Ebay Lifepo4 pictures -JimmyWu's (pic heavy)

[leamcorp]

I finally had a time to open up JimmyWu's battery and took some pictures - its a horror.

First it took me about 1/2 - 1 hour to get the duct tape off - trying not to damage more. There were several layers of duct tape, then a plastic film, and back to duct tape down to raw cell. This one is badly damaged and I'm trying to rebuild it with Pings BMS - here's the pics,View attachment 3View attachment 3View attachment closeup1.JPG

 

[leamcorp]

More pics,

 

[leamcorp]

Last batch,

 

[leamcorp]

Now I have a question - I need to reconnect the positive wire to the battery. How do I do that? Do I just solder the tab? Not very good at soldering - will I damage the battery by getting it too hot?

Sould I get a fresh tab and then solder?

And where do I get these tabs?

Thanks

 

[Link]

You can solder to the batteries, but you need a big iron (~45W) and a bit of skill to do it. You also have to work fast, since you can damage the cells if they're allowed to get too hot.

Unfortunately, I can't really think of any other way of reconnecting it without a spot welder. :?

 

[docnjoj]

Leamcorp! Links right. I use an 80 watt iron, dont use a gun! It wont retain enuff heat. Practice on some copper or brass first. Then use a stress reliever loop or tape the wire to the side of the battery firmly before U run wire out of covering! Use good solder, prefferably with lead in it! Then get a good BMS! The world class expert Bob Mcree says dont hold the heat on more than 5 seconds. So U have to use a big iron.
otherDoc

 

[dogman dan]

That is depending on too many spot welds for me. I think we need to build batteries out of at least 10 ah cells.

 

[pwbset]

That is depending on too many spot welds for me.

Haha... yeah, but here I am thinking, "damn... I need to build one of those $200 tab welders for my stack of konions"... gotta be sooo much easier than trying to solder together 120 18650 cells. Ugh! :lol:

 

[leamcorp]

Thanks folks. Iv'e just ordered a 80watt iron and 1lb of 50/50 solder. Thats should do it.

Oh well, learn from my mistake?

 

[fechter]

The cells say Valence Saphion, which are top quality cells (normally).

The trick with soldering cells is you need to finish the joint in something like 5 seconds or less. Any longer and the heat will travel into the guts of the battery and cause damage. If you don't get the solder to flow in 5 seconds, back off and let it cool for a while before attempting again.

Clean surfaces are also very important. Use Scotchbrite or sand paper to clean the metal. Use paste flux on the spot you want to solder. Use lots of pressure to get good heat transfer. There is a tutorial on soldering A123 cells posted somewhere.

In your case, it looks like you can solder the wire back to the existing tabs. If you solder to the tab half way between two batteries, very little of the heat will make it into the cells.

 

[johnrobholmes]

With a proper iron and tip you should be able to solder it in less than one second. It would be best to pre-tin the wire and tab where you will be soldering, then hit em both with heat to join them. I use an 80w iron and hammer tip- best tip out there IMO. Hold a lot of heat.

http://www.cheapbatterypacks.com/?sid=1327959&pgid=bldg scroll down to hammer



Awesome pics too. That is one helluva nasty looking pack.

 

[Ypedal]

If there is tape glue residue on there, wipe it down with rubbing alcohol or lighter fluid to remove all glue and oils before you get going.. and as everyone said above.

 

[leamcorp]

Okay you guys are making me nervous - I'll practice. I bought the solder with flux buildin. Do I still need the flux?

Also, any of you guys want to play with BL36? I have a sensorless hub/conroller in 700c - the wire was cut and I've reconnected it back but is not working. Don't know if its the motor or controller. I'll pay the shipping + your trouble. If you mess it up - no biggie.

 

[johnrobholmes]

You don't need the flux, but wiping a bit on the battery bar would speed up the heat transfer and make it faster. There will just be extra mess from the extra flux.


BL36? I could give it a whirl if you want. I play with electronics all day anyway. Never seen or used the combo, so I will be learning about it.

 

[dogman dan]

When I cut a wire on my bd36 it fried the controller.

