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

Well, I am by far any no expert, I myself have just got in to this venture, but from what I have read on this forum ( and I would assume u have too, (200+ posts), this would look like a typical duct tape pack. There are many topics on them, and the ways to test them. You sound a little fired up before you even test it..... plug it in, test it, break it in, then see how is goes...

This whole battery thing in still new, and it's people like us that actually test them.....bottom line..it looks good so far, so strap that baby on and go for it...then come back and say yeeee haaaaa. :0
 
Thanks for the feedback everyone!

Voltages at the leads read:

53.2
49.8
46.5
43.2
39.9
36.6
33.2
29.9
26.6
23.3
19.9
16.6
13.3
10.0
6.6
3.3

So most are 3.3 and two or so are 3.4 but none are under.
The ones that are 3.4 usually flickered on the meter between the lower and upper value so I wrote the upper.

So that looks very well balanced, yes? This is before any charging at all by me.

Now to look at the wiring and get cracking on that.
 
Well everything is wired up with temporary wiring. Only using 16 gauge to my controller but it's temporary - those wires coming out of the BMS are so massive it's impossible to put any kind of connector that I have on hand onto them, so I will have to go to lowes and see what I can come up with.

Apparently the charger just wires back into where the battery comes out, it's just like SLA, you charge back in where the power comes out? You just can't have it doing output while you are charging so I unplug that when I plug in the charger.

Charger wouldn't do anything, both lights on, so I assume the pack is fully charged @ 53.2v
Very quiet fan in that charger!

Thanks for everyone's patience while I figured all that out, so far so good, first ride on it in a few hours.
 
you have to charge using the charger negative wire to have the bms balance the pack. On the diagram, your charger postive and the discharge postitve get permanently connected together.

Sounds like your pack has survived an incredible journey. Mounting the 48v 20 ah round cell pack is a challenge. The rear rack is your only option, so you will need to get one that carries it as low as possible. It will feel bad at first, but after some riding, you will adjust to the balance of it.
 
sangesf said:
I've got a 24v 30ah pack from Mr. Lau.

Average ride usually gives me max 27 miles(by the way that's no pedaling). 99% of the time I do 90% DOD. I have (doing the math - 2500 miles / 25 miles per charge on avg) = 1000 Charges!

GO LiFePo4!
Click to expand...

Check your math. 2500/25 = 100 charge cycles not 1,000. You've got a long way to go to reach 1000.
 
needWheels said:
Charger wouldn't do anything, both lights on, so I assume the pack is fully charged @ 53.2v
Very quiet fan in that charger!
Click to expand...

Usually, two red lights means charging, one red one green means charge is complete.

I read a good tip in another thread: don't be tempted to immediately find out what your range is by riding to low-voltage cutout the first time out. Let it get a few charge cycles to break it in before stressing it to the LVC point.
 
Large "T" pins work well as probes, and you can take some small shrink tubing to insulate the shaft to avoid shorting. Avoid pooking holes in the insulation of any wire that gets exposed to moisture, it breeds corosion.

My SLA charger's fan only runs when it's actually charging and then shuts off when the packs get full.

Just got tracking info on my A123's, gonna be here today...ye haaa.

Good luck needWheels!! Break em in easy..
 
dogman said:
you have to charge using the charger negative wire to have the bms balance the pack.
Click to expand...

Wait, just to make certain, I am charging right back through the positive and negative leads that go into my controller right? There is no alternative negative wire from the pack, not that I am aware of.

In any case just got back from a 4 mile test run on level ground. :) :) :)

Pack performed perfectly, though I stayed under 20mph the whole time except for a short bit at the end where I have to ride with traffic and there is no bike lane, so I slowly pushed it full throttle. 25mph at the end of a run with no sag is a very nice feeling.

Still can't do over 25mph though, so maybe my BD36 simply can't do it. I doubt my temp. wiring would make me lose 4mph.

Pack voltage after sitting for an hour now is 52.9v which sounds good I guess? Only 0.3v loss, impressive.
My SLAs would be in the low 40's at this point, lol
 
I have received a Lau Chan's prismatic cell 48V 20Ah battery in the end of April and it came with the same PLC4806B charger. I measured the charging current and it was 4.85A. I have no motor yet, but I disharged the pack with 7A current about an hour and after this I measured voltages and battery was in balance.

