smart bms settings

m3vuv

100 W
Joined
Nov 16, 2017
Messages
222
Location
horncastle lincs uk
Hi all,i have a new 13s smart bms,what is the correct sequence to connect it to the pack,i assume battery minus first followed by the balance wires then the load?,just dont want to let the smoke out of it,tia paul m3vuv.
 
Just another question,this aliexpress smart bms came with zero paperwork,it has a bt modual connected to it,does that mean the bt is always pulling juice from the battery pack?,or does it only turn on when i pull a load or charge the pack?,this is what i had delivered( its the 60 amp version)https://www.aliexpress.com/item/33000762621.html?spm=a2g0s.9042311.0.0.496d4c4dAranMI
this is what i got from there site,poorly translated and as clear as mud!tia
 

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The question was answered in another thread. I'm not amazed at all. Sometimes people ask a question then start another thread and ask the same question again. So the repetitive thread gets ignored. I will look for it. So you don't derate me. But I know very little about BMS only what I read.
 
m3vuv said:
Well i am pretty amazed no one here has answered this relitivly simple question,seems i over rated the folks on here.

Seriously "over rated". FFS why should anyone have to wait an entire day for free support...
 
Thank you for that and making time to reply,seems its b- then ballance wires then,batterys been sat here 24hrs now while i waited for that info to finish of the build,cheers M3vuv paul.
 
Hi all,i have a 13s smart bms,i have set it to charge ballance using the Xiaoxiang app with my phone,its set to balance turn on at 3.9v with the balance provision set to 0.15v,when i write those settings to the bms,my charger light goes red and the current going into the pack via a avo meter in the charge /discharge bms wires sits at 800ma when the charger is red,it stays that way for about 20 seconds,then the charger goes green,the charge current goes to zero,if i submit the settings again on the app the proccess repeats,so how can it ballance when the charger disconnects,are my settings causing this?,i have one cell groupe at 4.28v,but isnt the point of the balance function to balance and not keep shutting the charger off?,tia paul m3vuv.
 
The charger does not balance the pack it looks for a max voltage. If you have one cell group at 4.28v then the charger should shut off. The BMS should start bleeding the highest group/s. when the highest bleed down enough the charger should start charging.
This is a slow process. This is why the packs should be balanced before and let the bms keep it in balance.
I need to read up on it but I would want my groups to be closer than 0.15.

I'm sure when you update the parameters the BMS will cycle and until it can collect data to see what it needs to do and that is to shut down because you have one group over charged.

I don't have any idea how out of balanced your pack is. It maybe fast for you to balance the groups your self. Have another member going thru the same thing.

You can read the last two pages of this link to get the idea. blance board

You can get a load and draw down your top groups or get you battery down to a lower level like 70-80% and charge up the lower groups to match the upper ones.

by m3vuv » Sep 03 2021 5:48am

Hi all,i have a 13s smart bms,i have set it to charge ballance using the Xiaoxiang app with my phone,its set to balance turn on at 3.9v with the balance provision set to 0.15v,when i write those settings to the bms,my charger light goes red and the current going into the pack via a avo meter in the charge /discharge bms wires sits at 800ma when the charger is red,it stays that way for about 20 seconds,then the charger goes green,the charge current goes to zero,if i submit the settings again on the app the proccess repeats,so how can it ballance when the charger disconnects,are my settings causing this?,i have one cell groupe at 4.28v,but isnt the point of the balance function to balance and not keep shutting the charger off?,tia paul m3vuv.
 
please cam someone recoment a good balance turn on voltage for a smart bms fitted to a lithium ion colbalt pack of 18650 cells pleased,ps,this is set to charge balance,at the moment blance it set at 4v but it doesent seem to be balancing,all cells are about 150 millivolt apart,tia.
 
You need the ability to monitor the per-cell voltages

in order to see when (if) the BMS is actually starting to balance.

Also check your cell-delta setpoints for start and stop.

Can you set the charger to 4.05V CV setpoint and very low amps?

With such a huge delta may take many days, or weeks to finish.

What Ah capacity? what mA balance current?


 
Hi all i have a 13s smart bms,i think its made by ltt i think,the bt app is the one with the elephant on it,i cant pronounce its name its chineese,if ppl are familiar with it,can anyone tell me the minimum android version it will work on?,ie ics gingerbreaf oreo etc,tia.
 
