Challenges with the larger JiKong BMS (external contactors) Electric Sailboat application

Deep6

New Member
Joined
May 20, 2022
Messages
3
Hello everyone,

I've been reading through the posts here and am amazed by this community, I only wish I would have found you all sooner it'd have saved me significant pain I suspect.
I foolishly started converting my sailboat from diesel to electric as a project to get done before my wife delivered our twins. Long story short, my twins are several months old, and my boat is still in the boat yard with an unravelling list of projects to finish before it gets back in the water, not the least of which is the electrification.

I purchased 2 of the larger JiKong BMS's the ones with the external relay controls I believe them to be the 2A balancer, with 24S support. I then purchased 32 304AH cells from Basen due to a friends good reviews. Lastly I purchased a myriad of Victron components to connect it all up, a 35A @ 48v 3000W inverter (Multiplus II) the smart shunt and the Cerbo GX. Over the last several months I've been working with the batteries and BMS and have had several challenges. I'm hoping some folks here can help a newbie through this.

I've had several shall we call them oh shit moments, the first was when in my Proof of Concept setup I had top balanced my cells and then arranged them in a 48v configuration foolishly I had the CerboGX and smart shunt connected directly to the battery "upstream" of the external contactor. I was doing some discharge tests and welp, life intervened (newborns are darn cute, but gosh a lot of work) long story short I came back to my entire bank being completely dead, across the terminals that had read ~52v when I started, it now read 6v. I only know the culprit now after some clarity of sleep helped, but that was several weeks ago. I immediately charged the cells back up to 3.65 and tried to top balance them again, which seemed to work, in so far as to say they were able to charge to 3.65. Though they "decay" quickly, I have reconfigured them back to a 48v system, and am trying to run a capacity test on them to see what I can pull out ouf them. They did swell, as a result of the discharge, but they still seem to be in somewhat decent shape (at least I think they are). I do have problems though with the BMS tripping the contactor due to an Under Current Protection. Though what I am challenged by is my volt meter is showing 3.~ volts, and even screen shotting the app leading up to the disconnect only shows values above the low voltage disconnect threshhold. I asked the folks HankzorBMS and they gave me a big schpiel about how inverter loads are not constant and how there's a sine wave and 4 different cycles contained in the actual inverter wave. My question is, is this normal, are these batteries toast? Why does my multimeter show a value much higher than the undercurrent protection value.

Secondly on my "good" bank I was also having problems with the other BMS with overcurrent protection. When trying to charge the batteries though the inverter, I was getting Over Voltage disconnects. With the other BMS it would sense the over current condition (again my multimeter was reporting things within nominal ranges). It would then trip the contactor and then cause the inverter to go into a fit and reconnect, and the cycle would repeat endlessly.

A few other questions I have is, how do I go about making use of the precharge circuit, and is it valuable in my applciation.

I was sent 2 of the displays but there were no cables included, has anyone made use of this display?, if so how was it wired.

Hoping some floks can help someone who's clearly over there head.

Thanks in advance!
 

acdoctor

Solar Addict
Joined
Oct 5, 2020
Messages
788
Location
Central Arkansas
If you can you may need to review and possibly adjust your BMS settings. It sounds like they are doing their job. They should disconnect on high and low cell voltage and pack over current. Is it possible your meter is not calibrated?
That BMS with Bluetooth should allow you to view SOC when configured properly so shut is redundant.
 

Deep6

New Member
Joined
May 20, 2022
Messages
3
If you can you may need to review and possibly adjust your BMS settings. It sounds like they are doing their job. They should disconnect on high and low cell voltage and pack over current. Is it possible your meter is not calibrated?
That BMS with Bluetooth should allow you to view SOC when configured properly so shut is redundant.
I've selected the LiFePO4 settings from the configuration menu, and they look correct.
My meter is very accurate, from my understanding.
 

Deep6

New Member
Joined
May 20, 2022
Messages
3
I was referring to the settings in the BMS.
Yah I just unlocked the BMS and clicked on the LiFePO4 button, and it adjusted all the settings to match that chemistry from my understanding, (prior to posting this so it's been using the correct settings all along from my understanding)
 
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