Stinky Turnigy 80-100 -Nuvinci semi auto

[HumboldtRc]

Bump

[Burtie]

I have been successfully using this big psu as part of my 75v bulk charger (for 18s lipo)

Charger in ammo box

ChargingTinSmall.jpg (87.84 KiB) Viewed 1230 times

The big psu outputs 52v. When placed in series with one (or two) Meanwells it pushes the output to 75v.

The Meanwell S350 is modified to provide the CC / CV behaviour that is required for a bulk charger
(Many thanks to the guys on this forum for working out the required modifications)
Summary details:
1) 220 ohm + 1k pot across R33 for current limit (lower the resistance to lower the current)
2) 1k across thermister to run fan permanently.


You can use a Turnigy power analyser/watt meter as a cheap way to monitor the charging. There is a 15v zener diode in series with the supply to the meter electronics (coz they dont like more than 60v)

This box will charge my packs at 1.5 or 3C.
Just park up next to the box, plug it up and in a few short minutes you are ready to go again

Burtie

[liveforphysics]

Outstanding!

Dirt cheap 3kw Lipo charging. I love it!

[HumboldtRc]

I'm using diode's mounted to a heatsink to limit the volts at the beggining of the charge cycle. Instead of the wire in water technique. Way more consistent and don't fry if not under water. ( I would upload a photo if anyone knows how to from an iPhone.... Maybe I have to upload it to another site...)

[HumboldtRc]

Diode setup
http://m.facebook.com/home.php?_rdr#!/p ... 1305054823

[Burtie]

The old cardboard box holding the batteries together had seen better days. Time for a re-work...

I have read a few posts about people using thermoplastics to make various ebike related parts, so thought I would have a go.


1) Took some plastic household rain guttering, Using a hot air paint stripper, heat it till it goes soft and make any shape you want

Flatten it out

SDC12680.jpg (85.12 KiB) Viewed 1119 times

Bend up the sides and edges

SDC12681.jpg (71.08 KiB) Viewed 1119 times

Fill it full of Lipo

SDC12682.jpg (94.05 KiB) Viewed 1119 times

Strap it to your bike

SDC12685.jpg (148.68 KiB) Viewed 1119 times

I love this stuff.

I expect to have lots more bits of bent up plastic on my bike soon

Burtie

[boostjuice]

Nice work burtie. Let us know how you go with pedal leg clearance running lipo packs in trasverse orientation. Im guessing it's going to be about 160mm wide including plastic coverings? Thats a tad more than even the stealth bikes transverse assembled headway cell packs that people complain about regarding leg clearance.

[Burtie]

Extra wide cyclone bottom bracket combined with bandy legged cycling technique provide bags of 'Lipo between the legs' capability


Pedaling is no problem, the pedals on this bike are never used much. They are really only for show, and to get me home if I should break down.

[HumboldtRc]

@LFP
The part no for the PSU is attached to the 1st photo. I did find about 3 pots inside the unit, one was a fine voltage control, one was something to do with the fans and the third was a mystery. I played with all of them, but couldn't get the psu to work in any sort of constant current mode. What is the trick to do this?

@HumboldtRc
I love that wire in water setup of yours I may just have to copy it

@LFP
I would also like to know how you adjusted the pots in your post?

Luke,

Any info on how you made the server PS go into CC mode or what you did to get them to bulk charge at their full potential with out having to change a diode setup in the middle of the charge cycle???

Thanks

[mwkeefer]

Hey guys

I just picked up (received) 2 of these HP 48v (51.4v) 57A power supplies (3kw) and it seems nobody has (as of yet) figured out how to really limit the current or widen the voltage adjustment range as we do with most all of the meanwell series?

Before I use one of them as a "play around" unit to figure out setting the voltage and current limits I figured I should ask clearly, I did read this thread and many others here and elsewhere but as of yet only Luke seems to have spotted POTs internally and they seemed of little to no use..

