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Question about the battery extension
#1
Have at the moment already a 14er package with 7.5KW (60P14S) on the run.

Would like to switch now also a second set of Akkus also 7.5KW (60P14S) in order
to come to 2x 7,5KW (60P14S).

How should the state of charge of the first sentence be.
The new set is loaded at about 4.15 V per pack.
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#2
All voltages should be fairly close to each other before you connect them. I'd aim for max +/- 0.1V per cell difference.
The higher the voltage difference, the more current will rush in as you connect them, possibly triggering the breaker.
You can charge the first battery up to close to 4.15V, or discharge the new battery to the level of the first battery, or a combination of both - it does not matter.

Have you considered going 14s120p instead of 2p(14s60p) ? With your current plan, you need a second set of BMS, wiring, and breaker. I think most people expand to about 14s200p before adding a new parallel battery.
Modular PowerShelf using 3D printed packs.  40kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#3
Ok, something was misunderstood.
I would like to extend the 60p to 120p.
The new 60p are to be switched parallels to the first 60s packages.
And will completely use the BMS of the first packages.

Construction as in the photo





Now the only question is how the condition should be from the first package.
Since the new is the second package at 4.15v.
or does it matter anyway from the first packet ... 3.5-4.15v
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#4
(08-16-2019, 05:55 PM)Walde Wrote: Ok, something was misunderstood.
I would like to extend the 60p to 120p.
The new 60p are to be switched parallels to the first 60s packages.
And will completely use the BMS of the first packages.
(08-16-2019, 03:32 PM)ajw22 Wrote: All voltages should be fairly close to each other before you connect them. I'd aim for max +/- 0.1V per cell difference.
The higher the voltage difference, the more current will rush in as you connect them, possibly triggering the breaker.
You can charge the first battery up to close to 4.15V, or discharge the new battery to the level of the first battery, or a combination of both - it does not matter.

As ajw22 states, these need to be very close to the same voltage as possible before hooking them up.

(08-16-2019, 05:55 PM)Walde Wrote: Now the only question is how the condition should be from the first package.
Since the new is the second package at 4.15v.
or does it matter anyway from the first packet ... 3.5-4.15v

Refer to the previous statement. They need to be equal voltages, all packs & full string.
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#5
Very neat construction!
But I don't quite understand what I'm looking at.
Is this the new 14s60p (looks more like 90p, if not more) charged to 4.15V, and you want to insert the packs of your old battery (now at 3.5V) into the empty slots on the far left and far right?

If so, definitely equalize the voltages before connecting! If you don't, you will fry your old packs.
I suggest you get a "Laboratory Power Supply" such as this one:

https://www.amazon.de/KKmoon-Schaltnetzt...way&sr=8-5

With this, you can easily set the output voltage as well as limit the max current. Very useful when you need to slowly charge something (eg. your Battery#1) to a specific voltage.
Also order the banana clips - they are not included in the package.

How to use:
https://www.youtube.com/watch?v=T8Z2EFrbtpU

Just a little nitpick regarding the units/spelling/capitalization in the interest of education. A lot of people seem to be confused by this, but it's not that difficult.

KW <- this would be "Kelvin Watt" - not what you mean
kW <- this is "kilo Watt", a unit of power. Eg. the power output of an inverter is measured in this

kW/h <- this would be "kilo Watt per hour" - not what you mean
kWh <- this is "kilo Watt hour", a unit of energy. Eg. if an inverter outputs 0.5kW for 3 hours, you get 0.5kW*3h = 1.5kWh of energy.
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Modular PowerShelf using 3D printed packs.  40kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#6
Its a photo of my setup ... how dit that get here ?  Smile

there are 3 strings of 14s90p ... kind of ... becourse all the packs are in paralel it is realy a 14s270p setup made with 90p packs.
it is all in my build : https://secondlifestorage.com/t-Instant-powerwall

The free slot is for future expansion.

If you add packs, they need to be very close in voltage...
___________________________________
18x 300Wp solar off grid and 10x 180Wp solar tracker grid-tie
10KW 3phase hybrid inverter. 40Kwh 18650 storage (for now)
My setup: https://secondlifestorage.com/t-Instant-powerwall
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#7
(08-17-2019, 06:49 AM)wim Wrote: Its a photo of my setup ... how dit that get here ?  Smile

there are 3 strings of 14s90p ... kind of ... becourse all the packs are in paralel it is realy a 14s270p setup made with 90p packs.
it is all in my build : https://secondlifestorage.com/t-Instant-powerwall

The free slot is for future expansion.

If you add packs, they need to be very close in voltage...

Have your system as in the photo as a model.
Mine is still under construction and not quite finished.
Was so free and took your photo so that the others understand what is meant by extension.
Because it seems to have given misunderstandings.
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#8
No problem ... Smile
___________________________________
18x 300Wp solar off grid and 10x 180Wp solar tracker grid-tie
10KW 3phase hybrid inverter. 40Kwh 18650 storage (for now)
My setup: https://secondlifestorage.com/t-Instant-powerwall
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#9
(08-17-2019, 11:17 AM)wim Wrote: No problem ... Smile

Wim.
How do you do it when you expand your system.

Tell me. that would certainly interest other people.
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#10
For what its worth - when I add a new 'battery' in parallel to the others... (each row in my picture to the left is 14s 'battery')
1) As prep - all 14packs are parallelized with each other (using 28 alligator clip wires) for several days to balance all the packs with each other.
2) Then use 'the system' to raise (PV input) or lower (inverter drain) the overall battery bank to match the voltage of #1
3) Turn things off / hook in the new 'battery'

and resume normal operations.
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