What's my battery voltage - 36v or 48v?

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aminorjourney
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Postby aminorjourney » Wed Oct 10, 2007 2:40 pm

What would be very useful right now is some photographs of the thing. It sounds like other people have really messed around with it. Of course, the standard charger won't charge up any auxiliary battery.

Upload some photographs of the whole bike, and any electrical bits (and modifications).

That way we can see exactly what you're working with.
However, the more I hear about the bike the more I think you will be better off saving your money and either doing a DIY build or something similar :)
Nikki Gordon-Bloomfield

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anachrocomputer
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Postby anachrocomputer » Wed Oct 10, 2007 2:56 pm

It does look like someone's already modified the bike! The standard bike has 36V lights, which are, of course, almost impossible to buy spares for. Your 12V "dry cell" pack looks to me like a modification, possibly to re-wire the bike's lights to 12V. That way, ordinary car/motorcycle bulbs would work.

It's very hard to give advice, though, with so little information. It would really help if you could bring the bike along to a Bristol local group meeting, or even arrange to pop it over to a member's house for a bit of looking-at.

Meanwhile, what sort of meter did you use to measure the battery, and what was the actual reading. Also, was the battery freshly charged at the time, or discharged, or even on-charge? A fresly charged 12V lead-acid battery will settle to about 12.65V, off-load. During charging, though, it will rise to 14.8V or thereabouts. It's likely that you have three (36V) or four (48V) 12V batteries in series. Can you open up the battery "pack" at all (the thing with "48V" written on it in marker pen, I presume)?
1994 Suzuki Cappuccino
1992 Mini-El electric bubblecar

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aminorjourney
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Postby aminorjourney » Wed Oct 10, 2007 3:13 pm

Good idea, John!

Yes, come to the next Bristol meet. That's November 4th :)
Nikki Gordon-Bloomfield

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badnewswade
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Postby badnewswade » Wed Oct 10, 2007 3:57 pm

Damn, my book club meets up then! (again)

Found the lost part by the way. It was a part of the charging system and removing it definitely improves acceleration at the expense of charging up the lights.

All measurements were done with a fully charged-up battery, on this analogue voltmeter:

Image

set to the "50v dc" range...

Here's the diode or whatever it was btw - it has two legs and has markings that read "47K" and two Japanese characters. Resistor?

Image

I'm pursuing a further modification to the lights, the first part of which you can see on my austinev page:

http://www.austinev.org/evalbum/1370

scroll down past the bit where I'm being a complete tart! :-)

Just waiting for the NiMHs to arrive now, then just swop battery packs around when I charge the bike up. Meanwhile, will upload more pics of the bike in a bit...

anachrocomputer
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Postby anachrocomputer » Wed Oct 10, 2007 11:59 pm

If it's labelled 47K, than it's probably a resistor. By the look of the small photo, it's a variable resistor or "pre-set". How many wires does it have? I think I can see two in the photo, but is there a third, possibly chopped off close to the body? And the blue thing on top, does that have a screwdriver slot in it?

Your meter is seriously out of adjustment! Look where the ponter is when it's not connected -- way to the left of zero. Also, I don't understand why the battery voltage should change with or without the "diode". Was the battery on charge when you measured it?

This is all getting really confusing! Please could you try to bring the bike along to a meeting? 'Cos we're just getting more mixed-up here, I think.
1994 Suzuki Cappuccino

1992 Mini-El electric bubblecar

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badnewswade
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Postby badnewswade » Thu Oct 11, 2007 2:31 am

anachrocomputer wrote:If it's labelled 47K, than it's probably a resistor.


Yeah, that confused me because it didn't have any of the markings normally associated with resistors. I thought maybe it was a transistor but I only saw two legs coming out of it... (see below)

anachrocomputer wrote: By the look of the small photo, it's a variable resistor or "pre-set". How many wires does it have? I think I can see two in the photo, but is there a third, possibly chopped off close to the body? And the blue thing on top, does that have a screwdriver slot in it?


Yes there is a screwdriver slot- and yes, while there are two wires, there is indeed a chopped-off, unused third "leg"!

