LifePo4-Request for advice about cell balancing?

[Dellmassive]

I've noticed that "MOST" DC-DC chargers will switch ON when the starter battery voltage creeps up from say EHU charger, back charging from solar, reverse trickle charger etc etc


regardless of thge IGN switch feed.

BCDC Classic Under Bonnet 40A DC Battery Charger

The REDARC BCDC1240D is a 12V, 40A In-vehicle DC to DC Battery Charger designed to keep your auxiliary battery charged when driving or with portable solar panels when parked.

www.redarc.com.au

View attachment 183619


example:



(IGN not connected - when engine not running) the BCDC 1240 - will switch ON when it sees the starter battery voltage 12.9V

the back OFF again when the starter drops to 12.7v

(*1Tested every 100 seconds)

(this will apply as the BLUE wire id effectively floating as no High 12v signal applied)

View attachment 183620




then with IGN feed connected to blue wire (when engine running):


the units ON above, 12.0v and off bellow 11.0v

View attachment 183621


++++++++++++++++++



its easy enough to test . . .


just reconnect you back trickle charger,

or connect a EHU charger to the starter. . .



then watch the Redarc LEDS

you will find with the engine OFF the Redarc will switch ON when the starter battery feed hits 12.9V





+++++++++++++++++


View attachment 183622View attachment 183623



if you get a chance to test it let us know. . . .




+++++++++

• DC-DC Charger - AUTO VSR - feature testing

[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

@Farnorthsurfer did you set the Dc-dc to lithium mode for the TN100 battery? Also have you got any more BM2 views showing more days? Yes the unit is set to Lithium profile. Easy enough to do when it was powered up. Yesterday was a flat line all day as it just sat on the drive. Back to work...

www.t6forum.com

++++++++++++++

@Loz

i just realised I've already tested it,

and the REDARC does have the AUTO VSR feature. . .




I've detailed them on the spreadsheet on page 1:

DC-DC Charger (for Leisure battery) -- How I Done It --

[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

DC-DC Charger (for Leisure battery) -- How I Done It -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...

www.t6forum.com

.

 

[Raul a/3]

@Dellmassive said:


@Raul a/3 said:


I have followed @Raul a/3's advice and can instantly see that this is going to be a slow burn! Even with the absorption set at 13.65V, cells 1,2 and 4 run away leaving cell 3 at 3.344V. It seems it would take forever before I'd see an improvement, given that the cells are only loaded with 50ma during 2 hours of balancing (during the absorption stage).

So I took a look at the BMS settings and have had a cautious fiddle. I temporarily changed the "balance only during charging" to be off.
I have also reduced the balance start voltage to be 3.375V. (Float 13.5V /4):
View attachment 183617

The effect seems to be that the cell balancing now takes place during the float stage when there is no current flow in or out of the battery.
View attachment 183618
I've not left the battery like this yet, but was just seeing what would happen with these settings.

If this is a bad idea can somebody please tell me why before I reinstate these settings and leave my van on charge for weeks in the hope that I will slowly remedy the small imbalance in my cells?

Hang in there, it’s 53mv delta, and 50mv balancer, small current to avoid the high cells run away and keep these settings for now. Se my message as well.

 

[Loz]

@Loz

i just realised I've already tested it,

and the REDARC does have the AUTO VSR feature. . .


View attachment 183624

I've detailed them on the spreadsheet on page 1:

That'll be it then,... I need to limit the "back feed" charge to 12.8v in that case, I need a more intelligent solution.

 

[Dellmassive]

That'll be it then,... I need to limit the "back feed" charge to 12.8v in that case, I need a more intelligent solution.

yes . .

i fitted the Ablemail AMT2-12 as its programmable, to get around that very "cycling on/off" problem

so that i can back charge the starter, from the large ROAMER 230Ah . . BUT,

keep the top starter voltage just below the DC-DC Charger trigger ON voltage. ( currently a Renogy DC50s )

it took a few weeks of tweaking to get the voltage levels set for my system. . .


but it fine now and works a treat:



I've detailed it here: [Guide] Battery Maintainer (for Starter battery) -- How I Done It --


Gen1




Gen2 has spade terminal instead of studs - to better reflect the 4A charger pulses,

[Guide] Battery Maintainer (for Starter battery) -- How I Done It --

Presumably a constant low charge will keep it topped up. The proof is when you come to start it :think smile bounce: Happy to report it started first time (despite a very cold morning) :thumbsup:

www.t6forum.com

this is my Gen2 Amt2-12 - i disabled it for the Portable power pack testing . .