Surley to god someone can answer this the app is called xiaoxiang.just need to know the lowest android version to use as i have an old galaxy gt-i9100 running a custom rom running android version 8.1.0,trouble is tho,gps dont work with this rom/android version,and it eats the battery,so need to know what phone to replace it with and the lowest android version etc,have emailed james@lithiumbatterypcb.com,thats the tech support for the bms,basicaly the tech support cant understand english and are as much use as tits on a bull!!.TIA.
 
its a 17ah homebrew pack if that helps,and a llt 40amp smart bms,i just need basic settings/parameters to do with the cell ballancing,its set to start balancing at 4v ,but 1 group is at 4.178 lowest highest is 4.229,total voltage is 54.6v its an 8p 13s pack.
 
m3vuv said:
... at the moment blance it set at 4v but it doesent seem to be balancing,all cells are about 150 millivolt apart,tia.
That's an improvement from 150mV variance to only 51mV variance of your recent post.
m3vuv said:
its a 17ah homebrew pack if that helps,and a llt 40amp smart bms,i just need basic settings/parameters to do with the cell ballancing,its set to start balancing at 4v ,but 1 group is at 4.178 lowest highest is 4.229,total voltage is 54.6v its an 8p 13s pack.

SUGGESTED EXPERIMENT:

  • Discharge your pack to 44.0V-45.0V so bounce back voltage after resting pack for a couple hours is about 47.0V-47.5V (3.62V-3.65V). Only then record voltages of the lowest p-group and the highest p-group. Likely the same two p-groups as above post.

    Change your smart BMS Start Balancing to say 3.80V and STOP Charging at 53.3V (4.10V) instead of 54.6V (4.20V). That way you will prolong c/d cycle life longevity.

    Instead of charging at 1.0C rate (2A) charge at 0.5C rate. 17Ah ÷ 8 = 2,125mAh x 0.5C = 1.1A charge rate. Allowing time to balance the 13 p-groups via discharge balancing.

    May only need to balance charge at 0.5C rate (instead of 1.0C) every third time unless cells are of questionble quality and as pack ages with more and more c/d cycles.

    Start Balancing sooner and at a lower charge rate allows the 13 p-groups enough time for balancing within 30mv of each other by the time the pack reaches 53.3V (4.10V).

A wise ES member so aptly said, "A Smart BMS is only as Smart as its owner" (paraphrased).

Depending on the condition of the cells you may need to start balancing at 48V (3.70V) in order to arrive at a variance no greater than 30mV at 53.3V (4.10V). Depending on the condition of your cells a variance of 50mV isn't necessarily bad. Some are satisfied with an imbalance of only 100mV with a DIY usable pack madeup of used salvaged cells.
 
but i am just asking for the basic settings,ie a starting point,once againe the answers go off the rails!,dont mean to be rude but stick to the question asked,ie basic charge settings ie open closed and start voltage please.
 
m3vuv said:
but i am just asking for the basic settings,ie a starting point,once againe the answers go off the rails!,dont mean to be rude but stick to the question asked,ie basic charge settings ie open closed and start voltage please.
Tht SUGGESTED EXPERIMENT: was with respect to ... "ie open, closed and start voltage". You may have to reread again in order to digest the relevance of its content to your query.

The start balancing discharge voltage will depend on the start setting. You said currently it is at 4.0V ... so i suggested to start it at 3.80V and explained why. Also mentioned the resting (open) voltage ... "about 47.0V-47.5V (3.62V-3.65V)". Also mentoned the final (closed) voltage of ... "53.3V (4.10V) instead of 54.6V (4.20V)" and explained why. Maybe, it was too much for you to comprehend .

Who's the one that's rude when you posted the following reply in your Sep 02 2021 thread ...
m3vuv said:
Well i am pretty amazed no one here has answered this relitivly simple question,seems i over rated the folks on here.

Maybe the answer to your question ("ie open, closed and start voltage") isn't as easy to answer as you thought in three "relitivly simple" voltages (open, closed, start). Or maybe you're partly confused in not knowing how best to ask (phrase) your question(s).
 
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