Begginers Guide to Processing 18650 Cells | Cell Database


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Batrium BMS Questions
On checking the battery this morning I was a bit surprised by this

 

There are two cells that are weaker than the rest ie. (have lower voltage, discharge quicker than others). The two with duct tape on them. I'll  call them runts  Big Grin

When I set up the 16s pack I considered positioning these 2  runt cells as positive and negative feed cells
(Cell 1 & 16). I had the thought that it might force them to perform better. Not sure if there is any merit to this thinking?

 Instead I placed them one cell back ( 2 & 15).

The lowest cell in the above screen is 2.89. This is the lowest any of these cells have been so far. 2.65 being empty.
The remaining 14 cells were betwee 3.14 -3.17v

With regard to my previous post about SOC, it seems the pack was a fair bit lower than I thought.
I have since reset the SOC to 15%.

I'd appreciate any thoughts on above and question below.

1. Would you position runts as cell 1 & 16, will it make any difference, or is this a bad idea?

Reply


Its LiFe Smile You need to top them off good so you get them all level. Top them up so all of them actually go to 3.5V so you know they are level. It can take some time and you might need to help the longmons drain the other packs Smile
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(09-13-2017, 04:20 AM)daromer Wrote: Its LiFe Smile You need to top them off good so you get them all level.  Top them up so all of them actually go to 3.5V so you know they are level. It can take some time and you might need to help the longmons drain the other packs Smile

Such is LiFe  Smile 

I'll push the amps into them and see how they balance at the top.
Thanks
Reply
What is the maximum cells in series for the batrium system?
Reply
250 in terms of number of monitors. I have heard numbers of above 700V in series voltage.

https://www.batrium.com/pages/how-many-l...e-watchmon
hbpowerwall likes this post
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply
(09-13-2017, 01:08 AM)Wattsup Wrote: There are two cells that are weaker than the rest ie. (have lower voltage, discharge quicker than others)...

1. Would you position runts as cell 1 & 16, will it make any difference, or is this a bad idea?

The only two aspects that occur to me are 
- they may run hotter than the others, which would then tend to (slightly) magnify any difference. An end position would have more cooling exposure, reducing the temperature difference and consequent effects. But this is unlikely to be of great practical significance. 
- and they would be more accessible when you replace them!
Reply
(09-20-2017, 10:03 AM)dougal Wrote:
(09-13-2017, 01:08 AM)Wattsup Wrote: There are two cells that are weaker than the rest ie. (have lower voltage, discharge quicker than others)...

1. Would you position runts as cell 1 & 16, will it make any difference, or is this a bad idea?

The only two aspects that occur to me are 
- they may run hotter than the others, which would then tend to (slightly) magnify any difference. An end position would have more cooling exposure, reducing the temperature difference and consequent effects. But this is unlikely to be of great practical significance. 
- and they would be more accessible when you replace them!

Good point, they probably would run hotter! 
Thanks for 
I think i'll  leave them where they are. Thanks
Reply


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