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3x separate 7S pack connectected series via 45A BSM = 135A MAX current ?
#1
Hey Guys,

Does 3pcs of 7Spack with 45A BMS could deliver 135A of constant current ? 
(That's max value, I know that 100% of load in long run could be harmfull for BMS.)
And 3x180A= 540A of peak ?
In real life they will be loaded 40-90A of constatnt current so should be ok. 

I bought these: Deligreen 7S 45A 24V PCM/PCB/BMS for lithium battery pack 18650 Li-Po LiNCM Battery Pack
Packs build:
7S1P 60Ah ~1.5kW SAMSUNG SDI prismatic cells - I'm looking for more info about them / PV if you know more Huh
7S84P 240Ah ~6.2kW from 588x cells LG MG1 2850mAh
Inverter - 3kW AIMS  pure sine
Solar - considering addding 220W with MPPT Make Sky Blue 30A
Set up for mobile gastronomy 2kW cooling compressor + 500W appliancies
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#2
Yes, as long as the bms doesn't cut out and cause a cascade shutdown of the others.

If you plan on high current loads, you'll want to add extra heatsinks to the side that has the FETs to keep them cool.
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#3
No, not if connected in series. That will increase the voltage, but not the current.

If you connect them in parallel, then you get the sum of currents. Provided the packs are reasonably similar in capacity and internal resistance.
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#4
Theoretically yes but done expect the max to work out very well. If one pack just have slightly higher resistanse the other take higher load = trips the over current and you got a nice rolling thing going.

You should either
1. Make sure you have a proper BMS and or have a common limit
2. Make sure you build n+1 where you always can remove 1 pack... And still utilize the max current.
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#5
After looking at the units I would say NO if you have 3 connected in parallel to the same pack and a cautious yes to separate packs.

The issue is if your pulling 90A and you have 3 in parallel on the same pack, the units do not share the same voltage trigger to shut down, so you could end up with two units shutting down early and all the current trying to go through the last unit due to build quality and tollerance variation in relation to voltage level. The over current issue daromer highlights is in addition to this.

The peak 90A is the short term rating of each FET (sub second) and looks like around 23A maybe a 'hot' continuous rating per FET. 45A through the PCB might be interesting with the thin through hole connection. If you know what the FET's are you can lookup the actual cointinuous ratings, which may unsurprisingly be different....

Due to the way these are built if you tried 180A peak through them in parallel the resistance variations between the conections of and to each unit you may find the current on one is 140A the second 180A and the third 2.. pop. Add plenty of margin. Daromers point 2.

If you have a BMS per pack and connect 3 packs in parallel, the resulting additional current drain on the packs "should" pull the voltage down enough to cut them off toghether, howerver the 0.5 second delay limits your maximum expected amps (60A per pack) to well below 180A, however this depends on your balancing of pack quality. If one pack is particularly good then this could try delivering the 90A while the other 2 have bad cells and shut down early (depending on connecting wire lengths adding to the voltage drop).
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