Mine is marked G.T.Power but looks like a dead ringer

 

Video review here:

 

YouTube - TURNIGY POWER ANALYZER WATTMETER REVIEW by Doctorbass

 

From the "power meter" thread:

 

http://www.pedelecs.co.uk/forum/electric-bicycles/4821-watts-up-vs-turnigy-power-meter-analyser-3.html?highlight=watt+meter#post64377

 

Cheers, Dan

These kits look like they could ease the construction of battery packs on :

 

Products

 

RC-Network.de - Akkulution

 

http://www.tppacks.com/prodimages/a123%20Pack%20Kit-bg.jpg

 

http://www.rc-network.de/akkulution/AL3003.jpg

 

http://www.rc-network.de/akkulution/AL0005.jpg

 

http://www.rc-network.de/akkulution/AL3001.jpg

Edited January 6, 201016 yr by daniel.weck

Too cold to go out and ride and too much time on my hands result =

 

http://www.hobbycity.com/hobbycity/store/catalog/CL8S.jpg

 

Its called a CellLog

 

More reading here and here. It has some promising applications including ebikes.

 

Anyway I ordered one to try. Will be usefull to see what is going on with my 2*6s1p pack.

 

Regards

 

Jerry

Edited January 8, 201016 yr by jerrysimon

Well finally the roads here have cleared so I went out for a ride the first in a week of so

 

Actually got to test the Turnigy meter in a real environment. Even back lit its quite hard to read so perhaps I need to mount it closer to my old eyes on the handle bars. I used the throttle a lot.

 

Quite interesting readings some matching what I expected and a few surprises.

 

On the flat if I am pedaling it barely goes over 1-2amps. On a small incline it goes up to 4-5amps but drops back to 2-3amps if I pedal.

 

On a steeper incline it goes up to about 8amps with me pedaling and about 10-12 if I stop.

 

Interestingly I had a peak of 17amps

 

The 15amp fuse didn't blow so it must have been for a m/s or so.

 

The total ride must have been about 5 miles though I don't have a trip computer fittted yet, must get one.

 

Readings

 

17.04 Ap

576.6 Wp

33.74 Vmin

1.69 Ah

61.8 Wh

 

Perhaps someone could help me with the Wp and Wh readings and tell me what these help show ? Can I work out more performance stats from my battery from these figures ? I assume the 33.74 Vmin was when I drew 17.04amps given the battery is 39.6v nominal ?

With 1.69Ah taken out the battery that leaves me 0.61Ah and its reading 39.13v so still 3.26v/cell assuming they are balanced. Thinking about it the battery is probably nearing discharge as I doubt it holds the full 2.3Ah though there was power left when I returned. I have to say I did not notice any drop in power really on the whole ride though, perhaps there was a fraction more if I didn't throttle for a bit and then tried again a few minutes later.

 

My cycle to work is about 5.25 miles so I think I probably could do a return journey (10.5 miles) on one charge, if I don't throttle a lot. I can easy take the charger to work or by a second one though.

 

Regards

 

Jerry

Edited January 10, 201016 yr by jerrysimon

Hi Jerry peak current draw will coincide with min voltage so Ap x Vmin gives you Wp.

 

Given the figures you've posted above I'd say your battery is undersized...

Given the figures you've posted above I'd say your battery is undersized...

 

Thanks.

 

Sorry to be stupid but what do you mean by undersized

 

It seems to work ok.

 

Regards

 

Jerry

Jerry, great work

 

I believe the 576.6 Wp is the maximum watts you have used sinse the reset

This ties in with the max current of 17.04A at min volts of 33.74V

 

17.04 x 33.74 = 575 watts

 

The battery should have a capacity of 2.3 (Ah) times the voltage (say 37V - a figure in between the actual of 39.6 and the lowest 33.74)

 

2.3 x 37 = 85.1 wh

 

so you have probably used two thirds of your battery capacity

 

Hope this helps

 

Herb

Edited January 10, 201016 yr by Herb

Well finally the roads here have cleared so I went out for a ride the first in a week of so

 

It will be a while before our roads are clear I imagine

 

http://farm5.static.flickr.com/4037/4254462953_358e1e43d6_o.jpg

Thanks.

