Greetings bright minds from Florida,
I am an electronics enthusiast for some time now, it started with micro controllers and programming simple sensors to a full blow electronics room! I have everything necessary (or mostly everything) for working and building projects. Many of the equipment is semi lab-grade quality.
I recently got started with wanted to build battery packs, I started with the DIY 18650 packs using a BMS and an enclosure for the pack. That has been fine and has been a great learning experience. No magic smoke, knock on wood.
Then I started getting into bigger batteries and decided to charge them with some solar panels in my back yard. I have different types of batteries and capacities, I'm using Li-ion EV car battery packs, Lifepo4 EV battery packs (brand new zero miles on both) as well as some of the solar company's batteries (Renogy Lifepo4) and their solar charge controller and battery monitor.
I am of course not mixing battery types, so each pack is only using identical batteries with internal resistances as close as possible measured with an expensive meter.
The packs are being placed in essentially bomb proof military surplus containers. Everything except the panels will live in there. I have added fire "proof" (resistant really) insulation rated for over 6000F without catching fire. I have multiple safety systems in place, including everything the company recommends and more, fuses everywhere, manual disconnect switches. I am using welding cable and I have gone at least 1 gauge higher (err actually lower you know what I mean) so that the cables can carry way more amps that what I'm pulling. This is a mobile setup. Everything will live inside the house minus the panels. I have inverters that I use just to power some things around the house. I'm not looking to do a whole house setup as I rent! I just want to tinker and harness the power of the sun for some free energy. I am using both 24 and 48 volt systems depending on my batteries. Initial testing has been good with the smaller packs (18650's) using a thermal imager nothing is heating up, then again I'm not pulling a lot of amps and never will.
Now to the question...
I want to add a Low Voltage Disconnect / High Voltage Disconnect DC voltage regulator into the mix especially for the Renogy pack. I know the solar charge controller is "supposed to do this" and it has. I also know that the BMS systems should control this as well. However, as a certified cave diver, redundancy on top of redundancy has been burned into my brain.
I started to research and I purchased a LVD/HVD monitor from ATO I believe, but since I am not familiar with this stuff it looks like I need either a contactor and/or a SSR. There a quick video by ATO on youtube showing it doing exactly what I want, killing power to the batteries if a certain upper/lower voltage threshold is breached, what they dont show is what other parts are needed to pull this off or how to wire it up. I have some no name brand small PCBs rated for 30A made in china i'm sure that allow me to do this, and they do work but I don't trust them. I want something more reputable. Can anyone help me out on what I would need to buy and how to wire it up to protect the batteries from low/high voltage in the off chance both the solar charge controller and BMS systems fail?
I was dumb enough to think buying just that one part was all I needed and after seeing the schematic on the side I knew it wasn't going to work, and I tested it anyways with my power supply and checked for voltage on all the different points on the voltage monitor, and nothing happened anywhere I got no voltage on/off anywhere while adjusting the voltage in and out of the parameters I set, though the monitor itself did turn red/green at the correct voltage but clearly more parts are needed.
I've also added temperature sensors everywhere using ESP32 chips so that if anywhere in the enclosure gets too hot alarms go off and I get a text to my phone.
I'm using 4x 100 panels in series, and they give me just under 5 amps of power steady during the day. I know I know you are laughing at me because of the amperage. Thing is I'm in no rush to charge these, again they are to power small devices around the house. Parts of my home office, my electronics room, some lamps, dumb stuff that draws virtually no power. I do plan to expand eventually to bump up the amperage by getting more panels and putting them in parallel. But I wanna hammer out this process first.
I have different solar charge controllers to ensure they are appropriate for the battery chemistry (Li-ion vs LifePo4). Plenty of halon and c02 fire extinguishers too and when not in use the packs are kept in an area I build that has essentially fire "resistant" boards, and then surrounded with firebricks. Not to mention connections are disconnected and secured when not in use.
Sorry for the long post, if you could help me out that would awesome and if you have any other suggestions for more safety measures please share. This is low amps I'm pulling and charging but batteries are no joke I so I take respect with them.
