BossCat's Push Trailer

[BossCat]

I took one of my wheels into my one of my local bike shops to get a longer axle put in. The buggers have had it 3 days now? I dont think I'll be going back to that shop to get anything technical done
While waiting for the wheel I got a few more things done - I fitted 2 new tyres to my bike and have made a plywood box for my trailer...

Box under construction.

I still have a lid to make and a sunken box to hold the batteries and controlller, then give it a lick of paint.

Regards
Tom

 

[BossCat]

I finally got my wheels back after 3 1/2 days they still never set the axle right, the way I wanted it

My new controller also arrived £17, this one's a bit simpler with the wiring...

I also got a lid made up for the trailer. Today I'll hook up all the wiring and batts and give it a test run at 36V 800Watts. I'll report back later with the results and pictures, keep yer fingers crossed

Regards
Tom

 

[BossCat]

Its a mystery?

I took off the 24V controller and fitted my new 36V 800Watt controller, I added another 12V battery to bring me up to 36V. I went for a test run and found that the trailer now only pushes me along at a sloooow walking pace? ...and yet the 24V controller with 2 12V batteries pushed me along a lot faster?
Is it because I bought the wrong controller 36V 800Watt instead of 36V 500Watt.

Anyone have any suggestions?

Regards
Tom

PS... Im going to hook up the 24V controller with 2 batteries again and see if I still get the same speed as before.

 

[deacon]

The size of the controller is not the problem. I controller limits the amount of current up to the max. Your max can be higher than needed. The lower ones will cause the motor to run up to the specified current but no more.

Pull the motor leads and hook your meter to them. then work the throttle to see how much current is going to the motor. It should increase as you work the throttle. At max throttle you should have 36v or close to it. If you have less check your batteries to be sure they are connected correctly. If you have the right voltage check the motor for binding. <y chain was too tight and caused mine to run like a pig once.

If the amount of power coming from the controller is less than or not close to 36v at full throttle you might need to have them dealer replace the controller.

 

[Happy Jack]

Anyone have any suggestions?

work the throttle to see how much current is going to the motor.

Current is not measured in voltage alone.

Suggestion = measure the amperage.
Without knowing the "LOAD" that the motor draws it is very hard to diagnose motor/battery/controller issues.

 

[deacon]

You are right of course but there is a relationship between volts and amps. If the voltage is low then the amps are low as well. if that is the case and the voltage from the batteries is correct then the controller is bad or the throttle is.

If the voltage is correct then something has changed to cause the motor to draw more amps. usually it is binding or a connection somewhere is bad. i would still check the throttle and controller just as i said and start from there.

Just what I would do.

 

[BossCat]

Here's what iv'e done so far...

I took off the new 36V controller and replaced the 24V one, I then took the trailer for a test. Great same as it was before. So the extra weight of the plywood surround and lid, plus an extra 12V battery in the trailer doesn't effect the trailer, I thought it might.

It started raining so I had to move the trailer into my workshop! - (workshop, Ha, I should be so lucky, its really my kitchen ).
I messed about with wires for about 2 hours trying to hook up my Turnigy watt meter, I eventually found I was using a wire with a fuse holder attached. I recut the wire and done away with the fuse holder and the watt meter worked fine - just need to learn how to read the bloody thing

I tested 2 of the batteries with the 24V controller. The batteries read 23.7V. I removed the motor leads and put on my multimeter and turned the throttle - it read 21.4V at full throttle.

As I have to keep cutting and snipping wires to join up with spade/bullit connectors, and the last couple of hours has done my head it, im going to have a rest with a coffee before I rig up the 36V controller and give it a try.

As to the wiring of the new controller...

I discussed the wiring with the seller before I bought this controller, he said I had all the wiring figured out, the only wire I was missing is the THIN red wire this needs to be connected to a switch and then + power back to the battery.
As I dont have a switch handy I just hooked this straight to the battery.