Is the smaller shrink taped BMS older and unreliable design? I do not have such huge BMS like you have got.

Let's keep fingers crossed, that batteries will last :wink:
 
I'm surprised your pack weighs 25 lbs. I received mine last friday at the local post office. It started out EMS and then to USPS. It's a 48v 15ah. The thick wiring on the pack says 6mm. About 3 times thicker than 12 gage. Radio Shack sells inexpensive multigage wire nuts.
Just twist them on and duct tape over the nut and wiring. To use andersons would require removal of
alot of the copper strands on the 6mm. Anyhow, my pack is a scant 15 lbs. It can't be 18650 cells (unless I was cheated on the amps) I still don't know.
I feel lucky as mine arrived undamaged. Very nicely packed. But the BMS is on sideways and would be tough to center.
Also, my pack shuts down on the BD-36 any time I throttle hard. I have to use it on my other bike.
 
Refering back to the lifepo4 hk wiring diagram you linked, its wire 4, from the bms. Usually there is three wires from the pack, one fat positive, one fat negative. Those go to the controller. Then there is a skinny negative to charge and the other charge wire is also the fat positive. No third wire anywhere?
 
RTLSHIP said:
I'm surprised your pack weighs 25 lbs. I received mine last friday at the local post office. It started out EMS and then to USPS. It's a 48v 15ah. The thick wiring on the pack says 6mm.
Click to expand...

I think his listing claimed the 20ah was 10.8 kg which is ~24 pounds and within the inaccuracy of my analog scale.

The 15ah packs have 176 cells vs this 224 so my math says you should be around 18.7 pounds ?

176 = 16 strands of 11 cells, so your ah range is 13.2 - 15.4

If the 15ah had a real 3C capacity I would have gotten that but since I have a brushed motor I knew better and I knew running it at 2C+ frequently will kill a cheap pack based on what I read around here.

RTLSHIP said:
Also, my pack shuts down on the BD-36 any time I throttle hard. I have to use it on my other bike.
Click to expand...

That's specifically why I got the 20ah, since I also have the BD36. I read in several places around here that the BMS on these lower end packs are specifically tailored to 2C, so your cutoff is 26-30a while the BD36 controller will try to draw 35a on hard acceleration/hills (plus or minus 5a according to what someone said earlier around here)

The good news is that brushless kits are getting cheaper and cheaper and seem to be tailored to 20a so I might upgrade next year myself. So much for a low cost ebike if we keep buying stuff eh? It's addictive. I bought $30 in locks today!
 
dogman said:
Refering back to the lifepo4 hk wiring diagram you linked, its wire 4, from the bms. Usually there is three wires from the pack, one fat positive, one fat negative. Those go to the controller. Then there is a skinny negative to charge and the other charge wire is also the fat positive. No third wire anywhere?
Click to expand...

Yeah that diagram doesn't reflect reality on this pack, maybe it's the newer BMS.
There is no third wire/skinny negative.

Going through my photos I wish I took more of the wiring but here's the most complete one - there are no other wires than what you can see in the photo. The two yellow wrapped ends are the only "open" wires for connections. The thick black one goes directly from the pack into the BMS, soldered in.

Is there any danger if I am wrong and I try to charge back through the negative that goes into the BMS?

 
Wait, I take that back, now that I think about it and look at my photos, there was a stub of a wire wrapped in yellow on the 16s breakout connectors. I didn't think anything of it because it looked too short and I figured it was just an unused connector, which I stupidly wrapped in tape for strain protection - I guess I better unwrap it and take a closer look. It's a strange place to put a connector, why would they do it that way?

View attachment wires2.jpg

View attachment wires3.jpg
 
Since CammyCC sells the same BMS I am looking closely at their photo.

http://www.superetrade.com/images/cammycc/bicycle battery/pic/cc5.jpg

Notice in the bottom right photo that thin black/red wire, it's going up the side.
Mine came with those black/red wires detacted in a bag so I have no idea where they go :(

Actually in this photo, it looks like the black and red thin wires are seperated and go directly into the board the same places the thick black and red wires come out of, so maybe on this BMS the power in is the same place as power out?

View attachment wires4.jpg
 
Well I went and tried the charger but I guess 0.3 volt drop is not low enough for it to be willing to try to charge.

I get one red led and one green led, so I take it that means it's charged.

