Big battery Issue

[1blakephildavis]

I am building a cabin in the mountains and decided to go solar. I checked many videos on the web and went with MPP Solar 24v(LV2424-MSD) system with a bigbattery.com A123 24V. I got the MPP unit, solar panels, and wiring in. I ordered the battery back on 11-11-20 and just got it in 12-8-20. I got it out of the box and dead on arrival. I called bigbattery.com and emailed on 12/8/20, no response. I called and emailed on 12/9/20, no response. I tried the online chat 12/9/20 and someone responded and arranged for them to call me later when I got home from work. No call. I called last night and the sales desk answered and setup another call today but I doubt I receive anything. I removed cover to start checking voltages and see if anything was apparently wrong. I have 26.7V coming from the batteries and 26.7V reading after breaker. I am only getting 3.3V from the anderson connector past the BMS. I think it may be a bad BMS or disconnected lead to battery. The cover says I will void warranty by removing that cover so the only other thing to do was reset BMS. I unplugged harness several times for several minutes but I got the same thing. I read about sleeping batteries and that resetting BMS may help. I am concerned I just wasted $950.00 and it will delay my barn completion. Any suggestions or help from anyone?
Blake

 

[snoobler]

Worry about delaying your barn completion, but not wasting $950. Their support is erratic at times, but to my knowledge no one has suffered a total loss on a purchase. They will make it right, though it may be a suboptimal experience.

You hare likely correct on identifying the BMS as the culprit.

 

[1blakephildavis]

Worry about delaying your barn completion, but not wasting $950. Their support is erratic at times, but to my knowledge no one has suffered a total loss on a purchase. They will make it right, though it may be a suboptimal experience.

Thanks for the reply. On another note, I have 4 x 100W grape panels to charge the 24V battery. I was planning on wiring them in series. I am just making sure that I don't need 24v panels. I thought I read several times that these panels to charge a 24V in series?

 

[snoobler]

I don't know what grape panels are.

Assuming they're solar panels, 100W are typically "12V" panels meaning they have voltages around 17-18Vmp and 20-22Voc. If you series them, those voltages add, so you'll have plenty of voltage. This will necessitate a genuine MPPT capable solar charge controller. If you have a PWM controller, you would need them in 2S2P configuration.

P.S. Welcome to the forum!

 

[1blakephildavis]

I don't know what grape panels are.

Assuming they're solar panels, 100W are typically "12V" panels meaning they have voltages around 17-18Vmp and 20-22Voc. If you series them, those voltages add, so you'll have plenty of voltage. This will necessitate a genuine MPPT capable solar charge controller. If you have a PWM controller, you would need them in 2S2P configuration.

P.S. Welcome to the forum!

Here is the table on the MPP Solar options (and grape panels specs)...I have the 2424LV-MSD which has MPPT controller.

 

[snoobler]

Yep. 2S2P or 4S is fine.

 

[1blakephildavis]

Thanks for your help!

 

[1blakephildavis]

Well, my battery is just turning off in the middle of the night at 24.6 volts (6 weeks of use on weekends only) . I tried to contact bigbattery but just a sales person stating they will contact an engineer. I was able to chat with someone last week to help with the BMS settings so I could fine tune my battery voltage range. It was stated I could set low voltage cutoff at 20V but I left it at 21V and my high voltage was 28.8V with 27 V float. I have never gotten above 27.7 with the gas generator constantly charging it due to low sun days in the winter. I have not had issues but I have never let it get in the 24V range overnight. It was cold so I ran my wood burning stove fan for a couple of hours which I usually don't do. When I woke up, I didn't have any power. I went down to the solar generator and noticed the battery was off. I turned it back on it displayed 24.6 volts. It kicked back in with the inverter working and 5 minutes later off again. This time I couldn't get the battery to come back on. I left it for 30 minutes and then it turned back on. I quickly hooked up generator to charge it back into the 25V range. I got it to 27.2V after about 1.5 of running my 4000 watt gas generator. I didn't have any more issues but I didn't stay overnight. It seems like there is something wrong with this battery. I wonder if it has a bad cell. I guess I will wait on them to contact me but this isn't a great experience if something like this happens ever month or 2.
I forgot to mention that my original issue was the BMS was unplugged under the cover that says don't open or void warranty but bigbattery finally contacted me and sent a new connector but as soon I they gave me authority to open the case I found the issue. The wire was to tight from battery to bms so it pulled out in shipping from CA.

 

[snoobler]

Not knowing the specifics of that battery, the most likely scenario seems to be one cell has gone below LVD and tripped the BMS.

24.6V/8 = 3.075V/cell - at this level, you don't have a lot of capacity remaining if the cells are perfect. One cell could be empty at 2.5V with the others 7 at 3.19 - not great, but a weak or imbalanced cell can look like that.

I would encourage you to push to 28.8V to establish if the battery is top balanced. It might trip at the top end, too, but you've likely been working with an imbalanced pack from the beginning, and your venture to lower than typical voltages has revealed an issue.

Note that the vast majority of charging occurs between 3.3 and 3.4V/cell, so peaking at 27.7V may be expected. While you may have a 4000W generator, you are pushing much less than that into the battery, and it may take you 4+ hours to get fully charged with no loads. The absolute maximum your generator can supply at peak battery voltage is 1440W (50A * 28.8V).

