Mounting Turnigy Watt Meter

[EVTodd]

Does anyone have any suggestions for mounting a Turnigy watt meter on your handlebars if your batteries are on the back of your bike? I hate the thought of running the power cables that far but I assume there's no other way of doing it is there? I'm using rc escs so I really don't want to extend them that far.

I keep thinking I'll probably just keep it between my legs on the frame's top tube but that's not real handy.

[kevo]

Todd,
Doesn't really answer your question, but I like putting the Watt Meter in the Topeak Wedge bag for a couple of reasons. First inductance problems are minimized since wire length only adds about 8". Second, I use the same Watt Meter (reversed of course) during charging. While I don't have the CA benefit of reading measurements during riding, I enjoy spot checking it during stops and at the completion of the ride. Not to hijack your thread, but even when the Watt Meter is not continuously available, the readout of max watts, amps, voltage are all useful regardless.

I've watched with great interest your build, especially for areas where the hills are significant.
-K

[EVTodd]

Todd,
Doesn't really answer your question, but I like putting the Watt Meter in the Topeak Wedge bag for a couple of reasons. First inductance problems are minimized since wire length only adds about 8". Second, I use the same Watt Meter (reversed of course) during charging. While I don't have the CA benefit of reading measurements during riding, I enjoy spot checking it during stops and at the completion of the ride. Not to hijack your thread, but even when the Watt Meter is not continuously available, the readout of max watts, amps, voltage are all useful regardless.

I've watched with great interest your build, especially for areas where the hills are significant.
-K

No problem at all. That's really helpful actually. I was thinking about just throwing it in my panniers with my batteries too. I would really like to see the readings in real time but I'm not sure that's an option in this case.

[Dave Sloan]

Add a mirror at the back aimed inward toward your meter that you view using your rear view mirror.

[Jeremy Harris]

This is a timely question, as I'm part way through modifying a Turnigy watt meter to do just this, without needing to run the heavy battery leads up to the handlebars.

Here's how to do it:

1. Undo the four small screws that hold the Turnigy case together and remove the circuit board and display.

2. Unsolder the display from the main circuit board (the row of pins along the top). Use a solder sucker and get all the solder out of each plated-through hole, otherwise you won't get the thing apart.

3. Unsolder the heavy leads from both sides of the main circuit board and unsolder the big surface mount current shunt from next to where the two black leads were.

4. Get a length of thin, three core cable, long enough to go from your handlebars to the battery pack. This cable can be really thin, as it's only taking a few tens of milliamps at most. Connect this cable with one lead on each of the three pads where the thick leads used to be on the main board and note which is which (input negative, output negative and positive).

5. Refit the display board to the main board and solder each of the pins carefully. Put the boards back in the case, lead the three core cable out of one of the side holes and screw the case back together, making sure the display is the right way up.

6. Cut your thick negative battery lead and solder the shunt in the break. Solder the input negative and output negative wires from your three core cable either side of the shunt, making sure the input one is on the battery side and the output one is on the controller side.

7. Connect the positive wire in your three core cable to the battery positive, on the switched side so that it doesn't drain the battery when not in use.

You now have a remote shunt power meter, which is a heck of a lot more user-friendly on a bike than the original design, as you just have a thin cable running up to the handlebars.

There are some options you may want to consider. You can fit a tiny switch in the unused hole in the case, which allows you to turn the meter on and off without needing to disconnect the main battery (if you don't have a main power switch).

You may, if you are careful, be able to get away without unsoldering the display board. You can gently lift the main board up and, with care, you may be able to get a soldering iron in between the boards to remove the black leads and the shunt. Having now done it by removing the display and found where the parts are I think this option may be slightly better if you're careful not to splash solder anywhere.

Unfortunately I didn't take photos as I took the meter apart, but I'll try and take some of it nearly finished later.

*edit*

I've taken a couple of photos that may help. First off, this is the inside of the meter and the remote shunt. I soldered the shunt to a couple of Deans connectors so that it's a 'plug and play' unit. I added an on-off switch just because I had one handy that would fit (it needs to be pretty small to fit within the case)

Modded meter.JPG (169.91 KiB) Viewed 4906 times

Here's a close up of the finished remote shunt, enclosed in heatshrink:

Plug in remote shunt.JPG (139.36 KiB) Viewed 4944 times

Jeremy

[jateureka]

Nice mod!

If you didn't want to go all out and relocate the shunt then I think you can get away with using a single thinner red wire for the positive lead instead of running a thick one up and back.

I also find mine is hard to read in bright daylight so some tint film might help that and you might want to make the meter a little more waterproof while you're at it.

[Ykick]

IMO - unless you're doing serious over-volting and/or performance tweaking - staring at realtime data values are of little importance. Once you know your system min/max values watching every little change is quite boring and provides little, if any, benefit.

I suggest you stick the power meter someplace convenient with a competent short wire run and develop the habit of watching/recording your min/max values at the end of rides. If you're like me, you'll eventually discover they really don't change all that much. You seen one 30A draw, you've seen 'em all...

