Need Help with Repair of 1960's Battery Charger

[Auggie1]

Hello, I am a new member and this is my first post. I have looked at a lot of electronics forums but the EEVBlog seems to have the most activity by far. I hope someone can help with my project or at at least steer me in the right direction where I can get some help. So, here goes.

I have an automotive battery charger from the early to mid 1960's. This was purchased by my father when he opened his first gas station. I remember having to wax this thing when I would work there on the weekends. All good memories. This is the main reason I want to restore it, not just to look good but to be fully functional.

Through much searching I have been able to find out that it was manufactured by the FOX Products Co., Philadelphia PA. The charger has some issues. It does power up but seems to not be putting out enough amps (if I am going about checking it correctly). The rotary timer/amp selector was replaced with an on/off toggle switch. I have checked with a company called Century Tool that stocks battery charger parts, but this timer/amp selector is no longer available. The lead tech at Century said that this charger used some kind of electro magnetic timer/selector , which apparently was very advanced for that time period. Also, the wires that were connected to the timer have been cut, which I have pointed out in the photos. There may also be other issues as well but I don't know how to go about checking to see if anything else is not working as it should.

To make matters worse, electronics trouble shooting gives me a headache, it is definitely not my forte. I don't know or understand enough about it. I am very systematic in troubleshooting a problem though and can follow directions if explained well.

For those out there who may reply with a comment that say I would be better off to scrap this idea of restoring this and buy a brand new shiney charger...please don't. One way or another, I will get this battery charger restored even if I have to modify it and use some other kind of timer.

Anyone up for a challenge? Any help and/or suggestions would be deeply appreciated. Thanks in advance.

For some reason it's not allowing me to upload photos. I will try and include those in another post.
 

[Auggie1]

I will try again to upload photos.

[Auggie1]

Here's some more.

[imidis]

It looks like you have your work cut out for you for the restore. What did you need help with? Morale support? 

[Auggie1]

More photos.

[daedalux]

Almost certanly this thing is not electronic except for some selenium rectifier or similar. Perhaps it operates on a mechanical vibrator. You'll have to remove a lot of rust, clean and adjust some contacts. WD40 or similar will be very useful for that.

[SeanB]

It has electronics in it, in the form of a nice very old design SCR control to shut off the charge current as the battery approaches float voltage. Crude but quite effective with wet lead acid batteries, and only used when the unit is set to slow charge. otherwise the circuit would be bypassed and the only current limiting is the transformer impedance and the forward resistance of the massive silicon bridge rectifier stack at the bottom of the unit. The big wire wound resistor is part of the float charge control, used, along with the light bulbs, to limit current into a flat battery. the light bulbs are across the SCR control, lighting up when the battery approaches float voltage and the SCR is starting to be turned off on each rectified cycle instead of shorting the bulb.

Interesting cooling fan there to keep the hot parts cool, and wonder if it uses a DC motor supplied from the output, or if it is an AC induction motor. whatever it is leaking lubricant from the front bush though, either it has actually been oiled during service, or the grease melted and ran down the shaft from age and neglect.

[Simon]

I've merged them all together. If you can't figure out that you need to hit reply on the thread and not just post random shit on the forum by starting a new topic every time you want to say something then you clearly have no idea how a forum works and will end up annoying everyone with nonsensical posts.

[Auggie1]

SeanB, Ahh...someone who appreciates the intricacies of how some of these old things were built. I wondered what the bulbs were for. I still don't understand it but it's good to hear someone does. It's amazing to me that you can tell all that from looking at the photos and not being familiar with it. Good catch on your part noticing what looks like a leak. I was actually using this charger up to about a month ago when it became apparent that it wasn't putting out as much amperage as it had been. It also started making a squeaking noise.

I had been wanting to restore it for many years so figured this was a good time. I took the shell off and squirted some wd-40 on the top bushing of the fan and it now purrs like a kitten. That's what the leakage is from.

I get the impression that this type of project is not really relative to this forum. Should I be looking elsewhere?

What do you mean by SCR control?

Thank you for your feedback.

[Simon]

I get the impression that this type of project is not really relative to this forum. Should I be looking elsewhere?

What makes you think that? Anything electrical is welcome here.

An SCR is a silicon controlled rectifier, it's a type of transistor that is turned on and off by a control signal. They are used for example in light dimmers.

[Auggie1]

Wow Simon! I can see that you are pretty full of yourself. Do you have self esteem issues? Maybe you suffer from the Napoleon complex. In case YOU can't figure it out, it wouldn't allow me to upload all those photos in one thread. Anyway, sorry to have bothered you. I'll sign off now and look for a forum that has a little more patience with a self admitted newbie.

[imidis]

I'd say mulligan. I agree Simon, that was a little harsh for someone with a low post count. I'd say apologies and do over. Really this is a pretty friendly place.

[Simon]

I'd say mulligan. I agree Simon, that was a little harsh for someone with a low post count. I'd say apologies and do over. Really this is a pretty friendly place.

err no! most people don't require instructions to figure out that if they make a new thread to answer/continue another one it will basically mean they cannot partake in the forum as no one will have a clue what they are on about. No matter which forum software is in use all forums follow the same logical principles.

Yes this is a friendly place. I really don't see the problem here.

[bob91343]

Your pictures aren't much help.  However, going back to basics, a battery charger is little more than a power supply.  It will have a main transformer that supplies alternating current to a rectifier.

Controlling the output is the hard part.  Generally taps on the transformer are selected to obtain the desired current.  There often is a timer, generally spring wound, that determines the length of time the power stays on.

