Beginners Guide to Processing 18650 Cells | Cell Database


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Batrium BMS Questions
#11
Korishan thats correct Smile  

Wattsup: If brand is the same i bet they are same chem and all.

You would not really stress them no. Because the battery that can give current will do that... And since they are in parallel they will equalize them self in end.

BUT, if you mix types or different resistance on the cells you need to beware of that current on high loads/charges may not be even spred directly. So one of the packs have to take a bit more. But as long as you oversize everything thats not a big deal either. (Like for our 18650 were we try to not stress them to much in the end)

I just released this video:


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#12
Great video.
Thanks for taking the time to put it together
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#13
Hi guys

Wasn't sure where to post this, mods feel free to move if needed .

So I bought a batrium system for my CALB cells LiFePO4 cells. I've had it for a couple of weeks but just finding the time to sst it up today.

I thought I'd share the process here and will most likely have questions  Smile

The bockmons and daisy chain cables are all mounted and green leds on all mons.

I'm busy reading the batrium website and watching Pete and Daniel's vids to work out the next steps. I dont have the shunt yet as they were out of stock.


 Photos below

  

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#14
@Wattsup 

Is this pack temporarily 12v and then will be reconfigured to 48v ?

Looking good, a few pointers about your install:
  1. For parallel multiple string make sure the feeding POS/NEG cables linked to the inverter/charger need to be at either end.
  2. Cable management ideal methods
  • a. Red cable from Blockmon should be position above the busbar link to reduce the chance of catching from tools slipping the wrong way.
  • b. keep the red wire looped with the cable slots near the positive
  • c. keep the comms cable (blue/yellow) on the far side of each mon between them so that if the cable is yanked this locks against the pcb and not pull out of the socket.
  • d. tuck the comms cable (blue/yellow) under the battery busbar to minimise it for be caught
  • e. some of the power lugs are above the Blockmon pcb, the power path should always be direct between the battery and busbar/lug, the blockmon is then above to avoid large currents from being transferred through the pcb.

Some of the above is outline in the document found on the BlockMon page
Connecting BlockMons (Battery Chain)


Arrows related to (e)


Arrows related to © & (d)


Example cable management of blockmons to avoid them being caught by tools or other objects.
Wattsup likes this post
www.batrium.com provider of battery management for lithium cells
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#15
(06-18-2017, 07:13 AM)Batrium Wrote: @Wattsup 

Is this pack temporarily 12v and then will be reconfigured to 48v ?

Looking good, a few pointers about your install:
  1. For parallel multiple string make sure the feeding POS/NEG cables linked to the inverter/charger need to be at either end.
  2. Cable management ideal methods
  • a. Red cable from Blockmon should be position above the busbar link to reduce the chance of catching from tools slipping the wrong way.
  • b. keep the red wire looped with the cable slots near the positive
  • c. keep the comms cable (blue/yellow) on the far side of each mon between them so that if the cable is yanked this locks against the pcb and not pull out of the socket.
  • d. tuck the comms cable (blue/yellow) under the battery busbar to minimise it for be caught
  • e. some of the power lugs are above the Blockmon pcb, the power path should always be direct between the battery and busbar/lug, the blockmon is then above to avoid large currents from being transferred through the pcb.

Some of the above is outline in the document found on the BlockMon page
Connecting BlockMons (Battery Chain)


Arrows related to (e)


Arrows related to © & (d)


Example cable management of blockmons to avoid them being caught by tools or other objects.

Thanks for the detailed response!

Yes I'm going to run the 100 ah cells at 12 volt for now until I get to know the system, then I will parallel the 60 ah cells and run at 48 volt. Is there anything else I need to be aware of in this case.


Can I ask the reason for your #1. response. Just want to understand reason for this.

I will tweak the connection/ cable management to your recommendations.

Ive just ordered some extra  blocmon cables from your store so will put the rest of the install on hold until I  have those.

Your site was helpful but Daniel's install video got quite a few more views today  Wink
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#16
Regarding #1. The thing is that the cables to induce resistance. And as we all know this will lead to voltage drop. If you have both neg and pos in same end of the packs you will have a resistance to the other end. So for instance under load you will have a voltage difference over those packs compare to the packs in the connected end.

In the end this will lead to that the batteries closest will be abused more then the ones on the other end.

The more packs hooked up in parallel the more complicated this will get Smile And as always make sure to keep the resistance to minimum for all wires that you use to paralell the packs to reduce the issues.
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
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#17
I thought that was the reason. Thanks
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#18
(06-18-2017, 09:56 PM)Wattsup Wrote: I thought that was the reason. Thanks

Yes, daromer explained it if each link is 1 milliOhm (typically it is more). Your current configuration has the far cells (left) with 6 additional links hence 6 milliohms more impedance than the closest (right).
www.batrium.com provider of battery management for lithium cells
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#19
Ok, I  have another question, or thought for you all.This is me thinking out loud really Wink

Since I  got my LiFePO4 cells I've been busy researching the chemistry while running my 12 volt system.

There is not a massive amount of info out there and a lot of it can be conflicting I've found.


The main focus of discussion around them is over charge/ discharging and balancing cells.

My experience has been my cells are all really well balanced, even at higher and lower voltages but there are a couple of cells that discharge to a lower voltage than the rest.

The other thing is that unlike Li Ion you can't rely on voltage for true indication of state of charge. The cells may be reading 3.45 volts per cell under charge, then take away the solar and they will soon settle to around 3.30v.

These are the reasons I have purchased a bms.

The next issue is finding a charge controller with suitable charging profile for LiFe chemistry. Some say it's as easy as restricting voltage to around 3.65v per cell and all is good... But is it?

This brings me to my question...I have only found a few that some say are suitable and a couple that are supposed to be designed around these batteries, one being the Australian designed GSL electronics GSL MPPT60-1L. Does anyone have any experience with these?

The other option I've been considering is either the Eltek flatpack 2. Or the Elcon TC 48v charger both of which I think can be controlled by the batrium system.


Would be great to hear your thoughts
Cheers
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#20
They are generally not more difficult to charge than any other. Yes their SOC curve is flat like hell between 20-85% (Or something). That makes it hard to see where they are if you dont have the shunt!

So unless you have gotten all cells to 3.5V or above you still have cells not balanced to the other and its hard to tell if the voltage sag is normal or not. Thats where the BMS came in to play. It will tell you if all of them are pushed up to top and are fully charged. So you should basicly run them and charge untill you get them up. Just make sure that no other cells goes bananas and go way above lets say 3.65V.  

I had to do this manually for almost 3 weeks untill i got mine balanced good enough.  And as long as you havent hooked your BMS up to the inverter in terms of regulating the charge current you need to manually watch the Batrium software and make sure no cells goes to high. If that happens you need to lower the charging current or if you use MPP products lower the voltage. And when you see that it doesnt charge and highest is at for instance 3.5V you raise the voltage 0.1V again and keep doing that.

3.5V is recomended voltage on most those cells for longeivity. 3.65V is maximum and you can potentially push it towards that while balancing.

[Image: X3Hw6O.jpg]
Example of my system right now. I have 1 cell at 3.55V that is being balanced and then next one is at 3.51. Rest is between 3.46 to 3.49V and pretty topped up. 

Hope that explains a bit. 

So no need to look for a specific charger really. Most chargers can be set in such a way that the float/bulk will work. Float only to be used briefly. I have mine 0.2V below the other and it works great so far. It goes to float for just minutes and then stop charging the battery when top voltage is reached. In above image the charging stopped just minutes earlier
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Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
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