up using regular C batteries n off the wall adaptor but I want to rebuild the CL-1 cube with new NiMh sub C cells.

I don't have the old batteries in the cube so I have no idea how the thermistor(s) was hooked up. Anyone have any ideas or perhaps have an old CL-1 cube I can compare it to for wiring?

I put a set of NiCads in the cube without the thermistors n it charges just fine but I am worried when I get the new NiMh I am running the risk of overheatting em.

Any info is appreciated.

[Mike Wilde]

Well, the thermistor would have been set to feed a temperature variable resisitance to a regulator circuit. The regulator circuit would have been calibrated to limit the charge current to not overheat based on the nicad charge characteristic, which is likely not the same charge characteristic as NiMH. NI-MH generally can be charged faster thatn Ni-Cad, as I recall. Look up the technical charactersitics of the cells.

I am old school. My packs are generally on the end of a coiled cable, and i make them up from gelled lead acid batteries. I charge them fully winthin two days after using them, and sometimes months will go by before I ned to use it again. It will be still fully charged, and ready to go.

My work digicam is fed Ni-MH AA cells. If you don't charge them before you need them you are screwed, because high energy density or not, they are flat within 3 days of charging them.

[paul ron]

Thanks Mike. I do understand how they work, I just have no idea how or where to wire em in.

The cube is arranged as 2 cells on either side of teh cube wired in series. The flash n charger are internally jumpered so they are actually working as 6V in series. The charger does have 4 springs one for each cell so there must be a regulator sensor in there.

The values of the thermistors have been calculated so my cut off will be 5K. So far all that theory is just fine, just the physical placement of em is my only problem right now.

I did make a 6V external battery many years ago using this CL-1 holder... thus the reason it is empty now. I don't need as much juice as I did back in the day so I want to scale back n use the original CL-1 cube again. THe replacement cells are very cheap and will be more than I will ever need on any shoot. I tried my NiCads n I cna do at least a dozen rolls of film no problem n still have enough go go juice to keep going for a few more hours.

So if anyone still has the old masher battery pack, can you open her up n let me know where those thermistors go?

.

[ic-racer]

The thermistors in the Rollie packs are placed between the cells with some cotton packing and white thermal grease. Is that what you are asking? Or do you need to know to which contacts the thermistor is attached?

[paul ron]

I need to know where they solder to the batteries.

[polyglot]

The thermistor does not solder to the batteries, at least, not at both ends. If I had to guess, I would say that one side attaches to the most-negative end of the pack (assuming it's a PTC not NTC) but the other side of it needs its own contact so that some electronics can sense its resistance.

[paul ron]

The thermistor does not solder to the batteries, at least, not at both ends. If I had to guess, I would say that one side attaches to the most-negative end of the pack (assuming it's a PTC not NTC) but the other side of it needs its own contact so that some electronics can sense its resistance.

I figured that out, but where exactly does it go? My batteries are arranged as 2 series cells on either side of a cube wth no cross connection between the pairs.

The flash has 4 contacts, 2 make an internal Minus to PLus cross connection... so the battery pack is acting as 4cells in series to make 6VDC.

The charger also has the same 4 contacts, with 2 internal formning a cross connection, but is charging with only 2 so the batteries are charging as 4 cells in series.

Now here is the hitch... the battery pack is keyed, it can be inserted in 2 directions, rotated 180°, so the terminals will still be the same polarity in pairs on both sides. ^=direction


^
+ _
l l
l l
_ +


internal cross jumper is at the back of both the flash n charger.

So where do you put the thermistor since both ends can be the front or back, none are end cells?

So if you have one of these packs, can you crack it open n tell me where it makes the connection? I'm not looking for therory, I need to know exactly where it physically solders to.



.

[polyglot]

I don't have one, sorry.

[paul ron]

I opened the charger today. It's a stupid charger with a bridge rectifier arrangement, some resistors, diodes and an LED. The LED comes on when the pack is inserted n goes out when batteries are removed. My guess is a thermistor is not the part to use, it should be a thermal switch of some sort to disengage the batteries when it gets too hot.

I'd really like to know what the origianls came with, stupid me threw it out years ago to make an external battery pack using plugs in the cube n extension wires to a sealed acid batttery.

.

[polyglot]

If that's what the charger is, I wouldn't use it - it will degrade your cells. Use eneloops or whatever in a proper smart-charger and insert them into the pack for use.