My power meter comes in more handy for charging - where it allows me to keep better track of what's going into the battery pack.

[EVTodd]

Wow! Thanks Jeremy! I was wondering about doing something similar. I was hoping it would be easy to remove just the screen from the unit and extend the wires but what you did makes a lot of sense.

And yup Ykick, I agree, most of the time I wouldn't need it right in front of me. After all, I've been without one for a couple of years. But, it would be kind of cool to see what my setups are doing in real time at least for a while.

[itchynackers]

I tried moving my meter from the bars, to just near my seat (by the batteries). It took out a lot of unnecesary wire, and I picked up 1.5 peak amps, BUT I couldn't read it realtime. I just moved it back up to the bars and ran the 12awg wires nice and neat. Until I get a Cycle Analyst for cheap, this will have to do.

[GTR2EBIKE]

Jeremy what are those connectors that you used called? Where can I get them?

[Jeremy Harris]

Jeremy what are those connectors that you used called? Where can I get them?

They are Deans ultra plug power connectors, used in RC stuff a lot. They are good for fairly high current, can't be connected the wrong way around and usually have a fairly nice gold plated finish. Your local hobby shop may well stock them, but in case not, try ebay. They are usually dirt cheap, especially if you buy them in bags of ten or more. I've no idea what the current rating is, but would guess that it's better than the small Andersons by a fair bit.

Jeremy

[TMaster]

I love the deans connectors. I've ran peaks of 120 amps thought them at 70+ volts. I acutally checked a few on my ebike last week to see how they were after 300 miles, and they look brand new. I run peaks of 90-100 amps through them on the bike. I think they are rated around 45-50 amps cont. The real deans are better I have heard, they cost about $3 a pair though. Thats what i use though. (Deans Ultra)

[spinningmagnets]

Jeremy, thanks for posting the plug-in shunt-adapter idea and pics!

I would like to take this opportunity to recommend servo-wire for this application (readily available in 22-ga/26-ga/32-ga), using Futaba plugs/sockets. Of course, other wire/cable types will work, too...(perhaps even the tiny 4-wire telephone shielded cable?)

http://endless-sphere.com/forums/viewtopic.php?f=16&t=23554

[RWP]

For very low amp wiring I use telephone or Ethernet cable, depending on how may wires I need. I attach an RJ7 or RJ45 connector to each discrete part. I use phone cable (Ethernet) adapters to connect an phone or Ethernet extension cord.

I am able to mount what I need where I need it and simply connect the parts with extension cords.

I know this may introduce errors as there are lots of connections and can be a bit bulky, but, so far this has worked for me. I like the flexibility and once I get everything sorted out I may choose to hard wire it all. I also have all the connectors and cable.

Maybe there is a better RC way to go about this?

[chvidgov.bc.ca]

Google "3M Dual Lock"...it is like Velcro on steroids, and you can "snap" on Watt metter to the handlebar. I would zip tie one piece of dual lock to the handlebar, and glue on another piece on the watt meter. I've used this with a CA and it makes a strong enough connection to withstand the vibration of a bike...

[adrian_sm]

I just did Jeremy's remote shunt mod, with a nice little switch and it works beautifully.

Thanks Jeremy.



- Adrian

[Jeremy Harris]

Glad you found it useful.

I've noticed that links to this thread appearing elsewhere on the 'net, so I guess it must be useful!

You can calibrate the Turnigy if you have a meter to hand. They are often off by a bit I've found (I have three and they all varied a fair bit from each other). There are multi-turn trimmers inside, mounted edge on, that allow the meter zero, voltage and current to be adjusted. I found doing this made a useful improvement to the accuracy, I just wish I'd remembered to note which trimmer adjusted which setting.

Jeremy

[adrian_sm]

TMaster posted that the top potentionmeter adjusts the amps reading
viewtopic.php?f=3&t=13607&p=350207&hilit=%2425+watt+meter#p349782

2. At 12 to 60V, do a constant amp load test with a reading, That means wiring up a multimeter or amp meter in series with the load. Then you can adjust the TOP blue potentiometer to match the load. This will be a load of under 10 amps because most multi-meters cant do higher then that.

You can calibrate the Turnigy if you have a meter to hand. They are often off by a bit I've found (I have three an. There are multi-turn trimmers inside, mounted edge on, that allow the meter zero, voltage and current to be adjusted.

I only noticed two potentiometers in mine. Is there a third? I got that impression from your post above.


- Adrian

[gwhy!]

Hi adrian_sm,
I think Jeremy means he has 3 meters. but I may well be wrong.

[adrian_sm]

I got the impression you could adjust the zero point as well by his post, thats what I meant by three. But I think I may just be misinterpretting since I can only see two potentiometers.

