I am mostly using it as a UPS for our refrigerator. Which we’ll only need once or twice a year.
My understanding is you shouldn’t store Lifepo batteries 100% charged. but in standard UPS mode it will be basically 100% charged all the time.
I’ll note that if i do a custom ups set to 60 or 70%. it would be enough for a day of power outage on the fridge. However in that mode the battery doesn’t act like a UPS, it constantly runs the load off the battery and then recharges the battery. which seems like it would degrade more?
So how best to to get the longest life out of the battery in this application?
@fessyfoo
Follow the Instructions suggested in the user manual to use the AC200L would be fine, kindly no worries. There is no specific method to extend its lifespan in UPS mode.
Here are a few suggestions:
Store and use the product at the temperature indicated in the manual.
Try to avoid overcharging and deep discharging; recharge the battery in a timely manner when the power is low.
Perform a battery calibration every 2-3 months (fully charge and fully discharge once).
The machine has a BMS management system to protect the battery.
@fessyfoo@BLUETTI regarding no.3 of your suggestion. What is better for keeping the battery optimal: Fully discharge to 0%-recharge to 100% OR discharge to 30% and recharge to 80% ?
Discharging to 30% then recharging to 80% will NOT calibrate the batteries. Because of the way LFP batteries work, the BMS can’t tell the state of charge based on voltage, so it needs to know the low (0%) and high (100%) values of the batteries to calibrate them.
Notice that this is only does once every 2-3 months.
There are two subjects here that should not be confused together:
Keeping LFP batteries at 100% charge: Some sources say that keeping LFP batteries at 100% for long periods of time may be bad for the battery. (source, source) However, others say it does not matter much. (source) Fact is that LFP batteries have a much longer cycle life than other types of lithium batteries. So it is probably more likely that the electronics die long before the battery cells get to an unusable level. If battery life is priority, you can keep them at max 90%. If emergency preparedness is important, charge them to 100% because power emergencies usually are not plannable. If you are not planning on using your power station for a long time, store it ar around 60% and charge it back up to 60% a few times per year. (There is some self discharge but not much)
Calibrating the SoC: Every Bluetti manual recommends to charge the batteries to 100% at least every 6 months and then let them discharge until they are empty and the output shuts off. Then immediately recharge them back to 100% using AC power. This to calibrate the SoC meter and keep the battery meter accurate.
Besides of that, most important is to never ever store the batteries at 0%. Because LFP batteries need some charge to recharge them. The BMS keeps some charge in reserve. So even when it reaches 0% and the unit shuts off, there is some charge left. Do not try to use this but recharge the battery. Hitting 0% does not hurt the battery. Leaving it at 0% does.
The user manual seems to suggest that storing the battery at 100% for long periods of time is not advised. that it should be kept at 40-60% SoC.
This would suggest using it as an infrequently used UPS and keeping it at 100% SoC would not be optimal according to the manual.
As noted above, it’s not possible to keep it a t a lower SoC and have it act as a a UPS (pulling power from mains unless mains goes away). instead it’s in an endless pull power from battery, and recharge from mains cycle.
but which of those two choices would be more optimal for overall life of the batteries?
If you do not need it as UPS and only need it twice a year, you have two options:
If you need it for unexpected power outages: Charge it to 90% or 100%. Turn it off and store it. Then whenever you have an unexpected power outage you have a charged powerstation ready to go.
If you need it for expected power outages, charge it to 50-60%. Turn it off and store it. When you expect a power outage, charge it to 100% before it starts and use it to power your refrigerator.
You still need to do the periodic calibration run. Do not use it in UPS mode when you do not need it as UPS. Because the idle power consumption is considerable and indeed, you have continuous small discharge-charge cycles from 100% to 99% to 100% again because the internal electronics always run from battery power, even when connected to utility power in UPS mode. This gives some wear on the electronics and battery. The unit is designed for this but it will last longer when you just turn it off as described above.
1-Be less reliant on the power grid and save some money in the process. I am only charging my Bluetti with solar. (im trying to, lately i have notice that even with the ‘charge from grid’ switch OFF, it will charge from grid to charge up around 10% on the battery once a day)
2-My Bluetti is feeding a 40inch TV, a computer, a NAS and network router. Its UPS function is very helpful in my case because power outage is frequent in my area. So my Bluetti is running AC output 24/7.
