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Ian

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Ian last won the day on January 31

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About Ian

  • Birthday 21/06/1964

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  • Gender
    Male
  • Location
    McGregor, WC
  • Interests
    I are engineer!

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  1. I see that new 280Ah LifePO4 cells are available on Ali for R1400/kWh. And the prices will just keep coming down - residential storage to go off grid is going to be a no brainier...
  2. All I can see is this accelerating migration to off-grid, which will just make their situation worse. They are in such a mess:(
  3. If he's planning to get the Pylontech 3.5kWh US3000, I see it can do 1.8kW continuous, and 5kW for 15s, so quite ok for your requirement I think.
  4. Hi Optic The current issue is a tricky one - best to check the specs of the battery that he's looking at, or supply the model number here. I know some manufacturers are sticky re warrantees if the inverter can overtax the battery, but hopefully there are other members here that can add more info. If the battery disconnects internally if overloaded then it should put that to bed at least. The inverter might also be able to be set to limit battery draw. but that's also something for the members here with experience to answer. Regards, Ian
  5. I'm assuming its a 48V system.
  6. Hi optics It would help to know the average power drawn by all the loads - this is the best way to know how many kWh have to be supplied by the battery for the time required... For instance, if the average draw is 2kW, and loadshedding is active for 2.5hrs, you would need 5kWh from the battery, which would need a 6.25kWh battery at least, assuming you use 80% of its capacity. The LA batteries he had were 9.6kWh in total, but you can only safely use 40% (3.9kWh) of their capacity without them degrading fast... One issue he might face regarding Li battery size: they can only supply a set maximum current, for several reasons. If he uses the full 5kW of inverter capacity, the battery will need to supply ~110A. This might not be doable with a single unit. He might need 2 or 3 in parallel. It would make a lot of sense to quantify the power draw before proceeding, as it will determine the batteries needed. Cheers Ian
  7. A quick Google.... https://solarequipment.co.za/product/revov-2nd-life-200ah-10-2kwh-lifepo4-battery/
  8. Scammers - a neighbour 'bought' 2 panels from them. Paid via Payfast, and that was the last he heard from them. Seems crazy that they are still operating after many months. Their ads pop up on Google all the time. He opened a case at SAPS, part of a long line of online fraud cases that day. Best to only use vendors that take CC's, unless you know they're legit.
  9. Hi All My neighbour has a Victron/Bluenova offgrid setup, which has been installed for a few years at his house. He's a Dutch resident, so only here occasionally. The system is set up so that the battery controls the charging cycle. As there is very little consumption, the battery cycles daily between 90 and 100% In the past the charge voltage has risen to 56.2 (max voltage set by battery) in the morning, and then immediately dropped to 55.5. There is a corresponding spike in the battery temp when the voltage gets to 56, and then it drops to ambient as the voltage drops to 55.5. Battery current is 0A at this stage. Speaking to a BN tech, the cell boards will dump/balance when the cell voltage is above 3.5, so that explains the battery temperature rise. Lately however, the voltage is kept at 56.2V all day, until the sun goes down, with the battery temperature sitting at 45-50C. I called BN, gave them access to the VRM etc, and while first saying all is ok and the temp behavior is fine, when pressed, said he should send the battery in to be checked by them. No other diagnostics suggested. It's obviously a big pain to send the battery in, and arrange a temporary replacement. The system needs to stay up to run the security system and cctv. Anyone have any experience with similar BN battery issues? I'd also like to know if it's possible to reconfigure the system to give the user more remote control of the charging arrangement. At the moment there's no way to set the battery charging behavior, as it's all up to the battery. Be nice to keep it at 70-80%(rather than 90-100%), and occasionally take it down to 20% etc, via VRM. Cheers Ian PS, I can post temp/V/SOC graphs if necessary
  10. Hi Smurf Are you planning to increase your output(kW)? If not, why don't you just parallel the cells? You can then just use the same BMS... Ian
  11. Hi Jaaks If you want more capacity, why not just double up on the cells and make a 16s2p battery? You can use the same BMS if your load hasn't changed. And you would need a larger enclosure, if needed. Seems the best bang for buck option? Ian
  12. I'll give them a try. Might start with 4, and keep 4 for emergency backup.
  13. Just my luck I'll come back to a pile of batteries and no bakkie
  14. Hi all After installing my DIY LifePO4 battery, I need to get rid of my 8 200Ah Ceil Gel batteries. They probably have 35% of their capacity left. What's the recommended procedure? Take them to a scrapyard? Cheers Ian
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