Chins Smart 12.8V 100Ah drop in

[electrongeek]

I recently ordered the Chins Smart 12.8V 100Ah drop-in battery from Amazon for evaluation. This is the version with a heating pad to warm the battery if less than 0 C and Bluetooth BMS interface, and paired with the EE-BMS app. According to the app, it had a tested 105.5 Ah tested capacity and had a manufacture date of October 2021. The battery arrived with a 13.20 V resting voltage, so I put it on my Victron IP65 Blue Smart 15 A charger with a 14.2 V absorption setting and let it go. Unfortunately it went into high voltage protection before absorption was complete This was concerning behavior, since the instructions that come with it specify a 14.2V to 14.6V range for charging. The app showed that one cell hit the 3.750 V cutoff, while the next highest cell was 3.520 V. I went ahead ahead and put it on my Itech electronic load at a 10 A or 0.1C discharge rate, and it delivered 103.3 Ah. Next I charged it with a 14.0 V absorption and it again went into high voltage cutoff with the one cell hitting 3.750 V. After a 15 hour rest period, the high cell was still 0.22 V above the lowest cell voltage. Communication with Chins customer service was prompt, and they agreed to send me a replacement since it exceeded the 0.10 V difference that they considered acceptable.

The replacement that they sent deceived me at first, since unlike the first battery their was no indication that the battery was the "Smart" version, and the EE-BMS app did not connect to it. Customer service again replied within a day to confirm it was the "Smart" version, and that a new app was to be used, BAT-BMS. That did the trick. The new app is much easier to use, since it doesn't require the input of the 666666 password with each use and still provides needed information on cell balance. Unlike the EE-BMS app, there doesn't appear to be a way to change the charging and discharging cutoff parameters, though I don't consider that to be a real problem. This new battery has a March 2022 manufacture date, according to the app, and a 106.9 Ah factory tested capacity. My own test resulted in a 105.5 Ah capacity at 0.1C discharge rate. I was able to charge it with a 14.7 V absorption setting without high voltage cutoff. Bumping absorption up to 14.8 V did result in one cell hitting high voltage cutoff, but that was only after charge rate had dropped to 0.40 A, far lower than the widely held recommendation to terminate charging at an Ampere charge rate of 3% of the bank capacity. At that cutoff, the highest cell was at 3.750 V and the lowest at 3.601 V. After a short 1 hour rest without charging, the difference fell to 0.003 V. The app does have a button for "AutoBalance", but watching the app cell voltages carefully with the total battery voltage in the 14.2 to 14.6 range, I was unable to discern balancing activity. A balance indicator on page 1 of the app always showed "Balance: Off".

I've attached some screen shots of the app during charging. Overall I'm satisfied with this battery, and Chins customer service, but it does point out the advisability of checking each battery's charging and discharging characteristics before putting them into critical service.

 

[Bob B]

What did you have to do to return the bad battery?

 

[electrongeek]

They sent a UPS label. Put it back in the original box and off it went.

 

[Bob B]

They sent a UPS label. Put it back in the original box and off it went.

Can't beat that.

 

[Herb]

Deleted

 

[electrongeek]

I think it would be quite a project to tear open those Chins and use a different BMS. Are you completely off grid? If not, I would just use a 12v charger with LiFePO4 settings, or a bench power supply, to top each 12V pair in turn.

 

[Herb]

I think it would be quite a project to tear open those Chins and use a different BMS. Are you completely off grid? If not, I would just use a 12v charger with LiFePO4 settings, or a bench power supply, to top each 12V pair in turn.

 

[electrongeek]

One of the cells in battery 1 might be triggering high voltage cutoff before the remaining cells in that battery are fully charged. I’m not sure how Chins would handle that. Obviously if you had the version with cell level monitoring you would know. I would capacity test that battery and see if it delivers at least it’s rated capacity. If it does, from a practical standpoint, you are probably fine. I have no experience with series configurations. Perhaps someone with more knowledge can give better advice.

 

[electrongeek]

According to the manufacturer the BMS that comes with these batteries do not balance them. From what I have seen all these LiPo4 batteries have a tendency to drift and some badly. If so which one should I use?

On another note, how did you learn that the built-in BMS for the Chins batteries does not balance? Just curious, but not surprised. I had thought that since Chins recommends charging to 14.2 - 14.6 V it was to allow the BMS to top balance. If that isn't the case, I'm not sure I would routinely charge the battery to that level, since if the individual cells are at least somewhat well balanced in capacity they should reach full charge at battery voltages below that range.

 

[Herb]

On another note, how did you learn that the built-in BMS for the Chins batteries does not balance? Just curious, but not surprised. I had thought that since Chins recommends charging to 14.2 - 14.6 V it was to allow the BMS to top balance. If that isn't the case, I'm not sure I would routinely charge the battery to that level, since if the individual cells are at least somewhat well balanced in capacity they should reach full charge at battery voltages below that range.

