Buying a 8000w E-bike?

[kennet_h]

Yes. The bikes fully assembled. They sent me pictures of the bike after it was fully assembled.

Then they ship it with the front wheel off, and the battery in a separate package.

Got the battery today from ups.(on day earlier than expected)

If the bike is not delayed, i will get it on thursday

 

[lionman]

Get in touch with Andy Kirby

https://www.youtube.com/user/andykdubs

He has a pretty nice bike he has built. He can supply parts too

https://cloudsto.com/store/andy-kirby-e-bike.html

He has tried and tested a lot of things out so you could probably learn a bit from his videos.

40MPH will drain the battery really fast. If want to sustain that for an hour it will need to be a pretty big battery pack.

 

[kennet_h]

I have seen some of his videos.

The battery is about 2.8kw/h

 

[kennet_h]

I got the bike yesterday, and i'm happy with it


It feels safe, i had it in 90 km/h on a road with lots of turns, and it felt good.

the brakes are okay not great but more than enough for it not to. be a safety issue.

The only issue i have, is that on the highest power setting, the motor Sometimes stops pulling on full throttle.

I don't know if this is normal?

Is it the controller stopping, because it reached its max amp, or could it be something else?

 

[kennet_h]

Some pics

 

[harmonist]

Looks mean, seatpost looks pretty long, does it hit the shock?

 

[kennet_h]

The shock goes down With the bike, so you dont need much clearance.

 

[Yermommy]

I got the bike yesterday, and i'm happy with it


It feels safe, i had it in 90 km/h on a road with lots of turns, and it felt good.

the brakes are okay not great but more than enough for it not to. be a safety issue.

The only issue i have, is that on the highest power setting, the motor Sometimes stops pulling on full throttle.

I don't know if this is normal?

Is it the controller stopping, because it reached its max amp, or could it be something else?

Sounds like you’re hitting the low voltage cutoff from voltage sag. Does this happen even when the battery is fully charged?

 

[kennet_h]

Yeah, it happens on full charge also. The battery stopps chargeing at 82,6v i think. Going to chek when it's full. The volt has never dropped under 70V on the monitor. I have never used more than halfe the power, before chargeing.

 

[Yermommy]

Yeah, it happens on full charge also. The battery stopps chargeing at 82,6v i think. Going to chek when it's full. The volt has never dropped under 70V on the monitor. I have never used more than halfe the power, before chargeing.

Hmmm are you familiar with "voltage sag"? Voltage sag occurs when you stress the battery with a high amp discharge. Neptronix explained this in another post:

Voltage sag is basically a lowering of voltage in response to electrical resistance.

All batteries have differing levels of resistance inside them, noted as 'internal resistance'. You will get some sort of voltage drop when you apply a load ( IE hitting the throttle on your bike ! ), and that amount varies on the IR of the battery you have, the higher the amount of amps required, the worse it is.

That is why you see "C" ratings on batteries. It is, loosely, an indication of their internal resistance.

The more energy your controller/motor demands, past the C rating of the battery, the drastically worse the voltage drop will get. Lead Acid batteries have such bad voltage sag, that they invented a term for it, lol.. Peukert's effect.

One example would be if you ran a set of 5ah 1C cheapo cells at a 2C draw ( 10amps ).. instead of giving you 36 volts, they'd give you more like 24-32v, limiting your top speed ( and beating up on the poor batteries too )

Make sense?

 

[kennet_h]

The cells are Panasonic ncr18650bd 20s12p.
So should be able to ro 120A continuous discharge.

The controller is not supposed to draw more than 100A.

It is not just that it gets a little less powerful like you would expect from voltage sag, but it stoppes pulling (almost)completely, and the motor makes a weird sound, if i let off the throttle for a sec, and don't pull it all the way back, it goes away.

It could maybe be som burst mode, that are programed in to the controller? That lets you go above the recomended specs, for a few seconds?

 

[2old]

Might not be analogous, but I had a 350w, 36V system that did what you describe, and it was the exact problem with the battery that was described above.

