Beware? Shenzhen GTKPower batteries - Aliexpress lifepo4

[mhanawalt1]

Ordered (2) 200ah lifepo4 batteries from this company 4/19/19 for a houseboat battery bank. Measured to fit a certain empty spot below deck.

Received confirmation and tracking # the next day.
In checking over the next 3 weeks the tracking # stayed inactive. Messages to seller - unanswered. After waiting 45 days the Aliexpress "dispute" option became available. Started "no items received dispute". Seller responded by message immediately, stating that they hadn't shipped because they didn't have the type of plastic case I had ordered. They would not refund my money but had put in a request to their supplier and should get some within the week. After another week I received the message "we are unable to provide the case you ordered" but we have other case sizes available. I was presented with 3 alternative case sizes none of which were narrow enough and with the lugs in the right places to fit the space I had available. It was now June 1, I had sold my other batteries and our 2 week annual houseboat vacation was coming up July 4 . Not enough time left to order from elsewhere, I opted to accept (3) 130ah, batteries that were narrow enough fit my space, (3)10amp chargers, which they guaranteed to arrive in a week, if I dropped my dispute. I would have 390ah in parallel instead of the 400ah I ordered but the thought of 2 weeks on the houseboat without a toilet macerater pump was frightening.

Received (3) of these in a week fedex:



At the time I did not know about Will Prowse and this forum. Batteries have now been in operation 6 mo.
In trying to determine "state of charge" , I ran across "Will" and this forum which got me wondering about my actual capacity.
Commenced to test my batteries.
Using drok meter like "Wills".
15amp discharge & charge current.
I completed 3 full cycles on each battery. with the following averages.

Batt #1 94.1ah 1258wh
Batt #2 94.0ah 1200wh
Batt #3 94.5ah 1218wh

Each battery has bms with bluetooth. Bluetooth app amp hrs do not track with drok meter. App shows nominal capacity from 124-130ah which
changes with each cycle.

Question??- are these actually 100ah batteries and did I get ripped off for the tune 100ah.

 

[electric]

How did you define a "full cycle" in your measurements? What top and bottom voltage limits?
Maybe your "full" cycle is not really full? Did you discharge until internal BMS turned off?
What was the charge target voltage and termination current?

 

[mhanawalt1]

*Started by topping each battery till bms shutoff. In each case shutoff was triggered by a 1 cell over voltage.
*Discharged until bms shutoff with 1 cell under voltage.
*Bms set to 3.65 high--2.5 low

 

[electric]

What are the dimensions and weight of each battery?
Based on your test numbers it looks like you have 100AH batteries, and not even good ones at that.
Based on how the seller has treated you I hope no one else will ever buy from them again.
I would use every possible option to get a refund or at least partial refund for lack of advertised AH capacity.

 

[electric]

Also, does BMS report voltages from each cell? Maybe there is a severe imbalance, in which case high cell and low cell would be different cells, not the same cell. Still, even if this is the case, the product is of terrible quality.

 

[FilterGuy]

I agree with @electric. It does not appear you got what was advertised. Contact them and see what they will do for you.

One thing that scares these sellers is a bad review. Post a bad (but honest) review and they are likely to make an offer.

 

[nosys70]

130Ah at best. you get what they said, but looks like low quality.

 

[mhanawalt1]

Yes I do get that cell imbalance @ 3.0 at low end and 3.45 on high end. Cells come in to balance as a pack, between 3.0-3.45
Above or below those values 1 cell will runaway and trigger a bms shutdown. Weird thing is, it is not the same cell in both directions.

Does not seem to be a way to contact Aliexpress directly once the dispute window has closed. Shenzen GTX Batteries does not
publish any direct contact info that I can find.
I did use the contact seller link in Aliexpress to send a message a week ago. No response yet.
Not likely I can reverse Credit Card after 6mo, but I 'll check on Monday.

Thank you for your observations - didn't want to besmirch the company with out cause.
The (3) batteries in parallel stay balanced between 30-80% soc and I use them in that range. so its not a total waste.