I am an electronics enthusiast for some time now, it started with micro controllers and programming simple sensors to a full blow electronics room! I have everything necessary (or mostly everything) for working and building projects. Many of the equipment is semi lab-grade quality.
I recently got started with wanted to build battery packs, I started with the DIY 18650 packs using a BMS and an enclosure for the pack. That has been fine and has been a great learning experience. No magic smoke, knock on wood.
Then I started getting into bigger batteries and decided to charge them with some solar panels in my back yard. I have different types of batteries and capacities, I'm using Li-ion EV car battery packs, Lifepo4 EV battery packs (brand new zero miles on both) as well as some of the solar company's batteries (Renogy Lifepo4) and their solar charge controller and battery monitor.
I am of course not mixing battery types, so each pack is only using identical batteries with internal resistances as close as possible measured with an expensive meter.
The packs are being placed in essentially bomb proof military surplus containers. Everything except the panels will live in there. I have added fire "proof" (resistant really) insulation rated for over 6000F without catching fire. I have multiple safety systems in place, including everything the company recommends and more, fuses everywhere, manual disconnect switches. I am using welding cable and I have gone at least 1 gauge higher (err actually lower you know what I mean) so that the cables can carry way more amps that what I'm pulling. This is a mobile setup. Everything will live inside the house minus the panels. I have inverters that I use just to power some things around the house. I'm not looking to do a whole house setup as I rent! I just want to tinker and harness the power of the sun for some free energy. I am using both 24 and 48 volt systems depending on my batteries. Initial testing has been good with the smaller packs (18650's) using a thermal imager nothing is heating up, then again I'm not pulling a lot of amps and never will.
Now to the question...
I want to add a Low Voltage Disconnect / High Voltage Disconnect DC voltage regulator into the mix especially for the Renogy pack. I know the solar charge controller is "supposed to do this" and it has. I also know that the BMS systems should control this as well. However, as a certified cave diver, redundancy on top of redundancy has been burned into my brain.
I started to research and I purchased a LVD/HVD monitor from ATO I believe, but since I am not familiar with this stuff it looks like I need either a contactor and/or a SSR. There a quick video by ATO on youtube showing it doing exactly what I want, killing power to the batteries if a certain upper/lower voltage threshold is breached, what they dont show is what other parts are needed to pull this off or how to wire it up. I have some no name brand small PCBs rated for 30A made in china i'm sure that allow me to do this, and they do work but I don't trust them. I want something more reputable. Can anyone help me out on what I would need to buy and how to wire it up to protect the batteries from low/high voltage in the off chance both the solar charge controller and BMS systems fail?
I was dumb enough to think buying just that one part was all I needed and after seeing the schematic on the side I knew it wasn't going to work, and I tested it anyways with my power supply and checked for voltage on all the different points on the voltage monitor, and nothing happened anywhere I got no voltage on/off anywhere while adjusting the voltage in and out of the parameters I set, though the monitor itself did turn red/green at the correct voltage but clearly more parts are needed.
I've also added temperature sensors everywhere using ESP32 chips so that if anywhere in the enclosure gets too hot alarms go off and I get a text to my phone.
I'm using 4x 100 panels in series, and they give me just under 5 amps of power steady during the day. I know I know you are laughing at me because of the amperage. Thing is I'm in no rush to charge these, again they are to power small devices around the house. Parts of my home office, my electronics room, some lamps, dumb stuff that draws virtually no power. I do plan to expand eventually to bump up the amperage by getting more panels and putting them in parallel. But I wanna hammer out this process first.
I have different solar charge controllers to ensure they are appropriate for the battery chemistry (Li-ion vs LifePo4). Plenty of halon and c02 fire extinguishers too and when not in use the packs are kept in an area I build that has essentially fire "resistant" boards, and then surrounded with firebricks. Not to mention connections are disconnected and secured when not in use.
Sorry for the long post, if you could help me out that would awesome and if you have any other suggestions for more safety measures please share. This is low amps I'm pulling and charging but batteries are no joke I so I take respect with them.
