Solar doesn't last

[Gourmetgame]

I have 4 Sunpower 190w panels, epever tracer 4215bn, 1 24v byd *techdirect special* probably heavily degraded 220ah 5.63kwh battery, and a 2000w inverter. I installed a 8s BMS (no bluetooth dongle) from batteryhookup (with no clue what I'm doing) and my solar is good for about an hour and a half maybe twice a day powering a 30a RV (on a 15a plug) when using about 250w continuously (a couple tvs, cell phones and mini fridge). I get a para. error on the epever when trying to adjust absorption and float beyond 25.0. I really am just grasping a straws with trial & error. I don't know how to capacity test the byd, I'm totally off-grid and trying to not run my generator all day. Do I need more batteries? I'm just trying to have steady power for more than a hour before being fully discharged. I know people that have a regular car battery, pwm setup that have better results than me. What am I doing wrong?

 

[upnorthandpersonal]

Ok, so 4 x 190W ==> 760W. If you want to charge that battery from empty to full this would take, in ideal situations, 7.5 hours of direct sunshine. In reality, you probably won't even get near that, so make that 14 hours. Let's assume this is all fine.

Please verify that you are getting power from your panels and that your charge controller is configured properly. Have you seen this post: https://diysolarforum.com/threads/r...er-tracer-4215bn-with-lifepo4-batteries.7792/

 

[chrisski]

Can you describe the panel setup? Shading can reduce output tremendously.

I am in an RV now and I parked for the view, and my solar panels are in the worst possible position, on the north side, with shading from an Air conditioner most of the day, and the 600 watts of panels tops out at 240. With the panels tilted and parked ideally, I get 440 watts out of them. So, at best I get 2/3 the rated max output, and if I park in the wrong direction I get 1/3. THese are 100 watt panels, six of them, hooked 3S2P.

I also have four 100 watt panels that are ground mounted, and I can position these ideally in the sun and I can get 340 watts from those, and move them a couple of times through the day to maintain ideal output. If anything crosses there path, the output gets reduced a lot. Even shaded by a branch.

Also, whatever you are charging with, if it can’t get the absorption and float, it probably takes even longer than upnorthandpersonal mentioned. If it’s capped at 25, a 24 volt system for my battteries would need 29.4 volts for bulk/absorption and 27.2 for float. If you’re not even reaching float, I don’t know if its got the strength to push the amps back into the battery.

If your battery bank is questionable, and it is a flooded lead acid, you can do specific gravity tests to get a gauge of its health. If not,

You probably have enough solar to run your fridge on electricity during daylight hours, but not enough to last through the night. You may need to power the generator through the night. For my RV, I’d need to charge my batteries for four hours with my generator if I did not get enough sun through the day to last through a night,

 

[DThames]

I have two of those batteries with the cells connected in parallel. Even still it is normal to see one cell group with higher voltage on charge and another group low on discharge. The BMS will cut off when one cell is out of range. With the two batteries together I am getting just under 5kwh delivered in the AC side, using a Kill-a-watt type meter on the AC load.

You should get the Bluetooth device for the BMS or get a cell level monitor so you can see what is going on all of the time. Overkill Solar has the same Bluetooth device if BatteryHookup is out of stock. I swapped them back and forth on my unit and they look the same and work the same. If you can measure your draw down from a full charge and you see about 2kwh, that would be within reason from what I have seen.

 

[Gourmetgame]

Can you describe the panel setup? Shading can reduce output tremendously.

I am in an RV now and I parked for the view, and my solar panels are in the worst possible position, on the north side, with shading from an Air conditioner most of the day, and the 600 watts of panels tops out at 240. With the panels tilted and parked ideally, I get 440 watts out of them. So, at best I get 2/3 the rated max output, and if I park in the wrong direction I get 1/3. THese are 100 watt panels, six of them, hooked 3S2P.

