I’ve now got my own similar problem with crazy voltages too. All voltages read good with multimeter but when I look at them through the bms I get wild fluctuations with two groups. I’ve plugged and unplugged numerous times and out of ideas.
As it is now the bms is only connected by the balance wires and B- but that should be fine.
I’ve got a lot more pics of it doing the same:
I think the bms is faulty. I can imagine no other reason this would happen.
That looks exactly like a bad balance connection - probably at the cell. The bms is trying to read the cell voltage without the proper reference between those two groups - the total voltage of the two groups is still correct. Test at the header manually
My multimeter shows those two cell voltages fine when checking at the balance plug.
@BenjaminF u can tell any possibilities?
Did you use enough super glue on your balance leads?
You can’t tell any reason this could happen either?
The super glue is still going strong though.
Super Glue in Electronics: Repairing Small Devices – Adhesive Guru.
You still think I’m a dangerous idiot for charging cells that got down to 2v? @jack.luis. u were having a fit that day and said if I didn’t stop saying it’s possible the world would end.
I left you unblocked for two days, tried to help you on your bad balancing pack and now here we are again. You are just the most aggressively non critical thinker with an inability to communicate via text effectively while also being so invested in being right that you give others poorly thought out possibly dangerous advice. Im so sick of being trolled by you man - change your name to ken m already
is it possible to remove those cells and switch em out just to see if its the bms
Hi, I have got my hands on a spot welder with some not so pristine electrodes.
What is the best way to get them in shape? And what is the best shape for spot welding? I’m imagining a cone shape whit a blunt tip. Like so:
Wow
. My critical thinking tells me that since the multimeter shows the voltages just fine, the bms must be faulty. What do ur great critical thinking skills tell u? What you consider “help” is nothing I haven’t obviously already tried. You really think checking the voltages at the header is something hard to figure? Nothing else u can think of? Any of the geniuses here?
What dangerous advice have I given?
My advice that it’s possible to bring back cells from low voltage?
(I posted the data sheets showing possible)
My advice to check a battery for damage before assuming it’s water damaged and throw it out? Yea I stand by that. My critical thinking tells me it’s worth at least removing shrink wrap on a battery and using a multimeter to see if it’s actually damaged before assuming. That’s critical thinking for u.
Not possible easily.
Sand/grind them. Make them pointy.
Easy fix, chuck them up in a drill or lathe and use a file to rough out a pencil ish profile. Then smooth it out with some 120 then 220 then 400grit sandpaper. I don’t think anything finer will do any benefit.
As far as the tip i prefer a rounded tip diameter of about 2-3mm. Anything sharper or duller doesn’t work for me and my methods.
Don’t breathe/eat copper or any copper alloys. Use a mask and clean up your dust. There are usually terrible things in them, lead cadmium, thorium. Anything that’s an electrical alloy or used in welding seems like they just add all the weird shit to make it taste funny
So that’s the extent of ur great critical thinking that I’m supposedly missing? Check the header?
I was hardly trolling you and just seeing if u had any other advice other than check header manually.
I agree with all this, except the progressive sanding. Copper is soft enough that I can just rough the shape out with a file or 80grit sandpaper, then jump immediately to 400grit to smooth it. Not that your way is bad though!
Nothing you can think of either?
the forum has become filled with know-it-alls who ironically have no answers.
@Pecos you’re not gunna also insult me about my supposed lack of critical thinking while not being able to post anything are you? Don’t just say it… show it. Show ur great critical thinking right here.
But if u need nuances on sanding to a point… they’re geniuses
if you had a second bms unit to plug in maybe you could see if the values change? i dont know how affordable they are
I don’t have an extra $150 30s bms.
I do have lots of lesser voltage bms and wonder if I could skip a bunch of sense wires and use a 20s bms and also skip the B- wire.
Considering I can get stable voltages every time with the multimeter on the plug I still can’t imagine any other possibilities other than a bum bms. I repeatedly asked those who allude to other possibilities but they avoid answering.
I have a dumb 10s 20 amp Daly, and wanted to check balance on my battery.
I have 2 of these inexpensive ‘capacity controllers’, that accept 2.54mm JST plugs, and the daly uses 2.0mm, so I got the components to make an adapter.
I had noticed on some 3s batteries, that some cell voltage readings would jump up and down by 0.015, and wiggling the connector would influence the behavior.
I applied some Caig Deoxit d5 to the pins and that behavior was reduced to a 1mv flicker and wiggling connector no longer had any effect
When I plugged my two controllers into my 2.54 to 2.0 adapter, on my 10s battery balance connector, the same behavior occurred. Jumping voltage on some cells, influenced by connector wiggling.
Deoxit D5 pins and sockets resolved it, again.
Granted this cell disparity was far less than your wonky readings, but less than perfect connector conductive mating surfaces seem to cause all sorts of weird issues that seem to defy logic.
Caig has some products like gold and shield for maintaining good clean connections, while the D series is more about cleaning compromised ones.
They have some kits with multiple products within and different ways to apply them.
I think my initial response was very clear, but in case it wasn’t:
You build your batteries like shit. You have been doing this for a very long time. Many people have wasted hours of their life trying to educate you on why your batteries are built like shit. You steadfastly refuse to learn or change.
So it’s extremely funny to me when your shitty batteries start to fail, and you conclude “I think the bms is faulty. I can imagine no other reason this would happen.”
This forum has become filled with people who are sick of wasting their breath trying to educate you.
