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Author Topic: Pylontech Charge Current  (Read 463 times)
greentangerine
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« on: April 29, 2020, 08:27:36 AM »

Now I'm controlling the charging of my US2000B stack during the Octopus Go cheap period, a query has been raised as to what the safe charge rate is.

My SoFar ME3000 has always been set to a maximum charge rate of 3kW when in auto mode (and it seems to do so) and the BMS says something like 65A maximum.

So I've been charging during the cheap period at 3kW too until it gets to the charge capacity determined by weather forecast etc. 

I'm logging the battery stats via MQTT every 60s and the temperature is around 24C and the charge current to the pile during this time is around 57A.   

The Pylontech specs. suggest a normal/recommended charge rate of 25A - given I have 8 batteries my simple, possibly naive, maths suggests that means each battery is getting a charge rate of about 7.2A during this  time.

Is this correct, or am I really pushing the rate to all the batteries near max? 

I can raise the battery charge by a maximum of 55% during the cheap period with a charge of 3kW - recently I haven't needed to do this (until last night) but over winter it is necessary to get it as high as possible.
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2.940 kWP (Sharp ND210/Solis 4G 2.5)
2.115 kWP (Kinve KV235-60P/SB1600)
2.000 kWP (Sharp ND250/SB1600)
65 x 58mm SunnPro/Torrent T280 RE OV/SunSpeed2 205
11kW Dean Forge Croft Clearburn 10,000 BTU
SoFar ME3000SP/Pylon US2000 19.2kW
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[url=http://pvoutput.org/list.jsp?id=4602&sid=195
pantsmachine
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« Reply #1 on: April 29, 2020, 08:33:35 AM »

I charge 3 at 75amps. 25amps per battery and this is autoselected by the charge controller. A little over 13kw if system was charging flat out but the bms keeps it under control and it step charges based on heat. I was playing about with pv master the goodwe charge controller app using it to ID a f'd battery the other month. I had all batteries disconnected and every permutaion during re connection to fault find. Each time I plugged a battery in the max charge/discharge in the app jumped by 25 amps, I hope this helps. I don't know how it work with 8 as that would be 200 amps which would likely blow your incoming fuse? I'm not sure, why not shoot a email to Pylontech China, they are helpful and fast responders?
I've pm'd you an address.

 The largest load I have pulled from grid is about 18kw during an Agile negative window. I'd set max incoming across all 8 to 100 amps, that way they are seeing 1/2 max charging load and go from there but i'd check my breaker and main fuse rating first.
« Last Edit: April 29, 2020, 09:31:05 AM by pantsmachine » Logged

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brackwell
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« Reply #2 on: April 29, 2020, 09:37:14 AM »

I am no expert but looking at the spec sheets (midsummerwholesale.co.uk  p18) for just your combination gives 1batt =25A  2batt=50A 3+ batts 60A
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greentangerine
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« Reply #3 on: April 29, 2020, 10:19:28 AM »

My ME3000 can only output a maximum of 3kW to the battery stack and does so at around 60A give or take; it won't go any higher, regardless of what the BMS might let it theoretically do.

I think therefore with eight batteries in the system, that means a maximum of 7.5A each (ignoring any balancing by the BMS) so I'm well under the 25A recommendation and nowhere near the permitted maximum.

At least I hope so, otherwise I need to restrict the 3kW charge to something lower.
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2.940 kWP (Sharp ND210/Solis 4G 2.5)
2.115 kWP (Kinve KV235-60P/SB1600)
2.000 kWP (Sharp ND250/SB1600)
65 x 58mm SunnPro/Torrent T280 RE OV/SunSpeed2 205
11kW Dean Forge Croft Clearburn 10,000 BTU
SoFar ME3000SP/Pylon US2000 19.2kW
immerSUN 2
[url=http://pvoutput.org/list.jsp?id=4602&sid=195
nowty
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« Reply #4 on: April 29, 2020, 10:36:23 AM »

With 8 pylontech batteries in parallel you might think the max is 8 x 25 = 200A but the limiting factor is the current carrying capacity of the 25mm cable that connects them.

It starts getting warm over 100A and hot over 120A.

I have a max of 166A charging power but I only go that high if I have both battery banks connected (8 x pylontech and 9 x growatt).
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kdmnx
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« Reply #5 on: April 29, 2020, 12:16:09 PM »

I had this for a bit when I upgraded my array. You have to sync the batteries to get them acting as a single unit and report correctly.

Step 1: Power all the batteries off using the switches, disconnect the data connection to the inverter and the data interconnects between the batteries, disconnect the positive (or negative) power connection to the inverter. Turn on the batteries one at a time with the switch, then one at a time with the red button (requires a long press). Observe the lights, the batteries will transfer power between each other to balance the stack. Flashing lights means receiving power, solid means sending power (or the other way round), off means doing nothing. When the light are all off the pack is balanced (could take a while).

Step 2: Switch all batteries off with the switch, reconnect everything, switch all the batteries on with the switch, wait for them all to be ready and turn the top one on with the red button (long press). All the batteries should now turn on and the pack is operating as a single battery. It should now report to the inverter the correct charging current.
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