Replace old charger selector knob?

[Brybo86]

Little cousins were over and broke off my selector knob on my old 141.068 manual charger booster.
plastic knob with 1/4 stem
The little metal nut spins off and leaves a threaded plastic bolt piece
The 1/4 plastic stem spins inside of it.

Is this something I can replace?

 

[JohnnyG]

See if you can get a replacement switch from the manufacturer. I'd say you need more than just the knob.

 

[Brybo86]

See if you can get a replacement switch from the manufacturer. I'd say you need more than just the knob.

This is all that comes up with the model number.
This charger is from the 70's I think
https://www.centurytool.net/141_068_Snap_On_Battery_Charger_s/48.htm

 

[JohnnyG]

Looks like #8 to me. Pretty poor pic.
Two parts. Total $57.60.

 

[KrisZ]

Oh man, this old thing begs for a 90 degree bent deck screw serving as a “knob”.

 

[Brybo86]

Oh man, this old thing begs for a 90 degree bent deck screw serving as a “knob”.

Or how could I cut a little slot in it and use a flat screwdriver?

 

[KrisZ]

Or how could I cut a little slot in it and use a flat screwdriver?

That could work, if the knob is not hard to turn, or doesn’t have hard detents, otherwise the plastic may crack.

 

[Nukeman7]

Take it apart and take a look at the terminals on the backside. If it is a 5 position single pole / 4 throw switch, you can probably replace it with this $10 switch from Grainger.

5 Position Rotary Switch

 

[mk378]

This would work and would fit in the original hole, but you will have to give up one of the settings such as 6 volt low. A 4 speed 5 position version may exist which would be exactly the original function.

https://www.amazon.com/Taiss-Position-Universal-Latching-terminals/dp/B09P9T86TT/

 

[Dave9]

Label reads "Charge up to 80 amps on discharged 6 or 12 volt batteries", "Boost up to 300 Amps for starting".

If that current is going through the broken selector switch, then the two suggestions made so far, do not seem nearly high enough current rated.

I'd open the charger up, label the wires' position on the switch, take a couple pics of that, then pull the switch and see if there are specs on it and a manufacturer/part #. After searching for that switch or suitably spec'd replacements online, if that doesn't pan out, then I'd see if the switch looks difficult to open, so you can see if that broken stem is a single piece with the plate it turns, or if it is separate and you might be able to substitute something else, like a piece of bolt, the smooth shank section of one, and then for the knob, something with a set screw to hold it on.

That might require a minimal amount of machining the bolt, hard to say how much without seeing it, nor knowing if that is within your wheelhouse. Another alternative might be finding some rod that already has tapped threads on an inner hole. It's hard to speculate what would work, without seeing the switch mechanism.

 

[Dave9]

Or how could I cut a little slot in it and use a flat screwdriver?

If the stem is broken off right where it exits the threaded neck of the switch, then cutting could be difficult, possibly a tiny burr bit on a dremel rotary tool, but what I would try instead, is spraying some lube around the broken off shaft to get a little down into it, then heating a small screwdriver blade and melting a slot instead, being very careful not to melt it too much. I don't really expect that to work well, and if there is any chance of substituting a different shaft as I mentioned previously, then all the more important to not melt it too much and damage the threaded neck of the switch.

 

[mk378]

The switch selects a tap to send 120 volts into the primary winding of the power transformer. It is not in the high-current 12 volt side. The current through the switch is the same as in the power input cord so that is the rating to consider.

 

[Eddie Hudson]

These people should have what you need, and they're great to deal with.

https://www.plpbattery.com/

 

[Donald]

I have an old Century battery charger. It needs some repair. But is it worth it with all the smart chargers available (and I have a few).

I know having a dumb charger can help start the charging process on a battery that was discharged to a very low voltage. But will that battery every be a good battery again?

 

[Brybo86]

Some pics

 

[Brybo86]

 

[Brybo86]

I knew that 50yr old plastic was going to break...

 

[Brybo86]

Seems like this is what I need.
https://a.co/d/5SyCeZK

 

[tcp71]

Edit: the above switch looks better than mine.

https://www.digikey.ca/en/products/...DoSArNUoQ1IFo6+sbmVgQAtOQIDlCGAK6uxJBkXqqWGUA

This is rated for 300VAC and 30 amps...more than the original. It has 5 poles instead of 4 so you would leave one position open and unused. The position of each pole probably doesn't align with the face of the unit either, but it would work

 

[Brybo86]

Edit: the above switch looks better than mine.

https://www.digikey.ca/en/products/...DoSArNUoQ1IFo6+sbmVgQAtOQIDlCGAK6uxJBkXqqWGUA

This is rated for 300VAC and 30 amps...more than the original. It has 5 poles instead of 4 so you would leave one position open and unused. The position of each pole probably doesn't align with the face of the unit either, but it would work

I think a 5 position switch has one position for OFF plus 4 selections.