 

[Loz]

View attachment 183627

[Guide] Battery Maintainer (for Starter battery) -- How I Done It --

Presumably a constant low charge will keep it topped up. The proof is when you come to start it :think smile bounce: Happy to report it started first time (despite a very cold morning) :thumbsup:

www.t6forum.com

this is my Gen2 Amt2-12 - i disabled it for the Portable power pack testing . .

I just ordered a gen2 and the bluetooth module for it.

 

[Dellmassive]

I just ordered a gen2 and the bluetooth module for it.

There great little boxes, and are now integral (if ordered) in the new range on ablemail dc-dc chargers.

I run mine seperate.... I had issues at first, and it was down to using thin wire on the spade terminal crimps.... Volt drop during the extended lifepo4 charge pulse I think. (Red crimps and thin wire)

I replaced the feed wires (pos,pos,neg) with decent gauge wire and blue crimps and that solved the problem.

I have the BT and pc USB module too..... But once the settings are programmed, it's fit an forget.

 

[Samro]

Hang in there, it’s 53mv delta, and 50mv balancer, small current to avoid the high cells run away and keep these settings for now. Se my message as well.

You are a star for helping me on this @Raul a/3!

Since turning off "Bal. only when charging", my rogue cell has become much more compliant.
So much so, that I have set my "single cell over-voltage trigger" back to the default 3.65V. (Roamer got me to change this to 3.75V in the summer, when I was having issues.)
I have left the "single cell over-voltage reset value" at 3.55V because I don't recall what this would have defaulted to.

I'm guessing that leaving the absorption voltage at 13.68V is the way forward, or should I increase this in a week or so?

 

[Raul a/3]

Cell over voltage disconnect at 3.65v, IF you have a second setting setting for cell over voltage disconnect recovery, that can be set lower 3.60v. This is to allow a buffer up, and time for the low cell to catch up. When pretty balanced the 3.55v is plenty.

Raise Absorb at 13.8v /3.45vpc when delta V has reduce quite a bit, but you have to move balance trigger voltage as well to 3.45v.

 

[Rids]

So here's an update on the random switch on of my Orion charger....

With the ignition off, but with the trickle charger from my Multiplus charging the starter battery, then the Van periodically activates what was the second battery charging relay... now the input to my Orion.

when the 200Ah leisure battery was low it would kick in at 30A for a while then cut off due to inout voltage cut out, but the gradual voltage rise from the 1A trickle was still detected by the van and it would take another bite at 30A, till eventually the starter was low enough to not do the starting thing!

I have made things better, ie not draining the starter battery, by setting the input voltage lock out values both higher and wider apart; I think last setting was 12.4V off & 13V back on.

Does this sound reasonable?

However I am wondering about looking for a different (proper) engine is running signal; suggestions where to find most welcome.

Comments appreciated...

 

[Dellmassive]

That sounds like normal operation for the Orion.(and most DC DC chargers)

Seeing the starter battery voltage rising from the trickle charge. To the point it will automatically switch on.

Are you using the BCM engine run signal on the remote H Pin? or are you just using the engine run detection algorithm?

 

[Rids]

So here's an update on the random switch on of my Orion charger....

With the ignition off, but with the trickle charger from my Multiplus charging the starter battery, then the Van periodically activates what was the second battery charging relay... now the input to my Orion.

when the 200Ah leisure battery was low it would kick in at 30A for a while then cut off due to inout voltage cut out, but the gradual voltage rise from the 1A trickle was still detected by the van and it would take another bite at 30A, till eventually the starter was low enough to not do the starting thing!

I have made things better, ie not draining the starter battery, by setting the input voltage lock out values both higher and wider apart; I think last setting was 12.4V off & 13V back on.

Does this sound reasonable?

However I am wondering about looking for a different (proper) engine is running signal; suggestions where to find most welcome.

Comments appreciated...

Hi Lee
I'm using the signal that was used to activate the factory second battery charging relay. Thing is its the van that is activating this whilst switched off... not the Orion itself.

Any idea where can I find a real engine run signal?

 

[Dellmassive]

that should be the engine run signal. . .

not sure if anything has changed on the T6.1

. . .

see here for Engine run signal:

[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

DC-DC Charger (for Leisure battery) -- How I Done It -- ************************************************** Dellmassive`s -- "how I Done It" -- Thread ************************************************** Kit List And Stuff -- How I Done It & What I Use --...

www.t6forum.com

and here to see when the output was active:

Stop/start...regen...smart Alternator... Dc-dc Charger For Leisure Battery Or Not?

So With all the talk regarding the Bluemotion thing and regen breaking and leisure batteries our T6 has finally arrived. The first thing we done was to checkout the factory fitted setup,...... Stop/start=check, Regen Braking=check, AGM starter battery=check leisure battery under passenger...

www.t6forum.com

.

