Author Topic: Sun Battery Charger -- 6V  (Read 1041 times)

Offline goodfellow

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Sun Battery Charger -- 6V
« on: October 10, 2020, 11:39:00 AM »
Note: These threads are old. I managed to restore these Sun Automotive Equipment threads from backups that I had made several years ago.
Hope you like them -

Since it's a crappy day outside, why not tackle a little project in the garage. I found this interesting unit on e-Bay of all places.

These are quite rare since they were mostly used to recharge the 6-volt batteries on many Sun diagnostic and distributor testers. In the early years (1940's and early 1950's) Sun used 6 volt batteries to supply the test voltage for their equipment (most notably in the distributor testers of the time). It was only in the mid- to late 1950's that they switched to integrated DC power supplies.

This one is OEM for my 1950 Master Distributor Tester (MTD). Although I built a power supply for my MTD, it's nice to have all the OEM equipment that came with the tester.

One thing to note on Battery chargers of the time -- they are configured for 6v POSITIVE ground systems, so in order to use them on more modern charging systems, the clips will have to be reversed -- or duly marked.

It was pretty ratty, but salvageable. I replaced much of the wiring, installed a proper grounded power cord, new charging clips, and finally painted the base and housing.

The only modification I'm going to make next week is to install a DC ammeter on the back to indicate current draw.





Pretty crappy and dirty lookin' -- lots of dead bugs ;D ;D







Transformer tested perfect -- amazing!!



Cleaned the heat sinks and repainted the base and housing












Offline goodfellow

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Re: Sun Battery Charger -- 6V
« Reply #1 on: October 10, 2020, 11:39:26 AM »
Here is the finished product, (with the ammeter installed) and how it functions in the 1950 Sun Master Distributor Tester. Not too many old Sun distributor testers still have their functioning OEM 6v battery chargers -- This makes it complete.

Note: The hardest part of this job was finding an acceptable ammeter that included an internal shunt (basically just a resistor installed in parallel with the circuit). Internal shunt meters are EXPENSIVE -- why?  because ripp-off artists on ebay can charge high $$$ for a "Shunt". So this meter is a cheap $4.00 unit with a $0.25 -- 60 ohm resistor bridging the terminals. The "Shunt" is nothing more than that cheap-a$$ resistor. Beware of this "false and deceptive" advertising when purchasing electronic parts.