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

No you don't understand - the charger does nothing, doesn't get warm, the lights never change, the fan doesn't spin high - even Mr. Lau confirmed the charger should bring the battery up to 56-59 volts. This is not the old chargers they used to use, several vendors including Cammy seem to use this new one. It does true 5A output supposedly, it should get at least warm.

If I plug it into the battery when it's 52 volts, the charger does not change the battery voltage even after a few hours. My SLA charger will bring the pack up to 55 volts within the same time. So the lifepo4 charger is certainly not working. At all.

ps. I've never gotten 3.4v after it settles, do you have a duct tape pack or shrink-wrap pack from him they are different
 
My mistake. Since your charger was putting out 53.8v I thought maybe it would charge if your cell voltage was discharged below that. Have you tried discharging down to 3 volts per cell and seeing what it will do?

Since the charger doesn't look to be damaged, I'm thinking the problem may be something simple. Have you checked continuity on the fuse?

I have a duct tape pack. I checked voltage after resting a few hours after charging; it averaged 3.4v per cell. I just got the cheapy 2A charger with mine but it charges the battery fully in about 3-4 hours.
 
I have it open again now and the fuse is fine.

I really can't visibly see anything wrong with this, no trace breaks, no solder breaks, nothing.
 
Since the charger has a 220vac label on it, I wonder what would happen if you plugged it in to a 220vac source. Could be the transformer windings just aren't enough for a 110vac source to convert to 59vdc at the bridge rectifier.
 
Hi there
At sometime your charger has been conected to the wrong polarity. The voltage you are reading is a resistor voltage not a true voltage there is a resistor next to the minus on the battery plug side, inside the charger to test unplug the charger completly test the resistor you will see what i mean even not plugged in it will show 52 volts if this is the case change the resistor it will cost about £0.80p hope it helps it happend to me

Good Luck
 
lotsa chargers get sent with the polarity backwards.
 
dogman said:
lotsa chargers get sent with the polarity backwards.
Click to expand...

Ha, great minds... about an hour or two ago I had that thought and very carefully tested the polarity of the battery connector vs the polarity of the charger ... but they are the same... oh well :( if only it was that easy...
 
Paul.............D said:
Hi there
At sometime your charger has been conected to the wrong polarity. The voltage you are reading is a resistor voltage not a true voltage there is a resistor next to the minus on the battery plug side, inside the charger to test unplug the charger completly test the resistor you will see what i mean even not plugged in it will show 52 volts if this is the case change the resistor it will cost about £0.80p hope it helps it happend to me

Good Luck
Click to expand...

Wow this is interesting... (reading backwards sorry)

I will open it yet again and take a look-see...

wait, how can something not even plugged in show 52 volts?
 
there may be a zener diode in the output to protect the charger from the battery being reversed, and the resistor is in series so when the resistor blew, the circuit was opened and no more current could leave the charger.

i though that was the problem, that no current left the charger.

if current left the charger, the cells would increase in voltage, it is that simple.

take some pictures and we can show you where to measure the resistance.
 
It does indeed have a resistor I am going to make sure the polarity matches the board label but I have to think that doesn't matter since I match it to the battery at the leads.

 
dnmun said:
there may be a zener diode in the output to protect the charger from the battery being reversed, and the resistor is in series so when the resistor blew, the circuit was opened and no more current could leave the charger.

i though that was the problem, that no current left the charger.
Click to expand...

That is correct, no current. I will take photos of all the zener diodes.

Actually I think there is only one and it's on a daughter board.

I am out of my element here quite a bit and I don't know if I can measure resistors while they are in the circuit and even really how to do so. That big greenish resistor on my meter set to 20K reads 5.02, when meter set to 2000 reads 1578
 
needWheels said:
wait, how can something not even plugged in show 52 volts?
Click to expand...

Capacitors can hold onto voltage for months once charged, especially if the bleeder resistor is blown. Doesn't look blown though. Are you sure your meter is set to "20K"? That sounds like an ohmmeter setting and would account for the strange reading if you are putting voltage into an ohmmeter.
 
Here's the daughterboard, check out the quality on this (not)
there appear to be three zener on there? no where else in the charger...

charger-daughter-board.jpg
 
jimw1960 said:
needWheels said:
wait, how can something not even plugged in show 52 volts?
Click to expand...

Capacitors can hold onto voltage for months once charged, especially if the bleeder resistor is blown. Doesn't look blown though. Are you sure your meter is set to "20K"? That sounds like an ohmmeter setting and would account for the strange reading if you are putting voltage into an ohmmeter.
Click to expand...