Because of my townhome and indoor office charging plans, I can't use a Radioshack box with water (did you adjust the saline content) as a bogus load limiter (but it's damn funny and probably works fine) so I will have to determine another way to either adjust the range and limit the current internally or externally.

Thanks and regards,
Mike

[HumboldtRc]

I've been using diodes to drop the voltage, to keep them from over-currenting. It works pretty well for 6s charging, using 4 of the 575watt PS's, series and paralleled, for 95 amps at 25.2 volts.

You will just have to use more diodes in series, to get a higher voltage drop, to match the wider range of voltage a 12s pack will be, at the end of the charge.

[Burtie]

Nuvinci developer kit now fitted. Added a gizmo to allow sequential gear shifting commanded by up/down buttons on the handlebar.

Test fit.jpg (126.44 KiB) Viewed 867 times

Started in nuvinci developer kit thread here: viewtopic.php?f=28&t=30641&start=345#p493457
continued here...

I am having major problems with the bmx chain skipping at the rear.
Have tried several combinations of New chains and New sprockets, some work better than others, but I cant seem to cure it

The alignment looks good.
I have a rear derailleur to tension the chain and cope with length changes due to the suspension. When I add an extra spring to increase the tension, it helps a bit, but..

I can not put enough power through this 17t sprocket to get above about 30mph before the chain slips.

I will try a larger sprocket (20t) on the rear to see how much it helps, but it will make the gearing less than ideal.

Anybody else ever had any similar problems with small sprockets and BMX chains ?


Burtie

[amberwolf]

I had problems with 16T and 18T on my 7-speed and 6-speed cassettes, back when I used to have a powerchair motor driving thru CrazyBike2's regular bike drivetrain. This was with regular narrow multispeed chain, rather than BMX, but I expect BMX would've done the same thing. My problems were at startup from a stop, but if I had been trying to get power enough thru it for high speeds it probably would've done the same thing.

My eventual solution was to change the gearing upstream for larger rings, so that I had more teeth on the rear cassette gear I used for the same "top speed", and avoided using the 16T and 18T (because the skips had damaged their teeth! Even now, I can't use those two sprockets even for pedal-only or it skips).


Another thing that would help is increasing chainwrap, so more teeth are engaged, but I don't know if you have room for that on there. You'd probably have to build a tensioner specifically for that, or order the one NuVinci sells if they still have it.

EDIT: Also, I thought I'd point out my solution to FS and chain tension is to use the swingarm pivot as the chainring center, so there is no growth/shrink of chainline during bump/droop.

In my case, the pivot is actually the NV, and the wheel will just have a chainring, but the reverse would work just as well.

You may not have that option with your setup, without frame modifications, though.

[recumpence]

That is really weird. I have run 40hp through a bmx chain without skipping........

I tend to think something else is happening.

Matt

[Burtie]

AW, Thanks for the ideas, guess I may end up re-working the reduction setup as you suggest, to enable use of a bigger sprocket on the NV.

That is really weird. I have run 40hp through a bmx chain without skipping........

I tend to think something else is happening.

Matt

How many teeth were there on your sprockets Matt ?
Did you use a spring loaded, or a fixed tensioner ?
Do you have a favorite brand of quality chain / sprockets that you would recommend ?

Burtie

[kfong]

Sounds like you just need to remove a link or two to get more tension Burtie.

[Thud]

Burtie,
Matts set up really doesn't apply in this senario. He is driving it as a reduction & yours is increasing ratio.

Ive had simular issues with a bottom bracket drive set up. It would start to skip under load in the higher gears. I assumed it was from wear, when a new set displayed the same problem, I looked a little closer. The cassets take a little liberty with geometry, I assume to aid shifting. I disassembled a casset & flipped the cogs (now rotating backwards) & the chain grips true.

