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Can you add gen2 leaf cells to a gen1 powerwall?
#11
(09-30-2020, 09:39 PM)BigDav Wrote: My plan was to add the gen2 cells to each parallel pack in my existing battery by reconfiguring the busbars and layout etc
So in each parallel stack I would have 4x gen1 modules and 7x gen2 modules

Very interested to see how you're going to design the busbars... seems like an impossible task without producing a spaghetti maze of wires, at least on quick thought
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Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#12
Or just create to different 48v pack's? and leaf your gen1 alone?
Just connect the gen2 at the 48v mainline???
Or is this really stupid?
It was just a thought thinking out loudfor perhaps 2 bms's?

This was my ONE cent thought, hope it will give food for your thought, i am open for comments.
With best regards Igor
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#13
Should be able to run parallel stacks eg 1x 48V Gen1 & 1x Gen2 connected at the 48V bus just fine.
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Running off solar, DIY & electronics fan :-)
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#14
(10-05-2020, 05:30 PM)100kwh-hunter Wrote: Or just create to different 48v pack's? and leaf your gen1 alone?
Just connect the gen2 at the 48v mainline???
Or is this really stupid?
It was just a thought thinking out loudfor perhaps 2 bms's?

This was my ONE cent thought, hope it will give food for your thought, i am open for comments.
With best regards Igor
(10-06-2020, 08:42 AM)Redpacket Wrote: Should be able to run parallel stacks eg 1x 48V Gen1 & 1x Gen2 connected at the 48V bus just fine.


I have considered having 2 different packs in parallel. My BMS is a Batrium Watchmon 4 with 7x Leafmon cell monitors. Obviously I would need another 7x Leafmons for the Gen2 48v pack, but would I need another Watchmon 4 supervsior? Or would my existing WM4 do the job for both Gen1 and Gen2 48v packs?
Battery Capacity: 14kwh  = 28x 2011 Nissan eNV200/Leaf Gen1 Modules (14s4p) with Victron Multiplus II GX 48/3000 AC Coupled Inverter
Solar Capacity: 3.18kwh = 12x REC 265PE BLK Solar Panels with SolarEdge SE4000 Inverter
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#15
(10-10-2020, 12:59 AM)BigDav Wrote:
(10-05-2020, 05:30 PM)100kwh-hunter Wrote: Or just create to different 48v pack's? and leaf your gen1 alone?
Just connect the gen2 at the 48v mainline???
Or is this really stupid?
It was just a thought thinking out loudfor perhaps 2 bms's?

This was my ONE cent thought, hope it will give food for your thought, i am open for comments.
With best regards Igor
(10-06-2020, 08:42 AM)Redpacket Wrote: Should be able to run parallel stacks eg 1x 48V Gen1 & 1x Gen2 connected at the 48V bus just fine.
I have considered having 2 different packs in parallel. My BMS is a Batrium Watchmon 4 with 7x Leafmon cell monitors. Obviously I would need another 7x Leafmons for the Gen2 48v pack, but would I need another Watchmon 4 supervsior? Or would my existing WM4 do the job for both Gen1 and Gen2 48v packs?
WM4 (+Expansion) can do up to 250 longmons (e.g. leafmons are same design - network chain).  https://support.batrium.com/article/90-h...e-watchmon     I run 84 longmons - so I'm confident you can do 14 if you decide to go that way Smile  
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#16
@offgrid,
Thinking out loud: i think you will need two different systems, speaking for myself: i would buy a extra wm4.
Yes one wm4 can do 250+ daisy chained longmons/leafmons, but those are different capacity's, would that not give any trouble?
Cous we are doing a lot of trouble to make every string the same capacity
Best
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#17
Just a heads up, chemistry has changed quite significantly between the gen1 cells and any other type of cell. The discharge curve is very top-oriented on the gen1/2 24kWh, but on gen3 30kWh and gen4 40kWh, the discharge curve works more like a "normal" lithium battery. This is because they added cobolt to the mixture on the 30kWh and upwards.
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#18
@Dala,
That would in play that my thoughts/feelings on a second wm was correct?
With best regards, Igor
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#19
Ultimately you will have a Gen1 48V battery & a Gen2 48V battery in parallel at the main positive & negative busbars.
If you decided to have two current shunt devices to track current separately, then maybe a 2nd watchmon might be needed or useful.
If you just had the one shunt then I don't see why a 2nd watchmon would help.

I have 4 x 16s batteries in parallel at the busbars via one shunt & have 32 longmon & 32 cellmon M8's & this all works together just fine (apparently!).

Maybe you could have the one Batrium system, one shunt there + a Victron BMV-712 shunt (or cheaper eBay model?) in series with each battery.
Eg Batrium does main BMS & balancing functions, BMV's just monitor for you.
Running off solar, DIY & electronics fan :-)
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#20
Thinking about 2 x Watchmon vs 1 and different chemistries.   I'm not sure 2 Watchmons are needed.

For me, I use Batrium (and the 84 longmons) primarily to monitor and throw shunt-trip is extreme conditions - e.g. an individual pack <3.1v and >4.15v.   I don't use balance except for touch-up after 6 months or so - and its not needed on a daily basis for healthy cells!      I operate in the 3.5v to 4.0v range for long life - don't get near the extremes and only do touch up balance once drifts to 100mv max difference - so 3.4 to 4.1 will still not hit the extremes. 

Thinking about this...  even though Gen1 and Gen2 might have different discharge curves and are in separate parallel batteries 
1) Batrium will see / report each pack separately - which is no problem monitor wise if you know that 1-7 are a bit different discharge curve than 8-14 - there's no harm, its just info. 
2) Batrium balance - you're not limited to 'top balance' you can use auto-level at various portions of the voltage curve.   So I'm sure somewhere - top, middle, bottom  - you can find a place to do touch-up (or initial) balancing, and then just turn it off.    Balance is not needed for healthy packs on a regular basis!
3) Extreme / shunt-trip - assuming your operating in the long-life/power range', e.g. 4.1v to 3.4v, then even with different chemistries - its not clear that one Gen will hit the extremes  of 3.0v and 4.2v (or whatever you choose) before the other...    especially if you're using a long-life operating voltage range as I mention above.  

In conclusion - I don't  see the need for multiple Batriums even if the chemistry is different  Smile    Of course it depends on 'how different' the voltage ranges are in practice - I'll be interested to hear about it once you get info and if you share - but really, they are both lithium-ion and shouldn't be wildly different?   


P.S. I think we already covered mixing Gen1 and Gen2 parallel wise - so this post is limited to the idea that they are not mixed.
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