max output from US 5000 pylontech batteries

[Tonyboy]

Good morning all.

Before I start I am not an electrician and am relatively new to this topic.

Current set up Axpert 5.5 Kw inverter, 7 x 420 watt panels in series and 2 x US 5000 Pylontech batteries paired (1 master 1 slave). System working fine will no issues.

I know this may have a simple answer but I have worked through the manual and have done some calculations but to be sure I thought I would post this and get it for sure.

The manual for the batteries says max charge/discharge current 100 amps and recommended 80 amps for a battery. I won't be using anything like these figures but my question is this.

I want to be able to draw 3.5 Kw to 4 Kw from my batteries in the event the sun goes in and the panels stop producing power so I want to ensure the batteries will provide the power I require. So far I have been able to off set the battery draw with sunshine or daylight so the batteries have only really been drawing 2 to 2.4 Kw according to the bms.

I realise pairing 2 batteries gives me 200 amp hrs and another would make it 300 amp hrs etc and the voltage stays the same 48V but I am unsure how the max Kw output is calculated for two or more batteries. I was given to understand that 2 batteries would give me 2.4Kw output and adding another would give me 3.2 Kw etc but is this the case. I do not use that much power generally but I want to ensure I do not overdo it when using battery only.

Any help or a definitive reply would be very welcome

Regards

Tonyboy

 

[kropaske]

Us5000 batteries have nominal voltage of 48v and nominal capacity of 4800W. Maximum charge discharge is 100A (4800W/48V) this is called 1C (your battery is charged/discharged from 0-100% or 100-0% in 1hr). You should avoid charging/discharging at 1C and use 0.5C which in this case is 50A(2400W/48V). You have 2 batteries in parallel so at 0.5C you can charge/discharge at 4800W or 100A.
If you add another battery that would be 7200W or 150A at 0.5C, however your inverter is rated at 5500W and that's max what it can provide.
Never discharge Your batteries to 0%, set depth of discharge in summer months to minimum of 10-15%.
In winter months you may need to increase it to something like 30-50% as there is not enough sun energy to charge them. Or it may be beneficial to disconnect 1 battery

 

[Tonyboy]

Us5000 batteries have nominal voltage of 48v and nominal capacity of 4800W. Maximum charge discharge is 100A (4800W/48V) this is called 1C (your battery is charged/discharged from 0-100% or 100-0% in 1hr). You should avoid charging/discharging at 1C and use 0.5C which in this case is 50A(2400W/48V). You have 2 batteries in parallel so at 0.5C you can charge/discharge at 4800W or 100A.
If you add another battery that would be 7200W or 150A at 0.5C, however your inverter is rated at 5500W and that's max what it can provide.
Never discharge Your batteries to 0%, set depth of discharge in summer months to minimum of 10-15%.
In winter months you may need to increase it to something like 30-50% as there is not enough sun energy to charge them. Or it may be beneficial to disconnect 1 battery

Hello Kropaske and thanks for the reply.

I have my inverter setting 2 set to max 50 amp charge and a max of 10 amps charge on the standby utility power if I need it to charge overnight.

So from what I understand the setting 1C is the max for discharge and charge, and with my setting of 50 amps this would then be 0.5C as you indicated i.e. 2400w for one battery.

Therefore if I wish to charge/ discharge at 0.5c my present setup would mean at 0.5C then the Max would be 4800w but would this be limited by my setting the max charge to 50amps on the inverter and therefore reduce the charge/discharge to 2400w accordingly. (would it effectively be 0.25C ?) Would I then need to up the max charge discharge to 100amps to be able to charge/discharge 4800w from the pair of batteries?

I am planning to add at least one more battery but I am not wishing to use more than a nominal 3.5 to 4 Kw at any given time. My usage is quite low as it is a small house.

Hope this makes sense?

Regards

Tonyboy

 

[kropaske]

Therefore if I wish to charge/ discharge at 0.5c my present setup would mean at 0.5C then the Max would be 4800w but would this be limited by my setting the max charge to 50amps on the inverter and therefore reduce the charge/discharge to 2400w accordingly. (would it effectively be 0.25C ?) Would I then need to up the max charge discharge to 100amps to be able to charge/discharge 4800w from the pair of batteries?

I don't know this inverter but if you set up correctly all the parameters (max voltages, capacity, etc) then inverter and battery bms should work out correct charging/discharging current. For example if you set total capacity at 4800W or 100Ah then charging/discharging at 0.5C would be 2400W but if you set total capacity at 9600W or 200Ah then at 0.5C you have 4800W

I am planning to add at least one more battery but I am not wishing to use more than a nominal 3.5 to 4 Kw at any given time. My usage is quite low as it is a small house.

If your usage is low what is the point of spending 1.5k on another battery. You have approx 3kwp system and you won't be able to fully charge those 3 batteries. On sunniest summer day you might generate around 16-18kwh but when winter come it will be 1-3kwh

 

[Tonyboy]

I don't know this inverter but if you set up correctly all the parameters (max voltages, capacity, etc) then inverter and battery bms should work out correct charging/discharging current. For example if you set total capacity at 4800W or 100Ah then charging/discharging at 0.5C would be 2400W but if you set total capacity at 9600W or 200Ah then at 0.5C you have 4800W

If your usage is low what is the point of spending 1.5k on another battery. You have approx 3kwp system and you won't be able to fully charge those 3 batteries. On sunniest summer day you might generate around 16-18kwh but when winter come it will be 1-3kwh

Hi Again

I have got the capacity set to 9600w/200Ah already on the bms and the only thing I have adjusted is the max charge at 50 amps on the inverter.
I will try setting the inverter max to 100A, this would give the 0.5C rate for the 200 ah of batteries, I think my initial concern is that I am worried about drawing more than 4200kw through the system as shown on the bms as I did not know what this represented in terms of the amount the batteries can supply in the absence of the pv.

Maybe I am looking at things from the wrong perspective. I know the inverter will top out at 5.5 Kw and my intentions are to use no more than 4 to 4.5Kw at any one time. Given the inverter is best used at this sort of level for its long term good I have no problem doing so. As I said at the start I am not an electrician and some of the finer points of inverters and associated battery charging do need some explaining.

In respect of the additional battery, I see your point.
regards

Tonyboy