May 2022 – Battery Electric Loco ‘Oddjob’ Enters Traffic

by Jerry Chivers

When ‘Oddjob’ received her first test back in 2020 she proved less than satisfactory. The motor cut out under load and she could hardly move her own weight. As with many projects, it was easier to move her to the back of the shed and quietly forget her.

This happened and for a number of months, she remained out of use. We still desperately needed a shunting engine, and so ‘Oddjob’ was returned to the works for a rethink. I think everyone thought this would be the last time they would see ‘Oddjob’, knowing from previous experience of other engines ‘permanently back at the works’!

There were several issues. Firstly the motor would need replacing and my first thoughts were to find a replacement 110v AC motor but this proved difficult. The second problem with ‘Oddjob’ was the generator which tended to stall under high load. After some considerable thought, I decided to go pure electric with batteries and use a pair of electric scooter motors I already had. Hopefully, they would be adequate at 26amps and 48v, that’s 1,250 watts each.

The motors were fitted each with their own chain to the existing mower gearbox, and a DC speed controller was purchased from 4QD. I also fitted a volt and amp meter to monitor the 48v system along with an electrical switch to give forward and reverse. This would allow all three speeds in forward and reverse.

She returned to the railway for testing and I have to admit I was not very hopeful, but to my surprise, she performed relatively well. The main problem for any electric loco is our gradients, they are steep and long. She slowed significantly under load and I decided to re-gear the motors to increase the top speed. She went from an 11-tooth to a 15-tooth gear. By my calculations that would increase her top speed by around 30%. Obviously, the current load would also increase but hopefully, the motors would be able to cope.

It took over a month for the new gears to arrive because the only ones available had to come from China. It only took an hour to fit the new gears and her performance was subtly improved, to the point that for a 0-4-0 narrow gauge loco it was fast enough.

Oddjob has now been in constant use for many months, shunting wagons and coaches and even two Exmoors at a time. She appears to be loved by all, especially the diesel haters!

She really is just too useful.

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