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Can I just simply plug my volt meter on the leads to see what voltage it's supplying? Should be that simple right?
 
So the CTEK MXS switches voltage once it knows it's charging AGM? Does one need to "tell" the charger it's charging an AGM battery. I'm assuming the 14.7 which is ideal for the AGM, may not be so for the regular?

The Noco says it's automatic but it's not really, I always make sure it is on the correct battery type.
I don't think any charger will detect an AGM battery. It must be told what it is connected to. And yes, 14.7 volts is too high for a flooded battery.

On the othervhand, I'm not sure if 14.4v is a problem for AGM batteries. I doubt it. I think that AGM can be charged faster at 14.7v. So it is an extra capability, not so much a requirement.
 
A 25 to 50% SoC would worry me greatly under the conditions you describe. How old is the battery ? Have you checked its SoH while disconnected from the car ? Under what conditions are you checking SoC ? Using a voltmeter at the battery while connected to the car ? Using the MFD - I hope not.
The car is about 1y old and the battery shows 100% SoH, when measured directly at its terminals. SoC is measured at the jump start terminals next morning with a DVM, after opening the hood, wait for all car systems are down again (lights & fuel pump) and judged by the temperature compensated web-calculator as suggested by Grim somewhere above. This corresponds also to the battery tester's reading. Next week, when back at home I will redo the morning DVM measurement by using a CAN-bus adapter cable for charging, not opening any door or hood before...but I guess results are the same...
 
So the CTEK MXS switches voltage once it knows it's charging AGM? Does one need to "tell" the charger it's charging an AGM battery. I'm assuming the 14.7 which is ideal for the AGM, may not be so for the regular?

The Noco says it's automatic but it's not really, I always make sure it is on the correct battery type.
No,
When using a CTEK, you must select the correct battery type… For AGM batteries, select the 'cold weather' option, indicated by a snowflake icon.


IDK how the NOCO works, look in your NOCO manual.

BTW, what about your NOCO makes you want to switch to a CTEK?
 
So the CTEK MXS switches voltage once it knows it's charging AGM? Does one need to "tell" the charger it's charging an AGM battery. I'm assuming the 14.7 which is ideal for the AGM, may not be so for the regular?

The Noco says it's automatic but it's not really, I always make sure it is on the correct battery type.
This manual for the CTEL MXS 5.0 details the current at each step of the charging process depending on the mode selected.
50013552F MXS 5.0 NA, Manual, Print file 001.indd (shopify.com)
This a link for all the CTEK manuals.
Manuals – smartercharger.com
https://www.bing.com/ck/a?!&&p=8ba1...HR0cHM6Ly93d3cubGVhcm5yZWxpZ2lvbnMuY29tL2Nyb25pbmctY2VyZW1vbnktMjU2Mjg3MQ&ntb=1
 
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Discussion starter · #866 ·
I took the car on a 2hr drive. I’m guessing the battery is near full, so I just plug in the 1A Noco charger, the following morning it’s already at full charge.
Seems I'm the only one using a Noco Genius10 and now I'm thinking it might not be good. :oops:
Which one do you own, 1 or 10 amps?

The output is NOT a flat 14.7V. There is a bulk charging stage, absorbtion stage, then the maintenance stage.

At this point you need to do some basic research
 
Which one do you own, 1 or 10 amps?

The output is NOT a flat 14.7V. There is a bulk charging stage, absorbtion stage, then the maintenance stage.

At this point you need to do some basic research
I have both. Now the urge to get the 5A.

Noco said the AGM setting charges at 14.8v.
 
The car is about 1y old and the battery shows 100% SoH, when measured directly at its terminals. SoC is measured at the jump start terminals next morning with a DVM, after opening the hood, wait for all car systems are down again (lights & fuel pump) and judged by the temperature compensated web-calculator as suggested by Grim somewhere above. This corresponds also to the battery tester's reading. Next week, when back at home I will redo the morning DVM measurement by using a CAN-bus adapter cable for charging, not opening any door or hood before...but I guess results are the same...
If the battery is 1 year old, something is wrong, possibly one or more of these, in no particular order:
  • the battery is defective
  • the charging system is not working properly
  • measuring the voltage at the jump posts is producing an incorrect value due to loads on the car. This could be true even though you may think that nothing is drawing current.
  • the voltmeter is defective (try a different one)
  • good contact is not being made between the voltmeter and the battery (test leads, corrosion on the jump post, loose battery post connection, other wiring defect in the car)

Testing the battery while it is disconnected from the car can eliminate several variables and at this point, were I you, I would provide an alternate power supply (not a battery maintainer) and test the battery alone under the same conditions you have described.

The SoC results link you provided for calculating SoC looks weird to me: 12.7v = 88.6% SoC on AGM while, 12.8v = 100% for AGM.
 
