OverkillSolar
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Some of the bugs...
I bought a Walmart brand (ONN) tablet for $40 brand new just for this.
Finally found a LiFePO4 BMS with Low-temp Charging Protection
- Thread starter Will Prowse
- Start date
Some of the bugs...
I bought a Walmart brand (ONN) tablet for $40 brand new just for this.
Sgt Raven
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Back a page someone is running a newer version, 3.1.1015 where yours is 3.1.1001.
The newer one crashes on his phone when discharging in "Monitoring Mode".
The Parameter Setting bug doesn't matter, because you can make all the changes easy in Parameter View.
Sgt Raven
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Did you switch to 3.1.1001? and did it fix your problem?
AndreL
More AH's
@OverkillSolar / master manual I have a question on how the BMS calculates AH.
I have been solar charging my 105AH BLS cells all day today in WA state after bottom balancing and was proud to say I captured ~32AH/33% capacity using a 100watt solar panel according to the BMS app on my phone.
So I called it a day around at 5pm and did not check the BMS again till about 8pm (was dark and so no charging) when I tested out a really old galaxy tab 3 tablet (android 4.4) as app host.
Now looking at the BMS the capacity was shown to be around 60AH and 62%. Do you know why this would jump, what is happening and what I am doing wrong so I can correct it?
I was hoping the BMS wound count AH's in and out.
I have noticed this on discharge also, ie a pause makes the AH and capacity shown jump in value. Does it have anything to do with the battery % settings in the app?
Any help or insight much appreciated.
Lastly this issue should have nothing to do with android version and V4.4 as all the data storage should be on the BMS I hope. Was using yellow elephant as your blue elephant will not parse on this old version.
Thanks
OverkillSolar
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All evidence is that it only uses voltage to calculate SOC, which is disappointing. There is a 5 or so point calibration you can tweek if you think it could be doing better. I have noticed that if the cells arent balanced then it gets some crazy ideas about SOC at the top of a charge cycle.
I plan to create a coulomb counter module that can be plugged in to the comm port. (open source) It should be easy, the comm port is compatible with arduino or Ras pi, and I have a protocol datasheet.
Its somewhat near the top of my to do list.
Sgt Raven
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Have you charged it all the way up with the BMS attached?
On my capacity test I started at 13.9V.
13.9V
13.5V 1 hour later
13.4V 2 hours later
13,4V 2 days later 1st time I recorded the %, 48% left..
13.4V 12 hours lster 40%
13.3V 5.5 hours later 37%
13.2V 7.5 hours later 29%
13.2V 24 hours later 15%
13.2V 10 hours later 09%
13,1V 12 hours later 02%
13,1V 1 hour later 01%
13.1V 2 hours later 00%
12.9V 16 hours later 00%
12.8V 14 hours later 00%
2 hours later the fridge shut down with a Error not enough voltage to start compressor
It showed I had 00% left for 34 hours
After charging the battery back up, my 280AH battery has 308AH according to the BMS readout...
If my cells were out of balance it was 0.05V to 0.09V
AndreL
More AH's
Thanks for the reply @OverkillSolar, I will tie in my VX8010f-80.
@Sgt Raven, these are new cells and so i had charged in parallel to 3.65v with no BMS to top balance, then connected the BMS and changed capacity from my 280AH cells ( in other thread) to 105Ah for the BLS cells. Then discharged at 21.5A in a 0.2C capacity check without break and the AH was exact. At 2.8V I bottom balanced to 2.95 volts each individual cell by selective cell charging bypassing BMS while still configured in a 4S pack.
Today was the big charge using my very moderate solar RV setup. I had seen the BMS capacity jump before but assumed that was because I was dialing in and saving BMS settings. This time I resisted and changes and still the capacity jumped. I think the BMS is fine if in constant charge or discharge, but when doing neither ie when it got dark, it chose to determine the SOC and battery AH capacity remaining based on voltage per the app parameter table.
Not sure if the DROK will measure SOC on LIFEPO4 as I have no idea on how it calculates that, but it should do the Ah counting. I'll jumper it in parallel, see how it goes and post back DROK Vs this BMS.
Sgt Raven
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During my big charge it back up, I was grabbing screen shots every 19 minutes of the dashboard. I ran out last night to a drive thru for some food. I shut the charger off because I wouldn't be there to babysit it every 10 minutes. You can see in this chart where that was..... and the 2nd is the end of that and a slow charge back today to finish it off....
Attachments
The same with 3.1.1001 In "Monitoring mode" .. Crash when discharging on my Xiaomi phone with android 9. Works fine in "Driving mode”.
AndreL
More AH's
Yup & thanks, the 1st chart looks good, but the 2nd chart shows the instantaneous type of jump in capacity I witnessed too when the charging current goes to zero for a certain time. Unsure on the logic here. Obviously the time it takes for a fast food run for you is not enough for the BMS to reassess. Not good though. A 50/50 solution.
My other long standing problem is that the Drok ignores parasitic loads (am testing but I think below 500mmA) so will drift up to 12AH per day. That seems insignificant but can add up and was one of the reasons I wanted to ditch the DROK.
This is great, let's keep testing and growing in our collective knowledge.
Sgt Raven
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Just a SWAG, it might be your phone and it's version of Pie. Lots of Companies add their own twist to the Android OS and not all of them are the same. OverkillSolar said he got a $40 Walmart tablet to run the app. That maybe the answer to your problem. Then I don't know what country you're in, either. To be honest I never heard of Xiaomi till you posted it. The Google ones are pure Droid. The Motorola ones add very little to Android in their versions. Most the other Companies have an overlay of their own on top of the basic Android OS. My Samsung Note 9 isn't the same as a Pixel XL in the way it runs Android OS.
