Gokwh 100ah Lithium Battery test and Teardown
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- Опубликовано: 27 авг 2024
- Here is the BMS - it is set to 8.8v (2.2v per cell) but is adjustable. The Manufacturer could wind this up to 2.5v, but would the battery achieve its rated capacity ? Probably not.
jiabaidabms.co...
Just realised I have a discount code for purchase of this Battery if you wish.
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p.s . The discount code is only applicable to the products linked above
Your tests on batteries and solar are the best on the internet. Great work. 👍
I would have to call it a pass. It performed to specifications, well made and no bodgy stuff.
Other batteries may well go below 2.5 cell voltage, but you wouldn't know because they dont have Bluetooth info.
Great information Craig 👍
Good job Craig, I do like BT & the idea of the top being screwed down for accessibility to change out the BMS should you ever need to. I would have liked a peek at those cells & their configuration. I am not a fan of pouch cells, I just feel they are a cheaper build quality than prismatic cells & add a lot more potential failure points to the equation.
No4 cell got down to 2.22v which is a red flag for me & out of spec, & then cell 2 on the second test was way down also, I think ur right in that not having BT on many other batteries we do not know what their actual cell voltages may vary up & down to, while charging & discharging, but I think I know what is going on, Andy found that some balancers only work (activate) on cell No1 voltage, & I noticed that cell 1 voltage just hit 2.5v as the BMS cut out, & I believe this is also why there was a difference in cell 2 & 4 voltages between the 2 tests when the BMS cut out.
JBD are generally not a bad BMS & are used in many battery builds, but the passive balancing is not the best & takes some time to do its job effectively, but I have to say you have uncovered a BIG flaw here and it is a definate FAIL for me.
I suspect if you fully charge this battery to 14.6v you will find that cells (other than number 1 cell) may drift well over the 3.65v threshold & the BMS will not shut down until cell number 1 hits 3.65v, or there is an average of 14.6v between the cells, meaning cell 2, 3 or 4 in the pack could be at 3.75v (or higher) as cell 1 hits 3.55v, and this variable could get worse if cell 1 is a bit slower to accept a charge, and worse again by the number of pouches that may be in parallel, as each pouch also needs to be in balance with it’s parallel connected cells.
Another benefit I see of prismatic cells is that (if) there is only 4 in a battery pack, each cell is being balanced individually by the BMS, and it is generally a simpler job to change out a cell if needed than it would be with pouch cells, which are mostly a throw away job with many more internal connections.
Insightful review, thanks for ur time & effort to bring us this info. Cheers
Thanks Craig! After looking at the video I wasinerested so explore more. I've just looked up pricing, these are cheaper than a Kings and really affordable, and they pay freight from China ( no such thing as freight free is there).
Nice video, while I am not certain that the cell voltage didn't turn off at 2.5 volts was due to the balance and protection being turned off in the settings as I noticed in the video. I would like to see a follow-up after those settings have been changed.
2V per cell is minimum, 2.5V is "Consumer Safe" in cell manufacturer specification, so I wouldn't be too worried about that.
Importantly, no mention of high and low temp cut off (low not as important as high).
2.5v/cell is minimum for lifepo4
30+ years working with a Large Japanese cell manufacturer says otherwise. 2.5V is the "consumer safe" discharge limit. 👍
@@PittsFlyI’ve added a 2nd short video and the manufacturer confirmed 2.0v - 3.75v working cell range. Happy to stand corrected and shows I’m still learning as I go. That said I’d rather stick to 2.90- 3.55v per cell. Not much real world capacity gained from going outside this and cycle life should be greatly improved in my opinion. What’s your thoughts on cycles V voltage?
@@craigsolaradventures This has always been a hot topic, especially due to social media. We have always used a loose "engine" analogy in this discussion... Just because your engine has a Red Line of 5000rpm, does this mean the engine will be immediately damaged if you cross that line a little; NO. Continual usage as such "may" shorten it's life but it's minimal if any. 2.5V per LFP cell is a conservative minimum voltage and was originally "set in stone" as the consumer safe industry standard test voltage. The manufacturer stated capacity and expected cycles is (should be) based on the 2.5V per LFP cell industry standard, and these numbers are most commonly the basis for the buyers choice of battery. So as long as it's capability suits the requirements, there's not an issue (re cell voltage). And no, there's is no issue sticking to 2.90V-3.55V per cell if this is what you are happy with; it's well within LFP cell specifications. Don't get too hung up on the voltage per cell/cycle life thoughts. Low and High temperatures of the cells is a much higher cause of degradation in consumer LFP batteries than low/high voltage.
BMS should cut the battery off when a cell got to 2.5V. Funny how the low cell on the first discharge was the highest on the second discharge.
It will probably still last lots of charge cycles. I must look up the price.
I'm watching back your video and noticed that you have the Balance setting turned off 11:29
You can turn this on in the Control section of the App. Try this and rerun the test.
Awesome stuff, I have two 140amp lithium's the BMS in them cuts them out at 12,8 volts is that normal
12.8v is actually very high and considered the nominal voltage for lithium Ferro, normal BMS low voltage protection is 10v to 11.2v, but as I've said I believe 12v is a good setpoint for both amphour output and cycles achieved.
To me it is a fail. Balance the cells and retest. In my opinion you should never exceed any parameters.