May 10, 20215 yr Hi Guys I have a friend with a Sunsynk 8kw Inverter & 5 x US3000 Pylontech batteries that he has linked up using the Canbus connection. He has 3x US2000's that he would like to add to his current stack of batteries Are there any issues with adding them that he should be aware off? I believe that the maximum number of Pylontech batteries in a string you can add is 8, is that a battery communications limit or a power bus bar limit? Specifically concerned with the mixing of battery capacities and the communications but if there is anything else would appreciate advice/comments.
May 10, 20215 yr 2 hours ago, Sc00bs said: Hi Guys I have a friend with a Sunsynk 8kw Inverter & 5 x US3000 Pylontech batteries that he has linked up using the Canbus connection. He has 3x US2000's that he would like to add to his current stack of batteries Are there any issues with adding them that he should be aware off? I believe that the maximum number of Pylontech batteries in a string you can add is 8, is that a battery communications limit or a power bus bar limit? Specifically concerned with the mixing of battery capacities and the communications but if there is anything else would appreciate advice/comments. As far as I am aware, Pylontechs are max 8 to a set. I have also heard of US2000 and US3000 Pylontech battery sets in parallel, the BMS handles the balancing. It's not something that I would personally do, but possible. As an added precaution, he needs to ensure that the batteries are properly balanced for a few days upfront (before connecting to the system) and ensure that all have the last firmware revision levels.
May 10, 20215 yr 1 hour ago, YellowTapemeasure said: As far as I am aware, Pylontechs are max 8 to a set. I have also heard of US2000 and US3000 Pylontech battery sets in parallel, the BMS handles the balancing. It's not something that I would personally do, but possible. As an added precaution, he needs to ensure that the batteries are properly balanced for a few days upfront (before connecting to the system) and ensure that all have the last firmware revision levels. The newer C models can be stacked with up to 16 batteries before needing the LV hub. Most additions I've seen is that the new battery is either the same size or bigger. Don't think the pylontech manual indicates what to do if the new battery is smaller than any of the existing batteries in the bank. I've already read that new batteries must be set to the master and that the biggest battery in the bank should also be the master. US3000 added to bank of US3000 or UP5000 added to US3000 or US2000. Never seen any mention of US2000 added to US3000.
May 10, 20215 yr 1 hour ago, Achmat said: Never seen any mention of US2000 added to US3000. Not a problem, according to Pylontech:
May 10, 20215 yr 33 minutes ago, ChristoSnake said: Not a problem, according to Pylontech: I get that and you might be misunderstanding what I'm saying. Adding a new US2000 to an existing bank of US3000 batteries. From the conclusion the bigger battery will always be the master even if the smaller battery is newer. Unless the price of the new US2000 are significantly less per kwh, I would stick with US3000 batteries or bigger to add to the existing bank of US3000 batteries.
May 11, 20215 yr Morning all, If I may chip in I also have a sunsynk pylontech question. Currently have 3 2.4kwh us2000 plus batteries connected to a infinisolar 4kw. Want to replace the infini with a 5kw sunsynk. I also want to increase the batteries (same type 2.4kwh). According to pylontech on the 2.4kw battery you can charge/discharge the battery at 25A with a maximum of 100A (4 batteries or 4800W). If I pair say 6 batteries according to my understanding the BMS will limit the current draw to 100A irrespective of the amount of batteries is this correct? Will the BMS also charge the bank to maximum of 100A? In other words will the BMS take over and only ask the inverter for the amps it wants? I want the extra batteries to supply by base load for longer I don't want to draw more than 100A from the bank.
May 11, 20215 yr 22 minutes ago, stoneyc113 said: If I pair say 6 batteries according to my understanding the BMS will limit the current draw to 100A irrespective of the amount of batteries is this correct? Will the BMS also charge the bank to maximum of 100A? In other words will the BMS take over and only ask the inverter for the amps it wants? I want the extra batteries to supply by base load for longer I don't want to draw more than 100A from the bank. If you place 6 batteries in parallel, the maximum that the batteries will allow is 6x 25A =150A. If you use the Sunsynk, you can also set the maximum charge / discharge rate on the inverter itself.
