MidNite Guru Needed!, Kid Charging LifePO4 issue's

[chris]

I am having an issue with a Kid controller charging a DIY 280ah LIfePO4 battery.

What happens is....any time the charge controller reaches float, the following day it will start off the day in float without ever starting a new bulk/absorb cycle. (no matter the SOC of the battery.) The only way to get it to start a new charge cycle is to reboot with a power cycle.

I just had it replaced under warranty as I and MidNite assumed it was faulty.....how ever..the new Kid does the same thing.

Current settings are... Absorb 14.4 volts for 20min with a 5 end amp setting and float 13.4

This morning I woke up hearing the charge controllers relay clicking off and on.
I thought maybe that meant I would start on its own.....nope.
When it decided there was enough sun on the panels to stay on...it went straight to float.

I don't get it, there has to be some setting that needs tweaking.


Has ever seen this behaviour?

Any help would be greatly appreciated

[chris]

One more question....I just read on another thread here that the kid should be calibrated wile it is in absorb?
I calibrated mine wile the battery was resting... there is defiantly a discrepancy between the 2 points

[Wizbandit]

Did you switch the ENDAMPS to use the SHUNT?
FYI The KID's MAX output of 30 amps may not be enough to charge a battery that big...

[ClassicCrazy]

One more question....I just read on another thread here that the kid should be calibrated wile it is in absorb?
I calibrated mine wile the battery was resting... there is defiantly a discrepancy between the 2 points

The BMS is going to be doing its balancing according to the top charge voltage that it is set for.
So that is why I think the place you want to calibrate to is the at the top of charge.
As Whizbandit said - maybe you have something wrong with the whizbang or end amps setup.
Why don't you try turning off the end amps and just use absorb time and see what happens.
Since you hear the clicking , makes me wonder if your battery is shooting up to your absorb setpoint and then to your ending amps of 5 which will put it into float. This can happen very quickly on a lithium battery.
How many amps are you drawing out of your battery at night ?
You say DIY battery - what kind of bms did you use on it ? Does your bms offer you any monitoring via software ?
Larry

[chris]

Did you switch the ENDAMPS to use the SHUNT?
FYI The KID's MAX output of 30 amps may not be enough to charge a battery that big...

Yup,  I have switched the endamps to use the Whizbang.

I actually have two Kids ..and have plans to at some point add the second one and link them to make a 60 amp controller. 

[chris]

One more question....I just read on another thread here that the kid should be calibrated wile it is in absorb?
I calibrated mine wile the battery was resting... there is defiantly a discrepancy between the 2 points

The BMS is going to be doing its balancing according to the top charge voltage that it is set for.
So that is why I think the place you want to calibrate to is the at the top of charge.
As Whizbandit said - maybe you have something wrong with the whizbang or end amps setup.
Why don't you try turning off the end amps and just use absorb time and see what happens.
Since you hear the clicking , makes me wonder if your battery is shooting up to your absorb setpoint and then to your ending amps of 5 which will put it into float. This can happen very quickly on a lithium battery.
How many amps are you drawing out of your battery at night ?
You say DIY battery - what kind of bms did you use on it ? Does your bms offer you any monitoring via software ?
Larry

Thanx for the reply Larry

  The top voltage makes sense to me....I'll calibrate tomorrow when the sun is up....thanx


I have been experimenting with end amps  (off and on) and absorb length of time over the last 2 weeks (the system is mounted in a motor home and we're currently wrapping up an Oregon trip)
I haven't seen any difference.
Once in a wile it'll start a new charge cycle on it's own but most days need a re-boot to start.

On average we are using about 80 amp hours a night

I used a 200 amp JBD BMS and have been using the Xiaoxiang app in order to follow SOC....for the most part I'm impressed with how well the cells have stayed balanced......usually within .003 of a volt.

