Koyaanisqatsi
Electron addict
I've got one of these 12V/460Ah IP67 batteries from Epoch. Had it about two months or so. Here are my thoughts about these units...
TL;DR: I LIKE the battery. I don't LOVE it. It will work for my needs. But I have to put WAY too much time into getting it settled into the system and to stop throwing BMS alerts during normal charging. And there are a few too many things that I can't fix or even read myself (without the password to the app to change BMS settings).
1. BMS needs to be programmed differently.
1a. It shuts off the charging FETs at 14.0V if charge current is under 3-5A (not sure the exact value, but it's a lot higher than it should be), with a Full Charge alert, which is a big pain in the butt because it throws all my other devices into a tizzy fit and surges the DC bus voltage, which could legitimately kill some things in my trailer, not the least of which is my fridge that throws an over voltage alert at 15V. 14.0V is a terrible threshold value for anything that charges up to 14.6V. My solar charges at 10A MAX. Most of the time, I am charging below 3A.
1b. It really needs to sense current down to around 0.1-0.25A. The low limit for current sense is ~1.2, which is just too low for anything but a heavy load case! Big batteries are not always used for high-loads. Just like compact cars are not just for short people.
1c. SLOW BALANCING!! Holy crap, put something more than a 50-150mA balancer on 460Ah cells! What the heck were your engineers thinking!?! (or was this a financial decision) The balancer should be 1-5 AMPS on this thing. After 8 hours of floating at 13.9V, the cells get closer by MAYBE 5-10mV. It's taken more than 100 hours of holding the voltage at an unhealthy high level to get the balance closer, but it's still more than 50mV out of balance as I type this.
1d. Too wide of a voltage allowance in the balancer. It's 30mV. Should be more like 5 or 10mV.
2. For love of all that is good, START WITH BALANCED CELLS!! or at least cells that are not egregiously out of balance!
2a. I started off with more than 165mV difference between low and hi cells. This prevented me from fully charging the battery for a while. Could only charge to 13.8V without tripping on cell OVP for the first few charges. First screen cap is from after I had already cycled a couple times.
3. The app looks pretty and is good to view info. But what about actually accessing that info outside of the app, for use within monitoring and control systems? The only info I can get over MODBUS is min and max cell voltage and temp. But the app shows all voltages and more temperatures. Everything in the app should be available over MODBUS.
3a. Specifically missing are:
3a1. Voltages for all cells.
3a2. All temperature values.
3a3. Whether balancing is active.
3a4. Whether charge or discharge FETs are active or disabled.
3b. Labels and terminology: "VOL" is for VOLUME, not VOLTAGE. Labels should be "Vavg", Vdiff", "Vlo", and "Vhi", or if you want to be less technical: "Avg Cell V", "Avg Diff V", "Low Cell V", "High Cell V", not these meaningless VOLDIFF, VOLLOW, etc. Stop using ALL CAPS. And the shortened acronym, for MOSFET is FET, not MOS. They are Field Effect Transistors. And there are multiple types, most of which are MOS. You don't call orange juice "orange". You call it "juice".
3c. Measurements should be displayed at the same precision that they are used. The four icons and values should show three decimals, not one. Can you imagine charging a Li cell based on one decimal of precision? You'd have fire.
3d. Let me rename the battery, so that it's not lost in the sea of BT devices near me. AND FILTER OUT NON-EPOCH DEVICES FROM THE LIST.
3e. If it looks like a switch, and you can touch it to turn if off/on, then KEEP THE STATE. The little charge and discharge switches can be switched, but just return to their original state. If I can't change them, don't display them as changeable. OR honor my input and do what I am telling it to do. One or the other, please.
4. Last but not least: Included accessories. I did not get the set of DC cables nor the mounting brackets that are shown in the YT videos. Would have been really helpful to get at least the brackets. Now I have a 100lb battery sliding around in my trailer with no way to secure it. Yes, the site indicates these things are optional. But the mounting brackets?!? Come on.
165mV!?! This should be considered a defective battery on that stat alone. The low cell is so low that it's near the bottom of the neck voltage range and needs a LOT of charge to catch up.
Total battery voltage: 13.97V.

