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Blackout prep, winter edition

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Joules22

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What's the best practice for power outages re a Bluetti EB200 (similar to AC200)? Conventional wisdom says not to store the units above a ~50% SOC but that's a very limiting parameter if the lights go out without warning. I have a couple of panels but I don't want to depend on solar to top off the unit in a crunch--which may well come at night.

I recently cycled mine down to 0, charged to 100% and then ran it back down to 80% in anticipation of possible grid issues this heating season. How long can I realistically leave it at 80% without causing myself a problem?
 
I posed a similar question in This thread a few months ago. It didn't get a lot of traffic. Manufacturers' recommendations seem to be in opposition to battery makers recommendations...?‍♂️
My personal opinion is that they are great tools to take to a job site, but may leave you wanting during a crisis.
 
The whole point of having a back up system is to be able to use it when needed. The batteries will not be damaged if they are kept between 85 and 95% by periodically recharging them with low voltage and low current.
1) Do not use float to maintain Li batteries at a fixed SoC.
2) Do periodically recharge the batteries with the minimum voltage necessary to achieve 95% charge. For LiFePO4 that would be 3.45V per cell.
3) Limit charging current to 0.2C and turn off the charger when the battery is full. Its full when the charging current falls off to 2 to 3% of the initial current.
4) A simple 7 day plug in timer could be used to turn on and off the charger. Observe the behavior for the first couple of times to determine the length of time to leave the time On.
 
BentleyJ said:
The whole point of having a back up system is to be able to use it when needed. The batteries will not be damaged if they are kept between 85 and 95% by periodically recharging them with low voltage and low current.
1) Do not use float to maintain Li batteries at a fixed SoC.
2) Do periodically recharge the batteries with the minimum voltage necessary to achieve 95% charge. For LiFePO4 that would be 3.45V per cell.
3) Limit charging current to 0.2C and turn off the charger when the battery is full. Its full when the charging current falls off to 2 to 3% of the initial current.
4) A simple 7 day plug in timer could be used to turn on and off the charger. Observe the behavior for the first couple of times to determine the length of time to leave the time On.
Click to expand...
The primary means of charging is the 400W power block that came with the Bluetti, so no real means to regulate/monitor voltage or current (what units are you using when you say limit charging current to 0.2C)?

It seems the best I can do here is charge to between 80-90% and hope the power isn't off for days.
 
Joules22 said:
The primary means of charging is the 400W power block that came with the Bluetti, so no real means to regulate/monitor voltage or current (what units are you using when you say limit charging current to 0.2C)?
Click to expand...
The "C" rate is an industry standard way of expressing charge and discharge current specifications. It has units of Amps and is based on the Amp hour capacity of the battery. For example if a datasheet recommends a charging rate of 0.2 C that would represent 20Amps for a 100Ah battery and 40Amps for a 200Ah battery. Likewise a datasheet could list 1C as a maximum discharge rate and that would represent 100A for a 100Ah battery.
 
I intend to keep my recently-acquired Bluetti full. I'm not cycling it much, so I presume it will last more than a decade with such sporadic usage. In the occasional outage, I would feel like a fool to have only a half-full battery backup system.
 
And....update here in 2023. In Central TX we had a big ice storm that knocked out power for several days. All my battery/inverter/solar toys are at another location, I just had the Bluetti and a couple of other random batteries. I'm quite glad the power station was charged to full! (My 60Ah battery was not even half-full; that was annoying as I was using it to recharge the Bluetti).
 
Do you have solar panels to charge it in the absence of grid?

Why not charge it to 100% through the winter and use it like a UPS to run a few essential things, like phones, refrigerator
 
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I just got married & moved to my wife's house in December. Most of my toys (panels, SCC's, inverters, batteries) are at my old house across town. Indeed, an eventual goal is to get more robust emergency power capabilities at her house. In this case, the weather was overcast, cloudy, and iced up so it's unlikely panels would have provided much. So we had to squeak by on what we had at hand.

Lesson learned: keep those batteries charge up!! :cool:
 
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