Unknown 43.8 V 21.2 Ah 928 wH Li-Ion Pack

[Timbo]

Anyone know what these packs are?

I got these second hand. Can't find anything more on google.

I want to use the pack as is... So I guess I need to know the input voltage for the BMS to charge the packs.

I like the BMS because it has a temp sensor and heater.

I attached the BMS manual pdf from the seller. But it is too technical and I can't find the input voltage range for the BMS in it.

Anyone recognise these and can help me out!

There is 7 packs in total. So 6.5 kW h!

 

[Oleksii]

The PDF is something like datasheet for IC bq78350.
The IC should be smaller one of two, more close to MOSFETs.
This is not about battery pack.

It indeed would make sense to use the pack as is, even if you will have to discard BMS, in case if you cannot make it working.

43.8V (on label) / 12 (number of cell rows on picture) = 3.65V, which is nominal voltage of Li-Ion cells. As this matches - this is good to make conclusion.
So, max allowed charge for the 12S pack should be 12*4.2V=50.4 volts. But who knows, maybe BMS wants lower charge level and will stop charging earlier.

 

[Timbo]

The PDF is something like datasheet for IC bq78350.
The IS should be smaller one of two, more close to MOSFETs.
This is not about battery pack.

It indeed would make sense to use the pack as is, even if you will have to discard BMS, in case if you cannot make it working.

43.8V (on label) / 12 (number of cell rows on picture) = 3.65V, which is nominal voltage of Li-Ion cells. As this matches - this is good to make conclusion.
So, max allowed charge for the 12S pack should be 12*4.2V=50.4 volts. But who knows, maybe BMS wants lower charge level and will stop charging earlier.

Yep, they are 3.65 V Boston-Power Swing 5300 Li-Ion cells.

Boston-Power Swing 5300 Li-ion cell test

Hi guys! I've got aBoston-Power Swing 5300cell tested and want to share the results with you. Boston-Poweris a US based manufacturer of Li-ion cells which makes them in China and Taiwan and supplies to NASA,HP, ASUS, Delfast eBikeand EV makers. The cell was bought fromQueen Battery, a Chinese...

secondlifestorage.com

Do you know what the storage voltage for 3.65 V Li-Ion cells are? Hard enough finding what it is for normal 3.7 V nominal Li-Ion cells!

Yeah. I don't want to put in 50.4 V~ I have no idea the range or how tolerant it is.

 

[Oleksii]

Storage voltage is something between 40-60% of charge level. This is not so important to consider it as you have already packs.

 

[Timbo]

This is not so important to consider it as you have already packs.

What do you mean?

 

[Oleksii]

Ok, why do you need to know some numbers of Store voltage?
If I'll say that it's or 3.6 or 3.7 - any of these will be ok as for Store voltage.

 

[Timbo]

I'm coming from RC. After flying LiPo packs. I meticulously put them back on storage charge.

I found when I was new at RC. I didn't know that. My first packs became puffy and lost capacity and discharge performance.

Storage voltage for LiPos is 3.80 - 3.85 V.

So why not do this for EV or Solar storage packs!

I suppose if I built a E-Bike or E-Scooter. I will put it on storage charge when done for the day. Could be left unused till the next weekend etc.

Solar, I suppose it's something like charge to 80% and use to 20% before charging up to 80% again with the next days sunlight.

Say I go on holiday or set aside things for anything more than a day. I would want to storage charge everything.

The batteries deteriorate. The rate is depending on how deep the discharge is or how high the charge is and left in those states for how long.

That is why I never discharge below 20% or charge more than 80% when I don't have to.

Li-ion is confusing me. Because I seen different cells with different nominal voltages. 3.60, 3.65, 3.70 V etc. Plus wildly different suggestions for different brands of Li-ion. Some being 3.30 V for storage voltage.

 

[Oberfail]

I can reccomend you this site, to check out how the voltage in relation to capacity works out for different cells. https://lygte-info.dk/review/batteries2012/Common18650comparator.php

You have a 12s pack (probably), so depending between which charge states you want to operate your pack, go with 12*Voltage for your needs.
My suggestion would be to stay between 48.00V & 40.80V for each pack.

The difference in nominal votlage is due to the different charge and discharge voltage limits and the internal chemistry. Just go for 3.60v as a safe bet, as long as you store them cool and not at full charge, they should be fine. If you're putting them aside for long storage and not for them to be used, discharge them to 3.5v, disconnect the bms and put them somewhere, where its cool and dry.

 

[Oleksii]

I found when I was new at RC. I didn't know that. My first packs became puffy and lost capacity and discharge performance.

Yeah, but these are cylindrical cells in hard metal case, so they do not have risks to get "puffy" as pouch packets (Li-Po).
So it's not a risk thing to keep them near 100% charger for a period of time, if you need that. It's just better for them to store not fully charged, as in this case they lose capacity slower.

Check this video too

View: https://www.youtube.com/watch?v=jAcgld6gtyo&ab_channel=jehugarcia