I asked them, and they said the ones that I purchased (not the smart ones) don't balance the cells. You have to do a manual balancing, I normally drain them to about 20% then re-configure into 8 in parallel configuration, hook the charger up at 15A output, is a Victron 30A but you can adjust the output. I'll let them sit and charge slowly for 2-3 days until the charger stops and get a Green light or the app will tell you too. I check the voltages and normally they are all the same, I let them sit for a few hours check the voltage again normally it drops to 13.6v on each battery, this is all IAW their specs. I set them up in series parallel and hook them up to the Growatt, reset the smart shunt to 100% rinse and repeat. I do this every six months and so far so good. But yeah Growatt said that their 3k, 48v model don't have a built in shunt, so you must use an external one or buy the server type battery with communications built in so it can talk to the Growatt and give the SOC of the batteries. So not really happy to find these little details after the fact but hopefully for the people that reads this don't have to find out the same way. In my case, once the server type batteries come down in price (keeping my fingers crossed) I'll look at them again and see, but 2K for 5Kw capacity is a little pricey for me right now. Hopefully Chins will make them by then, their customer service is awesome and I'm happy with the performance of their batteries, and for the price is hard to beat. Sorry about the long post. Edit, just to add to this comment, I think their smart batteries do some kind of balancing, I have a question, what causing the balancing when you top balance? The BMS? If so how? I'm trying to understand that specifically for the non smart batteries, since they already said that the BMS don't balance the batteries. I'm thinking that it has to do with how you connect the batteries, when they are in parallel they kind of balance each other naturally? Comments?

 

[zorrobyte]

I bought the same one. Battery came at a SoC of 6% with a mfgr date of 2021. Charged at 14.6v @ 10A and hit cell overvoltage (delta 0.3). Discharged to 0% SoC at 500W, then re-charged to 100% at 14.2V, hit overvoltage (delta 0.38). My "Real Capacity" is only 91Ah, when the battery should do 100Ah, I did not test cap properly, though. Cycle time also jumped from 2 to 5 after one cycle. I think the EE-BMS is weird and I am happy they are changing BMS..



CHINS customer service verified the version with EE-BMS app does not have cell balancing. They also offered to swap me for the "smart" version. They are very responsive. Typically I would be very suspicious of waiting until an Amazon return closes for an exchange.. but I do see good customer service on the forum


@electrongeek does your version have balance?

@CHINS Agent from CHINA I will reply with my findings and wait for a swap I will share my good findings here. I also need to buy more batteries for my RV power storage, I will buy more from you if all goes well.

 

[Herb]

I bought the same one. Battery came at a SoC of 6% with a mfgr date of 2021. Charged at 14.6v @ 10A and hit cell overvoltage (delta 0.3). Discharged to 0% SoC at 500W, then re-charged to 100% at 14.2V, hit overvoltage (delta 0.38). My "Real Capacity" is only 91Ah, when the battery should do 100Ah, I did not test cap properly, though. Cycle time also jumped from 2 to 5 after one cycle. I think the EE-BMS is weird and I am happy they are changing BMS..

View attachment 111820

CHINS customer service verified the version with EE-BMS app does not have cell balancing. They also offered to swap me for the "smart" version. They are very responsive. Typically I would be very suspicious of waiting until an Amazon return closes for an exchange.. but I do see good customer service on the forum
View attachment 111817

@electrongeek does your version have balance?

@CHINS Agent from CHINA I will reply with my findings and wait for a swap I will share my good findings here. I also need to buy more batteries for my RV power storage, I will buy more from you if all goes well.

Hello, good to know info. Yeah they have great customer service. When I first got mine I did a capacity test and got 110Ah each, they were at 30% SOC (guesstimated) since they are not smart batteries, but by my guesstimates they were at around 30% which is what they stated. I'm glad that they are backing their products, is hard to find a good reliable source now a days, they are mostly overighters. ?

 

[zorrobyte]

I will wait and use the battery in the meantime, will share my results and experience in November!

 

[electrongeek]

I bought the same one. Battery came at a SoC of 6% with a mfgr date of 2021. Charged at 14.6v @ 10A and hit cell overvoltage (delta 0.3). Discharged to 0% SoC at 500W, then re-charged to 100% at 14.2V, hit overvoltage (delta 0.38). My "Real Capacity" is only 91Ah, when the battery should do 100Ah, I did not test cap properly, though. Cycle time also jumped from 2 to 5 after one cycle. I think the EE-BMS is weird and I am happy they are changing BMS..

View attachment 111820

CHINS customer service verified the version with EE-BMS app does not have cell balancing. They also offered to swap me for the "smart" version. They are very responsive. Typically I would be very suspicious of waiting until an Amazon return closes for an exchange.. but I do see good customer service on the forum
View attachment 111817

@electrongeek does your version have balance?

@CHINS Agent from CHINA I will reply with my findings and wait for a swap I will share my good findings here. I also need to buy more batteries for my RV power storage, I will buy more from you if all goes well.

The new app for the current build of Chins “Smart” batteries has a button labeled “Autobalance”. When you charge the battery up to above 14 V you can tap the button, and the button seems to respond to the tap, but there is not any indication that top balancing is occurring, at least to my eye. Cell to cell delta V does not seem to change when holding voltage above 14V and pushing the button, so I’m concluding that there is no top balancing occurring. Maybe I’m missing something?

