Loco electric drive check

[darrene]

I've done a fair bit of research but nobody could accuse me of being an electrician so I thought it best to ask if someone can give my proposed installation a once-over before I go ahead and implement it.

I'm creating a 5" steam outline. It is to run in the garden, pulling a maximum combined weight of 4 adults.

Config as follows:

2x 12v batteries the tender
4QD DNO-10 (100a) controller
Two (possibly three?) 12v 4.9A Parvalux motors driving the 3.9" tender wheels

My plan is to run the motors at 24v and in parallel. This would give a 240w power with the
2 motors I have at the moment.
The 4QD can current-limit and I'll add a 63a mcb on the input to add battery isolation and wiring protection.

The gearing is 10t on the motor and 90t on the axle so giving 9:1 reduction.
Running the motors at 24v will give a 5000rpm maximum. With a 3.19" tread diameter that gives me a nominal 6.6mph maximum speed.

I believe i would need to wire the motors in parallel to maintain the 24v supply.

Would adding a third motor in parallel on the remaining third axle be worth doing now or is it going to add a downside? I can see that it will increase the torque and tractive power which would seem no bad thing, but it must come at a cost?

Thanks for reading!
Darren

[cplmickey]

As someone with no knowledge of electric locos perhaps I can give an "observers" view.

Firstly why do you want to add a third motor - what is the advantage TO YOU over the 2 motor system, do you need the pulling power or will 2 be enough. Are the gradients in the garden steep enough to need the extra oomph.

Downsides are obviously more work, more complexity, more to go wrong but also potentially more power used from the batteries. But I can't see why you couldn't do it if you wanted.

Ian

[darrene]

Thanks Ian, definitely - any input is gratefully received

I think (hope!) from my calculations it's likely to be fine as-is if the basic approach is sound. If that's the case, wondering what the electrical trade-offs might be given now is probably involves the least effort to incorporate a third motor.

Having mulled it over I think it makes sense to do it - having the extra oomph means any gradients or larger passenger loads are more easily accomodated. There's the cost of the extra motor, brackets and gears, but that's about it.

To my overly-simplistic way of thinking, if I discount the losses introduced by the third motor, the work being asked of the system won't have changed - the load on the controller and batteries would therefore be pretty similar but the work being done by the motors themselves would be reduced when shared across three.

Darren

[delaplume]

Dec 27, 2021 13:27:19 GMT darrene said:

Thanks Ian, definitely - any input is gratefully received

I think (hope!) from my calculations it's likely to be fine as-is if the basic approach is sound. If that's the case, wondering what the electrical trade-offs might be given now is probably involves the least effort to incorporate a third motor.

Having mulled it over I think it makes sense to do it - having the extra oomph means any gradients or larger passenger loads are more easily accomodated. There's the cost of the extra motor, brackets and gears, but that's about it.

To my overly-simplistic way of thinking, if I discount the losses introduced by the third motor, the work being asked of the system won't have changed - the load on the controller and batteries would therefore be pretty similar but the work being done by the motors themselves would be reduced when shared across three.

Darren

Hi Darren----- I run both steam and battery/electric locos so might be able to help??..........

Yes, 3 motors WILL give  more pulling power than 2.....You need to look at the motors and find the Wattage rating....Simply put, this is their electrical Power output.....and you just add together the individual Wattage  ratings to get the total---Thus 2 motors rated at 60W each has a total of 120W, and 3 motors will give 180W total........However, as the power source is a fixed output one ( A battery ) the greater the power demanded of it, the less time you will have to use that amount of power.....

But don't worry---I see you are using a DNO-10 made by 4QD..This is a proven unit, well capable of handling your proposed set-up and has quite a few adjustable settings and built-in safeguards........Your line speed is about right ( a brisk walking pace is often quoted as ideal) --- and with that humungus 9:1 overall reduction you should be able to pull like --------------well, like a steam train !!..LoL ..........( The general go-to reduction is about 6:1 )

Tip}----  Try to bolt the large gear wheel direct onto the tender wheel--------- if you can't and have to attach it to the axle then remember to add some sort of "key" between the axle and wheel, otherwise you'll be asking the fit of the wheel-onto-axle to transmit all that Torque as well..... a job it's not designed to do....