48v 20ah Mr. Lau Chan / Lifepo4.hk pack arrived (May '09)

[needWheels]

15ah pack made of 18650 has 176 cells
each cells is 40 grams
176 * 40 grams = 15.5 pounds
plus tape and wires and hot glue is probably another half pound

 

[RTLSHIP]

plus weight of BMS and duct tape would make it approx 16.5 or 17 lbs. mine weighs a little less.
How come Ping only sells 10 ah, 15ah and 20 ah packs on his website? If your theory is correct, then only his 20 ah
pack is prismatic. 10 and 15 ah are not divisible by 4.
Also, my pack dimensions are approx 8.5X 4.5x 5( with BMS). I don't know that 176 cells could fit into <.11 cu ft

 

[needWheels]

I can't explain Ping's ah change to units of five but we do know that v1 vs v2 / v2.5 use different kinds of cells.

In any case a 18650 15ah pack is 6 x 6 x 8.5 inches in general,
so yeah you are missing some volume there.

 

[izzzzzz6]

Hi everybody
My name is James and i am very new to this forum. I live up in the mountains in the french alps.
I have just had a very good experience with Emma who works with Lau Chan and i must say that things are working out very well for me. Here is my story so far.
I have been reading and researching endlessly for one week now, trying to gather information before purchasing what i need to build my 2000W/1000W off road heavy-duty e-mountainbike. I plan to use two Goldenmotor hub motors for steep off road climbing, the front motor can be put on a second bike for friends when not needed. Anyway:
Whilst about halfway through my research, i spotted a 48V 30Ah Lau Chan battery on ebay, it had a make an offer starting at 750$ so i offered 705$ (US$). I immediately regretted making this offer although a great price. I had realized that what i really wanted was more expensive larger cells such as the prismatic cells, i am prepared to find my own cells and BMS and assemble my own pack. I don't like the idea of a few cells dying in a pack full of hundreds of cells, larger cells usually can supply more current. Also with rough off road riding i was afraid that some cells could shake loose from their spot-welds. I had asked Lau Chan about a BMS upgrade and a bigger charger but was still regretting the purchase of the pack. Recently i have been in-touch with with at least 10 different battery manufactures and suppliers, i have many quotes on samples and i hope to start selling batteries in europe. For this reason i knew what i wanted, one of the problems was that the shipping quotes that i have been getting have been OTT.
Whilst waiting for Emma to reply i came across a post on this forum saying that under a different name Lau Chan had been selling some packs made with Prismatic cells, so i thought i would give it a try. I contacted Emma and explained a little more about the batteries intended usage and that i would really prefer prismatic cells if possible.
The reply came with photos of prismatic cells. Emma said it would take a while yo build and it would be more expensive, which is normal. I provided her with 5 options to keep the price down such as, i will assemble the pack myself, perhaps just go for 20Ah or another option was to ask for shipping by surface mail? i am currently waiting for her reply. My point is that by me changing my mind on an object i had purchased on ebay she had the right to ship the original battery, however she has provided me with great customer service and it looks like i will get exactly what i wanted. It looks like Lau Chan is getting it together.

 

[izzzzzz6]

Some pics of the cells they will use:

 

[needWheels]

izzzzzz6, do not buy from Lau/Emma unless you can afford to ship stuff back to China/Hong Kong for replacement out of your own pocket. He will also try to get you to pay for shipping upgrades out of your own pocket.

ebay/paypal will not protect you, they take significant fees out any amount of money they reward back to you even if you win a dispute

Lau/Emma is a smooth talker - everything is okay until its not okay and everything gets dragged out

Keep in mind I am still waiting almost 6 weeks now for a replacement charger, and that's just a $20 item for him. He has still not even shipped it yet and emails have stopped.

Also keep in mind Lau is just a middle-man. He is not the factory, he doesn't build/assemble anything himself. He simply takes your order and then sends it to the factory in China and has no real negotiation power with the factory. It's the same way with CammyCC - cammy takes the order and sends it to vpower.hk - you might as well order directly from vpower.hk since they are the factory directly.

Lau lives in low income housing in Hong Kong. I have nothing against that as I am fairly poor myself but I am also not trying to sell batteries that cost $400-$700 and have no way to replace defective parts in a timely and respectful manner.

He simply doesn't have the resources to cover what he sells.
Shipping an entire battery back for repair/replacement/refund will cost you over $100, ebay will take another $100 out of a dispute. Consider that before ordering.

Also consider Headway cells as an alternative for true ah capacity and very high C rates:
http://www.evcomponents.com/ProductDetails.asp?ProductCode=H4820
http://www.evcomponents.com/ProductDetails.asp?ProductCode=H4810

 

[needWheels]

OMG, check out the stupidity in what Lau just posted on ebay, I guess he switched factories:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120429528409

I guess I am about to get back a full refund including shipping fee:

(If you find one 18650 battery in our shop, we will full refund to you including your shipping fee!)