That being said, im located at around 45.8 latitude so at this time my solar 1000W array only give me 1 to 7 hours a days, depending on cloud cover, of free power to run the items i just listed. The only way i have found to keep the battery in a optimal SOC status is to set it ‘customizedUPS’ and LOW SOC at 59%, HIGH SOC at 60%. That way pass thru is activated when under 59% and solar is charging it back but rarely reach 100%. Its set to 59% because i want to keep a reserve of power in case of a grid down. The SOC is not respected at 100%, it was confirm by Bluetti that there is a 10% buffer zone around the SOC settings so its always off a bit when pass-thru is enable and when grid charging is activated (even if ‘charge from grid’ is at OFF it will charge, i hope this can be fix soon!).
I hope that having my AC output on 24/7 will last for a long time because otherwise this setup is just a very, very expensive UPS with a bit of free power along the way!
These power stations are designed to be on 24/7 in UPS mode. I would not worry about the battery cycles. Even after 3500 cycles you still have 80% of the original battery capacity left. Yes, having the device on will age the device faster than when it is off and standby, but it is most important that you get your desired use from it. It’s like a car. It will last longest when you put it in the garage and only drive it twice a year. But that’s not where people buy cars for.
Many users here use these devices 24/7 for years and years and have no problems. They are designed for this use. And if you happen to have the unlikely case of a bad device, then you have warranty for that. Your 24/7 use will make sure any manufacturing defects get discovered before the warranty expires.
Dear Bluetti Appreciators.
Andy here, from the little island of Great Britain, although the ‘great’, I feel, is rather presumptuous these days.
First I would like to offer my heartfelt condolences to those in the L.A. area for the horrifying times you/they are presently experiencing. Although I also sympathise with those in the States & the rest of the world for, what seems like our ever increasing dramatic natural disasters. Maybe they’re not exactly ‘natural’, but we won’t go there, as we are talking Bluetti.
For 4 months, over last summer, my only power was a wee EB3A 600 watt unit, my first experience of a Bluetti product. This served me grandly for 8 weeks & 1 day in a tent and then 6 weeks in my re-sited 36 foot static caravan. My present address is 400 yards down the muddy track and third field on the right. Zero utilities connected. Here after I was kicked off the small park where I’d lived for 7 years. “Mr Stuart, you are the first person we have had to ask to leave any of our sites!” A long story & I’m very proud that I didn’t just do an ostrich impersonation.
From October I upgraded bigstyle, in my eyes at least, and went for the same AC200L and B300K set up and now, off grid, we are talking minus temperatures and on the rare clear day a best wattage input of 65 from my 350 watt solar panel, so pointless. But all is brilliant. Heating & cooking rings are gas and I put a bag of ice in my camping fridge every 3 to 4 days. Otherwise airfryer, microwave, sound system, rechargeable vacuum, electronics, etc are all in use. And, of course, the electrics are connected up.
I charge up my units with a Champion 2200 watt generator, specifically bought due to it’s true sine wave output. And I only ever charge on Standard, around 12 hundred watts. Although i have been caught out reheating a cup of coffee in the microwave
and then the gennie trips. And spending an hour and a half making chips at 2000 watts in the airfryer, for my grandchildren, was a definate learning experience regarding consumption!
The only time my unit is off is for 7, or so, hours at night and when I’m out, which isn’t a great deal as I live my life of retirement. I was concerned that I’m over using the units, but am heartened by Quickfox’s metaphor, above, comparing usage to a vehicle’s usage.
After querying Bluetti they informed me that charging to 100% is fine but don’t discharge below 20% and that is what I’ve adhered to, but:
Should I vary the amount I charge to?
Again, thank you Quickfox & I will discharge to zero and then immediately recharge to 100% for re-calibration. But, as I’m presently re-charging every 3 days, or so, how often do you recommend I recalibrate?
And finally, whenever my phone offers updates to the Bluetti app I do so, but does this automatically update the system when I’m connected via Bluetooth? If not then what do I do?
Well, any of you who have survived Andy’s ramblings, congratulations. And, as a true Cornwall gentleman says to anyone, including a rough, tough, bearded builder, “Goodbye my luvvers”.