 

[Herb]

The new app for the current build of Chins “Smart” batteries has a button labeled “Autobalance”. When you charge the battery up to above 14 V you can tap the button, and the button seems to respond to the tap, but there is not any indication that top balancing is occurring, at least to my eye. Cell to cell delta V does not seem to change when holding voltage above 14V and pushing the button, so I’m concluding that there is no top balancing occurring. Maybe I’m missing something?

Hum, my understanding is that LiPo4 batteries either non smart or smart ones will balance each other if connected in parallel for a certain time, the longer the better, they call it a manual balance. I do this a little faster by charging at low rate, since I have 8 batteries it takes a long time still to accomplish this, next one I will do at 30A, to see if there are any changes on capacity or any other possible issue, if there are no issues, I'll go up to 40A and see. As far as being able to tell if there is active balancing taking place, what I do for my other battery bank that have dumb BMSs built in, with active balancing, is hook up some little volt meters I got from online store, they are pretty stable, and hook them up to each battery while in a parallel configuration, each meter will show the change in voltage as the balancing takes place if active balancing is taking place. If the batteries are pretty much balanced the active balancing will slow down. There are some active balancers out there, but not really convinced that they will do any better and I have seen mixed comments about them, some even sound dangerous IMO.

 

[electrongeek]

Herb - you are confusing cell level balancing within the battery to the battery to battery balancing you have been doing. Yes, batteries hooked up in parallel, of the same type and voltage, will tend to balance with each other when charged up. However, what is happening within that battery, at the level of each of the 4 cells inside each battery, is a different matter. Since these 4 cells inside the battery are in series, they can get out of balance with each other. A good BMS will redistribute voltage/current to each cell to try to bring them up to the same voltage and back into balance with each other. This is basically the same thing you are doing manually at the level of each battery in your series string. If a LiFePO4 battery with four good quality cells inside balanced to each other to begin with is treated well, they will stay pretty well in balance. High current draws, especially greater than 0.5C, will magnify differences between cells and increase the likelihood of coming out of balance if the cells were not identical to begin with. A balancing BMS will try to oppose these imbalances. I would hope the Chins "Smart" battery BMS does cell level top balancing, but it looks like it may not. That may not be important in my service, these inexpensive batteries will likely last plenty long enough without BMS cell balancing to be worth it to me. If at some point in the future, cell level balancing becomes so far out of whack that there is a significant impact on total bank capacity, I suspect prices and technology will provide far superior solutions to what is available now. I'm not too worried.

 

[Herb]

Herb - you are confusing cell level balancing within the battery to the battery to battery balancing you have been doing. Yes, batteries hooked up in parallel, of the same type and voltage, will tend to balance with each other when charged up. However, what is happening within that battery, at the level of each of the 4 cells inside each battery, is a different matter. Since these 4 cells inside the battery are in series, they can get out of balance with each other. A good BMS will redistribute voltage/current to each cell to try to bring them up to the same voltage and back into balance with each other. This is basically the same thing you are doing manually at the level of each battery in your series string. If a LiFePO4 battery with four good quality cells inside balanced to each other to begin with is treated well, they will stay pretty well in balance. High current draws, especially greater than 0.5C, will magnify differences between cells and increase the likelihood of coming out of balance if the cells were not identical to begin with. A balancing BMS will try to oppose these imbalances. I would hope the Chins "Smart" battery BMS does cell level top balancing, but it looks like it may not. That may not be important in my service, these inexpensive batteries will likely last plenty long enough without BMS cell balancing to be worth it to me. If at some point in the future, cell level balancing becomes so far out of whack that there is a significant impact on total bank capacity, I suspect prices and technology will provide far superior solutions to what is available now. I'm not too worried.

Understood, and thanks for the comment. The batteries I use are dumb batteries and there is no balancing according to Chins, so is all I got to go by. I know the same balancing cycle occurs within the each battery (4cells) inside but since they are dumb batteries I have to deal with the complete battery at 12v so I can't monitor them individually, unless I take them apart and install a smart BMS! But the method I'm using has worked very good, even though these batteries are affordable they have performed very well. I'm trying to speed up the balancing process (by increasing the charge voltage) during the balancing steps, and minimizing voltage checks by multimeter to determine how each individual battery is doing, which is what the little volt meters do for me, is just the way I prefer to do this (volts are not a good way to determine SOC on LiPO4 batteries but it gives me enough to tell if there is a problem or not). The way is recommended by Chins takes a long time. Which is the best and correct way at this moment, for their batteries, but still slow for me anyways. I'm trying new things at the moment to see how can I improve it. I prefer drop-in batteries since I no longer have the desire to DIY batteries. I have an older system I DIY 6 years ago and it still kicking it, all battery packs have BMSs and all stay balance very well, even after 6 years, the capacity has dropped but I push that one hard it runs all my lighting during emergencies! Thanks again.

 

[electrongeek]

I’ve had this Chins Smart 100 Ah battery installed for a few months now. Seems to have been performing well with the three Chins “dumb” batteries in parallel. However, the Bluetooth functionality has gone dark, while I’ve confirmed the battery is still supplying power.