View attachment lau-do-not-buy.jpg

Attention:
Do not use batteries more than 200W built with 18650 cells Because users complain it dies quickly
Please make it clear what kind of cells the LiFePo4 battery made of before purchasing,
Or please go to companies of good repute.

Why do not use 18650 cells for scooters? ((( Do not use 18650 cells or battery built with multi- monomer )))
18650 cells require big quantity monomers to build one battery, at least 100 quantity, or even 500 quantity more. The more quantity cells used, the longer the discharge process should be. 18650 cells definitely do not allow long-time 1C discharging, which has a serious effect on batteries and makes the battery die tragically short time.(over 90 percent lifespan shortened).What’s more, 18650 cells are welded by spot welding, spot welding cannot use bulk current, and does not allow peak current by batteries,. Large quantity monomers and spot welding definitely will lead to voltage and capacity inconsistency, a serious problem for batteries.
　

We can guarantee our LiFePO4 battery is single cell !!!
If you find one 18650 battery in our shop, we will full refund to you including your shipping fee!

 

[needWheels]

izzzzzz6, note that Lau's prismatic cells are only rated 1C max continuous, just like pings
if you read very carefully, 1C continuous, 3C max burst

Lau's 20ah prismatic:
Rated Discharging Amperage: 20 Amps
Max Peak discharge current: 60 Amps 15 seconds

Lau's 10ah prismatic:
Rated Discharging Amperage: 10 Amps
Max Peak discharge current: 30 Amps 15 seconds

If I manage to pull off a refund, I think I am going with the headways.

 

[RTLSHIP]

Mr needWheels, I looked at his ebay site and he has a 98%+ positive. There is a whole line of positive comments this year.
I didn't see your negative. You're probably waiting and using feedback option as leverage to force corrective action?

 

[needWheels]

I have not left negative feedback yet, it all depends how much more hassle he gives me on returning this. I was almost ready to just ask for a partial refund until this happened today:

I went for a 10 mile ride at near full speed. When I got back I noticed the battery seemed warm so I went and borrowed the infrared temperature probe from my neighbor.

An hour after I stopped riding, the sides of the battery measure 92 F and the center of the top seems to be a "hot spot" at 95 F

That can't be good, or normal right? This is before I even charge it. I thought lifepo4 don't get hot or expand much?

 

[RTLSHIP]

After I go for a long ride, maybe 10 or 15 miles, one side of the BMS gets hot. The opposite side of BMS also gets hot at the end of a charge. I have not noticed whrther the batteries themselves get hot, though. Maybe the BMS related heat gets spread into pack while riding.

 

[jimw1960]

I have not left negative feedback yet, it all depends how much more hassle he gives me on returning this. I was almost ready to just ask for a partial refund until this happened today:

I went for a 10 mile ride at near full speed. When I got back I noticed the battery seemed warm so I went and borrowed the infrared temperature probe from my neighbor.

An hour after I stopped riding, the sides of the battery measure 92 F and the center of the top seems to be a "hot spot" at 95 F

That can't be good, or normal right? This is before I even charge it. I thought lifepo4 don't get hot or expand much?

If you look at some of the battery tests that folks like docbass and bobmcree post on this forum, it is not uncommon for single cells to heat up to 120F under heavy discharge, including some of the mid-quality cells like headway. If a single cell can get that hot, then I would think an entire pack with less surface area per cell for cooling could get even hotter. I wouldn't worry unless it was getting too hot to touch.

 

[dogman dan]

I have often seen temps on my pingbattery around 100F while discharging at 1c. The center cells will shed less heat, so they get warm first. Nothing to worry about. In colder weather of course, the battery will not get that hot, but in summer, 100F in not so unusual. The high end of lifepo4 working temperature range will kill you pretty quick, so I stopped worrying about a hot battery. Lifepo4 stays a lot cooler than nicads, that can get pretty toasty and need to cool before charging.

 

[needWheels]

Thanks for the feedback dogman and jimw1960.
(RTLSHIP, all BMS get hot, that's normal, battery was surprise though)
But what was also weird today, my thumb controller got hot !?

It was really strange and startled me when I put my thumb down after a light.

I stopped and examined everything and I could not find anything wrong so I just came straight home.

Top speed is down again, I didn't see 28 at all. I dunno what's going on.

 

[needWheels]

Something is very wrong, my charger has been running full tilt for over five hours now.
I only went 11 miles today (just double checked).

