Its been my experience using AGM batteries only last about 3-5 years installed in the typical UPS battery backup. I've been burned several times when there is a power failure the UPS fails to supply the necessary load or only has enough reserve for a few seconds. The UPS I have is supposed to check the condition of the batteries every so often, and even that is not a guarantee the batteries are good. Measuring voltage when the UPS is in standby show 13+ volts but disconnecting them and then measuring each battery I usually find a bad one somewhere in the bank.
I stopped using those store bought UPS's in favor of a stand alone power inverter along with a smart charge control and two independant battery banks using deep cycle marine batteries. Just before switching in a battery bank I do load test, similar to those used for testing car batteries, before switching the bank into service. Each month I repeat the process. That way I find the defective battery before putting it into service.
Of coarse this is overkill for just a sump pump but if you have things you cannot afford to loose power its a good setup to have, plus using a regular power inverter you can get much more runtime than any consumer grade UPS.
If you do go with a li-ion battery, I'd go with a LiFePo4 battery pack. They're much safer for home use. Pretty easy to find high capacity cells as well.
I use a number of shelly uni to monitor the voltage of both my cab battery and my leisure batteries.
It’s only a case of connecting a few wires and I use the battery that I’m monitoring to power the uni as the current draw is minimal
With regard to the battery, it's a few years old, but it's always been maintained with the Deltran Battery Tender. To my knowledge, this was the only time it's been depleted. Right now it's holding the charge, but I should do a load test to make sure it's ok.
So, it sounds like might need a new battery and remove the inverter. I don't really need it, since my Reef Tank pumps are all DC. I just had the inverter to run the lights and heater, if I needed to. First, though, I'm going to test it with a cool automotive battery tester I got last year. It's funny, I never thought of using it on this battery.
... Yes, I've considered it, but didn't think I would need it. Although, now it's sounding like a great idea! In fact, I have a ton of reclaimed 18650 Lithium Ion batteries that I was going to create a battery pack with, So this might a good application ... or just buy one.
Thanks for pointing that out. I'll see what's out there. I really need to calculate the Amp/hours required and go from there.
That sounds awesome. Do I still have to set it up through and Arduino?
Also, a solar panel probably wouldn't work well in Michigan, but be a fun project.
Thanks for the PM offer ... We see how this project goes.
They need to be close but don't have to be exact. Your lower and higher cells will be your limits. The more off they are the more load individual cells will take. You'll want to match capacity though.
To match capacity would one have to perform some monitored discharge? Do you know a reference to how the capacities are matched? i.e. pure AHr or voltage vs some level of discharge.
Yup, that’s the one. You may want to compare the shipping cost of the Europe vs US store - I found that it was much, much cheaper to ship from Europe than from the US (I’m in Canada).
I finally got 4 pack of Shelly Uni delivered yesterday and hope to install them today. I got them from Shelly Shop USA for $43.63 + shipping with USPS 1st class mail ... it took almost 2 weeks to get them, so next time I'll upgrade the shipping. Hopefully it will go smoothly. I haven't decided on whether to use the Shelly app and/or Hubitat to monitor voltage and get alerts. I installed the Shelly app last week and it looks awesome, Now I want to also figure out how to integrate it with Hubitat.
This thread is great; thanks! @olliesshop from your description of everything, sounds like you're using the UNI to monitor the car battery and it's just an alert style setup at this point?
I found the thread looking for a solution to monitor 12v batteries for a similar scenario. My boat's batteries power the bilge pumps, so if the charger is not working, shore power GFCI trips and takes away charger power, etc., the battery can ultimately run down and let too much water build up because the pumps will no longer be working. I have a few Shelly 1's out on the dock already to shut off equipment, so I know wifi reaches out there. Sounds like I could hook the UNI to the relevant batteries and the existing Hubitat drivers will be able to expose the voltage readings so I could get an alarm if the voltage goes below a worrisome threshold?
