Nano batteries with Tongxin

[Scottyf]

Most people can solder... Its just practice that makes perfect.
You should be fine.

Good advice on the connectors though. Definetly do one cable at a time and make sure the other cable is far out the way. Don't want it shorting out @ 100+ amps ;-)

 

[NRG]

Not one of my smoothest moves....

 

[Scottyf]

I've yet to have any mishaps in the electrics on the ebike but have had a couple of house hold issues!
Try not to blow your fingers off!

 

[Dadplus2]

First run

Well after spending a good few hours in the garage leaning how to solder putting all my EC3 plugs on then soldering wires heatshrinking then Anderson connectors I was ready to test out the system.

Battery charged and checked all wiring ready, connect the batteries, flickering red light at the throttle and NOTHING!

Phoned Alan (sorry Alan thanks for listening) had another look at the fuse and it must of part blown 15amp fuse, I believe the controller is limited to 13amps. Changed the fuse all good wheel spins.

The set about routing the cables along the bike using some half round PVC trunking and cable ties. I than made up some rubber sleeving to go around the controller and to keep the top of the battery bottle on.




Finally got it all up together this morning weighed it 13.8kg bit heavier than I was hoping and took it for a test ride. All very nice and smooth, I have a steep hill just round the corner so went up that relying more and more on the motor to see how it coped. All good until it popped. The fuse again well to be more accurate the fuse holder. Close inspection revealed it was rated at 10amps. Need to find a better holder!

 

[Scottyf]

Nicely done. And an excellent weight!
Just have to get that fuse holder sorted and away you go!

I take it that the bike will be fair weathermwith the controller so low down?

 

[jerrysimon]

That's a very neat looking job. Well done.

It will be interesting to see how long/how many charge cycles some of these Lipo batteries manage compared to the A123 packs I have been using.

I just had a failed cell after 22 months, 2500 miles and about 400 charge cycles.

I had hoped the A123 packs would last double that, though I guess it was easy to replace one cell

Regards

Jerry

 

[Scottyf]

I'd imagine the a123 cells are more robust and a bit safer.
Lipo in soft cases are quite vulnerable.

The actual batteries are rated at huge c rates and resistance is very low. I'd hope to see with the application of an ebike means you don't really stress the cells any where near what they are originally intended to run at. I'd hope for a years worth of charges at least in everyday use and charging under the 1c rate.

Some people say having read on other forums they should be good for 800 charges but I'll await and see. I'd be happy with a years use as you can buy another set of 4bricks of lipo at £100.

However there's more hassle and higher risk on the batteries. The charge stations have to be watched rather than the alloy counter parts that you can just plug in and charge and leave and let the Bms and circuits take away the hassles.

But then you'll loose knowledge of what's going on with the cells.

They should perform well in small packs if you need it. And the cells are easy to break up or make into larger configurations and or voltages.

 

[Dadplus2]

Cheers guys, these batteries seemed to have no problems under load nothing go warm. I picked the nano lipos as they seemed to have a good spec, lightweight, very little resistance and therefore not be too stressed under load. They also apparently have twice the life cycle of a normal Lipo battery.

This should be an all weather bike (hopefully) as I intend to encase the controller and wiring in rubber. I need to improve on this part of the project and also put in some sort of plug so I can disconnect the battery bottle easily.

I will also black out the hub to make it look at bit nicer.

 

[NRG]

Would it not be better to place the controller in a small triangular frame bag instead of wrapping it in rubber...the controller needs some cooling and wrapping it in rubber is probably not a wise idea. Also it will move it out of the way of muck thrown up from the front wheel.

What are you using to monitor the LVC of each cell?

 

[Dadplus2]

Would it not be better to place the controller in a small triangular frame bag instead of wrapping it in rubber...the controller needs some cooling and wrapping it in rubber is probably not a wise idea. Also it will move it out of the way of muck thrown up from the front wheel.

What are you using to monitor the LVC of each cell?

I've changed this now so the wiring is encased in rubber, allowing the controller to keep cool. I probably won't use this bike in really bad weather.

