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green-techie asked

Mixing Pylontech Us5000/US3000C with 3 x SmartSolar MPPT RS 450/100?

I have five Pylontech US5000 batteries, which I wish to charge as quickly as possible from three SmartSolar MPPT RS 450/100 units (with around 22kWp of PV), to make the most of short bursts of winter sun. The inverter is a Quattro 8000VA, so I am not going to discharge the batteries as quickly as I would like to charge them.

The maximum output from the 3 x SmartSolar MPPT RS 450/100 is 300A, but at the Pylontech recommended charge rate of 50A per battery the maximum charge rate would be 250A.

I thought that DVCC would make the best of what was available to charge the batteries and if I went over 250A the rest could be used by the inverter, if required.

I see from numerous other posts, like this and this that there are many factors which effect the actual charge rate of the batteries, including some people claiming Pylontech batteries may only charge at 25A, to preserve battery life. Victron themselves recommend here splitting into two stacks, using an extra set of long cables.

Can I split five batteries into unequal stacks? I could buy an extra US5000 and use two stacks of three, but there are long lead times on the US5000. I can get US3000C batteries, but would one stack of three US5000 and another stack of two US5000 mixed with one or more US3000C batteries be better balanced to receive more charge?

I didn't see this problem coming when I purchased the batteries earlier this year!

Any thoughts/advice appreciated,
Jamie

battery chargingPylontechmppt rs
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2 Answers
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wkirby answered ·

The US5000 manual has a table which explains how to stack mixed models.
Basically, the US5000 should ba master followed by US5000 and then US3000C.

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The cables and connectors are rated to carry 120A maximum, more like 100A continuous.
With a stack of US5000 and US3000C you could use two sets of the long cables coming off each end of the stack, in other word a positve cable off each end and a negative cable off each end, like you have seen in the other thread, then you would have a 200A capacity.

This is only 10kW charge power though, so you would need four sets of cable and split the packs into two stacks. I would not recommend having unequal stacks though.

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Perhps you can get hold of two US2000C and do three US5000 in one stack and two US5000 / two US2000C in another stack. This is not ideal, but the 74Ah capacity of US3000C is not an easy number to balance with 50Ah / 100Ah.



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green-techie avatar image green-techie commented ·
Thank you, that may be the best bet if I can't get another US5000 (or three!). You don't think I'll have a problem with the potential to generate 300A from the charge controllers? Or will I need even more batteries?
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kevgermany answered ·

The US5000 have a recommended continuous max of 80A, and max continuous of 100A according to my recent data sheet. So you're well under that. The smaller models are much lower

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green-techie avatar image green-techie commented ·
Thank you, I had only seen recommended listed as 50A. What worries me is the many comments suggesting that the Pylontech BMS limits the true charging rate to a much lower value, to prolong battery life (with the suggestion that it's to meet warranty limits).
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