 

Sorry to be stupid but what do you mean by undersized

 

It seems to work ok.

 

Regards

 

Jerry

 

Hi Jerry undersized in terms of Ah vs current draw.

 

576 Wp is the Peak watts since the last reset. 17 amp is over 7C discharge rate and the voltage sag tells the story IMHO. Where on your run and for how long do think this happened? It may not be an issue if your commute is fairly flat.... I have a 15Ah 20C capable pack on my DIY bike and peak power is 850W, the voltage sag though is just 0.6v (29v to 28.4v, 7s3p Lipo based) under these conditions...

I think Jerry has already taken account of voltage sag by including an extra two cells in his pack (from 10 to 12)

 

For a 36volt motor circuit to have a maximum sag of 3 volts to 33 is truly a design master stroke.

 

Herb

Ah now I understand.

 

Up until I got home the max current draw was around 13amps. I am not sure where the 17amp draw occured, but when it happened it must have been very short given I have a 15amp quick blow fuse in there

 

I guess I need to do some more tests.

 

PS Herb thanks for the explanation. The battery is not my design many have done it before me. I have read a lot about people using 10 cells but in nearly all cases they later seem to add another 2.

 

 

Regards

 

Jerry

Edited January 10, 201016 yr by jerrysimon

Up until I got home the max current draw was around 13amps. I am not sure where the 17amp draw occured, but when it happened it must have been very short given I have a 15amp quick blow fuse in there

 

There's a big condensator in the controller, which charges-up when you plug the battery or when you use the switch to let the current flow. This may induce high Amps for a limited time, thus the reading picked-up by the power meter. My Cycle Analyst registers a peak Amps value that is higher than what I see when I climb the most serious hill...so it must be related. I read that some high-power applications require the use of a MOSFET in addition to a regular physical switch, to avoid the high-amp spark when connecting the battery.

 

++Dan

(still under 25cm snow)

Ah Dan so it may have occured when I switch off ?

 

I will check it again next time before I switch off. Maybe I should put a MOSFET thingy (sorry I am not an electrician) in the circuit.

 

I am currently charging the battery with the cheap charger and I have Turnigy connected in line so will be interesting to see how much it puts back into the battery. All exciting stuff lol

 

Regards

 

Jerry

Edited January 10, 201016 yr by jerrysimon

I think the peak occurs when the condensator charges, i.e. when the battery gets connected to the controller. Worth trying different patterns though.

Dan

I think the peak occurs when the condensator charges...

 

Yes that makes sense, though I am certain that mid way through my journey it was not higher than 13amp max. As you say more tests required

 

Regards

 

Jerry

I think we can concur that the battery is indeed not undersized for its proposed duty.

 

It will probably have a range of 8 miles, a figure than compares to my own 2.6ah 36v Bosch lithium battery.

 

It is also be a good modular approach using the latest technology to anybody wishing to build a battery of 2.3, 4.6 or any multiple up to and above the 10Ah that a lot of riders perceive as the normal capacity of a electric bike.

 

I need one.

 

Herb

Edited January 10, 201016 yr by Herb

Herb it seems so, but I think if you want a battery for regular longer distances it might make more sense to buy a 10Ah one given that the equivalent 4 of these would cost about £240 for just the new cells plus the build.

 

The real advantage of these for me is to be able to keep weight down for my short journey plus I wanted to make my Brompton as light as possible so I could carry it into work when I get there. Again I travel mainly on a flat route with a few small inclines. I may build a second pack as a spare/backup and as I say will probably just use one for work and get a second charger to keep there.

 

Battery charger has currently put 0.94Ah back in and still going

 

 

Regards

 

Jerry

Edited January 10, 201016 yr by jerrysimon

Cheap ebay charger put 1.594Ah back into the battery. Interestingly its rated at 1.6amps but it never charged at higher than 1.1amps. I guess there are some losses with the Turnigy meter in the circuit as well. Seems to confirm the charger is doing its job and cuts out at the right place.

 

Will be interesting to do a full discharge ride to see how many miles I get, how many Ah are used and how much goes back in to the battery on a full charge.

