Problems with keeping 302Ah in balance

[T3TRIS]

lower your charging amps to about 5-10a and give it about 1 hour.
furthermore remember not to leave the balancer connected.
manually start the balancer when cells hit 3.45 high, disconnect it after done.
you could solder an on-off switch to it to make that a bit easier

Ok, I read that before. Some people say to leave it running all the time and some others say only while charging and above 3.4V. The balancer I got isn't all that fancy... Is it really a problem to leave these connected 24/7? This is an oversized battery for the application.

As far as adjusting the charging voltage, I don't have that luxury. It's controlled by the Redarc Manager30 which can only define charging profiles based on battery chemistry. I wrote some of the details here but I can't control output current or voltage (safe for saying its GEL/AGM at 14.4V charge and 13.5V float, or Lithium at 14.5V charge and 13.6V float). I'm not sure what the charger does in the background, but it happily fed 30A to the battery in either mode, as if the cells were just thirsty for it!

 

[timselectric]

Internal cell resistance changes with SOC.
A Balancer working at a lower SOC actually increases the delta at the higher SOC. It works against the goal.

 

[houseofancients]

Internal cell resistance changes with SOC.
A Balancer working at a lower SOC actually increases the delta at the higher SOC. It works against the goal.

and badly too

 

[Alkaline]

good on the balancer, I say leave it connected and see how you like it. They made different versions of this the only I have stops working any time the average voltage goes below 2.9v.

I never had an issue with the AB as long as I would fully charge the battery. it works best on the upper SOC range when they are 3.6v. I never had an issue leaving it on it basically does nothing in the 3.3v range.

Note you may have small additional draw on your cells, but at 300AH I doubt it makes any difference.

So yeah keep it on and keep the charger on they will all balance out.

 

[Alkaline]

Ok, I read that before. Some people say to leave it running all the time and some others say only while charging and above 3.4V. The balancer I got isn't all that fancy... Is it really a problem to leave these connected 24/7? This is an oversized battery for the application.

As far as adjusting the charging voltage, I don't have that luxury. It's controlled by the Redarc Manager30 which can only define charging profiles based on battery chemistry. I wrote some of the details here but I can't control output current or voltage (safe for saying its GEL/AGM at 14.4V charge and 13.5V float, or Lithium at 14.5V charge and 13.6V float). I'm not sure what the charger does in the background, but it happily fed 30A to the battery in either mode, as if the cells were just thirsty for it!

You need to hit the 3.6v ranges for it to work, when the cell is 3.4 and the others are 3.3 it basically does nothing. It only works when the voltage difference is big and you only get that when 1 of the cells is full.

Just leave it plugged in and see how you like it vs plug in and off (pain in the ?) I'm sure you could get may be a little better balancing flipping it on/off but for me I would just fully charge my pack once a month and it would balance all the cells it usually took 2 hours or so to balance even shaddy grade B/C xuba cells.

 

[houseofancients]

You need to hit the 3.6v ranges for it to work, when the cell is 3.4 and the others are 3.3 it basically does nothing. It only works when the voltage difference is big and you only get that when 1 of the cells is full.

Just leave it plugged in and see how you like it vs plug in and off (pain in the ?) I'm sure you could get may be a little better balancing flipping it on/off but for me I would just fully charge my pack once a month and it would balance all the cells it usually took 2 hours or so to balance even shaddy grade B/C xuba cells.

not used to you giving bad advise on cells alkaline..
do have to add, if OP has one that stops at 3.9 , it wouldnt matter as you said, but i think they only made that for a specific aussie reseller.
the other option would be a neey , but that would mean a reorder

 

[Alkaline]

Go to alibaba and has contact the hankzor store they have a version that stops at 2.9v its the same price they also have a version that stops at 1.8v available to anyone.

 

[Alkaline]

To clarify, that Active balancer will not stop if ANY SINGLE cell falls below 2.9v, only when the average voltage in the capacitors falls to this level. So if you have a situation where 1 cell is say 2.5 and the other 3.3 it will still keep working because the average voltage would be like (3.3 + 3.3 + 3.3 + 2.5 )/ 4= 3.075v

 

[timselectric]

They need to offer one that stops at 3.4v
Who drains their cells to 2.9?
It's basically never off.

 

[houseofancients]

They need to offer one that stops at 3.4v
Who drains their cells to 2.9?
It's basically never off.

exactly..
one would want one to start at 3.45, and stop latest at 3.37.
ideally on would want the bms to control that like the jk does, or that custom one from australian
with the neey one can set that up as it is "smart"

 

[Alkaline]

They need to offer one that stops at 3.4v
Who drains their cells to 2.9?
It's basically never off.

3.4? You would never balance anything my guy... most of my cells chill out at like 3.35v just idling, Like as soon as I take them off the charger with in like 10-20 mins they are in 3.35 range and stay there.

I think 3.1 - 3.65 is fine the only mode I would like is for the AB to be off when battery is discharging no other mode, during discharging is where you can have voltage difference as high as 100-200 milivolt and this is where the AB makes the situation worse because it has no idea the batt is under a load.

 

[time2roll]

Keep in mind when at mid charge the cells will be so close there will be virtually nothing moving through the balancer.

 

[timselectric]

3.4? You would never balance anything my guy... most of my cells chill out at like 3.35v just idling, Like as soon as I take them off the charger with in like 10-20 mins they are in 3.35 range and stay there.

