Dengfu E10 - The CHEEB V1.0 - Discussion

[jimbob]

Here is a simple way to test the battery capacity with out any expensive tools or testing stations. As we all know a lithium battery cell is considered fully charged at 4.2V and fully depleted at 3.0V. In most cases the BMS will prevent the cells from over charge and stop the cycle at 4 volts, with 12 cells in series = 48V. The BMS will also most likely stop the cell from discharging past 3.2V or right around 38V on your pack.

So now that we know we can have a safe differential voltage of 10 How are we to find the true capacity of the battery? well that can be simple. what you need is a lamp, a 48v DC bulb, and an volt/amp meter. you could probably buy it all on amazon for 30 bux...

step 1, measure the battery voltage at full charge to verify 48 volts
step 2, connect the lamp leads to the battery + and - using some insulated stakon female flat connectors (make sure you use the insulated connectors to protect the battery from a possible cross connection)
step 3, Turn on the lamp and measure the amperage draw, since we already know the true voltage we can multiply the amperage for the real wattage consumption. A 9W bulb may in fact draw 10W due to power factor or other electrical losses.
step 4, Now you can do this step a couple ways but I would rather not actually measure how long it takes to consume 10 volts on a 9W bulb because that may take days. Instead, fully charge the pack again, verify 48volts, hook up the lamp, turn it on, start the timer, wait for the volt meter to show a drop by 1 volt and record the time.

Lets hypothetically say it took 240 minutes (4 hours) to discharge 1volt at 209 milliamps or 10W. We can take that time period of 240 minutes multiplied by 10(the amount of consumable volts between full charge 48v and empty at 38v) and we get 2400 minutes or run time / that by 60 minutes to get 40 hours. Now you take the available run time of 40 hours and multiply it by the wattage consumed (10watts) = 400Watts.

So now we know the battery can run 400 watts for 1 hour at 48V giving it an approximate 400Whr rating. I did this test on a few cheapo lithium batteries and found them also to be over rated on the label. Your real world experience CAN be different once the cells get out of balance. My girlfriends specialized levo would not charge all the way and would also discharge very fast when it was low. This was because the BMS of the pack is cheap as hell and the charger does not balance the cells the way it should. As soon as any of the battery banks reached 4.2 volts it stopped charging. I found 2 banks with cells that were only at 3.6v while the others were at 4.2 so it never got a 100 percent charge. Also when the cells began to drain those two banks that had a low voltage condition would drop out and it was the equivalent of losing 20 percent all at once.

Unfortunately there is rather a lot wrong with this post. I hate picking holes in what others say, but with the greatest of respect, I'm not sure what you've proposed is valid.

For a start, not all batteries will alow you to just discharge them. Shimano as example has electronic switches inside it to prevent just this without being installed in the system.

You also assume a linear discharge over the voltage range, which you don't get with batteries, and as already mentioned, the power available will be dependent on the discharge rate, which at 9W, will not be representative of use and so will result in an over reading of capacity.

I won't go into the rest of it.

 

[patdam]

I would add that battery is a very dangerous equipment and i do not recommend to somebody who do not perfectly control that he do, to follow "instructions" of other people to tinker. Sorry for another off-topics, but i think it is important to say.

 

[apac]

I would add that battery is a very dangerous equipment and i do not recommend to somebody who do not perfectly control that he do, to follow "instructions" of other people to tinker. Sorry for another off-topics, but i think it is important to say.

There's nothing wrong with Kentucky fried fingers. They're just part of the learning curve?

 

[Rob Rides EMTB]

thanks for all the suggestions on the battery stuff.

to be honest I’m not too bothered / skilled enough to get into the realms of electrical testing. ??

hopefully it is actually a 17.5Ah pack like they’re advertising though!

 

[patdam]

thanks for all the suggestions on the battery stuff.

to be honest I’m not too bothered / skilled enough to get into the realms of electrical testing. ??

hopefully it is actually a 17.5Ah pack like they’re advertising though!

I never been disappointed by china batteries capacity purchased to cpy with an history (reliability of bottle is another problem). I just checking cells brands (samsung or panasonic). For dengfu, melody say me there are Samsung 35E cells.

 

[apac]

In that case... 13s 5p configuration 65 cells.

