Is there by any chance somewhere a list with all optimum values for a JK Inverter BMS with EVE MB31 LiFePO4 grade A cells.
The values appear to change from time to time on the Internet. Even for Andy’s off-grid-garage settings. Mad that you have to search high and low just to get good values.
Different settings depend on different user requirements. Do you want more security? Do you want to utilize your battery capacity as fully as possible? Or do you want to maximize your battery life?
All relevant. The EVE cells have a datasheet that should have some information as well. Usually the voltages are tailored for the cells used and the questions tomberger asked.
Hi Tom. Good question. For me safety is key. I guess also a requirement for the insurance company. Just to be on the safe side of things. There’s no need for me to stress the battery bank. I rather add one. That is if required. Time will tell of course.
True Absolutely. I love learning new stuff, but also know my limits. Some people are cocky about their absorbed know how, but then something bad might happen. Like a back-wall of some building blowing off to eternity,
True you don’t know what you don’t know and i don’t either. And the problems with bad lithium set ups dont show immediately, (unless there was a catastrophic error) it is usually 2 or 3 yeas of use where the damage is noticed.
It certainly does not help that there is a lot of stong opinions mixed with fact and fiction.
So many different methods for balancing and ideas behind it.
The easiest way is to look at cell datasheets. Use the cells in the flat part of the curve. Maybe with a small overshoot on the top end of the curve for making sure it is full and balancing purposes and to keep absorption short.
Setting them up properly from the beginning like balancing the cells from the start.
Just like me. That’s why I only discharge the battery to a minimum of 20% SOC in the summer and only to 50% in the winter. And I charge to a maximum of 3.45 V per cell, just enough to allow for balancing.
Like I said. I don’t like to stress the prismatic cells. Not even the brand new grade A cells. And thus set the voltage to 3.45 and that is enough for me. I think that I use 3.350 as float voltage. Can’t really recall the used absorption voltage, but that should not be too far of it.
By the way. I noticed that the JK Inverter BMS reports a lower voltage. The SmartShunt is 0.8 volt higher than the BMS. SmartShunt is correct. Verified with my Fluke. No idea why JK BMS is this far off. I mean the Victron SmartShunt is connected to the BMS output, and goes to the MP inverter.
Voltage on the inverter is also spot on. I verified the voltage between bat-min and bat plus. Same voltage. JK is wrong.
Charge settings are specific to the battery (and vendor) not the BMS. I would use the same settings for my battery bank without regard to if I was using a JK or JBD BMS.
If you’re willing to read through a lengthy thread, this is a good read:
After calibration (in the JK Inverter BMS settings) the voltage is reported accurate.
But the JK inverter BMS has severe problems with SOC calculation. Until the last firmware update the SOC was reported much too high: after a week or so of not reaching 100% SOC I noticed that it reported 50% SOC but a (accurate) voltage of only 49.x V (which means less than 20% SOC). With the newest firmware the SOC tends to be calculated too low, and JK obviously achieved that with a really dirty trick: at charging the BMS reports a almost perfect current value, but when discharging the reported current is much, much too high. Obviously the new firmware simply multiplies a factor to discharge currents to get a more precise SOC. I have seen the BMS reporting a discharge current of 18 A, while the real discharge current was only 12 A.
Hi Jim. Of course. I get that. The thing is that the used text for the settings is. Well at least sometimes, a bit of a question mark. Not every vendor is using the same kind of text. Please note that this is my first ever JK BMS. After having used Daly BMS before.
Thank you for the link. You know what. I’ve followed Will from his younger years, whilst living in his RV. Great chap. Great info and always a pleasure to read the forum posts. Let me go check your link. Thanks