May 11, 20215 yr 9 hours ago, YellowTapemeasure said: If you place 6 batteries in parallel, the maximum that the batteries will allow is 6x 25A =150A. If you use the Sunsynk, you can also set the maximum charge / discharge rate on the inverter itself. Thank you, yes I understand that what I don't understand is if I have 8 in parallel according to the above the batteries will allow 400A. The connection cables are 25mm2 they will never handle that amps. What am I missing then? Do you get bigger cable sets to use? Do you wire them in banks of 4 and parallel the banks?
May 11, 20215 yr 9 minutes ago, stoneyc113 said: Thank you, yes I understand that what I don't understand is if I have 8 in parallel according to the above the batteries will allow 400A. The connection cables are 25mm2 they will never handle that amps. What am I missing then? Do you get bigger cable sets to use? Do you wire them in banks of 4 and parallel the banks? That would be the best Ilton and you can double the cables on the battery bank. I have 4 us3000 batteries and using two sets of cables to go to the inverter as on the pic below.
May 11, 20215 yr 16 minutes ago, stoneyc113 said: Thank you, yes I understand that what I don't understand is if I have 8 in parallel according to the above the batteries will allow 400A. The connection cables are 25mm2 they will never handle that amps. What am I missing then? Do you get bigger cable sets to use? Do you wire them in banks of 4 and parallel the banks? I am not sure how you arrive at 400A. With 8 in parallel, the BMS would allow 200A. Also, the Sunsynk can limit charge / discharge, as per my previous post, but if you want to be safe, how long are the 25mm sq cable runs (from battery to inverter)?
May 11, 20215 yr 2 hours ago, YellowTapemeasure said: I am not sure how you arrive at 400A. With 8 in parallel, the BMS would allow 200A. Also, the Sunsynk can limit charge / discharge, as per my previous post, but if you want to be safe, how long are the 25mm sq cable runs (from battery to inverter)? Sorry yes 200A I used the 50AH but 0.5C is 25A. No not long within 1.5 meters. Thanks for the replies all I have the answers I was looking for, I was under the impression the BMS limits to 100A irrespective of the amount but it seems it does not.
May 12, 20215 yr 11 hours ago, stoneyc113 said: Sorry yes 200A I used the 50AH but 0.5C is 25A. No not long within 1.5 meters. Thanks for the replies all I have the answers I was looking for, I was under the impression the BMS limits to 100A irrespective of the amount but it seems it does not. As per https://www.fabhabs.com/dc-cable-sizing-calculator your current 25mm2 cable at 1.5m is good for 56A. Anything more than that will need an upgrade. Doubling the existing 25mm2 cabling may be cheaper if you have spare cable lying around, and will give you a maximum of 78A. Yet if I look at https://enerdrive.com.au/wp-content/uploads/2015/04/Cable-Chart.pdf it states that 21.2mm2 cable will handle up to 100A. Which to believe? Edited May 12, 20215 yr by YellowTapemeasure
May 12, 20215 yr 56 minutes ago, YellowTapemeasure said: As per https://www.fabhabs.com/dc-cable-sizing-calculator your current 25mm2 cable at 1.5m is good for 56A. Anything more than that will need an upgrade. Doubling the existing 25mm2 cabling may be cheaper if you have spare cable lying around, and will give you a maximum of 78A. Yet if I look at https://enerdrive.com.au/wp-content/uploads/2015/04/Cable-Chart.pdf it states that 21.2mm2 cable will handle up to 100A. Which to believe? 25mm² single core low voltage cable is good for 125A in air 25mm² single core welding cable is good for 140A 100% duty cycle Consult the Aberdare low voltage catalogue. From this discussion it is advisable then to double up un the output cables for every bank of 4 batteries in parallel
May 12, 20215 yr 15 minutes ago, stoneyc113 said: 25mm² single core low voltage cable is good for 125A in air 25mm² single core welding cable is good for 140A 100% duty cycle Consult the Aberdare low voltage catalogue. From this discussion it is advisable then to double up un the output cables for every bank of 4 batteries in parallel I'll take a look at the Aberdare catalogue, thank you. So are you saying that your battery to inverter cable run of 1.5m isn't in conduit? Mine is, hence I ticked the Bundle/Conduit box.
May 12, 20215 yr 4 minutes ago, YellowTapemeasure said: I'll take a look at the Aberdare catalogue, thank you. So are you saying that your battery to inverter cable run of 1.5m isn't in conduit? Mine is, hence I ticked the Bundle/Conduit box. No it is not, it is strapped to perforated mesh from behind battery cabinet to inverter above.
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