How bad/what will happen over charging by 1.2v?

[Guda]

I am going to try not to over charge but. battery max V is 46.8v. My AIO will only go down to 48v. I have already OV (over voltage) a few times. The other day AC charging it got to 47.1v before I caught it. When I first got it it went to 48v 2-3 x before I installed the MNC250 (died yesterday). I am about a month away from having the $ to get a new battery.

1.2v over charge-

Fire?
Explosion?
Off gassing?
Other bad things?

Thanks guys! I am running for awhile so please excuse my slow response to any tech questions.

 

[rmaddy]

What battery setup do you have that has a max of 46.8V? A 48V nominal is 16 * 3.2V = 51.2V. I bulk charge a 24V nominal LiFePO4 at 28.4V so a 48V nominal should be bulk charged at 56.8V, not 46.8V.

 

[DJSmiley]

I'm also wondering which kind of cells.

46.8V doesn't make sense to me for LiFePO4
Those are 3.65V / cell max (or 3.8V for some LiFeYPO4 cells). None of them matches with 46.8V?

 

[Guda]

Looks like they (Big Battery) dont sell it any more. Will had one. I think it didn't work with his cart. I found tech direct club on Ebay. Called them to make sure I got the correct battery as ebay is not good to look at a stores full stock. ESL. I ended up with a not 48v battery that was advertised as a 48v battery.

All my #'s are what their website said. What will over charging by 1.2v do?

This is the new model of what I have. They changed the voltage

 

[Guda]

No one knows what a 1.2v over charge will do? Stumped DIYsolarforum 10-2-21. Down in the record books

 

[BobR]

1.2 volts between 12cells (36 volt battery)?

1.2 /12 = .1

 

[Guda]

I don't know how many cells tbh. Maybe I'll call them tomorrow.

 

[Ampster]

No one knows what a 1.2v over charge will do?

Without more information on the cells it is hard to reach a conclusion about what voltage is an overcharge. We don't know the chemistry and that pack could be 14, 15 or 16 cells in series and as @BobR pointed out it could be very little at the cell level.

 

[Guda]

Its Lifepo4. That was the main reason I called them was to make sure I got that kind of battery.

Its pretty stressful worrying about it. I run a heater or switch off the pv to avoid over charge. Micro cycling not the best.

 

[Guda]

Of coarse they don't answer. Every time I've complained about this big battery situation. Within a week BB sends either Will or Lithium Solar a free battery to review.

Here are my threads on this

Bad battery?

I got a 48v from techdirectclub.com/ . It showed up Monday, turned it on Wednesday & it showed 42v. Thats bad huh?

diysolarforum.com

MPP solar 48v lifepo4?

What are the charge parameters for lifepo4 & how do I program it? The manual says use the user setting 05. Okay once I am there, how do I enter the correct numbers & what are they?

diysolarforum.com

Anyone used this 48v battery?

48v I am thinking about one to use temporally as I wait for the cells from China. I want to use the MPP solar (LV-MK) 3000w 48v 110vac split phase Inverter. I am ordering 36 of the 280ah cells to make a 48v battery. I have learned here that 48v comes in multiple flavors & inverters are picky...

diysolarforum.com

People are hesitant to definitively say yes or no to fire. Before I asked here I looked around. I see if you just keep going higher & higher it will explode. I cant find a test where they over charge by just a little

 

[Ampster]

Its Lifepo4.

Earlier I asked how many cell groups. but never heard the answer. That is an important thing to know in order to calculate whether you are overcharging or under charging. I also see confusing statements so I do not know if this is a nominal 36 volt battery which normally would contain 12 cells or cell groups. At a per cell voltage of 3.5 per cell a safe voltage would be 42 volts and fully charged to the max of 3.65 per cell would be 43.8 volts.
So IF this is a nominal 36 volt battery with 12 LFP cells and you are charging to 46.8 that amounts to 3.9 volts per cell. Normally with LFP that would not start a fire. Note, I capitalized "IF" for emphasis since that is a big assumption. Also that is just an average and at that kind of voltage without a BMS there could be a runner that could go even higher. The best answer to to question about fire is for you to feel the temperatures of the cells and if one is getting warm you are approaching a dangerous situation. Worse than a risk of fire is the damage that could be going on with the entire pack at that voltage. Given that this is a Bigbattery of unknown heritage I think there is a risk of fire. The risk is compounded by the lack of information.
The good news is that this is good practice for when you get the cells you have ordered and after you have destroyed this battery you will have enough experience to improve your chances of being successful with your new battery.

 

[BobR]

I have not seen an example on this forum of a lifepo4 cell or battery bursting or exploding into fire. What I have seen is bad wiring and system construction practices starting fires.

 

[Guda]

I called to try to find that out but no answer.

The BMS is a good point. The BMS should protect it from over charging.

I feel lucky that I am getting a new battery from a company new to building them. I have not ordered cells. I don't expect you read all my posts but I will tell you this. I was sold a battery that was incorrectly advertised. I've done pretty good with getting fucked over by Big Battery false advertising. Had a MidNite Classic 250 not died after 14-15 months, I'd be fine.