Electrickery....................

[Gremlin]

Dear all

I am now at the stage of wiring in the electrics. i have good knowledge of circuits and wiring in automotive applications but i am a complete ignorant what type of batteries i should use.

I think i should specify what i have till now.

Motor, its from a mobility scooter rated at 230 watts with 20:1 reduction approx, complete with integral disc brake
Controller, Again its from sort of chinese made modility scooter rated 500 watts
Throttle pot is a plunger type

My intention to have auto brakes, meaning the brake solenoid will let off only when the throttle is depressed. relese the pedal and the car should come to halt as the brake kicks in. I think this is a feature used on mobility scooters. I must power up the solenoid to release the brake, this will be taken care of by some sort of relay, i still need to see how it will actually work as its all in my head right now.

So my questions for you electrical wizards out there,

Do you think the auto brake is a good idea?? (I thought it might work to avoid kids having more than 1 pedal.........)

Controller, i am a bit doubtful this will survive this application (chinese........ i know i should have bought a 4qd one.............) What do people think??

Batteries......... I thought a sealed type.......... but what Ah rate?? Acid or Gel?? liesure?? wheelchair batt??

What is the best and most cost effective battery i can get for the toylander??

If noone has the right opinions or answers can someone point me in the direction where i can get some clues of whats what .......

This is is one of the most confusing thing i had to decied upon on this project......................


Thanks, looking forward to lots of replies

Grem

[multisync]

HI
BATTERIES!!
There are a couple of things to consider.
First the ampere hour capacity, this is quite straightforward, 35 AH will produce 3.5 Amps for ten hours, or 35 Amps for 1 hour. (But in practice, the total available is a bit less, at higher currents.)
 So if you know the current being drawn you can easily assess the approx duration, but even when in use, the vehicle will not always be at full power, and play usage will be at rest as much as under power.
As an example, my wife has an invalid scooter, 24 volt, 2 @ 12volt, 35 AH batteries, it has a top speed of 4 MPH, thats a very fast walking pace, and will run about 20 miles on a charge. In general use on say, a day out at a steam fair or similar, she can get several days use from one charge.
Putting two 12volt 35 AH batteries in series will give you 24 volt, but still at 35 AH!
Lead acid car batteries are not really suitable, as they are designed to produce very high currents, for starting, then remain on charge while the vehicle is in use.
Leisure batteries however are designed for our purpose, to be charged, then the power is used up, then recharged.
Liquid lead acid batteries, "leisure batteries" CONTAIN LIQUID ACID, and can spill!
Gel batteries, wheelchair/scooter batteries have the acid in the form of gel which is much safer.
Generally speaking Gel batteries will cost you more, for the same AH capacity, but will be smaller and lighter.
I will probably fit two 12volt, Gel batteries in my Toylander when finished. This will be for two 12volt motors, or possible one wheel 24volt chair motor. Either 35 AH, pinched from wifes scooter!, or 18AH if I have to buy them!
Whichever you use, make sure to use the correct type of charger, many chargers will have a special setting for GEL BATTERIES.
Its a bit long winded but hope it helps, let me know if you want more info
best wishes
walter

[multisync]

Hi again
you say you have a 230 watt motor, is it 12 volt or 24 volt?
If its 12 volt, it will take about 20 amps to produce that power, actually a bit more in practice as the battery voltage will drop off a bit under heavy load, but until you try it you won't know how much of that available power is required. But it means that a 20 AH battery will give something less than an hour running, at fulll power, and actual running time, so play time of several times that.
Dont forget that you need heavy wiring, it must be heavy enough to carry the current, but also heavy enough to prevent any voltage drop in the wiring!
Just like a car, a 3 litre engine would run well below full power, but a 500cc may struggle with the same vehicle, and need lower gearing. The correct gearing will get the best efficiency from the motor.
Walter

[Gremlin]

Hi Walter, its 24volts, and the my battery choice till now, and what i have found in shops, is sealed lead acid 26ah, normally used in UPS applications and for electric vehicles (?45.00), so they should be fine.

Other batteries which are gel filled are double the price.

My next attempt is to try and go to the mobility scooter shops to see if they have some used batteries which might still have some life in them (trying to be cheap bugger!)

