How Can I Open Up An Old 7.2v Hump Pack?

[retroman]

Hi Everyone,

I recently bought an old second hand Hump Pack. The casing is in nice condition, but after repeated trickle charging and cycling, it appears that two of the cells are dead, and the remaining four are only discharging about 500ma! Not a good recipe for sparkling performance.....

Is there any way of getting the two halves of the casing seperated so I can fit new cells inside?? It would be handy if I could, because I need a decent hump pack for my Super Champ.

Thanks in advance,

Richard :-)

[rc-martin]

I don't think that there is an easy way to open up a hump pack battery. I have done it in the past using a hacksaw blade to cut carefully along the joint, then replaced the cells and taped the casing up again.

To be honest, you don't really need the case. I have a few hump packs I have made myself without the case and they hold together just fine.

There is a picture of one i did a few years back in my showroom.

[retroman]

Thanks martin,

I did wonder if it was going to be a hacksaw job! I just wanted to try and stick to the original hump pack in the Super Champ, as it looks like it is the only way to have the battery fitting nicely in the chassis. Otherwise, I guess that I will have to build my own hump packs without the case, and then stick foam blocks to the chassis to help secure it.

Rich :-)

[TomEG]

I cut one of mine open with a thin and sharp knife, put in new cells, and taped it with some gray heavy duty tape, that covered the side from bottom to top. Worked great.

Tom

[retroman]

Thanks Tom, I'll give it a try

[Mud-Plugger]

You can (in fact I often do) bring an old NiCd back into service by giving it a boost charge at around 2C or more. What this means is, if say the capacity is 1500mAh then you would put say a psu at about 12v and 3.0A or more across the terminals for a few seconds. What this will do is break through the dendrites and restore the battery for a period. Depending on the age and condition of the battery determines how successful this is. I must say though, if you aren't confident doing this, then I would suggest replacing the cells inside.

Mud.

[Live Steam Mad]

This showroom entry may tickle your fancy regarding some information on opening the hump packs (see the pictures in it).

http://www.tamiyaclub.com/showroom_model.a...17&sid=5475

Also, here is a picture that I took a while ago with one of my greatest hauls ever, loads of them NIB. Sorry if it looks a bit show off ish but I it's a picture that I took to show one of my vintage pals in USA what I had been up to. They kept coming up on Ebay regularly from a USA seller, price was silly money (i.e. 15 quid a pop, outrageously cheap). I could not understand why hardly any other TC regulars had not put bids on them as well as me. There were very rarely any bidding competitions on them. They vary from 1250 mAh on test, to about 200 mAh as they are probably very old now. You have to be careful to charge them slowly and don't delta peak them too hard. Easy with an MRC 969 charger. I got loads of them in a row, over about a 6 month period a couple of years back. In fact I actually have more now since this picture was taken, and all 10 are NIB

I would like to find a 6V flat pack in the same condition but they are rediculously rare NIB.

Cheers,

Alistair G.

[retroman]

Thanks mate,

The link to the battery pack that has been taken apart is very helpfull. I'll have another read through it before I strip mine down.

Rich :-)

[TomEG]

I'm not sure (it's over 20 years ago), but I think the cells I used to replace the originals were Panasonic "Pananica" (or a name similar to that....), and I now recall I had some trouble getting the solder points small enough to fit in the case. But it worked in the end, after some "fiddling".

Tom