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cjdelphi

Oct 26, 2011
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before looking at the screenshot...

does a BMS control/regulate current when cells are stacked in series?
 

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kellys_eye

Jun 25, 2010
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Without looking up a standard response...... I would take Battery MANAGEMENT System to mean anything between simple monitoring to full protection and control depending on how that system is offered up. I wouldn't expect BMS to mean a specific means of control.

Consider either approach - per your attachment - to be acceptable, no right or wrong.
 

cjdelphi

Oct 26, 2011
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Without looking up a standard response...... I would take Battery MANAGEMENT System to mean anything between simple monitoring to full protection and control depending on how that system is offered up. I wouldn't expect BMS to mean a specific means of control.

Consider either approach - per your attachment - to be acceptable, no right or wrong.

I disagree, I can't find a single bms that current limits, it only cuts it off it exceeds the max current rating

if a cell approaches fully charged, it switches off that cell, there's no mention of the bms taking care of the current limiter...

if it did, people wouldn't buy specific chargers you would hook up you 15v and off you go...
 

Martaine2005

May 12, 2015
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Isn’t a charger and BMS completely different circuitry?
With charger limiting the total current and the BMS monitoring each cell (balancing).
When integrated they would indeed monitor, sense and current limit.


Martin
 

cjdelphi

Oct 26, 2011
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but they don't limit current in the sense that a current limiter does, if over current occurs the fet go off, current isn't reduced same goes for charging it, you decide current draw just don't exceed the bms rating...

how else do I get decide to charge at 5amps or 10amps with my lifepo4 (with bms) battery... or up to 25ampers but if I exceed it, it does /not/ limit it to 25 amps, it gets turned off until the current drops again
 

Martaine2005

May 12, 2015
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but they don't limit current in the sense that a current limiter does, if over current occurs the fet go off, current isn't reduced same goes for charging it, you decide current draw just don't exceed the bms rating...

how else do I get decide to charge at 5amps or 10amps with my lifepo4 (with bms) battery... or up to 25ampers but if I exceed it, it does /not/ limit it to 25 amps, it gets turned off until the current drops again
I agree.
I charge at 1A or whatever I choose with my bench PSU.

Martin
 

cjdelphi

Oct 26, 2011
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The onus is on your to do that since you were the one initially disagreeing ;)

show Kelly's eye and myself the switch

a current limiter reduces the current
a switch switches it on and off

since it has no current regulation it's a switch ;)
 

kellys_eye

Jun 25, 2010
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A fuse is a current limiter. Exceed the current and it cuts it off, true, but it IS a limiter.

When you say "a current limiter reduces the current" it actually does no such thing. It stops it rising past a certain level - there is no 'reduction' at all.
 

cjdelphi

Oct 26, 2011
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A fuse is a current limiter. Exceed the current and it cuts it off, true, but it IS a limiter.

When you say "a current limiter reduces the current" it actually does no such thing. It stops it rising past a certain level - there is no 'reduction' at all.

a fuse is a switch as well, it's fully on or it's fully off, there's no current regulation
 

cjdelphi

Oct 26, 2011
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poly fuses, thermistors, MOV etc.. do control the current and are current limited....
 

cjdelphi

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When you say "a current limiter reduces the current" it actually does no such thing. It stops it rising past a certain level - there is no 'reduction' at all.

if you are referring to a bms, consider it a switch, it doesn't reduce current it over current occurs, it switches off until you reduce the current...

you don't have current limited power supplies you have switch mode power supplies because it's either on or off, so unless there's resistance involved it's a switch
 

kellys_eye

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You are conflating current limiting and current regulation - there is a distinct difference.
 

Arouse1973

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Dec 18, 2013
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Do we have to define if it is constant current or foldback limiting?
 
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