So amp draw should be round 10 amps, controller is able to handle 20amps, so in theory it should work.

Knowing this than, a 10 amp draw with 26ah batteries should give me ample play time, 2.5hrs maybe?? or until the voltage drops to 21v as this makes the controller shut down, its something which, if i could i would override, but i do not know how!

I Still have a feeling that the controller i have will be binned after some time, in favour of something more up to the job.

Grem

[multisync]

Hi
That all sound feasible to me, and thats a good price for a battery! I don't think I could buy in the UK for that price.  I would have doubts about used batteries, unless you can get them really cheap, they are designed as deep cycle batteries and benefit from exercise, so are best if fully charged, then fully used before recharge. Many users of invalid scooters, tend to recharge them before it is necessary, as they fear the problem of a flat battery when in use.
I have played about with some used gel batteries, coincidently from a UPS, that had been stood idle for a while, but I found that, even if they held a charge at all, they had very little capacity.
They were only 7AH though.
Best wishes
Walter

[quadra]

Just one thing to note is the total weight will have an effect on the amps drawn. I don't know how much an invalid scooter weighs but a fully built toylander weighs approx 80kgs.

[multisync]

Yes thats true, I havnt weighed the scooter, but it certainly takes two people to lift it!
Toylander will probably have a lighter driver.
In UK the legal max for an ordinary, pavement type scooter (4mph) is 113 Kgs, and a road legal type, (up to 8mph) can be up to 150Kgs.
Walter

[quadra]

Yes thats true, I havnt weighed the scooter, but it certainly takes two people to lift it!
Toylander will probably have a lighter driver.
In UK the legal max for an ordinary, pavement type scooter (4mph) is 113 Kgs, and a road legal type, (up to 8mph) can be up to 150Kgs.
Walter

What you aren't going to have a go yourself, we all know we build these machines so we can drive them ourselves but justify the cost by saying they are for our kids

[Gremlin]

Guys back to my original questions, especially the brakes bit, any ideas if its a good or bad thing i might be doing or has everybody run independent brake pedals??

Oh and another question, my controller specifies an 10k pot,the one i have is 5k, will it work?? what do i need to do??

Grem

[brian]

Hello Grem,

I don't think the automatic brake will be a feasible option, the brake would require quite heavy springs to apply and would require a powerfull solenoid to pull it off during movement of the car.  This would impose a heavy drain on the battery at the same time as the motor was drawing current and the battery run time would be considerably shortened.

A foot operated brake is easy for a child to get used to and you can go down the Toylander route or like some of us on here, design a brake system yourself, the bike type disc brake seems like a good option and is the method I am currently persuing.  I intend posting the methodology on here if you want to copy or improve.

All the very best with your build,

regards,

Brian.

[Gremlin]

Hi Brian, the brake came with the motor so its part of the mobility scooter system.



Its the shiney chrome bit at the end of the motor.

Grem

[multisync]

Hi Grem
My wife has a mobility scooter which has an auto braking system, its inherently safe and I believe is a requirement on mobility scooters.
The grandchildren can safely drive it, as they dont need to worry about brakes, just close the throttle to stop. It's also a parking brake of course. Sounds like a good option to me. If I go down the route of using a mobility motor, I shall certainly use the brake system as well.
I had a chat with Richard at Toylander, when I was ordering some parts, and he did comment that if you have a transmission brake, it won't work if the chain brakes! But I think I'll risk it.
Walter

[brian]

Looks like a good idea Grem, I thought you were going to make one but the mobility scooter parts are ideal, the current drain can't be any where near the drain that would be taken using a pull off solenoid, I would go with it if it's working ok.

I would like to know how it works if you know?

Regards,

Brian.

[Gremlin]

Ah good news than, thanks Walter

I just need to see how i will make it all work...........

Brian i have no idea how it works but its basically a large solenoid, power it up and it releses the little disc brake in the middle.

Patrick

[markh15]

Hi Grem, the car I built (red S2 in Gallery), has the same axle setup as your using. I have had no probs with the operation of the brake unit, and it stops the car very well. I left it in place because of its simplicity, and that it is operated by the control box, so the little lad doesn't get confused. Don't panic, it will work fine