found new cheap site for BMS, LiFePO4 & charger up to 18000W

[caleb7777]

I doubt it, the batts are packaged pretty well, he could've stuck the shipping label on it without the box me thinks

we'll just have to see what the next is like.

 

[Gow864]

Hey Allen - We've had this discussion already. You want to sell your products - go create your own thread in the advertisement section.

Michael, I like your style! LOL

 

[patrickza]

I've been in contact with Mandy about an energy transfer BMS for the headways I'm thinking of using. She mentioned that she has the 38120 cells in stock for $15 each. On the pricelist they list the 38120 10ah and 38120p 8ah. Sounds like the headways. could they be getting a discount from headway, would be nice if the price was that good. I've sent some messages enquiring so I'll hear soon I guess.

 

[dnmun]

since the pack was dead, it would really help to know why. can you take some pictures of the pouches and the BMS closeup enuff that we can look for shorts or something that coulda caused it to fail?

the 38120 may be headways, they had an older one with the brown paper sleeve, and then the sleeve changed to blue, still with the welded tab, and now they have the blue cell with the screw boss in the end cap.

 

[caleb7777]

sorry dnmun, all i really know is that one cell appears to have been dead and must have pulled the rest of the pack down with it. Couldn't charge with one cell down?

 

[dnmun]

but how? why was the one cell dead? it would help to know before more people buy these batteries. the manufacturer or reseller is not gonna tell us so we have to finger it out.

if i were you i would actually not take another battery like this from them without knowing why it died. jmho.

 

[caleb7777]

I understand and I agree with you. But I knew i was taking a chance with this seller and he has been very good about it so I want to see what the next battery is like. If it works properly then I still got a good deal.

if it doesn't then we will all know.

 

[v_tach]

Anyone have anymore experience to comment on with ecitypower lately? I've sent an email inquiry about a particular product and no response after three days.

 

[Ultraman]

Anyone have anymore experience to comment on with ecitypower lately? I've sent an email inquiry about a particular product and no response after three days.

I emailed Jack about delivery of my 36v15ah pack and two chargers a few days ago as it was a week after the promised shipping date with no updates. He emailed back and said he'd send the pack and chargers out after he got back from the big Dragon Boat festival in Guangzhou. Two more emails requesting my phone # to provide tracking info, but no tracking # and no further contact in the past 4 days. :x I'll email him again and see if I can get this back on track as my bike won't go without a battery.

 

[Achim]

Seems like not everyone was as lucky with their battery as I was
I have it (48v10ah) for a few weeks now, and until now I'm very happy with it. Despite the fact that I still don't have a functioning Wattmeter, I would like to comment on how it performs. Ok, the acceleration I get with my 9C is quite good, I can even do wheelies if I push the pedal hard once when I start! Also tried starting at a very steep hill without pedaling, and it goes to 15kph pretty smooth. On flats I do 46kph on a fully charged battery, which isn't bad either. Last weekend I went to visit my family, which lives 24km away from me. The route is pretty flat all the way, except one or two short hills. On may way there, I averaged 41kph, always WOT with some headwind, it took me 35min to get there. I charged it up at home and when I went back, I averaged 44kph! The controller was pretty warm on arrival, and I only felt a slight drop in acceleration and top speed on the flat was 43kph at the end. I wanted to check the battery voltage to see about how much electricity there was left. It still showed me 52.5v! I also measured no load WOT voltage, which dropped to 52.0v at the start and then rose again to 52,3!.

Is it possible that there is so much left after 24km no pedaling? Maybe it is, assuming that I pull about 9amps at full speed on flats, I would be able to ride for 53mins for 100%DOD, so after 30 mins there is still much left... How much amps do you guys pull at a similar speed and volts?

 

[kd8cgo]

I have ordered two chargers from this company just now, a 400W and a 600W model. I will report back once (if) I receive them on how the transaction went and how the chargers perform. I specified the voltage set points in the order comments, we'll see...

edit: The chargers worked, and still work, very nicely, even all this time later!

 

[pasteque]

as achim , i'm surprised to read the bad experiences of some of us with this dealer
formyself i'm at my third command of battery , the seven battery i get from them were excellent , always provided within three weeks and jack was always here and very kind to answer all the questions i asked.....

can someone explain me very clearly the difference beetween energy transfert BMS and resistor bleeding BMS.....i can't manage to get good info about it either with jack and french electric bike forum....... thanks!!

thierry

 

[webfootguy]

One of the functions of a BMS is to prevent overcharge of a cell while still charging the other cells. The usual technique is to "shunt" some of the charge current around the cell using a resistor. This allows the other cells to accept more charge while protecting the cell that is full. If you charge at too high of a current, you can overwhelm the bypass resistor so often the BMS has a way to tell the charger to throttle back (or it throttles is back itself via a FET). The extra energy shunted around the cell is lost as heat. Another technique to compare groups of cells (like cell 1 to cell 2) and charge up a capacitor (or inductor) from the higher voltage cell, then discharge it to the lower voltage cell. This "shuttles" excess charge from the fuller cells to the less full cells. This technique is more complicated, wastes less energy, makes your recharge time faster, and only works well if your cells are pretty unbalanced. It is hard to move charge when the difference in voltage between cells is small. Also if the highest cell and lowest cell are not near each other, the technique is not very effective. Does this help?
--phil

 

[julesa]

Unfortunately I haven't been able to test everything because I don't have my cells yet, but I've had a good experience with ecitypower.com so far. I received the wrong item, but when I contacted Jack he promptly shipped the correct item.

 

[shinyballs]

Got 2 of these bms boards for my 11s pack. Jack said it cannot be used for 11s, in ES we just don't concede without finding ways for it to work. Any inputs ...?