Stop/start...regen...smart Alternator... Dc-dc Charger For Leisure Battery Or Not?

So With all the talk regarding the Bluemotion thing and regen breaking and leisure batteries our T6 has finally arrived. The first thing we done was to checkout the factory fitted setup,...... Stop/start=check, Regen Braking=check, AGM starter battery=check leisure battery under passenger...

www.t6forum.com

the relay was switched on when RPM was dectected, and switch OFF when engine shut down on stop start events.





..................


you could try the same test on that wire, but mine a T6, and I've not tested if the T6.1 factory SCR runs the same.

 

[Raul a/3]

It sounds to me that your B2B is set to kick in by voltage sensing. It must be ignition triggered. You don’t want that for sure, as you discovered as it gets a bit of charge from multiplus, the voltage threshold activated the B2B. This Is a loop charging: from leisure to starter and from starter to leisure.
Make the settings low enough to eliminate this behaviour.
My smart alternator won’t even kick in at12.2v so I use a dc-dc converter instead, so it charges as soon as the engine runs. I do have a switch mid way to disable it in summer as solar covers all and more.

 

[Ajpepe72]

Not a roamer but I have built a diy 280ah lifepo4. Indeed a lot of the YouTube videos I watched also recommended turning off the ‘balance while charging mode’
As I used individual cells I had the advantage of being able to to balance the cells in parralel before building in series and this greatly helped the cell variation.

As a result the biggest cell deviation I have seen is 0.016v.
Maybe the cells were not top balanced before Roamer built your battery or may have gone out of balance due to extended storage time, but good to see the balancer is doing it’s job and it has improved.

 

[Samro]

Here is an update to an old thread I started over a year ago.

I have been patient and hung on for months waiting for my cells to (eventually) balance with limited success. I always ended up with cell 3 being overtaken by the remaining three cells and ultimately the cell voltages never satisfactorily aligned at the top of bottom of the charge curve. The Delta figure always exceeded what I considered normal.

I took some advice from a colleague at work, who suggested that it would be worth setting the balance voltage at a low voltage (3V-3.3V) and then leaving the battery to balance at the bottom end of the charge curve for a number of weeks. This was suggested as the cells obviously have less stored energy at the bottom of the curve as can be seen in the graph below:


It was pointed out to me that the cell voltages should align (at the bottom of the charge curve) and I should then restore the default BMS settings to balance at 3400mV and charge the battery to ensure that the cells are balanced at the top of the charge curve.

Here is what I did:
I discharged the battery (by simply leaving my fridge on and solar off), being careful to ensure that no cell got lower than 3V and then changed the balancer configuration to start at 2900mV. With the battery discharged to this level I had a delta figure of over 0.4 Volts, which I hoped to degrease significantly.

I then changed the "Bal. Only when charging" to OFF and also turned off the Discharge Port. (I was careful to leave the Charging Port on to ensure that I could charge the battery!)

I left the cells to balance like this, checking progress daily. The cell voltages aligned in two weeks.

During this process I gradually reduced the "Delta to balance" when I noted that that BMS was eventually aligning the voltages of the cells. I eventually ended up with all cells 100% balanced when the cell voltages were a shade under 3V.

I then turned the Charging Port back on and then adjusted my Balancer Settings back to the following:
Start Voltage 3400mV
Delta to balance 15mV
Bal. Only when charging to ON.

The battery was then charged overnight with a bulk voltage of 14V.

The result has been that my cell voltages now seem properly aligned at all points on the charge curve.

I am unsure if undertaking what I did is considered an ok thing to do.

I know that there are some clever bods on this forum, who will almost certainly advise me that what I have done is not sensible, but this worked for me and I'm quite pleased as I was reaching a point where I was going to have to remove the battery and charge the cells individually, which is outside of my comfort zone and a whole heap of hassle.

 

[Raul a/3]

Here is an update to an old thread I started over a year ago.

I have been patient and hung on for months waiting for my cells to (eventually) balance with limited success. I always ended up with cell 3 being overtaken by the remaining three cells and ultimately the cell voltages never satisfactorily aligned at the top of bottom of the charge curve. The Delta figure always exceeded what I considered normal.

I took some advice from a colleague at work, who suggested that it would be worth setting the balance voltage at a low voltage (3V-3.3V) and then leaving the battery to balance at the bottom end of the charge curve for a number of weeks. This was suggested as the cells obviously have less stored energy at the bottom of the curve as can be seen in the graph below:
View attachment 227874

It was pointed out to me that the cell voltages should align (at the bottom of the charge curve) and I should then restore the default BMS settings to balance at 3400mV and charge the battery to ensure that the cells are balanced at the top of the charge curve.