I currently have no method of monitoring each cell on the bike, when I charge the batteries I can see how the cells discharged and whether it was even. I could invest in a cycle analyst but they are pricey and I don't think it can monitor each cell.

Not even sure how this could be achieved.

 

[NRG]

There are various modules you could use to monitor each cell and give warning if a cell goes to low in use. Check out hobbyking for the cellog devices or similar, they are cheap and simply plug into the balance leads. With the nano batts it's probably best not to let the cells drop below 3.4v, they are effectively empty at this point and further discharge will cause damage....



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[jerrysimon]

Yep I use the CellLog device which is excellent and will even log voltages of individual cells during a ride.

See more details here

You can then use LogView to plot the results, see here

Regards

Jerry

 

[amigafan2003]

Bear in mind though that the celllog draws 0.5A/h on it's own though, so it's not really suitable for monitoring on the bike permanently. Ok for the first few runs to get an idea of your range but you wouldn't want to keep it connected due to it's constant amp draw.

 

[NRG]

You mean it draws 500mA when the alarm port is active! Otherwise it draws <8mA



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[vhfman]

Bear in mind though that the celllog draws 0.5A/h on it's own though, so it's not really suitable for monitoring on the bike permanently.

amigafan2003, I can’t agree with your figures with reference to the CellLog 8S require to operate. The CellLog 8S I use draw about 20mA with the backlight display on and 14mA in sleep mode which is not a problem for monitoring the batteries when in use but I agree could be a problem if you store the batteries for any length of time. I think there are some modifications that can be made to reduce the stand by current drain of the CellLogs down to micro amps. But they certainly don’t draw anywhere near 0.5A/h.
I think the 8S are a bit expensive if they are used just to monitor the cell level LVC, although there is a monitor only version, CellLog 8M with alarm available about half the price.

HobbyKing R/C Hobby Store : Cell-Log 8M Cell Voltage Monitor 2-8S Lipo

There are other cell monitoring meters with LVC alarm available for 6S cells like the BM-6 which are a bit lower in price than the CellLog 8M.

HobbyKing R/C Hobby Store : BM-6 Cell Voltage Monitor 2-6S Lipo (New Version)

Chris

 

[jerrysimon]

Interesting. I note the BM-6 is no good if you use A123 cells as the low voltage limit only goes down to 3.0v whereas the A123 cells go down to 2.0.

The Cell-Log monitor looks like it might be good to leave permantly attached to my two 6s1p packs, though that might be over kill. But then they ARE cheap.

Regards

Jerry

 

[Dadplus2]

There are various modules you could use to monitor each cell and give warning if a cell goes to low in use. Check out hobbyking for the cellog devices or similar, they are cheap and simply plug into the balance leads. With the nano batts it's probably best not to let the cells drop below 3.4v, they are effectively empty at this point and further discharge will cause damage....



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Thanks for the info 3.4V seems like a high number if they are full capacity at 4.1V. I checked mine yesterday after about 5-6 miles and they were at 3.7V all roughly the same. Charging took 1.5hrs.

Will look into a CellLog

 

[Deleted member 4366]

Thanks for the info 3.4V seems like a high number if they are full capacity at 4.1V. I checked mine yesterday after about 5-6 miles and they were at 3.7V all roughly the same. Charging took 1.5hrs.

Will look into a CellLog

Lipos are just about empty at 3.7v. They fall off a cliff at about 3.6v, so you shouldn't dare to go below that as they will very quickly go below the 3.3v minimum. It looks like your range is therefore only 5-6miles, which seems rather low. You might try charging to 4.2v for a bit more range.

 

[Scottyf]

4.1v is only at about 90% capacity so as D8veh said it would be worth charging up to 4.2v for that little bit more range.

 

[NRG]

If you you check the discharge curves on the RC group forums you'll see the Turnigy packs are good down to 3.2v the nanos around 3.4v

Some of the cheap packs off eBay may well be finished at 3.6v bit the better ones from hobbyking can be taken down to 3.2 or even 3 as an absolute minimum.

I know from first hand experience with the Turnigy packs there is plenty more capacity left at 3.7v

Charging to 4.1v is a good idea and the cell is going to be just about as full as it will get around 95% or more.





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