I don't get it. JK BMS with EVE 304AH, 12v setup

[SpankyOatmeal]

Just like the title says, I don't get what I am doing wrong with my settings for the JK BMS 4-8S, 200A BMS with EVE 304AH, 12v batteries setup. I have followed general settings for the JK Lipo setup, and have tried max charge to 3.65, 3.60, in-between, loweer, and what I seem to get is that @ 3.65 the battery will charge to 3.4 to 3.42, or so, and then the app will, by its self, raise the calibration voltage setting!

The JK app says the batterys is at about 79% charge. I have not drained the battery to close to zero and recharged from there. I started with the JK and this 'new' battery, at 3.27, all balanced.

I am unable to set the 'calibrating current'.

I am using a standard 10 amp/12V outputting about 14 volts, car battery charger, which does charge the LiPO battery, and decreases the amps over time, seems to me speedy enough. I also have a variable car battery LiPO charger, 10/30/100 amp, which I have not used yet.

The BMS does keep the cells very well balanced, though I suspect that maybe I am not leaving it long enough for 'saturation', if that is the correct word. I'm testing this charging battery setup independent of any other connections to anything with this type of trial.

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I know I am missing a good deal of understanding, despite my daily and nightly reading for a few months now, trying to finesse this JK BMS/battery process.

Can someone add some insight?

 

[TacomaJoe]

Not sure how much help I can be but I'll give it a shot. I use the Overkill Solar app so my screenshots are different. I wouldn't mess with the voltage or current calibrations unless there was an issue. In your case, I don't see any. Do you have any screen settings for % of capacity. On my battery 3.4V would be 95% (instead of 79%).

 

[nc73]

Not sure what is going on with calibration changing itself...if you want jk to say 100 percent just change the voltage so that bms trip and cutoff charging, at that point it will read 100 percent and you can change the charge voltage back to whatever you want...3.5, etc. That's how I force it or you can wait forever and it may correct itself.

 

[TacomaJoe]

Keep an eye on the voltage calibration value and the battery voltage. Are they tracking each other?

 

[SpankyOatmeal]

Not sure how much help I can be but I'll give it a shot. I use the Overkill Solar app so my screenshots are different. I wouldn't mess with the voltage or current calibrations unless there was an issue. In your case, I don't see any. Do you have any screen settings for % of capacity. On my battery 3.4V would be 95% (instead of 79%).

The second photo upper portions shows the remaining capacity, which today now shows correctly at 304AH -different than the second photo number, and above that is the remaining %

 

[SpankyOatmeal]

Not sure what is going on with calibration changing itself...if you want jk to say 100 percent just change the voltage so that bms trip and cutoff charging, at that point it will read 100 percent and you can change the charge voltage back to whatever you want...3.5, etc. That's how I force it or you can wait forever and it may correct itself.

Yes, when I set the "Calibrating volt", say to 13.** whatever, and go back to the first page which shows the main stats (second photo), when charging via power supply or solar charging (maybe not charging too - I'll have to check that), in the upper left corner is a large volt number, say 13. something, however as the things sets charging, what ever is that top left large volts number, when I go back to thebasic settings page, the "Calibrating volt" will be changed to the same as on the main, stats, top left.

I'm now thinking that the "calibrating volt", is the "current in time" actual total voltage of the battery, and not really a setting that limits the battery top voltage (which I'd like to set). Maybv I've confused the "Calibrating volt", is my thought. Now sufre where else I'd make the setting in the second page to limit the max volt, other than the Cell OVP(V). Hum.

 

[SpankyOatmeal]

Keep an eye on the voltage calibration value and the battery voltage. Are they tracking each other?

Yes. Please see reply above.

 

[SpankyOatmeal]

Not sure I grasp this: .if you want jk to say 100 percent just change the voltage so that bms trip and cutoff charging.

Where would I make that/those changes. Seems to me the "calibrating volt" is not the right [place, as that changes dynamically by its self when the batt is being charged, no matter what I put in there. I'd like the BMS to keep it at a specific set point.

 

[TacomaJoe]

The calibrating voltage setting allows you to fine tune the BMS sensing. If the BMS says your battery is at 13.62 and your truly accurate meter says 13.59V, you can change that setting to correct the BMS. In your case, it doesn't seem like you have the permission in the app to do that.

Think of the BMS settings as the safety switch. You should alter the charging sources to limit the battery voltage.

 

[SpankyOatmeal]

TacomaJoe,

Good info, thank you. Then that setting is not the ceiling charge level max, which would turn off charging? I do have permission to change the setting, but as the battery is being charged, that setting changes by its self to about whatever the charge level the battery seems to be, and raises or lowers depending on the seeming 'voltage level' form the top left most first page voltage reading.

As shared, if I increase the "calibrating volt" the charge volts will increase as well, but it seems the voltage coming into the battery wants to get into the low 14's, which is way above the max volt for the EVE battery when it is 100% full at 3.6 and @ 304AH.

I have all this setup in the kitchen/back deck at this point, and hope to get the install going next week. Rainy days here.

* * I'm thinking the BMS is not really meant to be the manager of the incoming volt/current charge really, but does have the ability to shut down charging, OVP, as example, and that the other device, Renogy 50A DC-DC/MMPT solar gadget and the inverter/charger are meant to 'control the ultimate charging output volts/current by their settings. Am I correct with that?

If I am correct, then I have an issue with the Renogy DC-DC 50A MMPT, because according to Renogy, it attempts to charge at something like 14.X, despite the batter being 100% full, and per Renogy, there is no way to change any setting in that system (yet), though they are working on a beta version which they say will allow 'user' set variables.

In the mean time, if I am correct about * * above, I'm looking for a method to limit the charging more directly/better, before it gets to the JK BMS.

 

[MisterSandals]

Then that setting is not the ceiling charge level max, which would turn off charging?

As mentioned previously, the BMS is a safety switch, like a parachute or car airbag. Things you hope to only use as a last resort, not everyday landing and car stopping use.

Your "charge controller" should control the charging. Possibly why it is called that.

 

[SpankyOatmeal]

Mr. Sandlas, yes, thank you.

 

[SpankyOatmeal]

I've been testing out the battterys, BMSs, DC-DC/MMPT charger, and shunt in the kitchen, panels on the back deck, for the last few weeks. All seems good. These batteries came mated.

The 3K inverter is rough installed and it's working as designed, currently for the lead acid batterys in the 02 Trek.

I'm thinking about the microwave and that I'll need to change that circuit breaker location on the panel (?) over, so I can run the microwave off the battterys, as well as from hookup and/or the generator.

Anyone find that this works OK, and if so, would you share how you accomplished that?

 

[dfwbmw]

I agree with Mr Sandals, however most of us rv people have chargers we can't control!