Building AA battery contact plates+springs?

[lpc32]

Any ideas on how to attempt to "build" plates with springs to replace corroded AA battery terminals?
In this particular case one spring has disintegrated, and I'm not sure the rest can be cleaned.

[Ian.M]

You can probably order something suitable: http://uk.farnell.com/battery-contacts/prl/results
Worst case, you may have to make plates to fit from tin plated brass or steel to carry the new springs.  Attach them by riveting them on with a small brass eyelet and solder the reverse.

[lpc32]

How would you rivet them, eyelet + hammer?

[Ian.M]

With an eyelet riveting pliers and the spring threaded over the setting post.  Compress the spring to remove the completed assembly.  Your only remaining problem is sourcing eyelets and pliers that closely match the spring's fixing eye diameter.

Worst case: you may have to make your own solid copper rivets.   Drill a small pilot hole right through a block of steel. Redrill to the rivet diameter and to depth for the desired length. Polish the bore carefully and chamfer the edge slightly.  Cut a piece of annealed pure copper rod of matching diameter to protrude from the hole no more than one diameter, lubricate it so it can be extracted, insert and peen to form the head.  Punch the formed rivets out through the pilot hole.   They *MUST* be re-annealed before use, and will need to be tumble-polished or wire-brushed to remove copper oxide if you want them to be solderable. You'll also need a setting anvil - take a steel rod that just fits through the end turn of the spring and drill or grind a dimple in the end to accommodate the peened rivet heads.  Clamp firmly in a vice , assemble the rivet and spring on the anvil rod, hold the plate in place and peen the other end of the rivet to set it.

[Don Hills]

In many cases, if you are handy you can form(*) new contacts from nickel plated spring steel wire. The remaining problem is where to obtain suitable wire. Does anyone have any suggestions? Some paper clips are springy enough, but are often too coarse a gauge wire.

(*) IBM maintenance manuals use(d) the word "form" when they meant "bend". Much more professional sounding...

[Ian.M]

Form a spring from an offcut of copper plated MIG wire, wound onto a conical hardwood mandrel, and tin the end coils as the copper plating isn't reliable against long-term exposure to salts and humidity.

[TheSteve]

Might be easiest to buy a 3 or 4 AA holder with spring contacts and transfer the contacts over.

[QuantumLogic]

Do the batteries need to be primary cells?  Could you switch to a NiMH pack (remove battery compartment ribbing for fitment) and use a connector for ease of removal for recharging?  I can't tell what device it is.

[lpc32]

Well, the idea was to jury rig something with household stuff, no special tools or ingredients. I thought, maybe random screw heads for the protruding non-springy contacts, and screws also to hold springy somethings.

It's a toy. I guess it doesn't absolutely have to be AA batteries, but it's more convenient. I haven't checked how much below 4.5V it can go. 5V is fine.

Don, maybe "bend" is random, "form" according to a design.

[matt6ft9]

Faced something similar about a year ago.  On a fluke thermocouple meter, the AA batteries had leaked.  The metal was beyond repair and some of the plastic had also started to disintegrate.  After cleanup, I ended up gluing an AAA battery holder in the battery compartment and soldered the wires down to the main PCB.  Worked well.
You would have to cut out the dividers between the cells in order to insert the AAA battery holder pack.

[Ian.M]

There isn't any miracle cure, and most of the bodges are more work than replacing the contacts properly, either with ones carefully fabricated to fit - or with a little luck, TheSteve's suggestion of robbing them from a cheap 3 or 4 cell AA battery holder may work.

[lpc32]

Yeah, perhaps.

I wonder if I can find on eBay battery holders with wires thicker than 100 AWG.