Ghetto volt meter

thewmatusmoloki

thewmatusmoloki

10 kW
Joined
Sep 16, 2008
Messages
664
Location
East Coast Australia
I run one of my bikes with 20 series zippys, usually I never go anywhere near the low voltage limit.
However the other day I went a bit further than I thought and when I got back the cells were at 3.6v each.
That's a little too close for comfort for me.

Can't afford a CA unfortunatley, so I got one of these $6 analog volt meters off ebay.volt meter.JPG
Didn't expect much, but it's surprisingly OK for the price...... pretty ugly, some might say, but thats just this bike for ya. 8)

I can bulk charge at 10 amps, stopping at about 82v and can tell at a glance if I'm approaching LVC.
Balancing is handled in parallel every ten charges or so by a li-poly balance chager. Cells are regularly checked with a cellog.
So far, so good ........
 
Yeah, I use a $3 digital vom tie wrapped to the top frame bar. Works great.
 
eBay link please.

I am building a mad max electric bike right now and this would be a perfect addition :)
 
Digital might be more vibration resistant. I was looking at some nice voltmeters on ebay too, but wanted 50-100v range. Couldn't seem to find one in that range that didn't need a seperate power supply of different voltage. So I said screw this and splurged on a second CA. Definitely happy.

But my plan had been to get several cheap voltmeters, so I could have one on every bike. Even the 0-50v meters would not have worked good, since 48v ping charges to 60v.

Let us know how this thing holds up. I'd still be interested if the analog meter doesn't get too beat up riding around. There is also the option of the 5 buck on sale HF voltmeters. I figured those would really conk out fast if carried much.
 
Thewmatusmoloki, on a side note, I see you have same speedo as I do. On the go and at certain (higher) speeds, does your current speed indication alternate between correct and a bit lower speed?
 
bobale said:
Thewmatusmoloki, on a side note, I see you have same speedo as I do. On the go and at certain (higher) speeds, does your current speed indication alternate between correct and a bit lower speed?
Click to expand...
Yeah, that speedo cost $1 off ebay from china i think delivery was about $3. 8)
It's ok up to about 64kph, after that it gets real dodgy. I suspect that the magnet on the spokes can't be read by the sensor because the wheel is spinning too fast. It seems to suddenly give a speed reading that looks like half of what I'm actually doing probably by only counting every second pass of the spoke magnet.

A friend has a CA on his bike that use's the same "magnet and sensor" setup and it seems to be quite accurate right up to 80kph, as fast as the bike can go. Maybe it has a stronger magnet on the spoke.

I might see if i can find a stronger magnet for mine to see if it helps.
 
Cheers Hillhater, that's a good idea !
I just made the adjustment and now it gets flakey at 16kph +. Weird :? Might be time for a better speedo, I think.

This leads me to a question that I've wondered about for awhile.
Does anyone know if it's possible to rig up any kind of analog speedo to a bicycle, cars and motorbikes get all the good gauges
and we're struck with these tiny LCD readouts that can't be read with your proriferal vision.
 
Anyone else remember these type of speedometer's commonly used on dragster bikes in the 70's...speedos.JPG I reckon one of them would look great on my chopper.
Trouble is that they are all made to read the speed from a 20" front wheel via this thing, dunno what the're calledsensor.JPGDon't think they can be modded either really.
I had these sitting in my box of junk in the shed from when I used to put ICE engines on dragsters 11 years ago.
 
I've got a few of the Sun Ding bike computers and they all work fine as long as you have the proper installation of the magnet and sensor. I did have the wireless versions, but they don't work right on ebikes because of the interference caused by the motor/controller. Now I've only had my bike up to 43mph, so couldn't say past that.
 
My digital speedo was getting flaky around 100kph whether I had it set to mph or kph. I divided the wheel circumference input to the bike computer by 1.609 (kph per mph), and set it for kph to be displayed. Now that kph speed and km distance is actually mph and miles, and the flakiness has gone away. I guess the little brain inside couldn't handle 3 digit speeds. 8)

Regarding the analogue meters, don't those needles bounce around while riding, or do they stay nice and steady at the voltage?
 
thewmatusmoloki said:
Does anyone know if it's possible to rig up any kind of analog speedo to a bicycle, cars and motorbikes get all the good gauges
Click to expand...
Yes; one "easy" way I had planned to do with CrazyBike2, until I got the Veloace setup on a PDA (using originally the analog dial display), was to use a little 6V friction generator formerly used to power a headlight, and a little 10V panel meter off some random piece of rackmount stuff I had laying around.

As I go faster, the generator outputs more voltage, then the meter moves the needle farther to the right. I'd just need to replace the panel meter's label in back with one marked in MPH, after determining what wheelspeed created what voltage.