 

[harmonist]

I like the look of that front light on it as well, anyone know the brand?

 

[EbikeAus]

Looks like a beast
What are those forks? Are they what it came with?

Enjoy

 

[harmonist]

They look like the DNM USD-8 forks, pretty standard with the EEB frames

 

[John in CR]

Radial lacing of hubbie, especially with the torque potential of a 273, seems like a bad idea. Did they offer any options for the lacing?

 

[lionman]

The cells are Panasonic ncr18650bd 20s12p.
So should be able to ro 120A continuous discharge.

The controller is not supposed to draw more than 100A.

It is not just that it gets a little less powerful like you would expect from voltage sag, but it stoppes pulling (almost)completely, and the motor makes a weird sound, if i let off the throttle for a sec, and don't pull it all the way back, it goes away.

It could maybe be som burst mode, that are programed in to the controller? That lets you go above the recomended specs, for a few seconds?

It could well be capable of delivering 120A, but that doesn't mean it won't sag a whole bunch when you pull anywhere near that. Those cells will sag about .5V at 10A.


https://www.e-cigarette-forum.com/threads/panasonic-ncr18650bd-10a-3000mah-18650-bench-test-results-an-good-10a-battery.774265/

If you are running 20S12P, that will add up to 10V of sag across the whole pack if pulling 120A. It won't be a whole lot better at 100A, are you sure it's only drawing 100A peak from the pack?

If I was going to pull 100A from a pack, I would aim for a 200A capable pack (20P).

 

[kennet_h]

Might not be analogous, but I had a 350w, 36V system that did what you describe, and it was the exact problem with the battery that was described above.

Where you're battery specs good enough, according to the spec sheet? Did you get a bigger battery, to get rid of the problem?

Looks like a beast
What are those forks? Are they what it came with?

Enjoy

They are the DNM USD-8

Radial lacing of hubbie, especially with the torque potential of a 273, seems like a bad idea. Did they offer any options for the lacing?

I don't know, they were cross laced, on the pic, so expected them to be, but they where not.
Im pretty shure you can get them to do it, the way you like it, as long as you specify it beforehand.

If you are running 20S12P, that will add up to 10V of sag across the whole pack if pulling 120A. It won't be a whole lot better at 100A, are you sure it's only drawing 100A peak from the pack?

If I was going to pull 100A from a pack, I would aim for a 200A capable pack (20P).

I Don't know how much it is actually pulling, But the voltage monitor never says it droops more than 10V.(Dont know if that is accurate?)
It is not really that big of a deal, as long as there is not something wrong, that will end up breaking early.

I hope it's just voltage sag, like most of you think, but if the voltage readings on the display are accurate, i dont see any reason for this to happen, when the battery voltage doesn't drop under 70V.

 

[2old]

A new battery resolved the problem. This was a "qualitative" situation since I don't have quantitative data.

 

[Tommm]

A new battery resolved the problem. This was a "qualitative" situation since I don't have quantitative data.

Where did you get the new battery from?

 

[2old]

Basically a replacement from the same kit company; they don't sell batteries that would satisfy your needs. Recent batteries are from Luna Cycle and they've been excellent; the first (52V, 10 a-h) is into its third year powering a BBS02 mid or 1000w, 48V rear hub.

 

[kennet_h]

A new battery resolved the problem. This was a "qualitative" situation since I don't have quantitative data.

Did you get the same spec battery? Or did you get a higher power battery, to get rid of the problem?

 

[www.recumbents.com]

Sounds like some type of current limiting feature in the controller to me. Is it a programmable controller?

 

[kennet_h]

That's what i'm thinking too.

It's a 72v 100A Sabvoton sine wave Controller.

It came with a usb cable, but i can not find a usb on the controller, so i think i need an adapter to be able to program it.

:edit

I found the usb port, from the controller, but i will have to do some reading, before i dare to mess around with it.

Any idea which numbers i should be looking at?

 

[2old]

Same battery specification; the "bad" one was adequate when new, but deteriorated rapidly and exhibited the characteristic within about six months of occasional use.