Calibrating my shunt. What is the correct voltage to set 100% Full?

bimmer

I have:
2 x 6V harris 224 AH batteries giving me 224AH.
A simple cheap AiLi shunt. Seems to be working well.
My dilemma is that I am not sure on what is considered to be a full charge on the Harris AGM batteries.
Youtube says AGM batteries 13.0V. When I charge them on shore power, they charge at about 13.6V with low 2 Amps or there about because they are close to fully charged and ready to float. Once they reach float and I disconnect them they settle in at about 13.22V with zero load. But getting to float at the low charge rate can take hours and hours. AND then more hours.

The Aili wants me to calibrate it, so it knows how to present the percentage of charge. I would like it to be as accurate as it can. It's a Personality quirk.
I put in that I have 224Ah. It subtracts and adds Ah and lets me know how much I've used or added by charging. 
Since the battery at rest is at 13.22V I've used that as a starting point. But is that actually the Voltage of the fully charged battery? Is it too high or too low?
 I mean I can put it wherever I want but it drives my OCD self nuts. 
It is currently charging at 2amps @ 13.64V and states it's at 216.8Ah and rising slowly, very slowly. It needs to get to 224Ah. Which is a product of where I set the fully charged battery Voltage, I guess by setting the percent value to 100%
So, in the end the question is. Is fully charged the float point, the rest point or the YouTube point, or any other point in between?  

pthomas745

There is a difference between "charged" voltage and "rested state of charge" voltage.  There are several different threads on this. The thread below has some info on what to look for.

https://tab-rv.vanillacommunity.com/discussion/16730/smart-shunt-settings-new-agm-battery

bimmer

@pthomas745 Thank you

qhumberd

I also have the AiLi shunt and found another wrinkle in setting 100% on the shunt. The converter charges as you describe and it takes a long time to reach the final voltage. Then I got a Renogy 100 watt suitcase solar panel with controller set to AGM and it used a different charging profile. I found it finished charging at 13.6 volts and seemed to charge to a higher voltage level than the converter in the trailer. 

At any rate I just let the solar controller tell me when the battery is full and then I set the shunt to 100% and 224 amp hours and that seems to work fine to track current to and from the battery. I don't have to reset each charge cycle but the voltage will slowly drop on mine to around 13 volts or a bit less with the battery disconnected. Shunt still shows 100% and 224 amp hours. So as my batteries get older I think the resting voltage is going down even when they are "full"

bimmer

@qhumberd Up until this morning I was using shore power to get the results I have. I have now connected my 300W solar panel and as you said the charging profile is different. I am now full charged, and the batteries at rest are at 13.22 V. (these batteries are 5 years old) I have been thinking about this for days now and have come up with an idea that the shunt manual actually hints at. It states to have the battery discharged. In the little manual sheet that comes with the AiLi Page 5 section 2. "Capacity Initialization". Discharge the battery totally (that would be 12.0 V I think with AGM in my case), then hold the left V button for 3 seconds to set capacity to zero.
Then charge the battery to full capacity. One would then know the how many Ah it pumped into it giving us a true state of Ah available. No?  Isn't this fun!

qhumberd

@bimmer I agree but I didn’t feel comfortable discharging my older batteries. I felt when the solar controller deemed them full I could set 100% and call it good.

bimmer

@qhumberd I agree... I'm not going to discharge them. I set it at 100% at a point I'm comfortable at which is FLOAT and am calling it good as you are. 
Now on to the next thing. No idea what it will be yet but I'm sure I can dream something up.