Now we are getting somewhere!

anachrocomputer wrote:Your meter is seriously out of adjustment! Look where the ponter is when it's not connected -- way to the left of zero.


If it's out of adjustment that way, then it would be under-reporting current? I need to buy a new voltmeter anyway... and Maplin's are having a sale (no doubt this sale will end the day I get paid as usual, grrr)...

anachrocomputer wrote:Also, I don't understand why the battery voltage should change with or without the "diode". Was the battery on charge when you measured it?


Ah - this is a misunderstanding. The battery voltage doesn't change (and no, it wasn't on charge). The power delivered to the motor, however, changes noticeably because that "diode" seems to be part of some wierdo circuit that taps off energy to charge up the 12v lighting subsystem - which is wierd because apparently earlier models of this bike just draw juice from the main battery for lighting, which is much simpler and makes more sense.

I think it's definitely an OEM change and not a funky mod btw - the Japanese-language tag on the wire that the resitor-diode-whatever plugs into and markings on the thingummy itsself indicates this.

Maybe the manufacturers were thinking of installing an "off road" switch or something? Or wanted to standardise mileage (you'd get reduced mileage at night if you ran lights straight off the main batt).

anachrocomputer wrote:This is all getting really confusing! Please could you try to bring the bike along to a meeting? 'Cos we're just getting more mixed-up here, I think.


I will try, I promise, but as I mentioned earlier, my book club meets later on the same day- again. :(

It's certainly an interesting case, no? Thanks for all your input! :)

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EVguru
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Postby EVguru » Fri Oct 12, 2007 1:32 pm

The hub is a sealed unit.


I don't think it is.

I was given a very similar looking machine by someone at work. The battery on mine fitted under the riders feet.

The motor looks identical and if so I would recommend taking the back wheel out, removing the ring of screws that hold the motor cover on and taking the motor and reduction drive out. The drive uses a two stage epicyclic drive and the gears don't appear to be hardened. Chinese grease has a reputation for being completely useless (not always true, but often) and I'd wash it out and repack. I got given my bike beacause the gears were completely shot. I don't think they'd have lasted well anyway, but the awful grease (which had seperated and the oil component was dribbling out) really wouldn't have helped.

The motor itself was a simple brushed PM design and seeing as it's inside a case with no ventilation, I'd not want to put any more power through it.
Paul

http://www.compton.vispa.com/scirocco/
http://www.morini-mania.co.uk
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aminorjourney
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Postby aminorjourney » Fri Oct 12, 2007 3:09 pm

Hi Paul,

You may be right on the hub design.

I did have a chance viewing of this bike yesterday as I drove past Andy on the way out of town. The bike appears modified; I think the controller has been replaced (no surprise since my own S200 is on it's second controller) and this rather strange lighting arrangmenet implemented.

I didn't see the preset resistor, but certainly from the photograph that is what it appears to be!

I also happened to take a reading with my own voltmeter directly across the battery at rest with no load. I made it 37.6 Volts (if I remember correctly). I know my meters are both quite accurate, so it does appear to be a 36 V bike. Personally, like John, I would like to see it at a meeting so we could take some time and dig around a bit.

Nikki.
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badnewswade
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Postby badnewswade » Mon Oct 15, 2007 12:02 am

Aha, yes indeed, egg on face. My new multimeter measures my batt at 39 volts or so. :oops:

I've measured the ampage that the lighting systems' drawing and it's around 1 amp for the headlight, .35 amp for the brakelight and up to .45 amp for the indicators. Mind you this is on a 12v bank of 2 amp NiMH batteries, and judging by the slightly off colour indicators they could probably draw more, let's say up to 3 amp (that was the lead acid battery it replaced)

Measured ohms on the same system and it said 2 ohms - I think I've made a mistake though, 'cause that implies it would like 6 amps and the battery's only 14 amps.

I don't have gears and the Sakura company says that it's using a brushless DC (assuming it's not been modded, which we don't know).

