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Lithium battery bank charging

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Joined
May 10, 2021
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13
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Bahia San Agustin Huatulco
Hi I'm new to lithium batteries. I have 9000 watts of solar, 2 strings, going to 2 growatt 80 amp charge controllers. These feed 6 growatt 5.12 kw batteries. I'm having 1 battery not charging at the same rate. 4 batterys are at for example 75% one is at 50% and the other is less than 25%. I changed the location of the controller attachment ti the bus bar to more even out the distance to the other controller feed and now its the same situation but with 2 other batteries. I'm looking at buying 10 more 440 watt panels and another controller. Am I correct in thinking I'm under feeding the battery bank? Thank you gor any help.
 
My first suggestion is to use kWh when referring to battery capacity. When you say a battery is not charging at the same rate, tell us the current and voltage of each of the batteries? Could it be at a different State of Charge than the others? Are they in parallel or in series?
 
My first suggestion is to use kWh when referring to battery capacity. When you say a battery is not charging at the same rate, tell us the current and voltage of each of the batteries? Could it be at a different State of Charge than the others? Are they in parallel or in series?
Thank you yes 5.12 kWh per battery. They are in parallel for a total of 100 amps. I have turned off 3 of the batteries that have 3 of their 4 leds lite up as showing charge of 75% already within half hour my lowest battery is showing between 25 and 50% charge. 19.67 amps charging. My fullest battery, 4th led flashing is charging at 20.59 amps
 
Thank you yes 5.12 kWh per battery. They are in parallel for a total of 100 amps. I have turned off 3 of the batteries that have 3 of their 4 leds lite up as showing charge of 75% already within half hour my lowest battery is showing between 25 and 50% charge. 19.67 amps charging. My fullest battery, 4th led flashing is charging at 20.59 amps
Please post a pictures of your system showing us how the batteries are paralleled and how they are connected to the rest of the system.
What is the system voltage?
Are the batteries LFP?
 
It looks like from the information you posted that the batteries are at different States of Charge. Over time if they are all in parallel the voltages should be the same if some current is flowing. I have no idea what 3 of 4 LEDs means. Could it be that one cell is over the limit and the BMS has cut off charging. Can you measure voltage at the cell level? What is the configuration of your pack? As @smoothJoey asked, we need more information in order to help.
 
Thanks for the quick replies. I'm in mexico and getting things is sometimes difficult. My 6 gyll 48v 5.12 kWh 100 amp batteries have been running for a month now. No issues with power just noticing different states of charge. I thought the BMSs in each battery were to equalise automatically. These batteries are designed to fit in a server rack. Unavailable were I am so I used a modified gorilla rack got .5 inch copper pipe and melted lead till they were full used appropriately 7 lbs of lead. I then drilled and bolted the cable connections. I can hook my computer up and get cell voltages. 20220102_133716.jpg
 
I probably would have used thick copper bar instead of copper pipe.

BTW, lead is a horrible conductor. Filling with lead was pretty much useless.

1641155171472.png
 
I just can't get copper bar here.
I did hear lead was plentiful in Mexico. My sister used to live there and she said one of the reasons that it was found in so much candy was that the sugar cane farmers would put parts of old batteries in their wagons to increase the weight of their crop when delivering sugar can to the mills.
 
The lead helps you make a tight connection using the clamps you chose…

I would get rid of them though.
Lead clamps SUCK as conductors go.

I would use terminals like you did for the battery connection cables…

I would get rid of ALL the pipe you used, get more pipe, and hammer it flat.
You want CLEAN connections.

On your charging cables, you have nuts spacing the lugs… you want ALL lugs in contact with each other, and the bussbars.

Clean the bar you have, clean every connector and tighten it down.
Don’t worry about spreading the cables, it will be fine how you have it. But get ALL the connections clean and in contact with the copper.
 
The lead helps you make a tight connection using the clamps you chose…

I would get rid of them though.
Lead clamps SUCK as conductors go.

I would use terminals like you did for the battery connection cables…

I would get rid of ALL the pipe you used, get more pipe, and hammer it flat.
You want CLEAN connections.

On your charging cables, you have nuts spacing the lugs… you want ALL lugs in contact with each other, and the bussbars.

Clean the bar you have, clean every connector and tighten it down.
Don’t worry about spreading the cables, it will be fine how you have it. But get ALL the connections clean and in contact with the copper.
Thank you I see your point of direct contact with the copper and not sandwiched between nuts.
 
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