New build.

[amigafan2003]

More updates (god I've missed having a project )

Got my Meanwell S-350-48 power supply on Saturday so set out to the garage last night to get it modded/set up (pic to follow).

First step was to lower the current it can deliver. As Lipo's have a very low impedance if you connect the PSU up to the pack it will deliver about 11 amps or 150% of it's rated current - this is because the PSU's are used in environments where a large peak like this might be required but only for a short period of time. leave the psu connected up to a pack charging at 12 amps and the psu will burn out in short order.

To trim this current down yuo can either do two things - fit a pot to the R33 resistor or file or snip one or more of the three shunts on the board. Ever being the fan of simpe solutions I just snipped through one of the shunts which resulted in a max amp draw of 8 amps @48v settling down to 7.5amps - a little higher than the rated 350watts of the psu but that should be fine.

The next job is to trim the voltage of the psu to match the max voltage you want your pack to reach. I'm using four 6s 5000mah lipo bricks in 2s2p config so that's a max voltage of 50.4v (12 cells @ 4.2v each). In order to leave a little headroom for safety and in a bid to extend the cycle life of the lipo packs slighly I have set the voltage of the psu to 50v - which equates to, in theory, 4.17v I have also mounted a panel mount voltage LCD display on the outside of the case so I can keep an eye on charge progress.

So, how does it work?

Well, the PSU is a CC/CV power supply, meaning it will attempt to put out a constant current whilst the "load" (in this case our battery" remians below the voltage limit of the psu. When the voltage of our battery approches that of our psu limit, the psu reduces the current exponentially - eventually to zero - so that our back and psu both have the same voltage (50v in this case) and no current flowing into the battery.

My first test I had my cellog8m monitor attached to one of the balance taps and put my ampmeter inline with the positive lead and set it off. Voltage started at 48v and pumped a stead 7.5 amps into the pack until the pack reached 49.5 v then the current started to steadily lower and at around 1.5amps the pack was sitting at 50v exactly. the current proceeded to reduce steadilly and the pack voltage never exceeded 50v and then I heard the psu click off when the amps reached 25ma - then they went to zero! Excellent - I wasn't expecting the psu to actually switch off when the pack was charged - that provide some re-assuring safety when charging lipo. Didn't time the charge (it was only about 20% drained) but it was deffineately under 30mins and it's going to be so much easier to charge than connecting it all up to my hobby charger.

Whilst I'm getting a feel for how the charge process works I'll be keeping a close eye on the pack - especially cell balance - bulk charging does not balance at all but I'm glas to sayy all cells withing the pack were within 20mv and all sitting at 4.16/4.17v. The aim will be to balance charge every 10 cycles - or at least check the balance every 10 cycles as some on Endless Sphere state they haven't need to balance in over 100 cycles, especially if they avoid a >80% discharge.

Right, what else can I do?

Oh yes - I'm building an 8ah lipo pack consisting of four 2ah 2s Turnigy Nano packs into a water bottle as a battery pack for my new MagicShine MJ-856 bike light (I don't trust MagicShines battery packs)

Pics to folllow!

 

[Scottyf]

Very good explanation of bulk charging. Pretty much exactly what I would do If I wanted to bulk charge.
Exactly the same peak volts as well.

They only ever seem to go slightly out when above that point 4.17v per cell.
Same at the bottom end also.

Least using the bulk charging method will enable you to virtually charge a pack in just over an hour from empty.
I've thought about the above but came to the conclusion I'd only be doing it as a project for myself rather than actually needing to do it.

Good explaination though. Some pictures will be good though of your handy work.

 

[amigafan2003]

I've thought about the above but came to the conclusion I'd only be doing it as a project for myself rather than actually needing to do it.

Good explaination though. Some pictures will be good though of your handy work.

Yup - it's 50/50 between "ooh, that'd be handy" and "oo, that'd be an interesting project".

Pics coming either tonight or tomorrow.

 

[amigafan2003]

 

[amigafan2003]

Another evolution.

Before:-

Wasn't quite happy with the battery solution or more specifically the carrying method. Yes it was light but it looked a bit ameteurish and I was concerned about the packs being upside down and stressing the cables and also about theft and susceptibility to dame, so I've "evolved" the solution.

This is what I've decided to work with:-

HAMMOND|1550WJBK|BOX, DIECAST, 66X175X275MM | Farnell United Kingdom

It's 1kg in weight so that's a bit of a shame but it's worth it imo.