* In my research Shenzen Co. uses 3-4 different names on Aliexpress all the ones begining with Shenzen.

 

[electric]

Yes I do get that cell imbalance @ 3.0 at low end and 3.45 on high end. Cells come in to balance as a pack, between 3.0-3.45
Above or below those values 1 cell will runaway and trigger a bms shutdown. Weird thing is, it is not the same cell in both directions.

Thank you for your observations - didn't want to besmirch the company with out cause.
The (3) batteries in parallel stay balanced between 30-80% soc and I use them in that range. so its not a total waste.

It only seems weird because you don't fully understand what "balance" means. Your batteries are severely imbalanced, all the time, at all voltages.
How severe is impossible to know unless you take them apart and properly balance, as BMS cannot correct so much imbalance in reasonable timeframe.
Same or similar voltage at any SOC between 10% and 90% doesn't mean squat. It only matters at top and bottom SOC, which is exactly why you see one cell take off from the rest at the top and different cell take off from the rest at the bottom. This means lack of balance, but amount of imbalance can be 5AH or can be 50AH, can't tell without proper procedure, which requires access to individual cells and proper equipment, such as bench power supply capable of 3.65V and CC/CV mode.
Also, can't tell if cells will stay balanced after proper balance, which speaks to their health. Cells might be healthy and supplier simply didn't bother to balance them during assembly, or they might be shot and re-balance will not stay too long. Can't tell until you try to re-balance.

I asked for dimensions and weight, because this can help approximate if your battery was originally 100AH or 130AH. LFP cells have known range of energy density, so one can try to guess what the AH is based on weight and size, although this method is too varied to be precise. Could be a decent guess. Or, if/when you take the lids off you will see cell ratings, unless they are scratched off.

 

[mhanawalt1]

OK,

No need to make me feel more foolish than I already do! My Avatar says new member, that is why I am here.

Each battery
23.8lb
13" long
6.5 wide
8" tall

 

[ghostwriter66]

Yes I do get that cell imbalance @ 3.0 at low end and 3.45 on high end. Cells come in to balance as a pack, between 3.0-3.45

Those are huge difference ... you could literally have the BMS shut off when the 3.45 cell gets to the max and the other two could be only at 20% ...

As Electric was saying ... you need to individually balance those other two cells to get those up to 3.45 ... Your BMS is NOT going to be able to get you balanced unless you have at least a week ...

Once you balance them -- then hit them with 14.6 and get them charged up to the right voltage for those batteries and then run your test -- i will bet you will be getting closer to 200aH by then

 

[electric]

No need to make me feel more foolish than I already do! My Avatar says new member, that is why I am here.

I am very sorry if I offended you in any way. This is just my weird personality showing in the way I write on forums. It is entirely on me, not you.
Welcome to the forum and thanks for sharing your experience, it could help others prevent making a mistake.

 

[electric]

Each battery
23.8lb
13" long
6.5 wide
8" tall

These are typical dimensions and weight of a Group31 100AH battery.
It is very unlikely to fit 130AH into this volume and weight would be more than 30lb.
So, my very experienced opinion is that you have 100AH batteries, with approx. 5AH of imbalance.

The seller has blatantly lied to you, which is not surprising based on their overall behavior.

 

[mhanawalt1]

Didn't offend me. Just feel more foolish for buying what I did. I really do appreciate all you thoughts.
and do hope it keeps others from doing the same.

If you folks don't mind sharing.:

*I have the batteries at home.
*drok meter
*15amp charger
*15amp draw using 300wat inverter using light fixtures.
* I have several months

I am near 70 and slowing down. Any simple suggestions for improving what I have, with what I got?

 

[electric]

Assuming you don't want to cut them open and buy additional equipment to charge at a single cell level, you need to make existing BMSs work as hard as they can to balance each battery. Here is where your charger comes in, but we don't know much about it. Is it a 3 stage with float, or 2 stage, etc. Model number and any custom settings would help to narrow the advise.
The idea is to make your batteries spend many many hours around 14.0V - 14.2V , so your highest cells will bleed off and lower cells will catch up. This is called top balance. Your BMS bleed rate is probably around 50mA-100mA, so to bleed off 1AH it will take 10-20 hours at the voltage above 3.5V per cell, as shown in your BMS. Also, can you change BMS parameters in the app? Maybe you can lower the balance voltage to make the process faster, but no lower than 3.4V.