There are multi-turn trimmers inside, mounted edge on, that allow the meter zero, voltage and current to be adjusted. I found doing this made a useful improvement to the accuracy, I just wish I'd remembered to note which trimmer adjusted which setting.

Anyway, I just recalibrated my meter (as per Jeremy's reminder) and can confirm that the left pot in this image adjusts the current, and the one on the right does the voltage. And don't be shy turning the little adjustment screw as it took heaps of turns to get the current reading back in calibration, and I repositioned,resoldering and obviously adjusted its resistance with the new solder.


- Adrian

[Jeremy Harris]

Thanks for sorting that out, you're right, there are only two trimmers, not three, my mistake.

I found the same when I calibrated mine - they were all out by fair bit. There are several posts dotted around the 'net referring to Turnigy meter inaccuracy, so I'd guess this is a fairly common issue.

Jeremy

[def215]

thank you very much for posting that tutorial jeremy.

i dont have the turnigy watt meter, but the hk-010 wattmeter. i just used the basic layout of your tutorial and adapted it to mines. the wattmeter that i have doesnt do data recording like the turnigy, so i thought this mod can be helpful so i can monitor in live-time since i did destroy 2 controllers recently...lol.

heres what i done:

testing it on my power supply to get some numbers.

pretty much finished, just need to tape everything up since i have an actual shunt(or 2).

no adjustment pots in mine so i cant calibrate it. as long as i can get numbers from this im happy...

[Mark F]

Hi Jeremy,

Thanks for your back channel help. I'm still a bit in the dark. My electrical knowledge is minimal.

I've got the Turnigy Watt Meter and want to mount it near the helm of my sailboat. This will require mounting the shunt remotely. I see the the photos of the removed shunt and reattached wires but I'm not clear on where the wires go. Where do I reconnect to the inside of the Watt Meter? If I unsolder the red wire will the shunt lift out?

I have a Sevcon controller, can I connect directly to the +/- contacts (B+ and B-) on the Sevcon? Basically short wires attached to the Sevcon B+ and B- with a connector and plug the shunt in there?

Thanks for your patience.

As an aside, would I be able to move just the display? Are there just 2 wires to the display - A and K on the circuit board?

Thanks, Mark

[Jeremy Harris]

Hi Jeremy,

Thanks for your back channel help. I'm still a bit in the dark. My electrical knowledge is minimal.

I've got the Turnigy Watt Meter and want to mount it near the helm of my sailboat. This will require mounting the shunt remotely. I see the the photos of the removed shunt and reattached wires but I'm not clear on where the wires go. Where do I reconnect to the inside of the Watt Meter?

When you remove the shunt from inside the controller, you run two thin leads from the pads where it was connected down to the new shunt location. The shunt is in the negative lead, so all you have to watch is that you keep the connection (load and supply) sides correctly wired.

If I unsolder the red wire will the shunt lift out?

The shunt isn't connected to the red wire, it is under the circuit board and has black wires running to each side of it, one from the load side (which normally goes to the controller negative terminal) and one for the supply side (which normally goes to the battery negative terminal).

The thick red wire can be discarded and replaced with a thin red wire to your battery positive terminal, preferably via a switch so that the meter isn't on all the time (you could connect it to your controller positive terminal, as that will be switched).

I have a Sevcon controller, can I connect directly to the +/- contacts (B+ and B-) on the Sevcon? Basically short wires attached to the Sevcon B+ and B- with a connector and plug the shunt in there?

The shunt has to connect between the battery negative terminal and the controller negative terminal (B-), with the thin wires from the shunt fed back to the meter. The new thin power feed wire to the meter can be fed from the controller positive terminal (B+).

As an aside, would I be able to move just the display? Are there just 2 wires to the display - A and K on the circuit board?

The display circuit board has a lot of connections to it (the long row of pads on one side) and the signals won't run happily over more than a few feet of wire. It's far easier to just remotely mount the shunt.

One thing to watch with your application is that the shunt doesn't get too hot. It's a 0.001 ohm 1% shunt, so at a continuous current of 20 amps it's OK, as the power dissipation will be 20^2 x 0.001 = 0.4W. The shunt has a power rating of 3W, I believe, so should be OK for a continuous current of around 54 amps; anything over that for more than a short burst will risk overheating the shunt. It's fairly easy to increase the power rating of the shunt by soldering it to some big copper tabs. This also makes it easier to create bolted connections to it. I've modded a shunt by doing this, then bonding the shunt to an alloy block (with a very thin bit of mica sheet under it and with one terminal insulated from the alloy block) to make a high power shunt capable of working at around 100A or so.

Jeremy

Thanks, Mark[/quote]

[Kepler]

Another "thanks" from me Jeremy. This is a very useful mod and turns a cheap test meter into a very useful ebike display. My meter didn’t have any adjustment pots to re calibrate but luckily it was still very close even after the mods.

I naively thought it would be 15 minute job to do. Ended up taking about 3 hours. De soldering the screen took an hour on its own. (I'm not very quick on this sort of stuff)