 

[jimw1960]

Hmmm. What kind of wild theory can I come up with here. Here's one: short circuit in thumb throttle causes throttle to get hot and also accounts for high drain on battery heat. Then again, thumb throttle shouldn't have access to that much current since it just sends a resistance signal to the controller. Dude, you are becomming the poster child for Murphy's Law.

 

[needWheels]

Starting voltage before charge was 52.6v
I just turned the charger off so I can watch TV (SLA charger is piece of junk that causes tons of RF interference, knocks out Wifi and HDTV signal)
Voltage so far is only 53.6v after five hours of charging.

You might be onto something with your theory, well at least something is draining extra current. Not good.

I'm going to measure the 16s voltage breakdown before I start charging again later
and make sure nothing is out of balance.

It's also possible I broke my SLA charger after so much use this past month, maybe it's stuck on a lower stage?

 

[needWheels]

I wonder if I have to worry about this balance, especially considering it's not finished yet, look at the 20v mark:


3.34
3.34
3.35
3.34
3.34
3.29
3.3
3.4
3.3
3.3
3.4
3.3
3.3
3.4
3.3
3.3

update: oh duh, nevermind, it's because my meter can't do hundredth on that 20.0v so it's rounded down

 

[DAND214]

Lau Chan has done right by me. I have a 36v 20ah and a 48v 16ah batteries from him. Both are great. The 36v 20 ah rests at a little over 21.4 amps on my CA with a 6 amp load. I haven't done a load test on the 48v 16 ah pack but managed 60 miles out of it with a lot of stop and go and 8 bridge crossings. I'm about 175lbs and my ride is a s-60 Schwinn mtb with a lot of added stuff. Powered by a the $180 rear hub from Jason (wish I bought more great motor) about 3 months ago. Top speed pedeling is just over 30 mph. I know it's hard to tell what we get from China / Ebay but the prices were great, I didn't pay over 650 for the both packs. Shipping was fast and well packed. I also have a PING 48v 12ah? pack but it has it's prblems it tests out at around 9 amps and it's only 8 months old so don't give all these guys a bad name untill we learn more. Ping has sent me replacement cells at my cost, but he has been very good communicating when you have a problem and so does Lau chang / emma I cchanged the connector on the charger looked at my dvm and didn't even notice I had the wires reversed and blew the charger, my fault so I can't blame him for my stupidity. As I said there will be good and bad and some so so deals on Ebay, ifd the price is right take a chance i did and I am very happy.
Thanks for listening.
Dand214

 

[needWheels]

48v 16ah is the old prismatic style. Is that the shrinkwrapped one?
60 miles seems almost impossible unless you were going very slow, like 20mph or less and definitely on a brushless.

All I know is Lau has no control over his stuff as it's drop shipped. You got lucky. I didn't.
Who wants to take that kind of gamble? I was very foolish.

It's now 5+ weeks from the original sale date and I STILL do NOT have a working charger, had to spend $20 to send the old one back, and may never get a replacement at this point. To my last email he just said that he will be away for the weekend and will reply next week.

Monday is dispute day at this point, unless he give me reason otherwise but I suspect not.

 

[needWheels]

Suddenly he shipped the charger today finally. Imagine that, all I needed was to dispute.

 

[lifeonourplanet]

Hi i just want to point out a few things about batteries as not everybody fully understands Ah (Amp hours, the amount of hours you can draw one amp or how may amps you can draw for one hour, etc.) and the discharge rate or C rate (how much power or current in Amps your battery is designed to provide at any one time, there is a constant discharge rate and a maximum rate, the maximum is only to be used for short bursts between .5 and 30 seconds depending on the cells).
If you have a 20Ah battery and it has a maximum C rating of 2C then you can draw a maximum of 40A at any one time, however you should try never to reach this maximum if you want your batteries to last long time :lol: If the constant C rating of each cell is 1C then you are able to draw a constant current of 20A if the finished pack is rated at 20Ah. Same thing applies, try not to push your cells to the limit. perhaps try to draw no more than 10-15A continuous if you really want to get those 2000 charges (assuming you have a good BMS (battery management system) which can balance the cells until fully charged or near fully charged, ie you don't want the charger to stop charging when the strongest cells have reached their top voltage as any lazy cells will start to get left behind more and more each time).
The C rating is just multiplied by the final Ah rating of the pack, the same cells could be used to build packs with different Ah by putting them in parallel (the desired voltage is achieved by placing the cells in series) so If the constant C rating was 1C and it was a 10Ah pack you can only draw 10A constant and you should be aiming to keep it down to about 7A to be on the safe side(just to get more life from your expensive packs). Not much power there! It would probably be over the limit on a 24V 250W motor (you may still reach fairly high peaks with a 250W motor when accelerating and when hill climbing), it would be ok if you rode it gently and no hills. However if there were three times as many cells in Parallel, the pack would be 30Ah so 1C x 30Ah = 30A constant, now you can start to ride bigger motors or tougher terrain and have more Ah usage on your bike. Generally if you want more power then try to find cells with a greater C rating such as 5C constant and 10C max. This all depends on how many Ah you want to end up with. There are many cells with a 20C max and some with greater C rating .
If you have a small motor then it's ok to use low power packs but if you need monster power and you don't want to damage your investment it is necessary to spend more money, if you decide wisely about which cells you are going to use for your type of riding then it should be money well spent. Saying that there is always the possibility that we will see new cells on the market every few years, i imagine the prices of new cells will not drop but old design cells will get cheaper. So perhaps you can thrash the little packs, get 2 years out of them and expect to get the same packs again in two years for half of the price? who knows? Batteries generally do not advance in technology as fast as computers.
So please choose wisely when buying packs, find out how much discharge current you will be drawing find out what the pack can deliver and try not to push it. There is nothing wrong with a vendor selling a 20Ah pack that won't run a 750W ebike as it may be fine on a 250W motor. 20Ah is just that it can deliver 20A for one hour or any division of this A/hrs it does not necessarily meant that it also has loads a punch to go with it.

