Watt meter placement

[veloman]

I got my Turnigy watt meter and I put on my connectors. The only place I can mount is under my seat next to the controller. I will be able to glance at it, but it's kind of dangerous to try reading that way.

How did you mount your watt meter?

It seems like it wouldn't be efficient to add 4 feet of wiring so you could put the watt meter up front.

Any solution like detaching and adding wire for the LCD screen?

 

[wasp]

i mounted mine on the handle bars(stem actually ) and used 12g wire...attachment method velcro

 

[veloman]

Well that would be adding a lot of extra wiring, and reducing efficiency then. Is it negligible though?

I'm charging through the watt meter right now, it hit 40.7 volts (topped off voltage) and it's been sitting near that for the last 15 minutes now, still charging. I have Bosch packs and using a Bosch charger.

Oh btw, I pulled a max of 842 watts and 22amps with that 36v 450w geared motor. It was as going up a hill with no pedaling, when the grade increased. 12mph on about a 8% grade I believe. Most of the time my peaks were in the 700s, and hill climbing averaged 600 or so.

 

[yopappamon]

The loses will be negligible as long as you use the right wire size.

 

[veloman]

Okay, I will probably do that then, with 12ga wire (same as my battery pack). BTW, what amps should 12ga be good for? 40amps? more?>

I calculated, based on readings compared with my road bike which tells me exact power, combined with hill gradient and speed on analyticcycling.com, that my motor/bike is 75% efficient at full throttle. Pulled 750watts up the hill, which of 560watts went to the back hub. Seems about right. Maybe efficiency is a little better during normal outputs.


This really makes me realize how little 1 hp from 'source' is when you are hill climbing. I dropped to a slow 12mph up that moderate hill.

Even on my road bike with minimal weight, 1000watts up a 20% grade is only 12mph or so.

 

[yopappamon]

Wire ampacity depends on type of wire, temperature, and how it's mounted.

Typically you will see 12ga copper wire in free air at normal temps rated 25 or 30 amps. Sometimes you will see it rated as low as 20 amps. I wouldn't go over 30 with 12 ga.

 

[dequinox]

I mounted mine in one of those Radio Shack project boxes thus-ly:



I just used an L bracket on the back of it, and shaved one end of it down to fix under the bolt that tightens down the handlebars. There are other ways of attaching the box though...

 

[veloman]

Hmmm, well I see the Turnigy watt meter uses 10ga wire, and that is suppose to accept up to 130amps.


The motor I am working with now on my new design is supposedly capable of 34 amps continous. I'll prob end up rewiring my Bosch pack with 10ga, (and adding at least a 4th pack in parallel). This motor also has 10ga wire on it. So that should tell me something lol.

My current ride has a 450w motor which pulled a peak of 22amps today. So the new motor which is double the power will prob pull 45amps peak I bet. 40 volts x 45 amps = 1800 watt peak..... mmmmm :lol:

I may eventually play with overvolting it to 48v as well. 3hp on a $50 scooter motor

 

[liveforphysics]

Well that would be adding a lot of extra wiring, and reducing efficiency then. Is it negligible though?

It's an inductive nightmare, and it's hell on the caps in the controller, and that doesn't matter if you use 2awg or 12awg.

Remote mounting the shunt to be in series with the shortest possible path from the batteries to the controller would be the hot ticket. Then just 4 tiny thin wires, (2 for pack voltage, 2 for shunt voltage) and you've got it made.

 

[Chillboy]

I used a zip tie thru the back vent and strong 2 sided tape to secure mine to a bike lock mount I had and put it far enough up the top tube to see it.
You could prob get directly onto the bars that way.
I contemplated epoxying the male release part from the lock to the case but I don't really want it removable.

 

[Hyena]

If you're running a front hub and have a small controller you can mount the whole thing on the handlebars. This is a bike I'm making for someone using a cheap kit so came with a big old 12 fet controller but if you have a little 6 or 9 fet job you could do it more neatly.
(ignore the red wire, I have to fit a switch there and tidy up the wiring)


Alternatively if you have the battery and controller in the triangle (or on the top bar as I have on my norco) it's quite a short run of wire to have it fitted there

 

[veloman]

My 3rd build on the full suspension will probably put the controller and batteries up front more. I will see. After getting to know what my system performance is, I won't be needing to stare at the watt meter all the time, just check it occasionally to see my ah and voltage.

No big deal, I got it figured out.

 

[USAEBIKECO]

I used zip ties to hold down the watt meter wires to the handlebars. Then I used plastic electrical wrap around the wires to the battery box. Seems to work well.

The watt meter is an awsome little thing.

 

[dequinox]

Well that would be adding a lot of extra wiring, and reducing efficiency then. Is it negligible though?

It's an inductive nightmare, and it's hell on the caps in the controller, and that doesn't matter if you use 2awg or 12awg.

Remote mounting the shunt to be in series with the shortest possible path from the batteries to the controller would be the hot ticket. Then just 4 tiny thin wires, (2 for pack voltage, 2 for shunt voltage) and you've got it made.

Isn't the shunt fixed to the board in the turnigy meter? I opened it up and didn't really see any way of separating the shunt from the board...but I don't really know a lot about boards this complex (i.e. more complex than a light bulb and a AA ). It would definitely be nice to not have all that extra wiring. I have about 8' of 12AWG total I think...

 

[Russell]

I initially mounted the WU meter on top of the handlebar mounted controller. The power cable ran from the trunk mounted battery up to the WU meter then into the controller which then fed the front hub motor.

View attachment 1

I used one of these brackets from Nashbar.com to mount the controller.



It was a neat set-up but I've since moved the controller to the seatpost and mounted a light on the bars. I don't watch the WU meter in real-time any longer, I just toss it in the trunk bag to keep track of trip stats.

-R

 

[Chillboy]

Ditch my advise on the top bar. I'm moving mine because I've hit it twice with my leg gettting on and off in the few short rides I've done since putting it there.
It's worth the few more inches to get it onto the bars, ride and learn I guess.