 

Regards

 

Jerry

Edited January 10, 201016 yr by jerrysimon

The battery should have a capacity of 2.3 (Ah) times the voltage (say 37V - a figure in between the actual of 39.6 and the lowest 33.74)

 

2.3 x 37 = 85.1 wh

 

so you have probably used two thirds of your battery capacity

 

The penny begins to drop

 

Freedom E quotes 91 Whr for these batteries so that must be based on the nominal voltage of 39.6v for 12 cells.

 

I need to fit my trip computer so I can get some distance figures too. Lets hope the thaw remains here and I can get out again this week.

 

Regards

 

Jerry

I think we can concur that the battery is indeed not undersized for its proposed duty.

 

It will probably have a range of 8 miles, a figure than compares to my own 2.6ah 36v Bosch lithium battery.

 

It is also be a good modular approach using the latest technology to anybody wishing to build a battery of 2.3, 4.6 or any multiple up to and above the 10Ah that a lot of riders perceive as the normal capacity of a electric bike.

 

I need one.

 

Herb

 

We'll have to agree to disagree At 2.3Ah and even at a 13amp peak draw discharge is still high at 5.5C maybe it will be fine for short journeys while the cells are new but given the heavy load they will age faster and die sooner, better would be 5Ah to get under 3C and stress the cells less.

NRG these A123 cells have a 30C (69 amps) rating for continuous discharge and over 4C (10 amps) rating for charging if you choose!

 

So 13amps average discharge (probably a lot less over the full ride) and 1.6amps charging is not really stretching them. At 10C they are quoted as having a 1000cycle life.

 

A123 Single Cell ANR26650M1 3.3v - electricwingman

 

Anyway we will see what happends after I have used them for a few months. I plan to monitor them closely.

 

Regards

 

Jerry

Edited January 11, 201016 yr by jerrysimon

We'll have to agree to disagree

 

NRG in the interest of forum harmony

 

I propose the following

 

I need one.

 

Herb

 

 

You on the other hand need two – keep your discharge rate down.

 

The upside of this compromise is a good battery for me.

The ability to run a small E-Bike factory with the spare battery capacity for you.

 

Herb

 

 

 

Edit, Did I write that ! This may seem harsh comment, but consider - one of the reasons we are able to debate is because of your expert knowlege and past record in batteries.

Edited January 11, 201016 yr by Herb

NRG these A123 cells have a 30C (69 amps) rating for continuous discharge and over 4C (10 amps) rating for charging if you choose!

 

So 13amps average discharge (probably a lot less over the full ride) and 1.6amps charging is not really stretching them. At 10C they are quoted as having a 1000cycle life.

 

A123 Single Cell ANR26650M1 3.3v - electricwingman

 

Anyway we will see what happends after I have used them for a few months. I plan to monitor them closely.

 

Regards

 

Jerry

 

My apologies! For some reason I assumed NiMh... :o

 

For reference here's the manufactures page for these cells:

 

A123Systems :: Products

 

Still....if it where me I'd go for double the Ah....OK I'll get me coat....

 

Herb: no problem, when do we start the new factory?

Edited January 11, 201016 yr by NRG

Ah now I understand.

 

Up until I got home the max current draw was around 13amps. I am not sure where the 17amp draw occured, but when it happened it must have been very short given I have a 15amp quick blow fuse in there

 

I guess I need to do some more tests.

 

PS Herb thanks for the explanation. The battery is not my design many have done it before me. I have read a lot about people using 10 cells but in nearly all cases they later seem to add another 2.

 

 

Regards

 

Jerry

 

I have a different brand of motor myself, maybe you remember the youtube video of winter driving I linked a week or two ago...

 

Anyway that kit blew fuse a few times, and when it happened I was always accelerating from slow speed. The controller is a 12A model, and it even blew a 20A fuse once!

 

That problem disappeared after I got the MMC box installed and the seller commented that it smooths out high current spikes that may have been caused by turning throttle fast.

 

Since then I have also installed the same Turnigy meter as you and it shows max. 13.7 amps which is very well in line with the controller used. I know this is a different kit but one possible explanation...

 

Regards

 

Taisto

That problem disappeared after I got the MMC box installed and the seller commented that it smooths out high current spikes that may have been caused by turning throttle fast.

 

Thanks Taisto,

 

What is a MMC box ?

 

Regards

 

Jerry