 

[lifeonourplanet]

By the Way yes i am also izzzzzz6 but i will be using lifeonourplanet as my profile name from now on. I am new on the forum and forgot to change my post the other day to the new profile name. I will be posting youtube videos later this summer to lifeonourplanet on youtube. There are currently no videos posted, i will let it be known when there is something interesting to watch.
As far as Lau Chan go's i will see on monday what he is able to offer me in the way of high rate cells. It was my mistake to make an offer on the 30Ah pack before thinking about how much current i needed to draw whilst riding in the mountains. The 30Ah pack would have been great for long distance road riding on a small motor, it probably would have been fine taking it easy on a 500W or 750W motor. Then i thought about the abusive riding i intend to put the pack through, bumpy with steep long hills etc. Hopefully he can help me find the cells i need. It seems his shipping price is ok compared to some of the big companies. Anyway i have tones of prices on cells, packs and shipping to compare the final deal to. I will let you know as i know more.

 

[lifeonourplanet]

This is the latest email, so so far they are trying to help:
Hi James
Thanks for your reply

I have checked for you.
"What i propose is that we find some high rate cells and build a 20Ah pack. If the C rating of the cells was between 3C and 20C constant discharge (depending on Ah) then we should be able to create a long lasting powerful pack at the correct size".

the prismatic cell I recommend is 1C constant dicharging, peak 3C discharging (15 seconds around)

I need to try to find the cells you mentioned.

If there is any news, I will let you know

By the way, I will be out of office on Sunday

Thanks and Have a nice weekend!
Emma

 

[needWheels]

Well like I keep saying, Lau is a drop shipper with no reserves, cash or parts, to handle damaged or failed parts. All my emails with him have been polite - then I realized after a month, it's a polite stalling technique, there's no real help coming.

I assume the only reason you are trying to negotiate is because he has your money and you don't think you can get it back.

I suggest you keep insisting on better quality high C cells which he won't be able to offer for a good price (or find) and then offer to pay him for the cost of the ebay listing and try to get the rest of your money back. PayPal allows him to do a full refund with no fees for 60 days after the payment. He could literally do a 100% refund and it would not cost him a thing except for the ebay listing fee (35 cents) and the final value fee (varies, usually 8%) but even the final value fee can be returned by ebay to him if he files the right claim.

Then get in on the headway group buy, ASAP.
It's what I would do if I could do it over again, which is looking less likely than I hoped.

Note his prismatics are VERY heavy.
The 20ah pack is 35 pounds, the 30ah pack is 45 pounds !!!
I couldn't even hold 35 pounds on my bike rack, at least not if I wanted to carry anything else.
The headway 20ah pack is around 25 pounds.

At least he is being straight up with you about the ability of his prismatic cells/packs, they cannot handle >1C for extended periods and definitely not 3C for more than a few seconds or you'll destroy their lifespan very quickly. It's just like the 18650. Their only plus side is that they don't suffer from 18650's 500+ welds which can fail over time (and they start at 58volts instead of 54volts which will give you a higher starting speed but watch out for blown controllers)


ps. did he try to negotiate with you after the sale to try to get you to pay more for shipping?
Several people report that is his typical technique and he also did that with me.

pps. make sure you look up how much it will cost you to ship things back to him when they fail, that might be a good motivator to try to get out of the deal - his address is in Hong Kong, not China, the parts ship from China but he has you return parts to him directly in HK