Model: BMS-12S-20AR
Description: 12 LiFePO4 Cells in Series Resistor Bleeding Balancing BMS/PCM

 

[julesa]

Got 2 of these bms boards for my 11s pack. Jack said it cannot be used for 11s, in ES we just don't concede without finding ways for it to work. Any inputs ...?

Model: BMS-12S-20AR
Description: 12 LiFePO4 Cells in Series Resistor Bleeding Balancing BMS/PCM

In the ES BMS thread manfred59 was asking about modifying that BMS to run with one fewer cell. Not sure how closely this BMS design resembles that one, but I think the basic principles are pretty close.
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=5416&p=139110
I'd love to learn more about this one, I bought two of the 16S versions.
I see they sanded all the part numbers off yours, too. :? Don't care that much about the FETs, but I'd sure like to know what that other chip is, I think we're stuck without knowing that. Might have a similar part on the old Ping BMS -- anybody have one of those laying around?

I'm an electronics noob, I'm a lot more comfortable building email systems. But you gotta learn somehow...

 

[dnmun]

the 14 pin package contains the 3-4 comparators used by the logic to control the FET gate output. you can figure out the leads because you can see the gate drive coming out and you know you have overcharge voltage, low voltage, shunt delta voltage all driving the FET gate driver.

 

[julesa]

the 14 pin package contains the 3-4 comparators used by the logic to control the FET gate output. you can figure out the leads because you can see the gate drive coming out and you know you have overcharge voltage, low voltage, shunt delta voltage all driving the FET gate driver.

Cool, thank you!!!! So we can see from the picture pin 8 (lower right) drives the lower two FETs, and I guess pins 9 and 10 are the inputs for that comparator... don't have my BMS in front of me but IIRC, the lower two FETs will control current to the controller, and the FET in the upper right corner controls the charger current.

 

[dnmun]

the trace at the very top has to be from the top of the battery imo, and it looks like the top left FET is driven by the output from the overcharge signal optoisolators. so the top row of optos is for the LVC, and you can find the signal trace going from the shunt over to one of the pins, and that should have an input from a resistor divider with the range set by a zener somewhere. but this is the BMS of the guy with the acupuncture problem, right?

i think the needles kinda short circuited his post, he stopped when he said inputs. not sure what input he needs but i don't see why he wouldn't just add another cell in series to get to the full 44V. more voltage, more speed, more voltage, more speed. but that is only a 10A BMS i think.

i can see the ground lead going to the 14 pin package from between the 2 FETs up there, not sure where or how it gets 5V for the logic and gate drive. maybe all that is in the 14 pin package and the resistor divider is done inside there too. maybe the zener is on the very top edge in that area where there are the 2 white squares. also the optos will need a voltage source themselves to signal when the level is excess or lower, so they need to have 5V to each of them to drive the output so that must come from the 14 pin package. so you should be able to figure out most of the pin outs on that package looking at it closely.

maybe the zener is internal and part of a voltage regulator they use with a resistor divider network inside also so there would be no need for a separate 5V source to the package, it would run off the pack voltage with a step down inside to the voltage regulator inside that package.

 

[julesa]

but this is the BMS of the guy with the acupuncture problem, right?

i think the needles kinda short circuited his post, he stopped when he said inputs. not sure what input he needs but i don't see why he wouldn't just add another cell in series to get to the full 44V. more voltage, more speed, more voltage, more speed. but that is only a 10A BMS i think.

:lol: LOL yeah it's the pinhead BMS, me and him both. :lol:

I'll dig into this more later tonight when I get a chance to look at my version of this BMS. Mine's got all 5 FETs installed and a few more channels but otherwise looks exactly the same. It's about time I got out my camera.

 

[dnmun]

so your avatar is the same guy but the sesame street version?

the thing easiest to find will be where the 5V comes off and goes out to the optos, and maybe you can figure which of the pins is the shunt input, some go underneath the package. or on the backside.

 

[julesa]

Yeah, there's all kinds of SMT fun on the backs of these boards.

The Pinhead character is from a 1980s Clive Barker movie called HellRaiser:
http://www.imdb.com/find?s=all&q=hellraiser&x=0&y=0

I don't think I've seen it since it first came out. I was in high school at the time.

 

[julesa]

Pics of the ecitypower 48V BMS custom upgraded to an 80A current limit.
Unfortunately my camera can't do better close-up shots, no macro mode.

 

[RoughRider]

so, WICH BMS TO BUY??

that shunt(resistor bleeding) or that energy transport thing??

after a few time charging, the cells will be nearly balanced, than you will not need that energy transport BMS...the shunt BMS will do its job also...and its much cheaper

at ecity the price for energy transport is 10X of shunt bms

 

[pasteque]

One of the functions of a BMS is to prevent overcharge of a cell while still charging the other cells. The usual technique is to "shunt" some of the charge current around the cell using a resistor. This allows the other cells to accept more charge while protecting the cell that is full. If you charge at too high of a current, you can overwhelm the bypass resistor so often the BMS has a way to tell the charger to throttle back (or it throttles is back itself via a FET). The extra energy shunted around the cell is lost as heat. Another technique to compare groups of cells (like cell 1 to cell 2) and charge up a capacitor (or inductor) from the higher voltage cell, then discharge it to the lower voltage cell. This "shuttles" excess charge from the fuller cells to the less full cells. This technique is more complicated, wastes less energy, makes your recharge time faster, and only works well if your cells are pretty unbalanced. It is hard to move charge when the difference in voltage between cells is small. Also if the highest cell and lowest cell are not near each other, the technique is not very effective. Does this help?
--phil

it helps very well !!!! thanks!
thierry