Low Voltage Disconnect suggestions

[Frank Castle]

I'm hoping someone with a lot more experience here can make some suggestions for my setup.

I have a few lifepo4 16Ah batteries that I connect to a 300W pure sine wave inverter via alligator clips to keep some of my home networking gear online when there is a power outage. I even recently bought a transfer switch so I can cut over to this inverter without having to swap cables around every time. My only concern is that right now with the power out the battery will drain down to 10V before shutting off (not great for the health of the battery). I would like to have it shut off at maybe around 12.9V (seems like a much safer value from what I've read here on the forums). Whenever it shuts off I just swap in another lifepo4 16Ah battery to keep everything going. My networking equipment is also connected to a UPS that keeps everything powered while I swap batteries. I do try to manually monitor the voltage of the batteries currently but if I get distracted it drops below 12.9V so I would prefer to come up with a better solution.

I have seen different low voltage disconnect devices from $10-20 cheap solutions on Amazon to more expensive battery protector devices from Victron so I am aware of some potential solutions. Right now I just use a lifepo4 battery tender to recharge all of the batteries once power has been restored, I do not currently have any solar panels. I know some solar charging controllers have circuitry to do low voltage disconnections and I wouldn't mind getting a couple solar panels at some point to be able to recharge my batteries even if my house power is still off.

Is there a solar charge controller that I could use to disconnect the load to my battery when voltage hits 12.9V even without any solar panels connected? And as a bonus, is there a solar controller that I can connect to shore power instead of solar panels to recharge the battery instead of having to use my battery tender unit?

So instead of just getting one of those $10 cheap low voltage disconnect devices that I imagine would work I would prefer to future proof my setup by getting a solar charge controller that does the same thing and allows me to utilize shore power and of course solar panels so I would have many more options available to top off my batteries. Assuming that is even possible I mean. Thanks in advance for any advice you may have to help me improve my current setup.

 

[Maast]

If you're going to be using shore power then a inverter/charger sounds ideal: it'll transfer power from your 'shore' to your load, allow you to set up high and low voltages, and it'll charge your battery from shore. I'm a fan of the Samlex inverter/chargers and have one functioning as a 2200W UPS connected to a 200AH battery set for my 8TB RAID6 home server. Basically its a giant UPS since the transfer time from wall power to battery is about 9ms the server doesnt even notice.

 

[MisterSandals]

Whenever it shuts off I just swap in another lifepo4 16Ah battery to keep everything going.

Is there a reason that you do not connect all of your 16ah batteries in parallel? Running one at a time and swapping them seems unnecessary and tedious.

 

[Frank Castle]

If you're going to be using shore power then a inverter/charger sounds ideal: it'll transfer power from your 'shore' to your load, allow you to set up high and low voltages, and it'll charge your battery from shore. I'm a fan of the Samlex inverter/chargers and have one functioning as a 2200W UPS connected to a 200AH battery set for my 8TB RAID6 home server. Basically its a giant UPS since the transfer time from wall power to battery is about 9ms the server doesnt even notice.

I was not aware that an inverter/charger device even existed. See this is exactly why I posted here. Thank you for the suggestion, I will look into them.

 

[Frank Castle]

Is there a reason that you do not connect all of your 16ah batteries in parallel? Running one at a time and swapping them seems unnecessary and tedious.

You are 100% correct. I have considered running them in parallel but have not done it yet for a few reasons. I just started reading up on batteries and solar stuff so I'm not super comfortable with everything just yet. Also I just got these batteries and so I've been playing around with each of them to see what they are capable of (how long they run my equipment). They aren't all super balanced so I wasn't sure about running them in parallel yet (some charge to high 13V while others are mid 13V. Finally they use the F1 terminal connector so connecting multiple faston/spade connectors is a bit of a pain. I'm sure there is a better solution (shunt setup maybe) but again I just started researching this stuff so I'm new and haven't got it all figured out yet.

Also, while that would certainly extend the duration my inverter could run my load it doesn't help with preventing the batteries from fully discharging so I still need to come up with something for that. Thank you for the comment and suggestion though, it is greatly appreciated and I probably will connect them in parallel at some point.

 

[Maast]

I was not aware that an inverter/charger device even existed. See this is exactly why I posted here. Thank you for the suggestion, I will look into them.

The least expensive that isnt junk is the Aims and Signeer inverter chargers (basically same unit, there are other brands) they're robust but have a nasty 55W idle loss, then there is the Samlex EVOs that are the best value of the 'quality' inverter chargers, closely followed by Victron, then the top quality last-forever Outback and Magnum.
Notice I didnt mention Xantrex - there's a reason for that.
I personally own a Aims, Samlex, Outback Radian, and a 11 year old Victron. The Aims and Samlex are doing UPS duties @ 24V with 2 100AH sealed lead acid batts attached.