 

[leamcorp]

You don't need the flux, but wiping a bit on the battery bar would speed up the heat transfer and make it faster. There will just be extra mess from the extra flux.


BL36? I could give it a whirl if you want. I play with electronics all day anyway. Never seen or used the combo, so I will be learning about it.

I'm waiting for a controller (48v version) from knuckle. Once that's in, I'll send you the WE kit and the new controller - in case the original controller is dead. Hope it gets here soon.

Dogman, thats what I thought too but I don't have the skill to tell one way of another. If John could determine that all I need is a new controler, that would be great.

Thanks

 

[ejonesss]

i would say horror it ises a bunch of 18650 cells series/paralleled .

 

[tapholov]

Hi,

I've also got a 'taped' battery bearing the same label. It was from 'United Western Music' or something like that...

And it's been hell ever since.

Short storey: I bought it on e-bay for cheap (an auction is an auction) $250. The guy wanted a $100 more, so I e-mailed to do it in the shape I wanted. Weird communication since he doesn't seem to read english properly. I wait. I e-mail. I wait. E-mail again. The guy is waiting for the charger. After a complain from PayPal, he finally sends the battery which is not shaped the way I wanted it and the charger is fryed. I bitch, I get my extra $100 back. He wants the faulty charger back (which I send) and I get a new one later. All of this took two months.

So I had plenty of time to reshape the battery pack to fit my bike. As you can see from the pics, it's not the greatest of job but somehow it worked.

Or seemed to...

 

[tapholov]

Hoop! guess the attatchments didn't go throught.

Here they are...

 

[tapholov]

O.K.

So in regards to this topic, I think welding only requires concentration... and a welding gun that works quick. I stuck to welding on to the thin strips.
Be prepared and make sure that every weld is done quickly. The flux bubbles, everything has to melt together real fast and let it cool.

I have to agree that the initial workmanship on the battery pack was a bit flimsy. I'm bad, he's worst.

And that wasn't the end of my problems.

Once the pack was together, I tried it for fun. I had 53V and why not!

It failed instantly and I had no way to recharge. So I waited for the charger.

And upon it's arrival, it failed to connect.

And I had to thinker this for a time until I figured that I needed to by-pass the BMS and charge directly.

This pack is made of 16 rows of 11 batteries and had all rows at 3.29V except for one at 1.9V. Something was wrong. Upon recharging directly, I got the overall volts to a level where the charger actually felt everything was charged (57V). I did this in time increments because I'm always afraid with working with electricity and all these stories about batteries blowing up really scare me. But logic prevailed and the battery pack went up to 57V and I though that was good. All 16 cells were up to par within a Volt.

Wrapped things up again, on to the bike, and the way we go.

Wow, that was cool! But the batteries failed constantly. It accelerates but shuts-off. I accelerate slowly and it goes to top speed (49km/h) and then fails again. I keep disconnecting the battery wires and reconnecting and things work again for a small while. But this situation fails the more I do it.

So far, more thinking is needed. What is wrong? Can these batteries handle the power pull of the motor? It works fine with the 36V 20AH. Is the BMS wrong and it cuts off too quick? Is there a block of cells that are wrong? This happened with the 36V pack. One battery went dead and was replaced by the company and everything is A-1 since.

The 'Western United Music' guy has disappeared from E-bay. I can't complain anymore.

I have to unwrap the pack again and figure out what every part does. But I suspect the BMS to be faulty. The weld job on it looks rather ugly, same as your's. Maybe it affected some of it's components?

Any suggestion from people in the know?

Hugues

 

[Ypedal]

That string at 1.9v is likely toast... ( either one cell in the paralell group is shot and sucking current from the others and will ruin the string ) .. If this is the case then the BMS is doing it's job because as soon as you apply load to the pack that string falls below 2v and the BMS kicks in..

possible problem 2 is that the overcurrent is kicking in and forcing you to reset if you pull too many amps..

Even tho your controller is a " 20 amps max " .. at low speed the pack will see much more than 20 amps.. it's weird but common.. :|

Time for a bench test !!!!

 

[dogman dan]

Gee I hope the bench test involves tying a certain someone to a bench and .....