You could also use a cable-operated unit from a scooter or moped; I once planned to use the one off a Honda Spree for CB2, just to see how well it might work, but never got around to it. Since the scooter had small 14" or 16" tires, and CB2 had 24", I would not be able to directly use the drive assembly from the scooter, but would have to make my own roller to the hub and gear it to match the ratio between the tire sizes, to read the right speed from it. That was more complex than I liked, so I put it on a back burner, and eventually decided I didn't want to spend that kind of time on it, given I had the VeloAce PDA version that worked pretty well, by then.
 
thewmatusmoloki said:
This leads me to a question that I've wondered about for awhile.
Does anyone know if it's possible to rig up any kind of analog speedo to a bicycle, cars and motorbikes get all the good gauges
and we're struck with these tiny LCD readouts that can't be read with your proriferal vision.
Click to expand...

Try this: http://www.ebay.com/itm/190566475193
I haven't any idea how accurate it will be, though.
 
John in CR said:
My digital speedo was getting flaky around 100kph whether I had it set to mph or kph. I divided the wheel circumference input to the bike computer by 1.609 (kph per mph), and set it for kph to be displayed. Now that kph speed and km distance is actually mph and miles, and the flakiness has gone away. I guess the little brain inside couldn't handle 3 digit speeds. 8)

Regarding the analogue meters, don't those needles bounce around while riding, or do they stay nice and steady at the voltage?
Click to expand...

With the cheap one on the left, the needle was bouncy, but the old sanden 80kph speedo on the right was steady like a car's. Old school quality.
It's a shame the wheel speed reader is only for 20".

wesnewell said:
I've got a few of the Sun Ding bike computers and they all work fine as long as you have the proper installation of the magnet and sensor. I did have the wireless versions, but they don't work right on ebikes because of the interference caused by the motor/controller. Now I've only had my bike up to 43mph, so couldn't say past that.
Click to expand...
Thanks, I had heard about the wireless speedo problems with ebikes, seems like I need a better quality wired digital gauge.
 
amberwolf said:
Yes; one "easy" way I had planned to do with CrazyBike2, until I got the Veloace setup on a PDA (using originally the analog dial display), was to use a little 6V friction generator formerly used to power a headlight, and a little 10V panel meter off some random piece of rackmount stuff I had laying around.

As I go faster, the generator outputs more voltage, then the meter moves the needle farther to the right. I'd just need to replace the panel meter's label in back with one marked in MPH, after determining what wheelspeed created what voltage.
Click to expand...
Hey that's REALLY thinking outside the box Amberwolf, good idea, I've got a couple of those dynamo's in the junk box. I might muck around with 'em a bit on the bikes. I suspect that the bearings in these suckers just aren't up to a constant 40 to 60 kph though.
The one on the left has 2 outputs 12v 55w and 2.5v 0.5 watt.
Samd said:
You might be interested in this cheapo voltmeter I put into my aprilia .
Click to expand...
Thanks Samd, I need one that reads 80+ volts tho.
 
thewmatusmoloki said:
I suspect that the bearings in these suckers just aren't up to a constant 40 to 60 kph though.
Click to expand...
Bearings? :lol: ;) The couple I've opened up over the years to fix only had brass bushings!
 
It's just the speedo, so it's not like a critical part...if it fails you just don't know your speed until you put a new one on. :)

FWIW, the first generator I ever had for lights was probably 20 years old when *I* got it, maybe more, with a rusty case and a disintegrating rubber cover on the friction part, which I replaced with first water baloons and then a bunch of rubber bands, replaced many times over the life of the thing. Until it was destroyed with the bike it was part of in my only car-related crash, it worked perfectly fine, with just a bit of oil put into it when I first got it years before that.

I doubt I ever went over 30MPH with it, and that would have been a rare case of downhill on a steep slope (North Mountain), but I did not have the lights on at the time or it probably would've burned out the bulbs. :lol:

Mostly I was probably at 10-12MPH; I never had a speedo that I recall. But it worked for many years. I expect using it faster would still be ok, just for a shorter life, so maybe instead of a 10-20 year working life, it ends up with 5...I could live with that, or even less.

Or just use a small brushed motor that does have bearings, like some of the small weedeater motors. Might ahve to use a gearing reduction on them, though, as they typically are high-RPM motors.
 
The analog meter had to go, not accurate enough, I had to keep re-calibrating it every few days. Bummer.
Fixed the speedo problem as well. Turned out to be the readout unit and nothing to do with the magnet and sensor. I just swapped it for an old one I had that had a broken magnet and it now works perfectly.

Cheers Samd, I chose blue ...
Pretty happy with it too. BTW your blog page is pretty cool !
 
You must log in or register to reply here.

Similar threads

R
    • Like
A critique of mid-drive riding recommendations (and hub drive criticisms)
Replies
22
Views
13,588
ebike4healthandfitness
ebike4healthandfitness
S
    • Like
I bought a used Chevy Volt - and you probably should too!
2
Replies
31
Views
16,386
jonescg
jonescg
S
Electric Car Battery Packs and Longevity
Replies
6
Views
2,720
Kvno
K
tigcross
Recumbent Electric Motorctycle/Bicycle
Replies
22
Views
3,965
Warren
W
M
update on > 45mph ebike after 4500 miles
2
Replies
32
Views
5,130
jkbrigman
jkbrigman
Back
Top