I bought the Asus tablet I'm using March 2017 and it is working just fine with that version. Yes there is a bug in Partameter settings, but I can change the setings in Parameter View, so all is good to me.
Sgt Raven
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That jump, I think, is when it went into the "knees" I had a 10 minute timer set on my phone to go check on the whole thing and take another screen shot of the dash board. The first few hours I was sitting at my work bench in the garage. Later I got a bit Cocky and was searching the Web on my computer at the kitchen table. In 10 minutes it went from slowly topping off to 100% full. I was shocked when it happened. It went from under 90% to 100% in a blink. If I ever charge it up that way again, once I get to 87%, I will switch to my bench PS, instead of my big LA battery charger I was using.. Still I think the BMS kept it from hurting the battery.
Yes I know, there may be some problem related to my new Xiaomi Mi Note 10 or the overlay. Will test with another phone some time later. I don't think Xiaomi is available in US but is quite common in the rest of the world.
ChapterNext11
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Hi Will,Spent the last few days and tonight testing BMS:
1. The "new" daly LiFePO4 BMS (that states in the data sheet that it has low temp charging protection) does not have low temp charging protection. And yes, it has a temp sensor attached. This disappointed me big time. Video to come.
2. Next, I programmed/tested this BMS for a couple of days:
View attachment 4222
And it failed. App would crash. Default low temp cut off was -5 degrees C. No manual and very difficult to work with. Had a lot of issues with it. Will cover every downside in my upcoming video. Avoid this BMS.
3. Then I tested the battery hook up 100A BMS that arrived this afternoon:
View attachment 4223
And low temp cut off was programmable and worked perfectly. Bluetooth connected perfectly as well. I was excited so I did a load test of 200Wh with 90-102A continious. Passed with flying colors, then pushed it passed its limit and it disconnected the loads. Heatsink stayed warm and did not heat up excessively.
I'll make a long video covering all these things and the testing methods, but I am going to go with this bms from now on. I am so tired of other bms failing. The battery hookup one is used on medical devices as well, which I need more information on.
The number one most important thing to know when using this bms is that you need the proper app. The app on the website is NOT what you want. You need the "enterprise" version:
Click Here for APK of enterprise BMS program app
Send it to your phone with an email (not gmail), then install in on your phone, then connect to bms.
Then go to parameter settings and change the low temp charging cut off to 2 degrees Celsius. Then the reconnect voltage to 5 degrees Celsius.
You can buy this bms by clicking here (my affiliate link) and the coupon code is "SOLAR" for 10% off. I am going to get a 8s model and build a big system with it. I like this bms a lot, so will be testing it like crazy. I also will make a DIY video on how to use it in the next couple days (possibly tomorrow if I get enough sleep tonight).
Biggest downside of this bms is 2x 10 gauge wires at P- and B-. But it has a hole and solder tabs for adding more wires.
Just wanted you guys to know about all this before you waste your money on the first 2 bms. I wasted $150 on those bms and they were a total rip off. The new bms seems to kick butt, so videos to come.
I enjoy your YouTube channel and was inspired by your videos to build my own batteries for my travel trailer. I bought 8 of the 100ah Fortune cells to make 2 12v batteries along with 2 of the Battery Hookup BMS's. The cells arrived at 3.28v+- .01v. I charged them individually to 3.6v and then put 4 cells in series and connected them to a BMS. They have been sitting since Sunday (so 4 days) as 2 separate 12v batteries and now all cells are at 3.5v +- .01v. Are the BMS's draining the cells? Some other problem? Thank you in advance for your response.
Sgt Raven
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After charging in parallel, and sitting for 18 hours, they dropped something like that or more.
On advice from those more knowledgeable here, I went ahead and built my battery.
You're at 14V right now. It could drop to 13.4V. On mine, during my slow discharge test it stayed at 13.4V for a long time before slowly dropping to 13.1V. Here's a write up I did on another thread about my test....
OverkillSolar
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I recorded an oscilloscope trace of the BMS comm port for reference. This is with the Bluetooth module active.
@astronom Just came across your post on leveraging a latching relay with your Chargery, were your successful in getting it installed? Does it work as expected? Did you have to do anything else to get it to work with the BMS? The link to the driver circuit is a 404 for me, if you can share the details or update the link that would be great!
Hi @solardad, indeed I've briefly tested this driver circuit + latching relay, which worked as expected. All is explained in the datasheet of the driver circuit as for how it works and should be wired. Basically the driver circuit transforms the ON/OFF signal sent by the BMS (Chargery or any other) usually used to power non-latching relays into impulsions suited to drive a latching relay. Therefore 6 wires on the driver circuit module: one high voltage to power the circuit, one ground, one for input signal, one for common positive for both coils of the latching relay, and two for the negatives of each coil. Here is the schematic from the doc:
The difficulty is to find high current DC latching relays to work with that though. All I could find for 48V was the one from the post you quoted. And the driver circuit is indeed no longer sold standalone at the link that is now broken, but the same online seller apparently still sells a combination of it with a 12V latching relay that can withstand 250A here. Otherwise I could find the driver circuit on its own here.
12 V two coil latching relays are available on the market between 100 - 200 Amp used on Lifep04 BMS application ifor RV's in Europe.
I've seen application where two relays were connected in parallel to double the current draw. Installation works reliable. The issue is to find a BMS that sends a signal with a max 200ms trigger.
I've seen application where two relays were connected in parallel to double the current draw. Installation works reliable. The issue is to find a BMS that sends a signal with a max 200ms trigger.
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