Sorry I am jumping around answering different things.
The resistor showed nothing on the voltage test, even at microvolt settings
so yes, I switched to ohms to try to see if the resistor was intact.

Here is a picture of the entire board, let me know if anyone wants it even higher res.

110 ac Input is left side, output is right

charger-hires.jpg
 
Report this postReply with quoteRe: 48v 20ah Mr. Lau Chan / Lifepo4.hk pack arrived (May '09)
by jimw1960 » Fri May 15, 2009 7:41 pm

Looks like some of those solder connections have some big gobs of excess. Can you check if any of them are causing shorts?


Looks like jimw1960 has spotted the resistor that looks iffy must have hawk eyes tried to blow it up more it looks not position and a dry joint what is attached#

Paul
 
there are 3 2W resistors, i think they are each 100 mohm, and they may be in parallel to act as a shunt for the output current. the green 1W resistor over on the end looks like it is 5.1kohm. if you look underneath you can follow the current path as it goes out to the wires. the feedback eventually goes over to you "daughterboard" and maybe you can follow it over there, and read the part number on the 3 terminal device in the heat sink there, but looking underneath at the traces you will see where the current comes from. but measure the 5k1R first, just stick the probe tips right into the solder at the base.
 
That bottom right one is actually okay I think when I look at it here in 3D, it's just elevated a little.

Lovely quality control there eh? Did you notice this one in the middle which has two of them touching sides to the middle.

daughterboard-closeup2.jpg
 
you can check to see if there supposed to be a bridge there or not, it could be bad masking before flow soldering, that would be nice if you could suck up that solder bridging and have it work.
 
Well I got too depressed over all that to deal with it for now so I am putting it aside for while.
I really don't have the skills or tools to properly remove solder on that small of a board and it's attached to the main board with only a half inch of clearance to the front so it's very difficult to access. I'd probably make it worse.

I'll say this much about Mr. Lau / Emma, at least they are not ignoring my emails, every single email gets an answer within 24 hours, the problem is the answer is never helpful. He is now saying that EMS might still cover it without insurance if it's their fault. But I have serious doubts about that getting proven, especially if it involves the USPS which is notorious for not paying out on insurance (you should ALWAYS use 3rd party insurance when shipping domestically like DSI)

Wow shipping costs have gone up alot.
I keep looking for a cheaper way to get it back to HK but it's not going to be reasonable.
 
use desoldering braid, place it over the section you wanna suck up and heat it from the back with the soldering iron. try not to pick up too much solder or overheat the surface mount parts because they might try to come off with the desoldering braid. use hotter iron than if you are actually soldering the parts on.
 
Sent back the charger today, cost me freakin' $20 and he is going to slow-boat something back to me which I bet will not be the same amp level but I hope works. Sigh. Lesson learned. No pizza or movies for me this summer, unbelievably broke.
 
needWheels said:
Sent back the charger today, cost me freakin' $20 and he is going to slow-boat something back to me which I bet will not be the same amp level but I hope works. Sigh. Lesson learned. No pizza or movies for me this summer, unbelievably broke.
Click to expand...

So I guess you already researched the cheapest shipping method -- what carrier was it? I have a little return shipping I have to do too.
Thanks!
-Jules
 
julesa said:
So I guess you already researched the cheapest shipping method -- what carrier was it? I have a little return shipping I have to do too.
Thanks!
-Jules
Click to expand...

Cheapest way is to pack it in your own box and directly take to post office, do NOT use the online discount methods as they only offer international priority mail online which is VERY expensive. In the post office make sure they ring it as international first class mail (I had to argue with the guy who finally said "oh yeah" and found it on the 2nd page of their menu and then apologized to me)

What really sucks is it was 2 pounds 1.5 ounces and there was no way to get that 1.5 ounces back which would have saved me $2.50 or so in postage. I packed it as light as I dared. I asked Mr. Lau several times if I could just send the main board or daughterboard back for an exchange but he said no.

I have a bad feeling he won't even exchange it at the factory and just give me whatever he has laying around (he was surprised it was a 5 amp charger, he wanted to send me a 3 amp) but we'll see if I am wrong, I hope I am wrong. It will be the end of the summer before I find out. I hope I don't burn out my other charger which isn't meant for this capacity at all.

At least the pack seems to be holding up but I may not know for a year or more if I go by what other people's experiences. I swear it had more torque the first few rides than it has now but that may be my imagination.
 
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