1st thing was to gring out the central ridge so the box could mount via the water bottle bosses:-

I then faced the battery pack (12s10ah of 4x5ah 6s Zippy packs) with some carbon fibre to protect the pack against the bolts and the wiring (you'll see later):-

Bike pack on left, light pack on the right (2s4p of 4x2ah Turnigy Nano packs):-

 

[amigafan2003]

Very happy with that

 

[wurly]

Fits in there a treat.
I did think of using an aluminium box for mine but never found one the right size for ping batteries. Is the top fixed to the frame as well? i say this because my water bottle threaded inserts started to pull out of the bike frame. I fear yours could do the same if the box gets knocked at all. A P clip screwed into the battery box and attached to the bike frame front and back might be a good idea.

 

[Deleted member 4366]

Fits in there a treat.
I did think of using an aluminium box for mine but never found one the right size for ping batteries. Is the top fixed to the frame as well? i say this because my water bottle threaded inserts started to pull out of the bike frame. I fear yours could do the same if the box gets knocked at all. A P clip screwed into the battery box and attached to the bike frame front and back might be a good idea.

I was thinking exactly the same thing. If the bike falls over, it'll rip out the inserts. Other than that a nice idea. Well done.

 

[amigafan2003]

A P clip screwed into the battery box and attached to the bike frame front and back might be a good idea.

That's exactly what I'm going to do - as soon as the two sizes of rubber lined p-clips I ordered arrive ;-)

Not sure if you can see it in the photos but it's effectively wedged in where it is with rubber at the top and rubber where it touches the controller.

 

[mxer125]

Wow!! What an awsome thread, Thanyou for sharing, Love the meanwell set up

Was going to do the same thing, but the clones as you know have there issue's atm (NES etc) so going for the varable alloy shell charger myself, like the idea of someone else setting the CV and CC and me just plugging it in (love the project tho) Great stuff

 

[amigafan2003]

Just ordered a pair of Zippy 3s5ah packs to parallel up then series into my existing 12s2p 10ah pack.

Lets see how long my little Tongxin lasts at 63v

 

[flecc]

Lets see how long my little Tongxin lasts at 63v

You might need fast reacting precision timing to determine that.

 

[amigafan2003]

You might need fast reacting precision timing to determine that.

Hehe, I'm building up a front wheel with a Q100 hub just in case.

Having said that, the Tongxin has just passed the 700 mile mark @ 44.4v so doing ok so far.

 

[flecc]

Hehe, I'm building up a front wheel with a Q100 hub just in case.

Having said that, the Tongxin has just passed the 700 mile mark @ 44.4v so doing ok so far.

That's good. I think it's more the loading and usage conditions than over-volting that exposes Tongxin mechanical frailty, though 63 volts is pushing it somewhat.

 

[amigafan2003]

That's good. I think it's more the loading and usage conditions than over-volting that exposes Tongxin mechanical frailty, though 63 volts is pushing it somewhat.

I think what will help the longevity of my motor is that my commute has only two really short hills (one 200m and one 50m in length) and I peddle them both and I NEVER use the throttle from a standing start, and I've kept the peak watt draw to 650watts which is 13 amps in the controller. I'll probably drop that to 11amps when I go to 63v.

 

[flecc]

That definitely seems to be a good recipe for the use of these motors. They seem to have been most frail when highly geared in large wheels and used liberally.

 

[wurly]

Be careful of slipping rollers against the motor shaft. You can hear it happen. They have a nasty habit of leaving grooves in them when that happens and they'll lock up making the situation worse. Good luck, i'll be interested to see how long the hub lasts

 

[amigafan2003]

Be careful of slipping rollers against the motor shaft. You can hear it happen. They have a nasty habit of leaving grooves in them when that happens and they'll lock up making the situation worse. Good luck, i'll be interested to see how long the hub lasts

Yeah, I've noticed that when the hub is cold especially, that you have to be very gentle on the throttle else you get the cluctch slip and associated "chatter". Dropping the controller amp limit from 15a to 13a seems to have solved most of that and if I'm rolling at 8mph+ I can full throttle instantly without chatter. I've found aroun 700watts peak to be about the limit for this hub without inducing clutch slip.

 

[Scottyf]

Thats actually higher than what I would have presumed the Tongxin was capable of to be honest. So good going on getting some clear figures.
Very useful for people creating new builds that still want a light fast rolling hub without destroying the poor thing.

 

[amigafan2003]

Thats actually higher than what I would have presumed the Tongxin was capable of to be honest. So good going on getting some clear figures.
Very useful for people creating new builds that still want a light fast rolling hub without destroying the poor thing.

Yeah, tbh I won't mind so much if I kill it - I want to give the other two lighweight hubs a go to compare as well - the Cute 100 and the Bafang SWXU.