 

[GrandPaBrogan]

thanks for all the suggestions on the battery stuff.

to be honest I’m not too bothered / skilled enough to get into the realms of electrical testing. ??

hopefully it is actually a 17.5Ah pack like they’re advertising though!

Yep, I hope you just plug and play Rob and withhold analysis or tampering for later. That’s the only way to assess the motor-battery-frame kit you’ve ferreted together - in ‘out of the box’ config so to speak.

If issues arise (always a possibility) then you’ll be able to correctly identify the realities and risks of such a project. But I must confess, deep down (I’m always for the underdog) I hope it kicks a$$ right from the get go!

 

[Doomanic]

There's nothing wrong with Kentucky fried fingers.

It's the Kentucky Fried House I'd be worried about...

 

[Nasty Nick]

thanks for all the suggestions on the battery stuff.

to be honest I’m not too bothered / skilled enough to get into the realms of electrical testing.

hopefully it is actually a 17.5Ah pack like they’re advertising though!

With time you'll figure this stuff out naturally. I can't wait for the day that access to work on the firmware is like any other bike part.

 

[Enon]

People please, stop justifying your unwillingness to learn proper techniques of riding technical or uphill sections, so that we can get back to the context of this thread. All this bickering is getting OLD... and boring...

Here, learn something you should've learned long ago, and just shut up.

I wouldn't view that as unwillingness to learn proper techniques- for example why don't you learn proper cornering techniques that don't necessitate the need for a super low bottom bracket height?

In my experience of riding quite a few bikes that have what are already considered low bb's, 324mm unsagged is ridiculously low and does the opposite of inspiring confidence for me as I'll frequently clip pedals in ruts and big compressions quite often on the terrain I ride. I get that a 324mm bottom bracket would rides very well on flow style trails without many technical sections, but painting people with "you haven't learnt the correct technique" is pretty arrogant. Different geometry suits different terrain which suits different riders that have different styles - there isn't one technique that is the "proper" technique

 

[GrandPaBrogan]

I wouldn't view that as unwillingness to learn proper techniques- for example why don't you learn proper cornering techniques that don't necessitate the need for a super low bottom bracket height?

In my experience of riding quite a few bikes that have what are already considered low bb's, 324mm unsagged is ridiculously low and does the opposite of inspiring confidence for me as I'll frequently clip pedals in ruts and big compressions quite often on the terrain I ride. I get that a 324mm bottom bracket would rides very well on flow style trails without many technical sections, but painting people with "you haven't learnt the correct technique" is pretty arrogant. Different geometry suits different terrain which suits different riders that have different styles - there isn't one technique that is the "proper" technique

Might be best to start a new thread about it, so as not to inadvertently hijack this one.

 

[Zimmerframe]

And if you used a vacuum cleaner, change the bag!

Whilst it might be advisable, I don't think it's necessary to change your lady everytime a man might use a vacuum cleaner.

 

[Zimmerframe]

Please tell me you were wearing a respirator when you did that!

I hope it will be part of the video .. voice over by Vader Rides EMTB ...

 

[Mteam]

Why are you painting it, it looks good as it is.

 

[Zimmerframe]

You did see what Rob did to his matt black rental jeep when on holiday last year ???

 

[paul-g]

You did see what Rob did to his matt black rental jeep when on holiday last year ???

View attachment 47480

yep definitely purply blue in that

 

[jimbob]

Do you need a primer, or can you put the base coat straight on?

I've painted a few cars, and it's all about the prep work. Every time I've thought 'that'll be OK, you wont notice' I've ended up having to re-do it later!

 

[Zimmerframe]

Primer first, base coat, colour, clear coat ?

Oooooh .... I hope you're going to film this in time lapse !! Could be really cool !!!

And maybe two other cameras .. one filming the empty spray cans and the other the empty beer cans ..

 

[GrandPaBrogan]

Oooooh .... I hope you're going to film this in time lapse !! Could be really cool !!!

And maybe two other cameras .. one filming the empty spray cans and the other the empty beer cans ..

Don’t forget the index finger cam (the one that presses the spray nozzle) ?