Almost funny that 4 miles has virtually no impact, my SLA's would be charging for an hour or two.

I guess I will try a longer ride today.
 
I'm suprised people are still buying batteries from Mr. Lau (a.k.a. Jimmywu66, EastUnitedMusic...etc.). Especially since many experienced horror stories purchacing from him as in this thread http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=6034. My experience was very discomforting at first but it turned out to be okay at the end. I've now got just over 2,000 miles logged on my 48v15ah battery pack and it's still going strong.

It works fine on a system that pulls only 1c from the cells with an occasional 1.5c draw when climbing hills or accellerating. But it definitely cannot take higher than 1.5c current draw and results in profound voltage sag. I've tried the pack on my other ebike with a 35amp controller and it's fine for the first 8 minutes of full throttle but then the voltage sags and I start losing speed. I think I'll keep it on my 1st ebike with just the 20amp controller.

needWheels I think you'll be fine with that battery pack on your ebike setup. I think your controller and brushed motor setup can possibly run at 24mph at full throttle and the batteries can handle it. But as you've found out ebiking is very addictive and I'll give you about half a year before you'll be wanting to upgrade controller or motor (or both) so that you can go for higher speeds or accellerate faster. :mrgreen:
 
I'm confused now too about the wiring, I'd get an email off to mr lau about it. Looking at the cammy pack pic, looks like the new bms has just the two outputs, and they put a charge wire on the same terminal. Odd that your charger isn't running, on mine it will start charging if i do a 5 second wheel spin test. Bad connection somewhere on the output wires? See if there is any voltage coming out of the charger. If there is a bad connection on the output end of a charger, the led's will indicate charged.
 
Looking again, that stub is on the balancing wires. Maybe its there for probing voltages? What I was expecting was another negative from the bms pack, not a wire between bms and pack.
 
If I got a lower end pack, then I'm a dodo. I could have bought one more like yours from volgood on ebay for less than what I paid. Thus, I bought a lower end pack at a higher price. The only thing I gained is 3 1/2 lbs less weight.
 
Just got back from a slightly longer 7 mile test ride today and it's the most fun I've ever had on my bike :) a year of sagging SLA was hiding all the fun! Lifepo4 was the best investment ever!

Hey dogman, I finally broke the 25mph wall - apparently after it hits 25mph, you need another quarter/half mile or so which I never had the space in the city previously to keep the throttle open all the way - hit 27.5mph for a few minutes and then duplicated the results on the way back so I know it was not a fluke with the wind. I wonder if that 1.5mph difference between mine and yours is the fact (as I suddenly remembered today) that part of my old circuit has 18 gauge wire in it to the switch because it was all I had a year ago on hand. Or my magnets could be slightly out of alignment.

Absolutely no cutouts, even had a hill on the way out and the way back, it didn't blink - I bet the better BMS has solved the problem (and that the pack is 20ah 2C).
I had an "emergency" full power start when I had stopped on the side of the road and then realized a car was coming and the pack did not let me down.

I was nervous but I am very happy now. Just last 5 years and I'll be thrilled.

ps. Voltage after 7 miles (with 4 miles yesterday) is 52.5 - about to test the charger...
 
Okay running the charger to my meter shows 53.1 to 53.4 volts output, jumping all around inbetween.

Should it be higher - considering the pack is 53.2-ish , doesn't the charger have to be higher than the pack?

The red and green led is on when connected to just my meter, not sure if that means anything.

About to try a battery charge...
 
Okay something is definitely funky with the charger.
The green and red lights are on and I am not certain if it's doing anything.
I will leave it plugged in for 30 minutes and check the voltage afterwards.

update: after one hour the pack is reading 52.6v so that's virtually no gain over 52.5
the bottom of the charger is very warm but not hot, the fan never came on

Going to look inside and take some photos...
 
My 48 v pack reads 59.5 v when fully charged. Thats what the charger goes to. Put multi meter onto DC charging part.
It should read 59 or 60. Once removed from charger mine will drop about 2 volts in half a day or so. I'm refering to my 48 v
15 ah.
At 15 lbs, I suspect this ebayer might have sent me 10 or 12 ah pack. I just emailed him. I say this because it should shut down at 30 amps not 10 amps. It's shutting down on 1/8 throttle with pedaling ( on BD-36) On the Brushless, no sweat.
 
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