Still trying to get my money back or a replacement for my crap Voltx 120ah lithium. It's got to the stage where Woolworths marketplace rep is no longer responding to my emails and won't tell me if they have an appeal process. The battery did not make claimed power on the tester, had high internal resistance, dropped well below 12.8 volts on even small loads, was fitted with a cheap BMS that only supports 50 ah continuous discharge (ok that was in the specs but I didn't know it was poor at the time) plus was faulty because BMS low power cut out didn't work. No way would I use VoltX or Woolworths marketplace again!

In contrast my Gokwh 320ah battery arrived 2 days ago which I bought from the manufacturer via AliExpress. The delivery time was quite long as I believe is the case with all lithium batteries ex China but a good couple of weeks before the promised delivery date.

Having been caught before by Voltx this one went straight on the charger and then straight on the capacity tester. Here it is last night when I went to bed having already discharged 313 amp hours still at 12.12 volts discharging at the near max 179.5 watts my tester can handle and stating 6% capacity left. I didn't want to run it down to less than 12 volts while I was asleep even though the BMS cut out is 10 (but from experience with the Voltx as well as the Bluetooth monitoring app on my phone it was very clear that the battery would make more than it's claimed 320 amp hours).

The Bluetooth BMS allows a good deal of information to be monitored via the phone app and it also has a cell balancing function.

One of the best things about this battery is that it is barely larger than my previous 120 amp hour battery so fits the battery compartments in my Clubman which is non expandable being part of the drop in internal liner. I don't know how they cram it all in there considering the ridiculous size of other companies 200 plus amp hour batteries but they do and it does not run hot. It has a 200 amp BMS which states that it gives 200 amp continuous discharge which is good for my hefty keel lifting winch. The only problem with a 200 amp hour BMS in a 320 amp hour battery is that the app readouts for power left in the battery are understated as they are presumably calculated from current voltage and hence percentage of battery used. The the percentage then appears to be applied to 200 rather than 320 amp hours. Once you figure this out it is fine and presumably the 200 amp BMS was chosen due to limited availability of larger ones and the probability that they wouldn't fit the extremely compact form factor. 200 amps continuous discharges plenty on a yacht anyway. It also means that when it had discharged 313 amp hours and red 6% of capacity left the capacity left was actually over 8%

The phone app caught me by surprise in a couple of aspects as it contains a switch for charging which must be on for it to charge. After total discharge I connected it up to the charger and walked away only to come back in hour later and see no charging had occurred. I looked in the app and turned the switch on and all good off it went.

One of the best premium functions of this BMS is that it allows viewing of individual cell voltages and reads out any imbalance between the cell with the largest voltage and the cell with the lowest voltage. This can then be corrected with the app/BMS cell balancing function. With many batteries of course you never know this. My tester discharged the battery in one 24 hour king hit and a cell imbalance of .089v did eventuate. I think you actually have to have a period of charge for the balancer to work. Anyway when I started recharging I made sure the balance button was on and watched the cell imbalance disappear in real time in less than 10 minutes whilst charging from 6 to 13 % capacity as you can see from the attached series of 4 app screen shots. Interestingly the balancer active light has gone out in the last shot when the imbalance is down to 0.006v

The app also gives access to historical information regarding volts, amps, temperature and number of cycles. I'm unsure if I should be worried about the one cell being so far below the others given that the balancer does sort it out?

Still learning but kind of chuffed with the new toy. I can now survive plenty of cloudy days with the fridge and other stuff working nicely. The price $754 was marginally more than I paid for the way way less powerful voltx and I got the voltx pretty cheap. Now to continue fighting to get my money back on the damn thing or at least a correctly performing VoltX battery or for that matter even my own dud returned battery back from them.

By the way does anyone know what the term "soft lock" appearing next to one of the buttons on the app means?

That's very interesting, thanks!

I think soft lock mean software locking. A protection layer that stop users from changing settings that could damage the battery, but I can't be sure until I find the app manual which doesn't seem to exist.

