10 year old lead acid 36V e-bike needing an upgrade!

[dogman]

It should spin faster with 48v.

Several things limit speeds for motors. Primarily the winding of the motor will yeild a set speed for a given voltage. So your motor may just be a slow type of winding. Another way to limit speed is amp limiting. You controller may allow a higher amp spike for a second to get going, then limit amps. If low enough, that low amp limit will limit speed. If there is x amount of power, a given weight and wind resistance is only going to go but so fast. That's the idea behind 200w limits for ebikes in some countries. Make it so the thing can't go fast, because 200w will only do but so much.

And then there is gearing, for motors that go through the gears. you can limit speed with low gearing.

You can keep adding volts and power to that motor, but at some point, a long ride will let the magic smoke out and it won't work anymore.

[monkeychops]

I think I'm going to try the 48V route. I've not got a lot to lose. If the motor or controller break, well I was considering replacing them anyway.
I've read a few posts on here from Powabyke owners who have overvolted successfully to 48V. I think my bike is very similar to these Powabykes.
It's only £25 for another 12V 12Ah SLA.
If it works I expect I will end up craving even more speed and power at which point it'll be time to move on from lead-acid.

I've attached a pic of the bike and battery case. I'm planning to plonk the extra battery on top, where I've drawn a box in the image. Any advice on how to attach it would be really helpful. I'm a bit of a novice at all this. The only solution I can currently think of involves using a lot of strong tape and drilling a hole in the current battery case for 2 wires to feed through. My main requirement is being able to lift the battery case out (as one unit) to take it into the office for charging at work.

IMAG0514_with_box.JPG

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[Gordo]

The only solution I can currently think of involves using a lot of strong tape and drilling a hole in the current battery case for 2 wires to feed through. My main requirement is being able to lift the battery case out (as one unit) to take it into the office for charging at work.

If you are concerned with water getting into the battery case, drill your hole on the side and use what is called a "drip loop." Form the wire down slightly in a "U" and then back up and into the case. Duct tape is good for a temporary test, then use Velcro plus a nylon strap. Velcro between the extra battery and current case, acting in shear, will not come loose if a strap around the case is holding it down.

[monkeychops]

If you are concerned with water getting into the battery case, drill your hole on the side and use what is called a "drip loop." Form the wire down slightly in a "U" and then back up and into the case. Duct tape is good for a temporary test, then use Velcro plus a nylon strap. Velcro between the extra battery and current case, acting in shear, will not come loose if a strap around the case is holding it down.

Thank you. I'll probably need to cover the extra battery with opaque tape or something, so it doesn't look too much like a bomb or something as I'm lugging the whole pack into the office!

[Samd]

Hows the build going?

[monkeychops]

Thank you for asking.
The extra 12V SLA arrived today.
It all seems ok on 48V except with zero throttle the rear wheel still wants to turn at a speed of about 1 turn per second.
Road tested it very briefly in the dark tonight and early indications are good.

with extra 12V SLA

Comparison of rear wheel rotation speed:
36V http://www.youtube.com/watch?v=xx_OJI_J348
48V http://www.youtube.com/watch?v=BT5Ej36rNZk

Will do a slightly better road test tomorrow in daylight.

[Samd]

Hey MC, thats good news. Speed increase would be interesting.

Same controller? If so, perhaps the old dedicated controller is looking for a certain minimum voltage in from the hall sensor/throttle and the input voltage to controller has now been amplified a small amount - because of the 48v stepup. Maybe a new controller is warranted to try.

[monkeychops]

Took it out for a quick test ride up and down the road in the light rain. Confirmed it reaches 20mph under power on the flat. Acceleration is noticeably better (but not greatly improved). now I'm annoyed it's the wrong season for riding to work. My route goes through a field for about 1 mile too, so really muddy now, this being England. I will give it a longer test if it stops raining tomorrow.

I may replace the controller, but I'm going to give the existing one a go too. I think that if I upgrade the motor to brushless then I'd need to get a new controller anyway at that point.

New digital voltmeter and charger on its way now, courtesy of eBay.

Does anyone know what voltage the 48v SLA pack should read and what an 'empty' one would read? Just ballpark figures.

[amberwolf]

Empty depends on how long you want them to last, but for each SLA, 10V is dead empty. 12V resting is probably a good place to stop if you want to keep them around at all, especially if you can't immediately recharge most of the time.

13.6V is usually "full" for a typical SLA in good condition. Some of them less or more.

So for four in series, 54.4 "full", 48V empty, 40V dead empty.

[monkeychops]

Good answer - thank you.

[Samd]

In the long run these are handy for measuring how many watt hours you have, as well as peak amps. Cheap. http://www.youtube.com/watch?v=kfs4Bs3H ... ata_player

[monkeychops]

Thanks for the link. I was already thinking about getting one of these somewhere along the line. Probably not yet though.
I wondered if they were easy to connect up? Since they measure current as well as voltage, don't they need to be connected in series and parallel at the same time? Or can they literally just be connected up to your battery as a normal voltmeter would be and they just work? From the video, I *think* he's got it connected in series...

[monkeychops]

Update:
Took it out for a 6 mile test ride yesterday. All went fine. Average speed 17mph, a few gentle hills. Didn't notice any heat from the motor or controller.
Battery voltage was sagging to 42v under load at the end.

