Cheap Lipo4 from China

[bode]

Well, that's certainly made me think again! Was yours definitely from the same seller as the one used by the OP and others in this thread?

 

[Deleted member 4366]

I bought one of the Duct tape wrapped packed (CammyCC, Volgood.. he uses a few names) and was happy with it until I got a Cycle Analyst- the 20Ah pack was only giving out 12Ah.
I wouldn't have known without the means to measure the Ah used in discharging that the CA gives.

I don't know about Cycle Analyst, but the other watt-meters that use shunts to measure the amp-hours are not very accurate.I've had only 6aH from a 10aH battery on one watt-meter and 9 on another for the same battery. Normally, you need to calibrate them. So be careful about drawing conclusions. Just because it says a number on an LCD display, doesn't mean it's right. If I understand it right and you use the CA plugged in to your controller, there's a necessary calibration procedure. The watt-meters that use hall snsors to measure the current are supposed to be more accurate.

 

[aseb]

The cycle analyst is fairly easy to calibrate. It's all through an on-screen menu. Expensive, but it's worth it with top quality support from Justin at ebikes.ca
My Cycle Analyst figure is confirmed as accurate as the CA told me my 20Ah battery was only delivering 12Ah. Measuring the voltages fed to the Battery Management system showed that there were a number of dead groups (3 out of 8) in the pack giving no voltage- both figures match- 3/8 x 20Ah is 12.5Ah and because it has been used for around 60 - 70 cycles will be slightly lower, and it explained why I'd never achieved the expected range out of the pack.

It's up to you whether you buy or not. But that coupled with poor construction and poor support means I won't do it again.


Here's a few threads to look at
VPower / CammyCC 48V20Ah LiFePO4 Repair by Amberwolf
Volgood 48V20Ah LiFePO4 Repair by Amberwolf
Help me fix my 48V20Ah LiFePO pack
HK LifePO Batt 48V 15Ah problem..only 4.7Ah?
Why not post a question asking the guys on endless sphere for their opinion? They are several technically more aware contributors on that forum- just look at the posts, advice and projects they've contributed/been involved with. No disrespect to anyone here, but for that side of things they really are in a different league.

 

[Deleted member 4366]

Ok, that makes sense. I've often wondered about 18650 cell packs. They're very heavy and only held together with a bit of heatshrink, it must be very easy to distort the pack and break the connections, especially if the spot-welding is a bit dodgy. What's happened to all the pouch cell batteries that they used to sell - like Ping's? All the cheap Lifepo4s now are either 18650 or 38140s or similar, which are all a bit on the heavy side.

 

[bode]

Oh well, in view of the balance of negative comments versus positive on these batteries, I guess it will be back to Plan A and a Ping battery!

 

[Old Timer]

Oh well, in view of the balance of negative comments versus positive on these batteries, I guess it will be back to Plan A and a Ping battery!

I had a message conversation with MalcolmW and then we spoke on the phone and he hasn`t had any problems using the battery I originally suggested ( I think that was maybe two months ago) I`m sure he would have phoned me back if he had any problems.
As I said in the early days after getting the battery it performed very well and gave me 23miles on high power on the Aurora over mixed terrain flat out with a couple of knee jerker hills of 1 mile each, the bike pulls like a train. It now sits in the rear pannier of my Evans MTB conversion and has had a lot of punishment in one way or another seeing as that bike lives in the back of my van where temps can reach to staggering heights during the summer on my drive. The BMs seems to work flawlessly and the supplied free fan assisted charger keeps it in tip top condition. Don`t get me wrong, I`ve no doubt that there are plenty of dodgy suppliers out their( inc in this country maybe) but I`m preety sure that this guy isn`t one of them. (and don`t forget he will make the battery up to any reasonable configuration)

Going on from that you might remember me having to replace the battery on my wifes 24V bike (also for our folder) so as you might remember I strapped 2 SLA batteries together and even after buying a real good charger the total for the top of the range SLA batteries + charger was around £70 and they work better than the original £200 batteries (of course you can pay £300 as well)

