Battery Hookup new listing “Case 100x 3.3v 2200mah - 200x 18650 Lifepo4” for $100.00 + shipping

[sam_sam_sam]

You might fine this YouTube video about creating a BMS battery charger that use a micro controller and shares the score code for this project

https://www.youtube.com/watch?v=MRjxQVYBM_k. I have watched the first to video #8 I plan on watching the rest of his videos on this subject

[eccerr0r]

Well, glanced through a couple sections and it's exactly how I envisioned it, pretty much has the same concept except done via software as an all analog version I had posted somewhere. Yeah the digital version is nice because you can easily change the constants as needed. I don't think I'll be going this route, at most I'll probably manually balance if the bms doesn't already have a 100mA balancing function ...

Speaking of which I would have thought it should do the balancing current as a ratio of the capacity of the pack, other than heat dissipation I wonder why it's otherwise...

[eccerr0r]

and interesting... I have a chinesium 40A 4S Li-ion Co/Mn BMS that has 10 mosfets on it. The weird part is that it actually spent the effort and designed the PCB to dissipate heat from the balancing resistors...though still probably can't dump more than a few watts or so.

Too bad it's not good for Fe cells.

[sam_sam_sam]

and interesting... I have a chinesium 40A 4S Li-ion Co/Mn BMS that has 10 mosfets on it. The weird part is that it actually spent the effort and designed the PCB to dissipate heat from the balancing resistors...though still probably can't dump more than a few watts or so.

Too bad it's not good for Fe cells.

Could please take a picture of it I might have seen a board like that before because I am curious to which version of it is

[eccerr0r]

"2.3"

[sam_sam_sam]

"2.3"

Yes I seen this version before but in the 12.00 volt versions not the 16.00 volt one though

And yes you can modify the battery voltage configuration by removing the parts for that section and jumping it out

These are limited to about 100 milliamperes if I remember right


Here is the exact same board but it has a heat sink on the mosfets but there description is not correct it says that it is a Lipo 4 BMS balancing board but it is not according to the description it is a normal BMS balancing board because the voltage is 4.2 volts per battery cells I have seen this so many times in the past looking Lipo 4 balancing boards it is not funny anymore so you have look carefully at the board and the description given to know exactly what to expect when buying them

https://www.ebay.com/itm/18444123588...3ABFBM1KKEzMtl

Here is the 12 version of the same exact BMS balancing protection board with the heat sink on the mosfets

https://www.ebay.com/itm/18456777921...BNGDE3XGC05DHQ


Here is the balancing protection board by itself I think I going to buy one and see if it can be modified for a lipo4 battery cell configuration or not I am curious about this so I only have the balancing protection board function to deal with I have a 20 battery cell version but it is different from this one in the way it is designed

https://www.ebay.com/itm/18499192025...3ABFBMrqzwzMtl

Here is the 12 volt versions of the same design as the 16 volt version

https://www.ebay.com/itm/18499195532...MAAOSw6OhhEsfO

[sam_sam_sam]

Here is a tear down of the BMS balancing protection board that you posted a picture about

https://circuitdigest.com/electronic...st-and-working


Here is another YouTube video about a board that is very similar to the one you have posted but a slightly different explanation for this particular BMS balancing protection board

https://robojax.com/learn/arduino/?v...3S_40A_charger


With this in mind I wonder if there is a version of over and under voltage version that is available with a data sheet for what is needed to adjust the voltage parameters I not that I ever seen a version like this but this does not mean that one does not exist

Not sure what you need to use in a search engine to find something like this because several things I have tried have not revealed very much

[eccerr0r]

hmm. 40A seems a bit optimistic then... yeah heatsinking is necessary to hit 40A but it's on the wrong side of mosfets...

[eccerr0r]

how long does battery hookup take to process orders?

[sam_sam_sam]

Usually you get it in about a week or less depending on weather or not they process the order over the weekend or not if you order on Friday if you order on Monday it might get delivered in the middle of the following week

[sam_sam_sam]

What are you thinking about buying from Battery Hookup just curious

[sam_sam_sam]

I personally have not had an issue with getting my orders the bigger issue is with the shipping company delaying your delivery date and you never know when it is going to happen unfortunately because of what ever reason I have had this happen several times in the past at least by one to three days on very rare occasions it came one day earlier than what they had for a delivery date

[sam_sam_sam]

I going to test another 24 volt battery pack to see if I basically get the same results as the first one that I tested

[sam_sam_sam]

I going to test another 24 volt battery pack to see if I basically get the same results as the first one that I tested

