Batteries and Chargers

[Ulu]

Years ago in a fit of tree-hugging self congratulations, I junked my outboard engine and converted my little boat to electric. It runs on 36v from three 12v Lead/acid deep cycle marine batteries.

Since that time I have been charging the batteries with individual Schumacher 12v chargers. Which burned out, starting with the newest one, of course.

I had some beefy transformers from old UPS units, so I decided to build a 36 volt charger. These transformers only made about 32 volts, and so I decided to rewind one.

To do that I stripped down the laminated core into hundreds of bits. The first ones are removed with a tap hammer and bar. After that it’s just paint holding the core together.

Here’s the core before rewinding. There’s 4 different coils of wire, and two were not needed at all. I added 8 secondary windings to raise the output voltage.

It was a mistake. When I tested it I thought the voltage was way too high, and I disassembled the transformer again to remove them. Just removing the two unneeded extra coils somehow got me what I needed without additional wraps.

Here is my test rig on the bench after rewinding. The rectifier circuit was modified from a Skil drill charger, which was only 9 volts. I stripped it down to just a full-wave diode bridge.

Here it is in the boat, cranking out 47.48 volts into 3 rv batteries, from just 2.9 amps @ 121.2vac. They have been on about 1 minute. These batteries haven’t been charged in about 50 to 60 days.

This did a fast job. It was stronger, faster, ran cooler, and was better than expected. I was well pleased that I got this right on the second try.

Now I need to really discharge the batteries, and give it a real test.

 

[Kevin B]

Ulu you're a renaissance man. You always just go for it and tackle problems making discoveries along the way. I admire your skill and tenacity.

 

[Ulu]

Thank you Kevin. I don’t get bored easily, or such tedious jobs would be less attractive.

Transformers don’t need to be complicated, but sometimes they are. This one had windings I didn’t want, and removing them was a pita (but with very positive results.)

But it was not frightening. I wound my first coil of magnet wire at 7 years old. Dad bought me a little electric motor kit with a laminated 2-pole rotor.

When I was 12, I built a telegraph with homemade relays and coils, that went 30’ to my neighbor’s house.

BUT, all my youth projects ran on flashlight batteries. 3v~9v.

Now I might want to build a charger that runs on 240vac, since the boatyard is wired for my welder.

 

[Da Gas Man]

Thank you Kevin. I don’t get bored easily, or such tedious jobs would be less attractive.

Transformers don’t need to be complicated, but sometimes they are. This one had windings I didn’t want, and removing them was a pita (but with very positive results.)

But it was not frightening. I wound my first coil of magnet wire at 7 years old. Dad bought me a little electric motor kit with a laminated 2-pole rotor.

When I was 12, I built a telegraph with homemade relays and coils, that went 30’ to my neighbor’s house.

BUT, all my youth projects ran on flashlight batteries. 3v~9v.

Now I might want to build a charger that runs on 240vac, since the boatyard is wired for my welder.

After all these years on the planet, I have come to realize that I know nothing about electricity.
I am humbled by your experience and masterful knowledge. If it were it me trying this I would
have burned down the garage or the boat or both by now. 240vac? That scares me. I salute you.

 

[twojs.bike]

After all these years on the planet, I have come to realize that I know nothing about electricity

I am with you. My understanding of electricity and electronics is pitiful. I think that is part of my attraction to vintage bicycles. A fully functional machine with zero electronics.

Although I have a bike in the stand now with a 1958 Sturmey Archer Dynobub. I have all kinds of ideas about converting to LED or creating a phone charger. But I don’t even own a multimeter and if I did I wouldn’t know what to do with it.

Maybe it’s time for me to learn.

 

[Ulu]

My education really started when Dad gave me his 1964 Popular Electronics magazine on simple TV repairs, back about 1967.

TVs needed much more repair in those days, but the repairs were commonly simple. Not much worse than changing a lightbulb.

Unless component values had drifted enough that you needed “an alignment”.

There were coils and trim pots, and you needed a scope and signal generator to set them up. Or at least those tools made it so you didn’t need lots of trial and error.

 

[Da Gas Man]

I am with you. My understanding of electricity and electronics is pitiful. I think that is part of my attraction to vintage bicycles. A fully functional machine with zero electronics.

Although I have a bike in the stand now with a 1958 Sturmey Archer Dynobub. I have all kinds of ideas about converting to LED or creating a phone charger. But I don’t even own a multimeter and if I did I wouldn’t know what to do with it.

Maybe it’s time for me to learn.

I re-enlisted back into the Army National Guard back around 2011. I was going to train in Aircraft Avionics
which would have been 7 months at Ft. Rucker Alabama. I was stoked. Mind you I was in my 40's at this time.
Made it through MEPS and into an aviation unit. But before going to train they informed me that my hearing
was just enough bad to keep me from the school and ultimate job. I was crushed. Still am. They let me stay
on as a cook. Big personal let down. A bit of a difference from Aircraft Avionics to cook. Sad but true. I did
retire out with over 20 years, which I wouldn't change. Or the new friends I made in that time.
I would love to strip down a transformer, re-wire it to the proper voltage I needed, get it working right and
actually use it. I was always more of a Radio Shack kid that never really paid attention to what I was doing. I was born in '67.

 

[Ulu]

I am experimenting with a low-voltage AC welder. I changed one transformer from 16 to 7 volts but the lams were welded, so it was not easy to make it neat. The used wire needed lots of straightening.