After well over 100 continuous hours of floating at 13.9V, in order to force balancing, I'm still almost 60mV off balance. (note the red highlight on the high cell. That indicates the balancing circuit is active on that cell. It runs for a few minutes at a time, and shuts off for a moment, and starts again).
Total battery voltage: 13.952V

EDIT: MODBUS, not CANbus.
EDIT 2: Battery voltage, not total cell voltage.
TL;DR: I LIKE the battery. I don't LOVE it. It will work for my needs. But I have to put WAY too much time into getting it settled into the system and to stop throwing BMS alerts during normal charging. And there are a few too many things that I can't fix or even read myself (without the password to the app to change BMS settings).
1. BMS needs to be programmed differently.
1a. It shuts off the charging FETs at 14.0V if charge current is under 3-5A (not sure the exact value, but it's a lot higher than it should be), with a Full Charge alert, which is a big pain in the butt because it throws all my other devices into a tizzy fit and surges the DC bus voltage, which could legitimately kill some things in my trailer, not the least of which is my fridge that throws an over voltage alert at 15V. 14.0V is a terrible threshold value for anything that charges up to 14.6V. My solar charges at 10A MAX. Most of the time, I am charging below 3A.
1b. It really needs to sense current down to around 0.1-0.25A. The low limit for current sense is ~1.2, which is just too low for anything but a heavy load case! Big batteries are not always used for high-loads. Just like compact cars are not just for short people.
1c. SLOW BALANCING!! Holy crap, put something more than a 50-150mA balancer on 460Ah cells! What the heck were your engineers thinking!?! (or was this a financial decision) The balancer should be 1-5 AMPS on this thing. After 8 hours of floating at 13.9V, the cells get closer by MAYBE 5-10mV. It's taken more than 100 hours of holding the voltage at an unhealthy high level to get the balance closer, but it's still more than 50mV out of balance as I type this.
1d. Too wide of a voltage allowance in the balancer. It's 30mV. Should be more like 5 or 10mV.
2. For love of all that is good, START WITH BALANCED CELLS!! or at least cells that are not egregiously out of balance!
2a. I started off with more than 165mV difference between low and hi cells. This prevented me from fully charging the battery for a while. Could only charge to 13.8V without tripping on cell OVP for the first few charges. First screen cap is from after I had already cycled a couple times.
3. The app looks pretty and is good to view info. But what about actually accessing that info outside of the app, for use within monitoring and control systems? The only info I can get over MODBUS is min and max cell voltage and temp. But the app shows all voltages and more temperatures. Everything in the app should be available over MODBUS.
3a. Specifically missing are:
3a1. Voltages for all cells.
3a2. All temperature values.
3a3. Whether balancing is active.
3a4. Whether charge or discharge FETs are active or disabled.
3b. Labels and terminology: "VOL" is for VOLUME, not VOLTAGE. Labels should be "Vavg", Vdiff", "Vlo", and "Vhi", or if you want to be less technical: "Avg Cell V", "Avg Diff V", "Low Cell V", "High Cell V", not these meaningless VOLDIFF, VOLLOW, etc. Stop using ALL CAPS. And the shortened acronym, for MOSFET is FET, not MOS. They are Field Effect Transistors. And there are multiple types, most of which are MOS. You don't call orange juice "orange". You call it "juice".
3c. Measurements should be displayed at the same precision that they are used. The four icons and values should show three decimals, not one. Can you imagine charging a Li cell based on one decimal of precision? You'd have fire.
3d. Let me rename the battery, so that it's not lost in the sea of BT devices near me. AND FILTER OUT NON-EPOCH DEVICES FROM THE LIST.
3e. If it looks like a switch, and you can touch it to turn if off/on, then KEEP THE STATE. The little charge and discharge switches can be switched, but just return to their original state. If I can't change them, don't display them as changeable. OR honor my input and do what I am telling it to do. One or the other, please.
4. Last but not least: Included accessories. I did not get the set of DC cables nor the mounting brackets that are shown in the YT videos. Would have been really helpful to get at least the brackets. Now I have a 100lb battery sliding around in my trailer with no way to secure it. Yes, the site indicates these things are optional. But the mounting brackets?!? Come on.
165mV!?! This should be considered a defective battery on that stat alone. The low cell is so low that it's near the bottom of the neck voltage range and needs a LOT of charge to catch up.
Total battery voltage: 13.97V.

After well over 100 continuous hours of floating at 13.9V, in order to force balancing, I'm still almost 60mV off balance. (note the red highlight on the high cell. That indicates the balancing circuit is active on that cell. It runs for a few minutes at a time, and shuts off for a moment, and starts again).
Total battery voltage: 13.952V

EDIT: MODBUS, not CANbus.
EDIT 2: Battery voltage, not total cell voltage.
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