Your 400W of panels may only provide you with a small fraction of your battery's capacity on a daily basis. If you're using more than your panels or generator provides, you will eventually run out of juice.

Lastly, if you can still access the cells and directly measure their voltages in the event of the next disconnect, that would help.

 

[iamrich]

Your 400W of panels may only provide you with a small fraction of your battery's capacity on a daily basis. If you're using more than your panels or generator provides, you will eventually run out of juice.

I agree with this. I think you are way under paneled for both the the LV2424 and your battery at 400W.

I am running 2250w of panels through the same system (x2 batteries).

 

[1blakephildavis]

I finally got Bigbattery to respond on chats. We finally agreed that something was wrong with battery and I needed to return. I needed to pay for the 180.00 shipping to return. I got my repaired battery a few weeks ago after paying 180.00 for shipping which they said they would return if they found an issue with the battery. They were suppose to tell me what was wrong but I never got a response. I took the battery back to cabin and it came in a new case but it turned off at 24.8 Volts again. I quickly started the generator to charge through the solar generator. It charged to 28.8 Volts and I left for the weekend. I had set the low voltage cutoff at 24.0 V which is the highest possible for the MP2424lv. I left the inverter on with no load and returned the Saturday. The battery was dead. I usually can leave it off for a few hours and it will come on for enough time to power up solar generator so I can charge from generator. It didn't work. I have a dead battery that I can't charge now. Suggestions? I have never seen this battery go below 24.6 volts on the display. How will I ever get the low voltage cutoff to work if the battery can get there? I have charged to 28.8Volts and discharged and I know I am underpanelled but this doesn't explain why I can deplete the battery to the point of no return without a charger. I think I still have a battery issue but they want me to reset BMS. Ok, i will go to the mountains and reset the BMS and it may come back but I will most always have a dead battery if my Solar generator can't protect my battery at 24.0 Volts. This has been a terrible experience....should have gone with Battleborn but you get what you pay for. Any further help would be appreciated?

 

[iamrich]

Can you show us how it is wired up? The MPP should be shutting off at 24v, so something else must be draining the battery

 

[Wellbuilt]

I would not leave the system on when you are not there , it seams like you don’t get enough solar power to power the inverter for the week .
I use lead acid batterys, and have 4500 watts of solar .
I just turn off every thing when I head home for the week .
I don’t know why the BMS didn’t turn off to protect the battery .
I don’t buy from China even have family that live there and speed most of the dialects .

 

[1blakephildavis]

MPP solar was beeping at 25 volts to warn that it was getting low on voltage. Battery read the same voltage on indicator. After it reached 24.8 the battery went dead and the indicator was off with no voltage.

 

[iamrich]

If the system is cutting out at 24.8v, the battery is not dead. That means something is cutting off the power flow at that point. Likely the BMS or the MPP has a low voltage cutout that you are hitting. I would look at your BMS as the likely culprit.

 

[1blakephildavis]

Ok not dead but not enough to power the MPP to charge itself. Did you see that I returned battery already? Are you saying that I need to change the BMS on a new battery that was just returned and not fixed? I can't eat 180.00 every time some says that I would check BMS. The MPP is set at 24 V so I can't be hitting that already. I just want to see voltage on this battery lower than 24 volts on the indicator. This is like having an engine without a starter and everyone just tells me to keep the gas tank full.

I think the original cells were kept in battery and they just provided a new case. I guess we are in agreement that something is still wrong with battery but bigbattery just is giving me a run-around until I give up and buy a battleborn.

 

[iamrich]

I am not suggesting you send it back. What I am saying is that it appears the BMS or MPP is set to shut off at 24.8V. That is pretty close to the bottom anyway so I don't think I would go much more. I think 24.8v is in the 10% left range. The inverter itself uses about 50wh of power, so if you are leaving it on all week you are using 1200wh per day (8.4kwh per week), but your solar panels (even at 400w) should cover that if you are getting at least 3 hours of sun a day. I get the feeling you are not charging off the solar, or you have another load (besides the inverter itself). How much power has the MPP generated since you installed it?

Also what are your MPP settings?
Battery Type setting?
Bulk Charging Voltage?
Floating Charging Voltage?
Low DC cut off battery voltage?
PV energy Generated totally?

You may want to reset he PV energy setting and then see how much power is generated between weekends.

 

[1blakephildavis]

Mpp settings were straight from Will's website. The only change was to move low voltage cutoff to as high as it will go at 24.0 volts. To me nothing else matters if I am allowed to use the battery lower than it takes to power the MPP solar. I want the Mpp to turn off before the battery goes below 24 volts so that if I get there and everything is off I can reset battery and Mpp and hook up generator to recharge. I plan to add 4 more panels but a week of rain and clouds could put me in the same place.

 

[iamrich]

Which model battery do you have? I know you said bigbattery.com A123 24V, but what are the specs? Is it the 3kwh model? I don't see anything else in that price range (prices have gone up though).

 

[1blakephildavis]

2.4kwh 8s5p 100ah....no documentation of course