So far the results are very similar to the first one that when it almost fully charged it voltage becomes very spread out from each other so I could really do a battery backup voltage above 27 volts and the battery pack probably be around 85% charged and maybe even a little higher than that because the same thing happens when the battery is almost depleted the battery pack voltage is spread it also very high but the working amp hours are very decent at over 5 amp hour for what the specs say are a 6 amp hour rated for battery packs that were made in September 2021 so almost 4 years old for Chinese made battery pack cells impressive

On the individual battery cells do not have on them who make them unfortunately

I will be testing this one at 10 amp load as well to keep the parameters the same plus I do not think that the battery backup would go that high in amperage unless I were to really load down the battery back up to maximum which I try not to do just get a bigger one is my moto about this situation

I am also testing some more of the battery cells that this post was originally topic in the first place

I going to test the 12 volt @ 12 amp BMS balancing protection board that I bought for these battery cells to charge them but I going to make it where I can charge and use either the low current or high current capacity battery cells

Because most BMS protection boards are just turn off when the battery voltage on any battery cell get to high or to low and yes this type of BMS protection boards provide minimal protection from these conditions but are not very effective for charging them they are great for discharging them through a load I would use them for this purpose all day long as long as they are not to low before turning off the battery connection from the load

[sam_sam_sam]

Well I have the results from the second 24 volt battery amp hours are 5.150
The issue is that cell number 2 is way off from the rest of the battery cells as much as 0.270 volts at the greatest point where as the first battery was around 0.120 at the greatest point but it recovered faster than this pack but I still got over 5 amp hours and 30 minutes running time even with devastation between battery cells

The mosfets get very warm at a ten amp load but you can still touch it without getting burned the battery cells do get a little bit warm but that about it

Now to spit this into two battery packs I think can be done fairly easily but you would need to have a very steady hand and a small dermal cutoff wheel and a plastic prying bar and separate the crazy glue that was used and probably need to replace the heat shrink tubing and use battery holders to separate the battery cells if you plan on using this battery pack at 10 amp I would not recommend going much higher than that unless you put heat sink on the mosfets and separate the battery cells I would also recommend that if you run the battery pack down until it shuts off from the BMS balancing protection board that you do not fast charging unit the battery cells voltages go above 3.20 and the difference between cells are very small then you can fast charging up to 3.5 which seems to work very well and the charging graph curve look very good a little steep but you expect that with the higher charging current

One note about fast charging this battery pack with this BMS balancing protection board if you do not slow charge until the battery voltage between battery cells becomes balanced and you just fast charge only the battery cells do not become balanced for some reason I have not figured this out this is the first BMS board that I have seen this but it could be because I never had a individual battery cell meter module before so this might be a normal thing because if you checking each battery cell with one meter by the time you can hook up your leads to the next battery cell it probably has catching with each other

Now with the 9.6 BMS balancing protection board it kind a does this as well but not as long as this battery pack does it could be because these battery cells have a lot of age on them is my guess about this I could be wrong about this

But to get the battery testing machine to do BMS balancing protection boards and not voltage spiking the hell out of mosfet board on the battery testing machine so you have to watch the current on the display to know when the BMS board has shutoff the voltage when charging and discharging you do have to modify the BMS board a little bit to accomplish this endeavor to keep it from destroying it self if I had not figured this out I would have already destroyed the mosfet by now doing what I have been doing now I have tested several different voltage battery packs now and I consider this a good option for testing purposes because at one point I thought I might not be able to accomplish this task without making my own data logging system and doing it the hard way and probably not having the best graphics curve charts

Now with my other battery testing machine that 12 to 72 volt version that does not have a charging controller this is an issue if you do not have a buck converter that has a voltage and current and is adjustable you would not be able to test BMS cutoff voltage for charging and discharging function very easily with consistently and with accuracy because it very difficult to see when the BMS board shutof

Now with a switching power supply that has voltage and current that is adjustable this process is very simple to do but if you want 200 milliamperes it is a little bit difficult to achieve it can be done but you have to turn the pot control very very slowly or you go below 100 milliamperes and the testing machine turns off by default and this valve can not be lower than thi it can be higher with no problem sometimes 200 milliamperes is still a little bit high when you are trying to see the charging voltage cutoff is

The individual battery cell voltage monitor module makes checking BMS balancing function very easy to do ( set it up for Chinese or English and you only need to do this once and it is always ready to use ) as well yes to put all this together is not cheap at all but if I am going to build battery packs that are used and give them a second life in another application or device I need a accurate way of testing them I use to do this the hard way and my results were not very reliable or did not have the running time that I was after