Oh and I tested the diodey thing, I think it's a chopped up PNP transistor of some kind, gives a reading of 1.44 somethings, which change as you turn the screw in the top. (have been playing with new multimeter :) )

I don't want to take the hub motor to bits until I'm sure I can put it back together again I'm afraid, I'm well aware that I'm about at the limits of my competence here. For the same reason I'm not going to check amperage of the main system, at least not tonight anyway. It does seem however that tossing a couple more amps in would be a cool idea - extend the range and all that.

(I'm gonna need more range to get to the meet anyway :-) )

I'm designing a circuit that can be switched on and off, will put 2 amps in at 36 volts and will cut out if anything goes wrong. Is this likely to fry the controller though? 'Cause if it will then I'll build a second controller and put the extra amps straight into the hub... well, try to, like I said, limits of competency and all that...

Thanks for the advice and roadside look, will be back as soon as I learn more 8)

Cheers
Andy

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Postby EVguru » Mon Oct 15, 2007 9:45 am

badnewswade wrote:I don't have gears and the Sakura company says that it's using a brushless DC (assuming it's not been modded, which we don't know).


If it's a brushless motor, then there would most likely be seven connections to the motor; Three larger wires for the phase coils, three smaller wires plus one common for the hall-effect sensors.

If you're thinking of gears as in a four speed manual, then no, you don't have gears. You may well however have a reduction drive, even if it's a brushless motor (though they can be designed driect drive). A reduction drive will most likely use gears.

I don't want to take the hub motor to bits until I'm sure I can put it back together again I'm afraid, I'm well aware that I'm about at the limits of my competence here. For the same reason I'm not going to check amperage of the main system, at least not tonight anyway. It does seem however that tossing a couple more amps in would be a cool idea - extend the range and all that.


You're still mixing up units. The current drawn from the batteries is measured in amperes (A). If you want more range you have to increase the Amp/hour (Ah) of the batteries.

Oh and I tested the diodey thing, I think it's a chopped up PNP transistor of some kind, gives a reading of 1.44 somethings, which change as you turn the screw in the top. (have been playing with new multimeter


Ok, now you're scaring me.

It's a trimmer of some kind. It could be a resistor (very likely), a capacitor (possible), or an inductor (very un-likely). There's no way it's a transistor.

Try connecting your multimeter accross the two terminals and measure the resistance. I'm betting you'll get a reading between approx. zero and approx. 47,000 ohm as you turn the adjuster.

I'm designing a circuit that can be switched on and off, will put 2 amps in at 36 volts and will cut out if anything goes wrong. Is this likely to fry the controller though? 'Cause if it will then I'll build a second controller and put the extra amps straight into the hub... well, try to, like I said, limits of competency and all that...


You can't (shouldn't be able to) damage a controller by connecting a larger capacity battery to it.

What I think you're trying to do is add a 2 amp/hour string of NiMh cells in parallel with the existing battery pack.

It's possible, but not straightforward.

You would need a diode to stop the main battery from back charging the additional battery.

You need to match the voltages of the two packs. The main Lead pack will vary between 37.8 volt and 33 volt (both on-load). I'm guessing the controller has a low voltage limit of 33 volt. Thirty NiMh cells are going to give a slightly too low voltage (under load) and you'd be better with one more.

How are you going to limit the current drawn from the NiMh battery? The 2Ah 'AA' cells are not really suited to supplying more than 2 amp.

How are you going to charge them? Nimh cells are easily damaged by overcharging. You can't charge 30 odd cells in series without a cell management system. The cells will all have slightly different capacities (at least +/- 10%) and different internal impeadances. Some cells would likely get badly overcharged whilst others were undercharged.

If the motor is a brushless DC, then the controller is quite complex and is in effect three controllers, one for each phase. It is possible that the commutation circuitry is built into the motor and it's just a simple external controller, but unless you know exactly what you've got and what it's voltage/current limitations are, you risk damaging the motor if you start raising the battery voltage or increasing the controller current limit.
Paul

http://www.compton.vispa.com/scirocco/
http://www.morini-mania.co.uk
http://www.compton.vispa.com/the_named


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