I also have four 100 watt panels that are ground mounted, and I can position these ideally in the sun and I can get 340 watts from those, and move them a couple of times through the day to maintain ideal output. If anything crosses there path, the output gets reduced a lot. Even shaded by a branch.

Also, whatever you are charging with, if it can’t get the absorption and float, it probably takes even longer than upnorthandpersonal mentioned. If it’s capped at 25, a 24 volt system for my battteries would need 29.4 volts for bulk/absorption and 27.2 for float. If you’re not even reaching float, I don’t know if its got the strength to push the amps back into the battery.

If your battery bank is questionable, and it is a flooded lead acid, you can do specific gravity tests to get a gauge of its health. If not,

You probably have enough solar to run your fridge on electricity during daylight hours, but not enough to last through the night. You may need to power the generator through the night. For my RV, I’d need to charge my batteries for four hours with my generator if I did not get enough sun through the day to last through a night,

My panel setup is facing southeast ground mounted at about 100 degree angle. Nothing fancy, just kind of leaning on a structure. I'm planning to build something more stable in the future, I just wanted it up for now. No obstructions. Battery says it's full with happy face on the MT-50 but the inverter display rarely shows more than half full.

 

[Gourmetgame]

I have two of those batteries with the cells connected in parallel. Even still it is normal to see one cell group with higher voltage on charge and another group low on discharge. The BMS will cut off when one cell is out of range. With the two batteries together I am getting just under 5kwh delivered in the AC side, using a Kill-a-watt type meter on the AC load.

You should get the Bluetooth device for the BMS or get a cell level monitor so you can see what is going on all of the time. Overkill Solar has the same Bluetooth device if BatteryHookup is out of stock. I swapped them back and forth on my unit and they look the same and work the same. If you can measure your draw down from a full charge and you see about 2kwh, that would be within reason from what I have seen.

I will look into Overkill Solar for the bluetooth device, I thought it was only effective using a Apple device (I have Android). But yeah, it probably needs balancing and all that. I don't know all the hookups to do it. I saw a video using a ISDT 8s...

 

[chrisski]

I Can’t speak to your setup, but I just went through a process of getting my Victron BMV-712 battery monitor calibrated to my batteries when the readings were off. I had to redo some voltage settings and current settings, and after a couple of days and a bit of help from this forum, it now works.

How do you like your Sunpower panels? I am thinking of getting the flexible panels, two of the 170 watt ones. They’re the only comany I can find that makes a panel that outputs enough voltage to power a 24 volt SCC without having to put panels in series. Space is becoming an issue where I plan the install and the higher panel voltage is a selling point.

 

[Gourmetgame]

I Can’t speak to your setup, but I just went through a process of getting my Victron BMV-712 battery monitor calibrated to my batteries when the readings were off. I had to redo some voltage settings and current settings, and after a couple of days and a bit of help from this forum, it now works.

How do you like your Sunpower panels? I am thinking of getting the flexible panels, two of the 170 watt ones. They’re the only comany I can find that makes a panel that outputs enough voltage to power a 24 volt SCC without having to put panels in series. Space is becoming an issue where I plan the install and the higher panel voltage is a selling point.

I actually like them. I got them from batteryhookup a while ago (they sold out in hours), at first they were a pita because they were an older model with mc3 connectors but after the adapters everything with the panels seems legit. I wish I could say the same about this byd battery, I should have held out for the one on wheels that ready to go. Low key I was trying to go as plug n play as possible.

 

[DThames]

I will look into Overkill Solar for the bluetooth device, I thought it was only effective using a Apple device (I have Android). But yeah, it probably needs balancing and all that. I don't know all the hookups to do it. I saw a video using a ISDT 8s...

Balancing those batteries is difficult as the cell connections are welded. If you bring out "balance" lead that can handle a few amps, you can add or remove power to adjust one cells state of charge. Also, being worn, they have various capacities from cell to cell. So it is rather hard to resolve that problem.