One note I have tried the BMS balancing module that shows the battery voltage in real time but the issue I have had with the one that I tried is that screen is too small and it has to many functions and features that you have to setup to get it to work no I don't think so and they are limited to 8 battery cells or the ones that I have seen the ones that can do more battery cells then start having to pay an arm and a leg for them this does not cut it for me either

This is the setup for doing BMS balancing protection board testing for building battery packs


Single channel battery testing machine around $60.00 to $90.00 up to 20 battery packs load test 5 amps load test
Single channel battery testing machine around $300.00 for battery packs from 12 volts to 72 volts 20 amps load test
Individual battery cell voltage monitor module about $60.00 this depends on the accessories that you buy depends on the price

JST 2.00 12 pin wire harness $12.00 for a pair of them


Nobody has to take the route that I have taken to be able to do this one thing that I would recommend is that you have a way to monitor all individual battery cell voltage to be able to see in real time how balance a battery pack really is for best results

I know a very long time ago I have a BMS balancing board that was extremely picky about the battery cells to be balanced as close as possible I going to revisit this BMS balancing board and see if I can get it to work properly with the setup that I have now this the battery operated soldering iron that I was reviewing there unit that has a built in battery pack there were two different versions of I have both versions but other BMS balancing board has a different issue with but I can not remember exactly what the issue with it was but it would not charge the battery pack up completely when I got it because it came with Chinese battery cells and I not sure if that was the issue or not

[sam_sam_sam]

I test another BMS protection board out of this batch boards and I do NOT like what I see in these results it seems like these BMS boards were rejects because one reason or another one of the other ones that I tested was a little flaky about turning off as well but not like this one you might as well not even have a voltage cutoff control because this one definitely does not work correctly at all look at the results I woke up to from testing this board last night

I am going to run this test again after it chargers back up again and see if I get the same results again if I do I will reject this BMS protection board I have at least 90 of them I think these were on the high current capacity battery cells because this one is slightly different than the low current capacity BMS protection boards

I also looked at the results of the 24 volt battery pack that I was testing last night as well that was very unbalanced after discharging it last night I set the charging current to 200 milliamperes and left it all night long and the amp hours were over 2.00 and now the battery cells are very balanced again so I put up to 3.5 amps until it fully charged again and run the 10 amp load test again and see if it goes way out of balance again

In conclusion about the 24 volt battery pack they are decent for what you pay for them they are rated for 6 amps according to Battery Hookup ( the results that I am getting is over 5 amp hours which is decent ) the BMS balancing protection board function is decent for the function of it but you need to be aware of the fact that if the battery cells are unbalanced when fully discharged they will stay unbalanced unless you slow charge them back to being balanced again then you can fast charge it again now it become balanced again by itself but I am not sure if you would have as much running time if you do not get them back into balance again before one of the battery cells terminate the charging cycle before they are fully charged I personally do not want to test it that way because it would take several charge and discharge cycles to get back the running time again to me it makes more sense to just slow charge them until they get balanced again ( or only use it to 4.5 amp hours and then you would not have to worry about thsi issue ) and then you can fast charge all you want you could possibly fast charge up to 5 amps and still be fine doing that the switching power supply that I am using only goes to 3.5 amps

[sam_sam_sam]

In the picture below you will see the load test results and you will also see how unbalanced they become after the load test
In conclusion the best way to handle this issue with these battery packs is to load test them and determine where they become unbalanced and terminate the load test just before it gets to that point so that when go to recharge them you will still be for the most part will still be balanced and will get the most running time unless you want to remove all battery cells from each other and rebalance the milliamperes amp hours I am not sure just how much more running time you gain by doing this because even though they are unbalanced the cutoff voltage is very near that point anyway

One note this picture was taken sometime after the load test was completed so the battery voltage had time to recover but you can see that battery cell number two has an issue that the other cells do not have

One other note the circle is where the voltage starts to roll off but where you see the heavier red marking is where the voltage is 24.2 volts and the amp hours is at 4.5 so you lose about 5 to 10 minutes of running time this might be a good trade off for not having to slow charge this battery pack

[sam_sam_sam]

I going to prepare another 24 volt battery pack for testing later on today and should have the results later on tonight

One note this battery packs will fit in my battery backup I can put two of them in there I to modify the battery holder that makes the battery connector at the bottom of battery pack compartment so that it will make a good connection I have to find two battery packs that are very close to each other in testing results so I can get best running time results

More to come later when I do the battery backup load running test and see if I have to remove one battery cell for it function properly or not when I have done this in the past I did have to remove one battery cell because the battery pack would not completely charge up correctly