 

[Waynemarlow]

Just buy the " Glossy" version from the factory, looks stunning in the flesh and shows just how good the layup of the carbon is. The Gloss also acts as a filler and protective barrier to the softer carbon and if you want to tart it up, then get it wrapped, cheaper and when you tire with the scheme, change it.

We ordered ours back in the summer and it arrived hassle free in about 5 weeks from order ( I was expecting months ). Bit scary though sending funds off to some private Paypal account. You can save considerable funds if you ask for it to be sent via train and pre tax's paid, saved nearly £ 150.00 for the loss of about 2 weeks.

 

[R120]

So how much is getting a frame done going to cost at Rob's Resprays?

 

[2wheeledwalbert]

https://youtube.com/shorts/AH5iKO5nZYI ?

 

[Pyr0]

I just saw that vid earlier.
Glad Robs rear triangle looks more substantial

 

[2wheeledwalbert]

I just saw that vid earlier.
Glad Robs rear triangle looks more substantial

Yeah it does tbf. Would still be in the back of mind though sending it off a drop

 

[Slowroller]

That Luna frame is totally different in design and geometry isn’t it?

Luna doesn't know much about anything about bikes afaict if you read any of their product descriptions, especially of the worst of them. Just buying stock Dengfu frames has been a step up over previous products. They tried designing their own and they were horrid. Still sold ofc. This was a flagship product for years, people still want it lol.

Luna Apex

Distributors and builders of life changing electric bikes.

lunacycle.com

 

[Mydriaze]

I was about to post it but I saw you already did. I just post it using the media link in order to "see" a preview only. Chinese standard are not European or other countries standard. Be careful.

 

[GrandPaBrogan]

I just saw that vid earlier.
Glad Robs rear triangle looks more substantial

Cracks me up (excuse the pun) when the guy on that video buys a cheap 'Chinese' frame... breaks it... then says, don't buy/trust Chinese carbon. That frame didn't fail because it's Chinese carbon... that frame failed because it was a bad design and poorly engineered (if at all). I've seen more expensive "European or American" carbon frames fail too... but no one ever says, "don't buy 'such and such country-of-origin' carbon."

I've toured inside a Chinese factory that makes high-end carbon frames specifically for a German brand (whom I can't remember ?) that are tagged with "Made in Germany." Not heard of any of those failing. Maybe it's because of the sticker that says Germany-made makes it stronger? ? Or was it because those frames are properly designed by qualified engineers (Germans or otherwise) and strict production guidelines were followed the Chinese factory (or by any ISO accredited factory in the world would have been required to)...

 

[GrandPaBrogan]

ps - I have also seen catastrophic failure on high end commercial ebikes from big brands.

I'm glad you mentioned that. It would be a shame if xenophobia surreptitiously crept into this DIY project.
Whether Denfu carbon frames are any good or not (for your intended application) has yet to be proven obviously... hopefully from an engineering standpoint without racial prejudice.

It's hard to spot cracks on black carbon (matt or glossy)... so I think it's a good idea that you're painting yours with a lighter colour.

 

[Rob Rides EMTB]

Regarding China frames:

Quest makes carbon frames for both Trek and Canyon. According to the Quest website. Located in Dongguan City,China

Quest Composite Technology Corporation

Quest Composite Technology has been in business since 2007; building composite products primarily serving sporting goods, cycling industry,wheelchairs and eyewear industry.

www.questcomposite.com

Composite Bike Frame
Quest is a key partner to the best bike companies in the world-Trek and Canyon. From advanced research to R&D and mass production, Quest ensures the bikes are produced with the highest quality and performance standard. We are proud to be producing some of the bikes that have won the world's biggest races.

 

[04fuxake]

Luna doesn't know much about anything about bikes afaict if you read any of their product descriptions, especially of the worst of them. Just buying stock Dengfu frames has been a step up over previous products. They tried designing their own and they were horrid. Still sold ofc. This was a flagship product for years, people still want it lol.

Luna Apex

Distributors and builders of life changing electric bikes.

lunacycle.com

From what I've seen, a lot of importers of low-end Chinese e-bikes don't know dick about bikes in general. I called one out once for saying their bikes had Deore gears when the only Deore part was a rear cassette. They rely on selling to other people who don't know what they're buying but are happy to drop 3K+.