This morning:
Charged the batteries up to full, reading about 52v. Motor seemed dead, throttle did nothing. Back wheel was still turning at one turn per second when I turn the ignition key to on. I had to get my normal bike out, which felt awful
Came back to it later, took the cover off the controller and started testing things with a multimeter. All of a sudden the motor seemed to come back to life just as I was testing the throttle voltage on the controller. Shortly after that, noticed the controller was getting *very* hot. So hot I could only touch it for about 3 seconds. I wonder if it suddenly started working when the input voltage had dropped off a bit. When I tested it yesterday the batteries were probably only about half charged.

Maybe I need to replace the controller. What do people think? I know Samd has already suggested this.
Something like this one: http://www.ebay.co.uk/itm/Electric-Scoo ... 0590002122
350 watts might not be enough?

This one better? http://www.tncscooters.com/YK40-4.php

Any advice appreciated

[monkeychops]

Further update: if the battery voltage is below 51.5v when I turn the ignition, the throttle works fine. If it's above 51.5v I can get the throttle to work by turning the key whilst turning the throttle at the same time. It seems like the controller needs to 'see' less than 51.5v before it starts working.

I went for another 6 mile ride after I'd got it going and all seemed fine. Average speed 18mph with some pedal assist.

[monkeychops]

Oh dear, further update: I think the controller broke.

I was just setting off and had to turn the ignition off and on again in the first mile of the journey (to get around the 51.5V cutoff problem). Then while stationary, the motor kicked into life of it's own accord. The throttle would not respond. In other words when I turned the ignition key I had instant full power, regardless of what I did to the throttle. The only way to cut power was to turn the ignition back off. Made for an interesting 15 mile journey back home! I don't think the throttle itself is malfunctioning because the brake levers (which previously would cut power when pulled) also didn't stop the motor.

Time to buy a new controller I think.
Something like this be ok? http://www.ebay.co.uk/itm/Electric-Scoo ... 0714562156
or this? http://www.ebay.co.uk/itm/Electric-Scoo ... 0590002122

The motor is 200W (or possibly 250W I'm not sure). So presumably the 350W controller would work ok?

Any advice greatly appreciated.

<edit>
I've got a feeling those controllers are for brushless motors, so might not be any good.
This sort of thing would work I guess? http://www.ebay.co.uk/itm/Scooter-Elect ... 0569778580
</edit>

[Samd]

Thoroughly recommend the YK40-4, have reliably put 1100 watts thru mine on another Aprilia Enjoy, 500km on the clock already. Case barely gets warm to the touch despite the tiny size.

[monkeychops]

Thoroughly recommend the YK40-4, have reliably put 1100 watts thru mine on another Aprilia Enjoy, 500km on the clock already. Case barely gets warm to the touch despite the tiny size.

That looks perfect. Any idea where I can get one that ships to the UK?
Showing out of stock here:
http://tncscooters.com/index.php?route= ... uct_id=184
None on ebay.

[Samd]

Any of those
http://www.ebay.com.au/sch/i.html?_nkw= ... m270.l1313

[monkeychops]

Thanks for the advice.
I ended up buying this one:
http://www.ebay.com.au/itm/400244692042
With a SLA battery, I didn't want one with a LVC plus this one seems to be the best fit in terms of size for my bike. It specifically said it was for a brushed motor, which is what I've got.
Crossing fingers it doesn't take to long to arrive, that it's the right size and then I don't break it by wiring it up wrong!

[Samd]

Hey MC - text reads "Compatible with 3 phase 120°and 60°brushed motors". Is your motor single phase or 3 phase do you think? We skipped over that bit....

[monkeychops]

Good question. I have no idea is the simple answer. Any clues how I can find out?

if it helps, it seems the same motor as I have seen on the old Powabyke series ebikes.

[Samd]

Looking at your very first photo (controller) I think single phase - there are only two wires heading off to the motor Mplus and Mminus.

Take a look at the closest point of your motor and how many wires coming out - two (single phase) or three (3 phase)

Cheers.

[monkeychops]

Ah, so it probably won't work. There are only 2 wires from the motor to the controller. So I guess it won't work

I found it quite hard to find anything when I looked a few days ago. I'm pretty sure I need it to be a 48 volt controller because I am using SLA batteries and don't want a LVC (plus the controller I broke was 36V and don't want to brake another one in the same way). Also it's a brushed motor and most of the controller seem to be for brushless (although they often don't say but judging from the number of connections I'm guessing them to be brushless and won't work with a brushed motor). And also (ideally) I want it to be 10x7x3 (centimeters) or smaller so it fits in the existing housing, although of course I could have the controller in a different place if I had to.

Any advice gratefully received!

[Samd]

You could contact the ebay vendor, may have suppin in single phase.

I would pick any of the tnc scooter listed ones down to 24v, just choose your amp limits. Dont wory about volts. Youll be fine. If you get stuck you can have my old yk40 if you pay freight from oz..

[monkeychops]

Hi Samd, thanks for your reply.

I've messaged the eBay seller to see if he can help. I have a feeling he may already have shipped the controller, I'm not sure.
I've also contacted Chris at tnc scooters for help.

The 48V controller I was looking at on his site has a 41.5 volt LVC which I'm not keen on. I measured as low as 33V on my 48V SLA pack at the end of a long ride (I know this is bad for the batteries).

I guess a 36V controller would have a lower LVC and so this would be ok? It's just that I've already destroyed one 36V controller. I guess the tnc scooter ones are more robust? I found with my 36V controller (before it broke) that the motor wanted to turn (about 1 rev per second) even before I had applied the throttle...

<edit>Samd - I've just realised what I am suggested above is what you already suggested to me a couple of weeks ago!</edit>