 

[mhanawalt1]

I think understand what you saying.
I only have standard chargers which would keep the voltage to high, and keep triggering the bms shutdown.
I would need a charger that I can set to 14.2v and no higher correct ?

Would this one work: https://www.ebay.com/itm/12-15-Volt...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Set start balance to 3.4 Static or charge? Then wait till cells balance ?

 

[Navig8tor]

Didn't offend me. Just feel more foolish for buying what I did. I really do appreciate all you thoughts.
and do hope it keeps others from doing the same.
...

Believe me when I say no one is safe from such a purchase. There's no reason to feel bad about it.

I have spent a few thousands on Ebay, Amazon, Aliexpress, Wish, Banggood, Gearbest, etc... And I have had my share of bad experiences, mostly with sellers from China (no matter the platform).

Aliexpress and Wish have the worst buyer's protection. You are allways buying "kinder surprise eggs". Even if you know what you want, you may not get it...

Prices on items from China sometimes are so much cheaper that we just think: "it's worth the risk". The problem is that not many China sellers are honest, and they will try to take advantage of you.

 

[Steve_S]

Didn't offend me. Just feel more foolish for buying what I did. I really do appreciate all you thoughts.
and do hope it keeps others from doing the same.

If you folks don't mind sharing.:

*I have the batteries at home.
*drok meter
*15amp charger
*15amp draw using 300wat inverter using light fixtures.
* I have several months

I am near 70 and slowing down. Any simple suggestions for improving what I have, with what I got?

Please do not feel foolish for getting duped. I got duped on a ShunBin Pack purchased through Amazon.CA ($3K USD). nice click stainless steel box with built in BMS … Grade-B or used 174AH cells (supposed to be 200AH) a dumb BMS (terribly assembled by a child I think) and CCA wiring internally. I got a refund after posting a bad review with supporting photo's of the "junk" on Amazon CA & COM. I'm not a noobie but got phookered anyways. Slick, looks good but krap. Link to a long thread of discovery in my signature. The refund at least Covered the new BMS, Bus Bars & Bolts and some of the sundries to rebuild the pack to acceptable status.

Parent Company of ShunBin : Shenzhen Shunbin Electronics Co http://www.szshunbin.com/
Amazon Profile: https://www.sellerratings.com/amazon/usa/shun-bin
Alibaba Profile: https://shunbin.en.alibaba.com/

You really have only a few options.
1) continue testing as you are doing with adjustments to the BMS via the app to see if you can squeeze more out.
2) get a proper LFP charger that can push max amperage & voltage the batteries can take (per their specs) hopefully they gave you that.
** do not use a regular car battery charger, they operate outside of LFP voltage ranges. CC/CV charging only for LFP.
X1) if the above fails, the only other options are to use them as is, knowing what numbers you have for real (use the DROK not the internal BMS one because the DROK is telling you what the pack will give you in reality)
X2) break them out of their respective cases and do the hard deal of rebuilding. Those cases are glued together and most if not all can't really be put back together after being cut open. You can see how some are crazy hard to take apart in Will's video's... he scares me when he brings out the "Power Tool" to cut the plastic casing open, visions of sparks & magic smoke ! Being a geezer myself, I like to go slow & easy when it comes to things like that...

 

[FilterGuy]

We all have stories. Just this morning I recieved a 'New' Victron solar charger from an ebay seller with 100% positive feedback. As soon as I opened the package I got a super strong smell of burnt electronics. I clearly received a used/returned unit. I hope I can do a return.

 

[Pierre]

Also had an experience on Amazon where I placed an order. They zapped my credit card on the spot which was unexpected as they normally only debit just before shipment a few days later. I cancelled the order within 30 min from placing it and got a message from Amazon confirming the successful cancellation. Still took 2 weeks to have the transaction reversed after filing a dispute with my bank.