Here is what I did:
I discharged the battery (by simply leaving my fridge on and solar off), being careful to ensure that no cell got lower than 3V and then changed the balancer configuration to start at 2900mV. With the battery discharged to this level I had a delta figure of over 0.4 Volts, which I hoped to degrease significantly.

I then changed the "Bal. Only when charging" to OFF and also turned off the Discharge Port. (I was careful to leave the Charging Port on to ensure that I could charge the battery!)

I left the cells to balance like this, checking progress daily. The cell voltages aligned in two weeks.

During this process I gradually reduced the "Delta to balance" when I noted that that BMS was eventually aligning the voltages of the cells. I eventually ended up with all cells 100% balanced when the cell voltages were a shade under 3V.

I then turned the Charging Port back on and then adjusted my Balancer Settings back to the following:
Start Voltage 3400mV
Delta to balance 15mV
Bal. Only when charging to ON.

The battery was then charged overnight with a bulk voltage of 14V.

The result has been that my cell voltages now seem properly aligned at all points on the charge curve.

I am unsure if undertaking what I did is considered an ok thing to do.

I know that there are some clever bods on this forum, who will almost certainly advise me that what I have done is not sensible, but this worked for me and I'm quite pleased as I was reaching a point where I was going to have to remove the battery and charge the cells individually, which is outside of my comfort zone and a whole heap of hassle.

I’m sorry to say this, you received bad advice, and you unbalanced your cells even further. There is no such thing equal voltage equal SOC. You want to start balancing above 3.45v only, this is the only meaningful voltage to indicate 95%SOC or above. Your equal voltages in the flat curve means nothing.
On the charging curve, when cells start to fill up, that’s when the imbalance shows, and that reflects with the voltage rise. Usually a battery with cells at 3.45-3.5v on the charge curve and a delta of 0-40mv it’s pretty balanced, and when you start discharging this will change. I have built few packs now with JK bums and active balance. Even a 2A active balancer will take few days to balance. If I catch them on absorb in time, I set float at 14v for few hrs and repeat next day if necessary.

 

[Samro]

I’m sorry to say this, you received bad advice, and you unbalanced your cells even further. There is no such thing equal voltage equal SOC. You want to start balancing above 3.45v only, this is the only meaningful voltage to indicate 95%SOC or above. Your equal voltages in the flat curve means nothing.
On the charging curve, when cells start to fill up, that’s when the imbalance shows, and that reflects with the voltage rise. Usually a battery with cells at 3.45-3.5v on the charge curve and a delta of 0-40mv it’s pretty balanced, and when you start discharging this will change. I have built few packs now with JK bums and active balance. Even a 2A active balancer will take few days to balance. If I catch them on absorb in time, I set float at 14v for few hrs and repeat next day if necessary.

I don't understand. The cells voltage are now much closer aligned and so don't understand how I have imbalanced my cells further that they were?
If you look at post #1 i had a Delta of 0.269V at 14.2V. Are you saying that if I charge of 14.2V I will now have a larger Delta figure?

 

[Raul a/3]

So what’s your delta at 14.2v absorb?
You said it was 100% balanced at a shade under 3v, that’s not balanced, it may be equal voltages but not equal SOC.
Balanced means equal SOC, and it will have equal voltages when full or close to full. Any other time doesn’t mater.
So I ask again to clear confusion if you DID balanced your pack, what’s the delta voltage at 14.2v absorb? That moment in time counts.

 

[Samro]

I'll place on charge and increase the absorb voltage to 14.2V tonight and take a screenshot of the delta at when at 14.2 Volts.
What I was was finding before my latest experiment was that the Delta was impossible to reduce with an absorb of 13.8V. I was finding that cell 3 would get to 3.45V and then with the minimum absorption time of 1 hour. This is the minimum absorption time that is permissible with VE Remote Configure:


I agree with what you are saying about the Delta in the flat curve meaning nothing, but the bottom end of the curve is not flat and I was seeing a high delta as a result of cell 3 as being low at both the bottom and the top of the curve.

 

[Raul a/3]

You don’t want to balance at the bottom curve, neither anywhere in the flat. The bottom it’s only valid for LVD. You want TOP balance as that’s where the bms balances and that’s where you cycle the most, the top.
The reason you haven’t finished balancing the cell 3, is you got stack at 13.8v. When delta narrows, you step up in small increments to force the delta as the cell fills up. After 3.5v if delta comes down, then you are done.