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Silent Hunter said..
That's very interesting, thanks!

I think soft lock mean software locking. A protection layer that stop users from changing settings that could damage the battery, but I can't be sure until I find the app manual which doesn't seem to exist.

Thanks that would make sense as when the button is not on it is entitled protection. I'm not sure what I did to turn it on however although I'll probably figure it out eventually.

Just an update on Woolworths Marketplace. They have finally given me store credit with the original seller which is obviously unsatisfactory. They say I can convert that to actual $ credit so one more hoop to run through.

Could you install overkill solar app and make screen of the bms settings for 320 AH battery? This App allows you to change any settings you want in bms sitting in gokwh 12v 320 ah battery. I would like to compare settings with mine. Most concerning setting is total cycle capacity that in my case is only at 264 ah.
Did you notice any sudden change in remaining capacity during charging or discharging? Mine can jump from 100% to 52 %. It is very strange.

Sorry I have been away on my boat for 10 days and for the first time have used this battery for that length of time. I left home with it fully charged and I was charging it with the solar most of the time away with the exception of the first and last day when I was driving home and the second last day when it was a bit rough at sea (for my solar set up) from Lakes Entrance to the oil rigs. It was at 66% when I got home.

The app that you use seems to be a lot better than mine and I've yet to come to grips with it as I have just downloaded it.

The battery has so much power that I have never used it down to below 60% which is where it is now after messing with raising and lowering the keel in the backyard a bit. This is with the exception of when I first received it and did a capacity test.

I have not ever noticed any large jump in remaining capacity appear during either discharge or charge. Sorry I have no idea why yours would be doing that.

I have however noticed that one cell massively overcharges when I let my 40A charger to do its thing and turn off by itself when it senses full charge presumably based on the average of the four cells. The balancing function does bring the cells back into equilibrium but it takes 9 hours or so. A picture of this imbalance at 100% charge is attached. I'm not going to let it charge unattended any more as obviously this isn't good for that cell. Now that I have downloaded your app I noticed that it says that there has been a single cell overcharged 58 times. I don't think I have yet charged my battery 58 times so that is a bit of a worry. It also appears that they have been under voltage twice which I didn't do.

Now that the battery and boat are back home and sitting in my backyard they are sitting at 60% charge and nicely balanced.

I have been aware since the outset that the app I was using was using two hundred amp hours as the maximum capacity of the battery and was therefore simply applying the remaining percentage of power to that figure to give me an incorrectly low remaining power approximately 2/3 of actual. I couldn't see how to change that in the app I was using . It would be good to change that figure with your app but if I write this to the BMS I want to make sure that all the other parameters below it are correct as well as I assume it will write all the parameters not just the one I changed. What have you used for these parameters?

In your app I went to settings and put the total capacity of the battery at 320 amp hours which appears in the picture below (all figures below that however are the default figures in the app which I haven't changed) but I haven't written this to the BMS yet and aren't even sure weather the BMS will accept it if it is a BMS designed for a 200 amp hour battery. I assume the totals cycle capacity of 160 in the picture below is simply the default setting for a 200 amp hour battery as most people don't like discharging below 80%. Presumably the bms will shut the battery down at this level and that is the reason to enter it. Your 264 figure when divided by 320 represents 84.5%. Was this the factory delivered figure in the BMS when you received it?

If you havnt already, you guys should check out this resource :

off-grid-garage.com/

His Youtube channel has quite a few posts on BMS settings that might assist.

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Andrew68 said..
If you havnt already, you guys should check out this resource :

off-grid-garage.com/

His Youtube channel has quite a few posts on BMS settings that might assist.

Yes thanks for that. I looked at his videos a while ago and I think he had an early video recommending some settings but sometime later revised them in light of his learning experience. I don't think he was very knowledgeable when he first started out.

Hi, just wondering if you have any update on the Gokwh battery? I am considering a similar upgrade.

