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Hi Bean,
What type of battery would you recommend for extended backup? TIA
In my previous tank I had large (huge, could barely move them) deep cycle 12v batteries, but tech has changed a lot.
Hi Randy,
Total wattage of the equipment you want to backup and for how long?
Are you looking for something that you can plug into when needed, or something that is always inline and ready to go?
As for battery tech: Lead Acid is still very viable and safe, but you are correct, the tech has changed a lot.
A few general thoughts:
LiFePO4 vs Lead Acid
Characteristic | LiFePO4 | Lead Acid |
---|---|---|
Lifespan (recharge cycles) | 2500 | 400 |
Relative Weight per storage | 1 | 3 |
Power Output | Stable voltage over large discharge span | Voltage drops faster as cells discharge |
Discharge Depth | Little harm in 80% discharge | Frequent discharge below 50% can degrade cells |
Charge Rate | Faster than lead acid | Slower than LiFePO4 |
Self Discharge | Lower than lead acid | Faster than LiFePO4 |
Upfront Cost | High | Low |
Charging | **Complex Battery Management | Simple and safe |
Overall Safety | Dangerous if mismanaged | Extremely Safe, especially AGM types that do no off gas. |
If you consider most of the general traits, they don't mean much for a standby battery system that is hopefully rarely discharged. Charge rates, weight, lifespan (total charge cycles), etc. are all fairly irrelevant.
Even discharge depth and voltage stability are not significantly relevant in terms of the rare full discharge during an outage. Both will provide similar runtime. If these were regularly getting discharged the LifePO4 would live a much longer life and/or the lead acid would need to be sized to only discharge about 50%.
So, In the end the biggest difference is going to be overall cost and safety.
**Safety. As mentioned on the prior post (and you likely already know) Lithium cells can fail catastrophically if punctured or overcharged, flooded, with water, etc. Of all of the current Lithium formulations LiFePO4 has a better thermal runaway profile and tends to smoke more than it does create flames (as long as other combustibles are not present).
High quality cells and battery management are an absolute must. As I mentioned in the prior thread, most of raw cells you will find are EV seconds and of lower quality. A lot of it is pure garbage being rebadged and sold on Amazon and dozens of other "battery" type sites.
So that brings us to actual advice
1 - I would stay away from a DIY LifePO4 setup where you buy LiFePO4 batteries and BMS and put it together yourself. If this is something you want to do, then I would stick with US made batteries and BMS like those from Battle Born, Relion or Bioenno.
2 - If you are going to do a DIY inverter and some cells, stick with AGM type cells and a well regarded charger and inverter. There are too many brands to list.
3 - If you do decide to go with LiFeP04, buy a name brand "battery generator", preferably (again) with US made or assembled components. https://lionenergy.com/ is one of the better companies.
I know that EcoFlow, Jackery and DJI have a large followings. I would not trust any of those to be plugged in unattended in my home, period.
That brings us full circle to the original questions. For most reasonable power loads where you want automatic backup power, I would still simply go with an AGM based true sine wave UPS with expansion batteries to get you the runtime that you need. APC, Liebert, Tripp-Lite, even CyberPower. Safe and reliable and time tested. LiFePO4 UPS system are around, but expensive.
If you want more the of "generator" type setup where you can plug things into during and outage, then Lion Energy is a good choice, peace of mind. If you are willing to babysit while in use, then EcoFlow, Jackery or DJI.