It seems odd that the single nuvinci cog would employ the same goofs... I don't know if you can flip it over or not in this application..(offset may make it impossible)

Having tried derailers as tensioners in my serial right side drives...I have never been satisfied..I can make BMX chain skip off a 16t freewheel under pedal easy enough.

You'll save time by using as short a chain as you need to accomindate suspension growth & finding or fabing a strong tensioner....(shoot for 3x the tension of your derailer as a starting point)
good luck
T

[liveforphysics]

Need more chain tension. Bicycle chains love to slip when you load them. Then they love to break when they get skippy.

Tension is kinda a band-aid to help relieve the symptoms.

[AussieJester]

Never had a single issue with bicycle chain...running the wider BMX variety also 1/2 link chains,
tension and alignment is the key Burtie...

KiM

[Whiplash]

I agree as well, I was getting over 40mph running through an 11T rear sprocket so I am sure something else is causing your issues... good luck! Im sure you will figure it out!

[Tench]

What about fitting a tensioner wheel above and below the swing arm pivot quite close to it, with correct positioning and tensioning it may be possible to maintain correct chain tension throughout the suspension travel?

[deecanio]

Hi Burtie,

i had the same issues when running a single speed through the rear deraileur, but i think you can cure it quite easily:
the photo tells me two things, your chain is too long, and your deraileur is still set in its standard guise.
i found that the deraileur doesn't give you enough "wrap" around the freewheel, the photo suggests the same, being as you are running a single now you dont need the sideways adjustment on the deraileur for going up and down gears, so that can go, you also dont need the "s" shaped part of the deraileur to dangle down at the original angle either, more point it at the crank.
in essence you only need the deraileur to tension, not derail.
wheres my damn phone? ...................here's how i set up and i haven't had to look at it since, i stand on my pedals uphill with no concern, its solid. This is the setup with a 3 speed chainring upfront + full suss on my stinky, so im fairly confident it will help your setup enormously...... you'll need to remove the tensioning spring and washer from where the deraileur bolts onto the hanger, and you may not be able to lock your arm to the frame as i do because you have a 17t as opposed to my 15t, but, you'll get an immense improvement. dont forget to lock your alignment using a small piece of cable where the normal cable goes, looks like youve done it already but cant quite see.


D

[Hardcarve1]

I had this problem with the my setup with the chain always skipping when you put load on to the pedals. Drove me nuts working it out.
I had to put a sing speed cain tensioner on and get rid of the deraileur and I put it down to chain tension. The chain wrap was not the problem in my case as the deraileur gave more wrap than the simple chain tensioner. If you could increase the spring tension in the deraileur this may work but I couldn't find a stronger spring. In the end I didn't need the forward sprockets and was happy with the single speed.

[Burtie]

Thanks for all the replies folks.
I have tried to maximise the chain wrap, have increased the tension with an external spring, and am using the limit screws on the derailleur to set the chain alignment.

NV chain drive.jpg (229.44 KiB) Viewed 600 times

Tried a few different sprockets ( see the different tooth shapes on these new fixed wheel sprockets from different suppliers )

Compare sprocket tooth shape.jpg (142.13 KiB) Viewed 600 times

The sprocket that works best is the one above on the left, with the square shaped teeth.

The chain skip issue is much improved, but something still skips a bit when under very heavy load driven by the motor. Maybe it is not the rear sprocket any more.
I will continue to look when it stops raining

Burtie

Think I might use #219 on any future chain drive bike projects Good idea ??

[drewjet]

bURTIE,

219 ROCKS! Never had a problem with it.

How many watts are you putting into the Nuvinci? What kind of speeds are you hitting?

I have created some problems with mine by hitting it with 7500 watts. A full 2500 over specs. Funny thing is as long as I keep the rides short it works fine, more than about 8 to 10 miles the hub gets warm and starts not wanting to engage after letting off the throttle and allowing internal frewheel to freewheel.

Could you check the hub temp next time you ride for around 10 miles?

Thanks Drew