I think 3.1 - 3.65 is fine the only mode I would like is for the AB to be off when battery is discharging no other mode, during discharging is where you can have voltage difference as high as 100-200 milivolt and this is where the AB makes the situation worse because it has no idea the batt is under a load.

You're not top balancing below 3.4v. You're actually un-balancing.
I do agree that you should only be balancing while charging.

 

[12VoltInstalls]

just can't get over getting fooled with that whole grade A from what I thought was a reputable shop and paying a premium for this (and asking a premium from my customer). Just doesn't sit right.

That may be merely your mindset. Other experienced folks say not to worry, and ‘nominal’ is a good word. The customer should never run the extremes you did and I personally have the opinion you are delivering 100% of what you promised.

Don’t let your OCD bring you to the point of discounting your good work.

 

[T3TRIS]

Thanks again for all the inputs and the OCD reality check
Here's where my OCD seems to pay though... I swapped the 302Ah CATL cells for the 280Ah EVE cells that I had laying around. Did a top balance on those followed by a quick capacity test (around 274Ah). The cells' voltages were never more that 5mV apart during the capacity test (except at the extreme of course) and during the following recharge.
I've now set my power supply to 14.48V at the end of the leads and cranked it up to 50A. Those 280Ah cells are doing just fine and now have just been "sipping" current and balancing themselves at the top end. It's been like that for a good 20 minutes now and no over-voltage was triggered. All the cells are above 3.600V and the 5A active balancer is disconnected... And that's also despite cell #4 being behind by almost 70mV at some point...

I'm going to deliver this battery with these 280Ah cells instead of the 302Ah. The 302Ah didn't test any better than these anyway and these seem to work MUCH better. I'm happy with this functioning like this instead of having the BMS limit the upper threshold of charging.

So... yeah. Not too sure what to make of all this except that my 302Ah cells seem to definitely NOT be "grade A" (I know it's kind of a made up term). I'm definitely OCD, yes... but this different result is tough to argue.

By the time I finished writing this, the batteries were still taking a charge and balancing using ONLY the Overkill Solar tiny bleed resistors:
Cell 1: 3.635V
Cell 2: 3.636V
Cell 3: 3.606V
Cell 4: 3.617V
Apparently these tiny bleed resistors are enough to balance 280Ah when they are matched and top balanced properly.

 

[TomC4306]

By this point there were all within 40mV, above 3.61V

This is a nicely balanced battery. There is no reason to regularly charge so high.

 

[sunshine_eggo]

This is a nicely balanced battery. There is no reason to regularly charge so high.

+1

14.2-14.4V @ 30 minutes absorption is typically plenty.

To minimize customer issues, 14.2V for 1 hour should be enough to maintain a decent balance.

 

[T3TRIS]

I don’t disagree with any of your inputs and I truly wish I could customized the Redarc Manager30’s charging profile to lower its voltage to more manageable values, but there it is…
14.4V is what I have to work with (there’s no changing that charging system, though I guess I can contact Redarc about it).

I guess you need some top notch batteries for the Redarc stuff!

The other element of course is selling grade B cells under grade A advertising from once reputable vendors.

 

[sunshine_eggo]

I don’t disagree with any of your inputs and I truly wish I could customized the Redarc Manager30’s charging profile to lower its voltage to more manageable values, but there it is…
14.4V is what I have to work with (there’s no changing that charging system, though I guess I can contact Redarc about it).

I guess you need some top notch batteries for the Redarc stuff!

The other element of course is selling grade B cells under grade A advertising from once reputable vendors.

At least it's not 14.6V.

 

[T3TRIS]

Right? Their charging voltages are 14.4V for GEL/AGM (13.5 float) and 14.5 (13.6 float) for Lithium. It's close to 14.6V though!

 

[TomC4306]

Right? Their charging voltages are 14.4V for GEL/AGM (13.5 float) and 14.5 (13.6 float) for Lithium. It's close to 14.6V though!

Given the choice I would use the AGM settings.

 

[sunshine_eggo]

Given the choice I would use the AGM settings.

+100

13.6V can result in low current overcharge. 13.5V avoids this.

 

[T3TRIS]

+100

13.6V can result in low current overcharge. 13.5V avoids this.

Huh?
In AGM setting, the charger will do boost charge and absorption at 14.4V, then float at 13.5V.
In lithium, it's the same but at 14.5V, then float at 13.6V.

Avoid 13.5V?

 

[sunshine_eggo]

Huh?
In AGM setting, the charger will do boost charge and absorption at 14.4V, then float at 13.5V.
In lithium, it's the same but at 14.5V, then float at 13.6V.

Avoid 13.5V?

No.

13.5 is good.

Go for GEL/AGM

14.4V absorption and 13.5V float - much more likely to have a happy customer.

 

[T3TRIS]

Well, never mind… I connected the battery with those beautifully balanced 280Ah cells and cell #4 triggered the over voltage protection (though they were all much closer to one another than the 302Ah).

So... my 60A power supply can spit out 14.4V (at the end of the leads) at 50A and the amperage reduces as the battery ends up sipping the power pretty evenly.
However, the 30A Redarc, which spits out 14.4V seems to just shove 30A until a cell triggers the over voltage protection.
This is all on the same battery going through the same BMS.

So what's going on here? I guess I'm due on a call to Redarc.

Back to taming my OCD tendencies… it’s CDO by the way because of alphabetical order! ?