Power cut again!

[dofbikes]

Sorry Bart, you're right, your cells are not compatible!
For sure that "Les" or "Elmer" can tell you were to buy replacement cells exactly with the same dimensions, voltage and amps.
From my experience with GoldenMotor battery pack I can tell you that the best option is to buy a LiFePo4 DIY kit and a BMS like this - http://stores.headway-headquarters.com/-strse-101/DIY-36v16a-lifepo4-battery/Detail.bok?category=DIY+BATTERY+PACK+KITS.
There are so many options over the web, for me it's a question of reliability and having the chance to change something easily.
Shipping cost maybe a problem to sell your dead pack.

Rui

[Leslie]

Alright, so I have the right controller, the right charger, the right battery.  I think I have finally found my problem - sorta.

I have a 36V battery that is only putting out 29V!!!  I opened it up (since China doesn't return my emails, I figure there's no warranty) and I didn't find anything obviously wrong...  FYI, the charger is putting out 42V and the controller is correctly wired and reading the V from the battery.

HELP???

Here's some pics of the guts.  I tried to take multimeter reading where possible - each section of batteries measured 4.1V and wherever I measured all of them it only came to 29V

Please, if anyone has advice, let me know.  Otherwise I am done with this... Which is a shame because I built a very cool and expensive bike.

Is this the Pack GM messed up on?  The pack is a 24v pack in perfect working order and is LiMn because that's awful high voltage for a LifePo4 cell.  So is that pack still working perfect you don't want to pull it apart?. 

So you paid $80 for this bad pack all up?  Dude a microwatt don't pass without me knowing about it.

[Bikemad]

My pack did work fairly well for a few days, and hasn't worked since.

Hi Bart, you do seem to be having problems with your batteries, you must be the first person who has experienced a problem with one of the new LiFePO₄ packs.

I have some questions for you:

• What is the voltage reading of the fully charged pack?
• How does this reading compare with the voltage stated on the charger?
• Can you try and measure the battery voltage just before it cuts out?
• Did this battery come with a LiFePO₄ specific charger

Although the LiFePO₄ packs use different cells and BMS to the LiMn₂0₄ packs, they still have the same key switch and power connectors which sometimes caused problems on the earlier batteries.
It's probably worth double checking the power contacts for burning, and perhaps even try bypassing the switch to eliminate the possibility of poor switch contacts.

Although these new packs seem to be very good on the whole, there is always a chance with mass produced battery cells that the occasional cell is not going to be 100% perfect, so there's a real possibility that a single weak cell might be giving up under load, allowing its voltage to drop low enough to cause the BMS to shut down the power.
If this were the case, you would have to measure the individual cell voltages while the battery was under load in order to locate the faulty cell.

Anyone want to buy my 36V LiFePO4 (not working)

If only you lived in the UK, because then I would definitely have been interested!

Incidentally, if anyone in the UK has a dead LiMn pack they want to get rid of, please let me know.

Alan
 
P.S. I noticed on your video that your pack is actually labelled as a "Frog Style Battery Pack".

[Leslie]

Yes so Bart if he tries to swap out his cells in his first 24v pack testing at 4.14 (4.1) v*7=29v with his new LifePo4 pack

So here's where I am at.  I think I am going to try to take apart the battery and swap out the cells for new ones.  I have two of these batteries (a 24V and a 36V - the 36V is bad).  I have opened both the 24 and 36 batteries, but the 36V is different inside - it's all wrapped in plastic and hard to remove from the shell.  I can post photos and such later, but here's my initial question:

Thanks.

Yes so If Bart attempts to swap his old 4.14*7= 29v (24v pack) LiMn cells with his new 36v LiFePo4 pack he is going to end up in more trouble.


I just thought seeing he was going to pull the pack appart he may desire to help another with some spare cells..

[Leslie]

Also now Bart has made Rui's thread about Barts problem. 

FYI, the charger is putting out 42V and the controller is correctly wired and reading the V from the battery.

I hope he isnt using  his LiMn  4.2*10= 42v charger on his LiFePo pack 3.65v * 12 = 43.8v charger.

His battery could be way outta balance.

http://www.value-e-bikes.com.au/ElectricBicycleBatteries.htm

Li-ion chargers have 42v charging voltage, and LFP chargers have 43.8v
(If you are not sure of your battery type, see under side of charger)

Bart, I suggest you pull nothing apart.

[Leslie]

Lifpo4 12 cells and must be charged to 3.65v.  If Bart, just by chance is using the 42v LiMn charger he has.


Here

3.65v* 11 cells= 40.15v with a 42v charge the 12th cell could by now be sitting at 1.85v. 

Being a brand new pack, with some shelf life and self discharge, I do not like the prognosis for his new Lifepo4 pack, if my suspicions are correct.

[Leslie]

• Did this battery come with a LiFePO₄ specific charger

And if so, has he put this LiFePo4 specific charger away to save for ron.  (Later on.)  "And thought" I'll just use the old 36v LiMn charger that GM sent with the 24 LiMn pack and keep this LiFePo4 one new..

The possibilities are such Alan if you look back in Bart's post history. 

This has possibly snowballed from the original mess 24v LiMn battery, 36v LiMn charger way back in 2011, is now charging a 36v LiFePo4 battery and I am starting to feel empathy for Bart's pain and the hard learning curve he has been presented with from the initial problem..  And this is where I get pissed and need to go and do something else for a while.  Grrrr.

[Supatrike]

Hey Les and all, sorry to steal the thread from Rui, I'll start another.

Bart

This link to the new thread added by moderator.