Regards
Tom

 

[deacon]

so you know your throttle is okay, since it worked with the 24v system... you know the motor is not in a bind or any other reason that it would pull inceased amps... So hook it up and give it the throttle test. I would try it once with the thin red wire hooked up and once without it hooked up. Usually there is a second wire to the switch that makes a circuit. But if it works at all it should work correctly but I would still try it if I got wanky readings. If you do get wanky readings when it is working then I would say you have a faulty from the factory controllers. I just burned a heavy duty one up recently how I don't know except that the bike is over fused and it might have got enough draw to burn the controller when it did a runaway in the shop on me. It stopped working about that same time. I should refuse those bikes I suppose.

 

[jdcburg]

BC - If you are using SLAs, maybe you should check the batteries first. 23.7v is too low for for 2 12v SLAs in series. I would check the voltage before the controller. If that is up there (25.5-26.5v), you could try seeing if there's a voltage drop across the poles of the batteries with the with the motor running (maybe with the chain disconnected or the wheel off the ground.) You could also experiment using a HD switch or relay instead of the controller and throttle. Just make sure you are moving along before you switch it on, and also that you have a secondary way to cut the power in case the contacts weld together. Probably better just bench test if you are using a simple switch. Running the power wire from the trailer to the handlebars and back is a long run for a low voltage/high draw situation. If you use a relay you can just run the switch wire up to a convenient place and leave the relay and heavy wires back with the battery and motor - jd

 

[BossCat]

BC - If you are using SLAs, maybe you should check the batteries first. 23.7v is too low for for 2 12v SLAs in series.

I think you may have missread my last post, or we have our wires crossed?


I tested 2 of the batteries with the 24V controller. The batteries read 23.7V. I removed the motor leads and put on my multimeter and turned the throttle - it read 21.4V at full throttle.

by this I mean I checked the voltage of the batteries first. 2 12V sla's wired in series gave me 23.7V.

I have since tried the 36V controller, and before we get mixed up again --- I checked the 3 batteries wired in series first, which gave me a reading of 34.3V.

NOTE: The batteries haven't been fully recharged since I last used the trailer at the weekend.

I removed the motor leads and stuck in my multimeter then turned the throttle and got a reading of 33.6V.

Now here's a thing?
With the 24V controller hooked up, turn the throttle slowly up to full and motor spins up and turns the wheel, everythings ok. Now remove the motor leads and put in a multimeter and the voltage changes as you slowly turn the throttle.

Now try the same with the 36V controller hooked up and everythings the same until I hook up the multimeter. It doesn't matter if I turn the throttle just a fraction or to full, I still get the same reading of 33.6V ?

Controller Testing.

I'll have to hook everything back up to the trailer and test it running again tomorrow, but for now its late - 1:50am and the workshop/kitchen has closed

Regards
Tom

PS... I dont seem to be having much luck with 36V controllers?

 

[jdcburg]

BC - 23.7 for 2 and 34.3 for 3 is too low for SLAs, so that could be the problem right there. One thing SLAs are very sensitive to is being left in a state of low charge. That kills them quickly but you might be able to bring them back with the epsom salts trick. Also repeatedly discharging them deeply is hard on them, which is why they are not really well-suited to ebike use but that's another issue.

If the batteries are shot they may show good voltage right off the charger but will quickly sag under load. That may be why the controller only puts out 21.4. Does the motor run OK at that voltage? I'd be surprised if it did.

I would check each battery individually. Fully charged they should be at about 13.25 or about 26.5 in series. You can hook your multimeter up in parallel with a load and check the voltage as well. By that I mean you can touch the probes to the + and - of the batteries while the load (motor) is on. Just don't try to run the load through the meter. The voltage shouldn't drop too much, especially if you are bench testing.

I don't know why one controller would show an increase in voltage from the throttle while the other would be steady at 33.6. That could be something to do with the low voltage or because there's no load or some other characteristic of the individual controllers' designs. It might be interesting to put the multimeter probes into the + and - of the motor connections while the motor is running at various throttle settings to see what the readings are - jd

 

[deacon]

I think he read the batteries after the ride if I understood it correctly. If not you guys seem to be on the right track but i don't get how it runs fine with those batteries on one controller but not the other unless he is adding a bad battery to two good ones. that would do it. If it died under load it would kill the power of the pack and make it run like a pig. but might still have enough V to turn the motor slowly. Mine does that when I run the sla down to about 12.5 each

 

[corgi1]

I've had car batts.play the radio light the lites but go flat under crank load,,,mine was bad batt

 

[BossCat]

If the batteries are shot they may show good voltage right off the charger but will quickly sag under load. That may be why the controller only puts out 21.4. Does the motor run OK at that voltage? I'd be surprised if it did.