[ClassicCrazy]

You should be able to find the ending amps by watching your bms app . See what the amps are ( whizbang amps going into battery ) when the bms gets to its finishing voltage and starts to balance the cells.
Steve S had an end amps formula in another lithium discussion on group here - I forget right now what it is but you could see how close what you observe and what the bms does in regards to ending amps.
Larry

[chris]

You should be able to find the ending amps by watching your bms app . See what the amps are ( whizbang amps going into battery ) when the bms gets to its finishing voltage and starts to balance the cells.
Steve S had an end amps formula in another lithium discussion on group here - I forget right now what it is but you could see how close what you observe and what the bms does in regards to ending amps.
Larry

  Sounds good, I'll give that a try.
Any suggestions on how to get the Kid to start a new day on it own?  I'm just about (again) reboot it

[ClassicCrazy]

Have you tried turning the Float setpoint up or down ?
Larry

[ClassicCrazy]

Have you read this ?
They mention rebulk - wonder if you could play with that and see if it can be tweaked to make your system work right ?
http://www.midniteftp.com/support/kb/faq.php?id=87
Larry

[chris]

Have you tried turning the Float setpoint up or down ?
Larry

  Yes, one of the first things the guys from MidNite had me try was that...tired setting it really low and high..unfortunately no difference

Have you read this ?
They mention rebulk - wonder if you could play with that and see if it can be tweaked to make your system work right ?
http://www.midniteftp.com/support/kb/faq.php?id=87
Larry

  Thanx I'll go have a look at that now.....
Side note, I calibrated  the Kid wile in bulk mode...could be coincidence but it did start a charge cycle yesterday morning 
However, at rest its reading .3 of a volt lower then what the battery really is (I don't think that is a big deal?)

The 10awg max size wire is the only thing about the kid I dislike....I've got like 4-5ft max between the battery and controller yet I get voltage drop between the 2 at max output.

[ClassicCrazy]

You could always take the 10 gauge short distance to a breaker or  terminal block  that will accept larger gauge wire .
It shouldn't matter if the voltage is different at rest since it isn't controlling for anything then.
Larry

[Vic]

Hey, chris,

Any news to report?

Inquiring "minds" would like to know, no?

TIA,  Vic

[FNG]

So check something for me, Well after sundown when the kid should be resting please look and see if it still says float not resting. A phenomena on the kid I have seen is if the float voltage is lower than its resting voltage or another source holds the battery voltage up the kid will not go to resting thus it never sees a new day.

if this is the case take note of the battery voltage at this time (I would say like 8pm just for a good consistent time) and try setting float just above that.

Also can you share the Absorb and float settings and brand of battery.

I will talk to the Customer Service tech as well as they should have had you check this first to save the hassle of swapping the kid

Ryan

[chris]

So check something for me, Well after sundown when the kid should be resting please look and see if it still says float not resting. A phenomena on the kid I have seen is if the float voltage is lower than its resting voltage or another source holds the battery voltage up the kid will not go to resting thus it never sees a new day.

if this is the case take note of the battery voltage at this time (I would say like 8pm just for a good consistent time) and try setting float just above that.

Also can you share the Absorb and float settings and brand of battery.

I will talk to the Customer Service tech as well as they should have had you check this first to save the hassle of swapping the kid

Ryan

  Hi Ryan,
   I had checked the voltage a few times at night, the batteries usually sat around 13.2 iish with the display reading "resting"
Settings are 13.4 float 14.2 absorb for 20 min and 5 amp end amps (set to the whiz bang Jr)  my Battery, 4x280 amp/hr cells with a 200 amp JBD BMS with blue tooth.

   Not only would the Kids not start a new day.....but many days they just switched to float without ever hitting the absorb voltage.

  I had spoken to you a few times via email, And did try moving all of the setting up and down several points as per your suggestion... But it didn't help

Sadly,  I was so frustrated after weeks on the road having to re-boot the unit every morning and sometimes again mid day that I stopped and bought a Victron 100/50.  I hooked this charge controller up with all the same wiring and settings and have never had an issue since.

  It's really to bad as I do prefer the MidNite product.  (and well now I have a spare charge controller sitting in the garage)