Battery leakage; damage repair ?

[howard]

Hello,

I have recently acquired a stunning 1970s ITT Polo which works fine on 240v mains but not with batteries due to quite bad damage to the metalwork in the battery compartment, obviously due to batteries being left in there too long

Obviously I can scrape away in there until it starts to work but I was wondering if anyone was aware of any chemical treatment which might clean off some of the damage and neutralise the alkali no doubt still active in there ?

Howard

[Radio_Dave]

Hi Howard,

You could try some mild acids like vinegar, citric or lemon juice.

If that fails I'd try to remove the contacts and soak them in one of those limescale removers (Viacal, etc). They're normally made from a quite strong solution of either phosphoric or hydrochloric acid, be carefull, do it outside (well ventilated) and wear gloves!

David

[David G4EBT]

Originally Posted by Howard

I have recently acquired a stunning 1970s ITT Polo which works fine on 240v mains but not with batteries due to quite bad damage to the metalwork in the battery compartment, obviously due to batteries being left in there too long

Obviously I can scrape away in there until it starts to work but I was wondering if anyone was aware of any chemical treatment which might clean off some of the damage and neutralise the alkali no doubt still active in there ?

Hi Howard,

There are products such as "Rust Eater" which you can get from places such as Halfords or B&Q. (Handy for cleaning up and neutralising areas of rust on steel chassis).

However, from my experience once you get rust of the spiral springs of battery holders they lose their "springyiness" and abilty to make good contact.

I think a better idea, which I've used with success several times, is to get a new battery holder from somewhere such as Maplin (Even an 8 x C or 8 x D size are only a quid or so and have several springs in them). Remove the springs from that and adapt them to repair your damaged one.

Usually the coils are fitted with eylets, which are easily removed, then you can fit the new ones using small panel headed screws, nuts, washers and solder tags (say 4/6BA).

It's worth removing the battery compartment anyway to throughly wash it and get any corrosive residue off it, and to make sure that there isn't any on other connections or the PCB etc.

The flat connectors can often be given a new lease of life by cleaning them up and tinning them with solder. If you use mutlicore solder, add a touch of plumbers flux - it works much better on steel than the resin in multicore, which isn't aggressive enough.

If you need to make new flat connecting strips, you can use thin brass sheet. Cut it to size and tin it so that it doesn't tarnish. You can punch raised dimples into it with say a nail with the end blunted round with a file. You can get thin brass sheet from JA Crew at: www.jacrew.net

They also sell lots of other useful bits.
EG nuts and screws. (1/2" x 6BA brass, 80p for 50).

Hope that helps.
David

[Aerodyne]

Just a point: you will probably find that a jelly-type rust killer would be easier to control and apply. Also after scraping, applying, removing, scraping and so on until the metal is blackened and completely clear of rust, you should wash the area with methylated spirits to kill the acid action or further problems will develop over time.
-Tony

[howard]

Hello again,

Many thanks for all your suggestions.

I'm used to working with rusty metal (I used to restore cars) but then that metalwork didn't have to conduct electricity. I dont think sandblasting this frail little unit will do it much good ..... so I will take this battery box apart and maybe replace the springs with ones from a new Maplins box. Kurust is good stuff but it does leave a coating which I suspect is not conductive so the backing plates I will clean up with something milder such as vinegar or citric acid and then neutralise that totally with sodium bicarbonate. The battery damage has not gone beyond the box, phew, and this old Polo radio really does work well on mains. Another one for success stories soon I think !

Howard

[Paul Stenning]

Originally Posted by G4EBT

I think a better idea, which I've used with success several times, is to get a new battery holder from somewhere such as Maplin (Even an 8 x C or 8 x D size are only a quid or so and have several springs in them). Remove the springs from that and adapt them to repair your damaged one.

I've done this a couple of times too, and as expected it works well. Better results and a lot less mess than trying to clean the originals.

[mikelect]

Originally Posted by G4EBT

The flat connectors can often be given a new lease of life by cleaning them up and tinning them with solder. If you use mutlicore solder, add a touch of plumbers flux - it works much better on steel than the resin in multicore, which isn't aggressive enough.

Hi if you do use plumbers flux (not recommended ) make sure you clean every little bit of as it is basically phosphoric acid in petroleum jelly and will give you a bigger corrosion problem than you started with . A better choice would be electronic flux sold by most of the big wholesalers and places like Maplins etc


Mike

[Mike Phelan]

Hi Howard
If you are using a rust remover, phosphoric acid H3PO4 (Kurust, Jenolite, Coca Cola) is not really a good thing for this. Tannic acid or oxalic types (Exit Rust, Corrodip) are better, but still do need to be washed off. I endorse the comments on replacing the springs - pitted springs will eventually break.

I often wonder if it is worth trying to nickel-plate these things at home?

Fluxite is a good flux for steel, but needs washing off; I think it is zinc chloride based?

[howard]

Hello again,

I managed to get this ITT Polo working again fine with batteries The plastic battery box in this radio is welded in place so it was impossible to remove it to work on So I cleaned it out with B&Qs sticky stuff remover which is obviously acidic - it smells citrus - and that removed all the remaining goo. I then used some wet and dry sand paper to clean up the ends of the three springs and the three metal contacts and fortunately the leakage hadn't damaged the contact between the springs and backplate

It took me ages to do and it still looks a bit grotty in there but now this mint 1976 ITT Polo works a treat both on mains and battery

I've cleaned it all up now and so another ITT model is added to my large collection of 1970s ITT radios, great sounding and very pretty radios these

Howard

[batterymaker1]

If it's brown mess from zinc-carbon batteries, it usually can be removed with a rag soaked in ammonia.

If corrosion's lightly damaged the contacts, I take an emery board and scrape it off.

If it's too far gone, replacement is the only option. Mouser Electronics has replacement springs and contacts.

Bill

[Kat Manton]

Hi,

Just thought I'd revive this thread to mention my little experiment earlier. Cobweb has recently acquired a lot more Lego, among which was a battery box - which contained the leaking remains of 6 AA Alkaline cells.

As expected the battery contacts were corroded, being covered in a blue deposit. As I felt like trying an experiment I mixed up some warm water and kettle descaler crystals (Benckiser "Scale-Away") I found lurking in the cupboard under the sink. The solution went in a margarine tub and in went the battery holder. Within a few seconds the corroded areas were fizzing away; and after about 20 minutes the corrosion had gone. No damage to the uncorroded parts of the contacts occurred. (As a side-note I figured there was enough life left in the solution so poured it into the kettle afterwards.)

The original plating on the contacts had been eaten by the corrosion in the first place, so the results aren't "good as new" but the battery holder is usable and completely free of corrosion after rinsing and drying without use of any abrasives.

Attached is a picture taken after rinsing; just a little polishing up with steel wool is all that's needed now.

Just thought I'd share this; the next time I find anything with corroded battery contacts I know what I'm going to do

Regards, Kat