Yes the motor runs ok at that voltage, it spins the trailer wheel fast enough to cut diamonds

First thing i'll do today is recharge all 3 of my 12V 14.0amp batteries. I should get a reading of around 13.2V from each battery, at least thats what they read last time I charged them. I then start the test again with fully recharged batteries.

While the batteries are charging I'll make some mudguards for the trailer. That should keep me busy for a couple of hours.

Regards
Tom

 

[BossCat]

I didn't get anything done until late in the day as I was running around doing this that and the next thing. When I finally got round to my trailer I fixed the lid and cut a couple of strips of a large plastic shop sign to make mudguards with while I had the batteries on charge. I cut up some wire and put spade & bullit connectors on to connect to my batteries and motor. When the batteries were charged I setup my trailer outside and did a test of the Batteries/Controller/Motor...

Trailer Setup.

Batteries.
3 Batteries wired in series showing 38.3Volts.

Throttle Test(s)
Once i'd plugged everything in I gave the throttle a turn, the trailer wheel seemed to be spinning a lot faster than last night? ...or maybe it just seemed as though it was?

I then pulled out the motor leads and hooked up my multimeter and gave the throttle a turn. As you can see I still got a reading of 38.3Volts. So far so good.

Humm! Everythings starting to look good!
I put everthing in the trailer and wired it all up. I didn't use the throttle you see in the picture as this is a spare. I have the throttle of the little scooter on my bike. I crossed my fingers and went for a test run.......?

Whooooosh........ Yipeeeee Its working.
I dont know what has changed since lastnight barring a recharge of the batteries, maybe a bad connection or something? Anyway all seems well. I only managed a couple of test runs around the block as it was getting dark and I dont have my lights rigged up yet.

Happy Bunny - Happy Bunny - Happy Bunny ......... err did I mention that I was a Happy Bunny.
Tomorrow I'll give it a proper test run and see how it all holds together. Keep your fingers crossed that no gremlins show up during the night.

Regards
Tom

 

[silverbear]

Way to go, Tom. It sounds like you got things figured out.
SB

 

[deacon]

sounds like you have it worked out. Putting together and taking apart often leaves a bug or two. I left my rhino untied down on one side last night.

 

[jdcburg]

Sounds good. I think the voltage was low causing the lack of power. Read up on the wattmeter and get it going. I'll bet that will tell you a lot about what's happening - jd

 

[BossCat]

Yesterday I took the trailer for a test run. It didn't run good at all, rather slow in fact? I ran it for a couple of miles wondering what could be the problem, I hadn't changed or altered anything in the setup, all I had done was remove one of the batteries connections and locked everything up for the night before.
When I returned home I checked the batteries for voltage...

Battery 1. Showed 12.8V
Battery 2. Showed 9.6V
Battery 3. Showed 12.8V

I think battery 2 may be the problem? Today I'll try batteries 1 and 3 along with my 12V 90amp deep cycle battey and see how I get on. The trouble with the deep cycle battery is the weight, I think its around 5 stone.

I did get a little done yesterday before the rain came....

I fitted a couple of mudguards and painted the lid of the trailer silver. The paint had a grey lid on it but when I came to spay the lid I found out that it was silver? Never mind, it may look good in silver and black as my bikes a sort of grey/charcole and light silvery gray.
Still have a couple of small brackets to add to the mudguards to alter there angle a bit. Mudflaps to make - trailer to paint - lights to wire up. It all takes time, but I'll get there in the end

Regards
Tom

 

[deacon]

The 9.6 is a bad battery./ You need to junk it. 11.75 is about as low as they can operate and that's way lower then they are useful. When mine get down to 12.5 they are dragging around. The 12.8 sounds about normal but the other one is low.

When I leave my house my 36v pack reads 39v every time. if the total gets down to 36 it is dragging bad.