Before going away with it last month I measured it at a extremely low voltage across the terminals. Bluetooth BMS however was telling me that it was about 75% charged where I had left it two or three months previously and that each cell was fine.

Tried to contact the manufacturer via AliExpress but no response. Over 6 months since I purchased using PayPal so no refund. I thought what have I got to lose so I took the top off the battery which was a bit easier than I thought expecting to see some loose connection, undersized components or that the Bluetooth BMS was lying to me and one or more of the cells was in fact dead. Using my multimeter inside the battery on the cells confirmed that each cell was indeed in good shape. No swelling and everything looked really beefy and very well connected and of good quality. Decided to unplug one of the plugs into the BMS to try and cut it off and reboot it as after all it is just a computer and that is the first procedure to try and fix any computer. The blue flashing light on the BMS duly stoped flashing confirming that it was off.
Plugged the BMS back in and everything is fine. Put the top back on the battery and resealed with 291. I had managed to remove the top and break the original 291 like sealant without any damage to the case. Job successfully concluded.

I guess if it happens again I will have to replace the BMS. Perhaps I should have installed an externally accessible reset button/switch but I didn't really want to mess with it. Apparently BMS failure is a thing even with the best bms's and products. Whilst not exactly thrilled that this happened after looking inside the battery I would have to say that it appears to be a quality product at a great price and I would probably buy again.
The extremely small size for 320ah (which capacity is fully genuine and I have tested) is achieved because the cells sit upright right next to each other and there is no foam padding around them. Not a lot of air space around the BMS either. That's fine as otherwise the battery would not have fitted in my recess which is part of the internal liner of the boat. The battery came in an enormous cardboard box with tons of good quality foam around it. Once out of its packaging however you have to be a bit more careful with it than with far more bulky competitors which presumably have tons of foam in them so as not to dint an actual cell.

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julesmoto said..
Before going away with it last month I measured it at a extremely low voltage across the terminals. Bluetooth BMS however was telling me that it was about 75% charged where I had left it two or three months previously and that each cell was fine.

Tried to contact the manufacturer via AliExpress but no response. Over 6 months since I purchased using PayPal so no refund. I thought what have I got to lose so I took the top off the battery which was a bit easier than I thought expecting to see some loose connection, undersized components or that the Bluetooth BMS was lying to me and one or more of the cells was in fact dead. Using my multimeter inside the battery on the cells confirmed that each cell was indeed in good shape. No swelling and everything looked really beefy and very well connected and of good quality. Decided to unplug one of the plugs into the BMS to try and cut it off and reboot it as after all it is just a computer and that is the first procedure to try and fix any computer. The blue flashing light on the BMS duly stoped flashing confirming that it was off.
Plugged the BMS back in and everything is fine. Put the top back on the battery and resealed with 291. I had managed to remove the top and break the original 291 like sealant without any damage to the case. Job successfully concluded.

I guess if it happens again I will have to replace the BMS. Perhaps I should have installed an externally accessible reset button/switch but I didn't really want to mess with it. Apparently BMS failure is a thing even with the best bms's and products. Whilst not exactly thrilled that this happened after looking inside the battery I would have to say that it appears to be a quality product at a great price and I would probably buy again.
The extremely small size for 320ah (which capacity is fully genuine and I have tested) is achieved because the cells sit upright right next to each other and there is no foam padding around them. Not a lot of air space around the BMS either. That's fine as otherwise the battery would not have fitted in my recess which is part of the internal liner of the boat. The battery came in an enormous cardboard box with tons of good quality foam around it. Once out of its packaging however you have to be a bit more careful with it than with far more bulky competitors which presumably have tons of foam in them so as not to dint an actual cell.

Thanks for that, I am considering the swap and your comments re the lack of response from the Chinese supplier are very interesting to me. I am one that believes that crap sometimes happens, it's not what happens that counts but how you deal with it that counts.