First locate the rectifier.  With many high current chargers, the kind of rectifier used could vary widely.  Everything from silicon to germanium to copper oxide to tungar, to name just a few.  So try to identify that part.  It will usually be full wave, but not always; that means three connections to it.

There will be a circuit breaker for overload protection.  Also there usually will be cooling for the higher power units in particular, which takes the form of a fan or blower or just lots of ventilation.  Sometimes the power is applied through a contactor or relay, and other times just via a switch.  Sometimes there is a 'float' position of a switch which provides low current charging to maintain charge for long periods once the battery is up to full.

The hard part is cleaning it up so you can see the parts and try to identify them.  How substantial is the power cord?  That will be a clue as to how much power this unit was intended to deliver.  Wire gauge is the main thing, 16 AWG is good for maybe 15 Amperes and a wild approximation.  This is in the primary side, that goes to the power line.

Bob

[james_s]

If the timer is missing entirely then tracking down something similar could be tricky, is there a schematic? I wonder if it works like the moisture sensor on a clothes dryer, on mine each time wet clothes touch a pair of sensing pads it momentarily cuts power to the timer motor. The more moisture in contact with the sensor the lower the average speed the timer advances.

[ArthurDent]

As others suggested the thingy with the green painted plates is a selenium rectifier. The number of plates between terminals determines the voltage it's designed for and the square area of the plates determine the current rating of the rectifier. If I remember correctly each plate between the terminals is good for about 20 volts. Also if there are just 2 terminals, it is half-wave, 3 terminals-full wave, and if is like the photo link attached (which isn't likely for a charger) it's a full wave bridge.

What generally happens with age is the forward voltage drop increases from an initial 1 volt per plate to a higher and higher voltage drop until they are no longer suited for their intended application. High temperature will also shorten their life so if the fan in your charger stopped that is bad. It appears to be a standard shaded-pole A.C. motor with a porous bronze bearing with a felt washer that was originally soaked in light oil to keep it lubricated and this has dried up. If you don't have an oiler with a long thin tip it is fairly easy to remove two long screws that hold the end plates with the bearings on to get to see the felt and squirt some oil onto the felt until it is soaked. There may be steel washers on the end of the shaft so don't lose them.

The timer would be similar to those used on toaster ovens or old hot plates and you may be able to find an old one that will work as a replacement for the original. Generally these were for a quick high rate charge and would time out within a few (maybe 10?) minutes. The cut wires apparently disabled the low charge circuit that used the bulbs and the oval shaped transistor on the metal plate. Without a schematic the charger will probably only be usable as a quick charger with a timer or as a high rate charger with the existing switch. It's more of a keepsake for you than a usable item.

http://www.cehco.com/wp-content/uploads/2015/01/K362B2EN1_SR3-300x264.jpg

[floobydust]

I've restored old chargers smaller than this one.
Just start with sketching out a wiring diagram.

The main hassle is that replacing the green selenium rectifiers with modern silicon ones gives much higher output voltage. This ended up overcharging everything and really frustrating. I never did find a way around this.

Caution- shorted selenium rectifiers "spit juice" and their smoke is highly toxic.

With this old charger, I can barely remember using them.
As I recall it would not close the output relay if connected to a backwards battery. The pair of 1156 light bulbs lit up and was bizarre to see the inside glowing.
On the circuit board, I see a 2SB337 PNP Ge transistor. The 1156 light bulb connects to the transistor's base on Fox polarity-correcting designs.

It has automatic hi/lo charge control, I think the big wire-wound resistor is (timer) switched in.
Some controls have been cut out of the charger, the "Charge OK/Activation OK" lamp is disconnected.
The on/off switch looks to originally have been a mechanical timer, which probably switched in the resistor or light bulb for low/float charging.

[Cyberdragon]

The main hassle is that replacing the green selenium rectifiers with modern silicon ones gives much higher output voltage. This ended up overcharging everything and really frustrating. I never did find a way around this.

Use a copper oxide rectifier. If you can't find one, you can easily make one at home. This should give you a roughly equivalent voltage drop.

EDIT: These chargers may already have copper rectifiers. They look just like seleniums. Make sure what you are replacing are actually seleniums (or just unidentifiable), and not just something that looks like one! Otherwise leave it alone if it works. Yes, they can fail, but given that you can build a replacement literally out of garbage I don't think reliability matters too much.

[oldway]

This battery charger has suffered obvious damage from moisture, or even exposure to the rain.

In the 1960s, most transformers were not impregnated with varnish and it is very likely that transformer insulation (cardboard Nomex) is also damaged.

One can not reasonably think of switching such an old charger on main voltage, there are too much safety risks.

[floobydust]

The history of electronics can be fascinating. People applying what seems like crude tech (today) to real problems in the day.

Fox Products lists 33 US patents on the label. It was certainly state of the art in its time. Reverse polarity protection, battery temperature sensing, using transistors in 1956 here, using PTC for charge control etc.
Even (late 1940's patents) using vacuum tubes for charge control, thyraton etc. and copper sulfide-magnesium diodes.

You can kinda figure out this charger's circuitry from the patents, a few:
US2456978 may explain the timers.
US3171076 using PTC for current control.
US3267347 if OP's charger had sense wire on the clip.
US3258672 possibly explains the transistor.
US3387200

If the power transformer is old and fails a hi-pot test, the charger chassis is earth-grounded and the secondary-side may be as well.
So I would not expect a shock hazard.

I have trouble with antique gear, fun to fix and sometimes there is crossing a line towards not restoring it.
People here like to "bin it" and the antique radio forums are all about restoration. OP might find better support there.