February 22, 20224 yr Ok, so based on this datasheet the recommended charge / discharge A is 50: https://cdn.shopify.com/s/files/1/0536/3964/3304/files/51.2V16cell-100Ah-Resi-5.12Kwh-SHOTO.pdf?v=1630084875 The installer set the charge to 30A (should be fine there?) BUT I see the discharge A is set to 120A on the inverter. Do I need to adjust down to 45A or lower? My BMS system charges the battery to 100% at intervals irrespective of the inverter SOC settings. Current settings are to charge to 80% during the day. Overnight this obviously drops down.
February 22, 20224 yr 9 hours ago, RyC said: Ok, so based on this datasheet the recommended charge / discharge A is 50: https://cdn.shopify.com/s/files/1/0536/3964/3304/files/51.2V16cell-100Ah-Resi-5.12Kwh-SHOTO.pdf?v=1630084875 The installer set the charge to 30A (should be fine there?) BUT I see the discharge A is set to 120A on the inverter. Do I need to adjust down to 45A or lower? My BMS system charges the battery to 100% at intervals irrespective of the inverter SOC settings. Current settings are to charge to 80% during the day. Overnight this obviously drops down. I am pretty sure the BMS would not allow a steady and prolonged discharge at 120A. And your 5.5KW battery cannot produce 120A anyway. Some manufacturers claim 1C discharge. In your case, its probably a 100/105Ah battery and 1C means that it can discharge at max amp of 100/105A I think it may be safer to go with 0.5C which means charge at 50A or slightly below. My Pylontech batteries are rated at 0.5C. Also note that if you drop down to 50A discharge, the system can only produce about 2.4Kw during load shedding. It is possible that the BMS may allow discharge of 1C at the full 100/105A (about 5KW) which is the capacity of the inverter I must mention that i am no expert and my advice is based on my own reading on the subject and i tend to err on the side of caution So my advice would be to drop down 50A discharge. But if a knowledgeable installer or manufacturer says to leave it then that may be fine for your particular battery.
February 23, 20224 yr 6 minutes ago, RyC said: So I could set my charge up (to say 40A) and my discharge down to 100A (Max): According to your datasheet, it seems 100A will work but it is listed as a Max and not a recommended. Personally i would go on a lower discharge at around 50 or 60A. But that's just my cautious outlook. At Max output and if your load is also drawing the Max, the battery will be depleted in under an hour. Even though it seems possible to discharge at 100A, you also need to consider what are the essential loads to supply during a power outage. Geyser, electric stove, aircon, etc. are usually excluded and inverter is wired accordingly through the DB. Bottom line, it is not ideal to discharge at max current but for this particular battery, it seems possible. Although expensive, it is advised to scale your batteries in such way to discharge at 0.5C and still deliver the max output of the inverter. In your case it would mean 2 X 5Kw batteries.
February 23, 20224 yr Thanks, still battling to understand some of these concepts 😁. I'll set the discharge current lower and up the charge current. On the cards for end of year will be expanding my solar panel installation as well as adding another battery. Based on previous load shedding experience (with current settings) the battery depletes by around 40% overnight if we have 2 sessions of 2.5 hrs.
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.