So! the rule of thumb re: you get what you pay for: still in general holds hard and fast but I`m afraid I have discovered that depending on what the item is and what demands you are going to put on it (like maybe a safety harness for mountain climbing in these times of tight cash and an expanding 3rd world then there are some bargains to be had for sure.
Now, I think I`ll take my Evans+ cheap lipo4 out for an airing

original link http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=130380738444&ssPageName=STRK:MEWNX:IT

Dave

 

[bode]

So! the rule of thumb re: you get what you pay for: still in general holds hard and fast but I`m afraid I have discovered that depending on what the item is and what demands you are going to put on it (like maybe a safety harness for mountain climbing in these times of tight cash and an expanding 3rd world then there are some bargains to be had for sure.

That's why I think I will stick to my original intention to go for one from Ping, as I have heard no bad things about his, even though (perhaps because) they are more expensive.

I'm going to get a 20Ah battery because I really want the extra mileage, so I don't feel like gambling with that sort of expenditure!

P.S. I am using 3 x 12v 12 Ah SLAs at the moment because the bike's original owner installed them for reasons of economy (they cost him £52!), and they perform surprisingly well. But that performance is already starting to deteriorate, and they weigh 11.5kg!

 

[aseb]

Measuring the voltages fed to the Battery Management system showed that there were a number of dead groups (3 out of 8) in the pack giving no voltage-
.

Sorry- slight inaccuracy in the above- they were my initial measurements before I had finished the checking, I looked at my initial notes for those figures. The end battery groups voltages aren't monitored through the ribbon cables, and there are actually 12 groups of batteries in the way the pack is organised. The end by the no-voltage groups also had no voltage, others were ok, so bad groups are 4/12. This means 4/12 * 20Ah are available from the pack when new which is 13.3Ah. In relation to my earlier figures it just means the pack is a bit more age-worn than was suggested- it is over 2 years old now so no surprise.
(It'll teach me to double check my figures before posting next time- it just popped into my head last night that I'd said 8 banks of cells!)

I've now got all of the Duct tape off but not split the 2 halves of the pack. I've already seen one of the battery connections hasn't been spot welded at all, a few broken connections, a few of the spot welds have burn marks so the heat was applied for too long (that can damage cells), the voltage monitoring cables are damaged in a few places exposing bare wiring, and the worse bit so far is that the main +'ve battery lead just fell out so was has been making only pressure contact. It's got a nice coating of black soot!
Can't wait to see how pretty the middle connections are when I split the pack to see the wiring in there!

 

[aseb]

Just a few more small pics- showing burned & trapped cables, and some of the broken welds. I've decided to rebuild what is there and re-measure the capacity before breaking those spot welded busbars.
Once I've got an updated idea of the working capacityof a properly built pack I'll look to search out the bad cells and either replace them or reduce the pack capacity- it'd only drop 1.1Ah from the actual peak capacity of 19.8Ah for every 12 dead cells found. Then I'll probably split the pack into 2 parts so I can fit them lower on the bike for better balance/ weight distribution.

 

[aseb]

and a pic of the batteries under all that Duct Tape and card:

 

[Scottyf]

That makes my lipo setup look like a piece of **** to work with.

I hope you sort it out but that many cells and splitting out looks a nightmare.

Good luck!

 

[aseb]

That makes my lipo setup look like a piece of **** to work with.

I hope you sort it out but that many cells and splitting out looks a nightmare.

Good luck!

Added to the above- I found out that 4 channels of the BMS are not functioning correctly so before I start messing with that spaghetti type busbar mess (there's nearly 10 metres of the stuff used on the battery) I need a new BMS, so it's ordered- a proper one not a Cammy one. Once I've got that I'll recharge the pack, try a run to exhaustion (battery exhaustion- I'm already exhausted with the thing) to remeasure capacity and see if a bad BMS has added to the capacity issue.
At that point I'll decide whether it's worth cutting the thing to bits to check individual cells. I think I'm more or less decided to make my own pack up early next year- using cells with a higher capacity and C rating than that pack. I can make an easily maintainable pack and cutting the number of cells down to a very manageable level with more capacity- only 12 or 24 of them depending on the final choice instead of 216 in the Cammy one. And it'll far easier for checking if there's any problem in the future.