How much faster is top balancing cells individually?

[ericfx1984]

A general toss out, not at you, but be offended if you wish, better to smile instead and have another Root Beer.

It's still coffee time my friend. I'll admit I was a little offended... But like I say no hard feelings. And some root beer and a tobaccy pipe does sound good

 

[gotbeans]

No guys, I think it's more than 4X faster to charge a single cell vs 4 cells because... battery impedence, Ohm's law, Moore's law, the 3rd law of thermodynamics, Spock, the singularity, and biggest reason of all, pretty sure that @Steve_S says so.

But don't quote me on that.

ohms law? If you have them in parallel you're putting power into 1 cell basically, it's just spreading out

If that is directed at me, I think you need to reread what I wrote...

I build the pack in 4S

Do a quick charge to near 100%

Then reconfigure into parallel... And charge to 3.65 volts and hold it there overnight

PS... If you're not directing it at me I apologize... If you are directing it at me I would say, "sadly, so few people have reading comprehension skills... ".


Also either way... No hard feelings.

Your method is generally regarded as the fastest. The best method of doing what you do is just configure them into 16S and plug it into the inverter and have the solar charge it up. This will make a 1-3week process into a 1 day or less process

After that, you then connect them in parallel to balance and top them up with the slower method.

The problem avoided is the higher amps by just going higher voltage.

 

[kolek]

There is a difference between Top Charging cells in Parallel to building a 4S pack with BMS and top charging it that way.
Sadly, so few RTFM and think they know more than the engineers & chemists.

@Steve_S So you're saying it's better to do the entire top charging process in parallel with a power supply?

 

[toms]

There is a difference between Top Charging cells in Parallel to building a 4S pack with BMS and top charging it that way.
Sadly, so few RTFM and think they know more than the engineers & chemists.

There are zero engineers / chemists that recommend parallel charging LiFePO4 cells to upper knee voltage until current reaches zero.

Sadly, too few youtube heros and the sheep that follow them realise that.

 

[Steve_S]

@Steve_S So you're saying it's better to do the entire top charging process in parallel with a power supply?

I already covered this in post 11 about how " I do it" and that for me this works.

There are zero engineers / chemists that recommend parallel charging LiFePO4 cells to upper knee voltage until current reaches zero.

Sadly, too few youtube heros and the sheep that follow them realise that.

Quite Right ! can't/won't go snorkelling there again... dead horse. I did say that I cutoff @ Endamps in Post 11 or even as low as 1/2 the endamps.

 

[Brett V]

I guess I’m more lazy and less impatient. Every battery I’ve built (230 Ah,) started out as 16 cells in parallel with a 10 amp CV power supply connected until they reached 3.65 volts and the current dropped below 1amp. Yes, it takes about 12 days. They’ve been in service for some time now and the delta never exceeds .06 so it’s once and done.

 

[AshleyL]

I guess I’m more lazy and less impatient. Every battery I’ve built (230 Ah,) started out as 16 cells in parallel with a 10 amp CV power supply connected until they reached 3.65 volts and the current dropped below 1amp. Yes, it takes about 12 days. They’ve been in service for some time now and the delta never exceeds .06 so it’s once and done.

Meanwhile, the alternative is connecting those cells in series and buying expensive 10A or 15A active balancer to do the job within hours.....Aint cheap though....parallelling is much more cheaper.
I mean how often does one top balance anyway?

 

[ericfx1984]

Meanwhile, the alternative is connecting those cells in series and buying expensive 10A or 15A active balancer to do the job within hours.....Aint cheap though....parallelling is much more cheaper.
I mean how often does one top balance anyway?

Yeah but you still have to hold them at a reasonably high voltage for this to work

Otherwise they end up being bottom balanced right?

 

[kolek]

My advice - ask your cell manufacturer (not reseller), how they balance and match their cells and follow what they say.

Okay, right, I contacted them and they said 狐假虎威

 

[gotbeans]

Okay, right, I contacted them and they said 狐假虎威

The fox pretends to be the tiger's power

 

[kolek]

The fox pretends to be the tiger's power

But in this case, of course tiger represents the batteries, it's all highly symbolic and philosophical. Sure glad I contacted the manufacturer.

 

[gotbeans]

But in this case, of course tiger represents the batteries, it's all highly symbolic and philosophical. Sure glad I contacted the manufacturer.

They're probably gonna get a team to decipher this message and never respond

 

[kolek]

They're probably gonna get a team to decipher this message and never respond

No that was their response to me, not my message to them.

 

[AshleyL]

Okay, right, I contacted them and they said 狐假虎威

It literally translates to "The fox borrows the tiger's fierceness" or "A fox assumes the majesty of a tiger." It's often used to describe someone who relies on the power or authority of others to intimidate or exert influence, despite lacking such power themselves. Basically, it refers to someone pretending to be stronger or more important than they really are by borrowing the strength or authority of someone else.

They are insulting you....you know....

 

[gotbeans]

No that was their response to me, not my message to them.

oh sorry.. wow that's great
If we go all philosophical on it, they're saying the shy battery absorbs the power from the strong battery? so they just parallel all of them and let it auto balance?

 

[kolek]

oh sorry.. wow that's great
If we go all philosophical on it, they're saying the shy battery absorbs the power from the strong battery? so they just parallel all of them and let it auto balance?

LOL

 

[gotbeans]

LOL

It makes more sense with ashleyL's translation. I'm guessing maybe they know chinese or something based on their location.
Mine was just from google translate
Respond to them say you had a team of experts to figure out their code and ask them if they did indeed parallel them

 

[time2roll]

If speed of assembly is important.... just assemble with an active balancer and put the battery in service.
May have to limit top charging voltage until the balancer has time to work. Keep the charging voltage low enough to avoid over voltage at the cell level.

 

[gotbeans]

If speed of assembly is important.... just assemble with an active balancer and put the battery in service.
May have to limit top charging voltage until the balancer has time to work. Keep the charging voltage low enough to avoid over voltage at the cell level.

yep hooking up to solar charge controller is by far the fastest way to charge

 

[hwy17]

I'm just gonna take this opportunity to evangelize and spread the word that you do not need an active balancer to build then balance. I think it took me about 12 hours of balancing with 150mA passive.