If the battery is 1 year old, something is wrong, possibly one or more of these, in no particular order:
  • the battery is defective
  • the charging system is not working properly
  • measuring the voltage at the jump posts is producing an incorrect value due to loads on the car. This could be true even though you may think that nothing is drawing current.
  • the voltmeter is defective (try a different one)
  • good contact is not being made between the voltmeter and the battery (test leads, corrosion on the jump post, loose battery post connection, other wiring defect in the car)

Testing the battery while it is disconnected from the car can eliminate several variables and at this point, were I you, I would provide an alternate power supply (not a battery maintainer) and test the battery alone under the same conditions you have described.

The SoC results link you provided for calculating SoC looks weird to me: 12.7v = 88.6% SoC on AGM while, 12.8v = 100% for AGM.
Thanks for commenting, what voltage do you measure next morning?
 
Thanks for commenting, what voltage do you measure next morning?
I have not taken battery voltage measurements with the battery disconnected. However, if you use the MFD while understanding its limitations, this info can be very useful:

As super smart as the Macan is about "knowing" its battery's condition, it is "stingy" with this information and owners are never advised of a battery in decline until things get very far along. We who have read this thread know that the Auto Stop-Start will function less often and eventually not at all when the battery is in poor health, but not all of us use that function. We also know that loss of functionality, and especially transient loss of function of various systems can also be a sign. For me, it was the ACC (cruise control and distance emergency braking system) that sporadically reported that it was not functioning, along with the direction to see a dealer (of course $$$$ ! ;) ).

After observing the MFD's voltage display both before and after replacing the battery, I have another indicator to look for. Note: The following applies to a car started and then driven for more than 10 miles without being switched off.

Under normal circumstances, when the ignition is switched on and with the engine still off, the displayed system voltage (not battery voltage) will be something above 12 volts and usually never higher than 12.7v. What exactly you see will depend on the battery's state of charge, switched on devices and how long you keep the car in this state before starting as it will steadily drop over time.

Then, after starting the engine, voltage will at first drop from the large demand placed on it, and then, voltage from the alternator will be fed into the system. As the battery takes on a charge, system voltage will increase from 12 or more volts or so up through 14.6 or 14.7, possibly more in cold climates.

A battery in poor health will see this voltage stay in the 14.4 to 14.7 range (more in cold climates) steadily without changing much. Switching on high demand devices will cause this to drop but overall, the voltage will stay in the 14s. This is not a good sign because it means that the BMS is trying to charge a battery that is not fully accepting that charge. One weird exception is that sometimes, the charging voltage will show voltages in the 14s for longer than expected. Then shutting off the engine and restarting it causes it to get into the 13s fairly quickly after an initial drop in voltage. This happened to me just last night for at least the 2nd time in a year I have seen this.

A battery in good health will signal the BMS to drop the charging voltage back into the 13s, usually 13.2 to 13.6 volts. If you never see readings this low after driving for a good distance, your battery is in failing health.

Finally, there is the regenerative braking effect. On descents with the brakes on the BMS is made aware that you are braking and assumes that you will not mind the decelerating effect of additional load being put on the engine. The alternator will be signaled to generate higher voltage in the 14s. Very elegant. You will quite quickly see the voltage rise from the 13s into the 14s when this happens. As soon as you stop braking, voltage should drop back down to the 13s. With my old battery, my car would not do this in recent memory, but on my trip taken yesterday with my new battery, it routinely did it on mountain road descents.
 
I looked at different sources online and there is no precise consensus regarding the SoC of an AGM battery. e.g.
https://sunonbattery.com/agm-battery-voltage-capacity/ reports that 12.85v =100% and 12.25v = 50%
Battery State of Charge Chart - ElectricScooterParts.com reports that 13.00v =100% and 12.05v = 50%
Car Battery State of Charge Calculator reports that 12.787v =100% and 12.291v = 50%

If you use a different calculator you may get very different results because there is a fair amount of variability in these numbers. I think that each specific battery design may have slightly different values based on the exact materials used (e.g. the specific gravity of the acid used) and manufacturing techniques used. So these numbers can be considered directionally correct, but not absolutely correct. Given that very small voltage differences work out to large SoC differences that we see in the data, you may be way off in estimating your SoC.

It would appear that AGM batteries do put out a slightly higher voltage than flooded batteries do, but here again, the differences are quite small. I found this chart which at least acknowledges that there is no one precise voltage that corresponds to a specific % of SoC. So using voltage is an imprecise way to get to SoC and more so if the discharge behavior of a specific battery is not known. BU-903: How to Measure State-of-charge
View attachment 282992
 
Discussion starter · #872 ·
Given that very small voltage differences work out to large SoC differences that we see in the data, you may be way off in estimating your SoC.
Read

which basically says to ignore all they internet experts. Just use on of the cheap battery analyzer. It will tell you the SOC and SOH. Its close enuff.
 
Who has a relatively new Macan with a new battery? Just turn the key to accessory (turn on accessory but not crank the engine) to see if the battery voltage display shows around 12.1v.

My 5-year old battery shows 12.1v.
My 3.5 says the same 12.1v (fan off).

14.3v once started. Bar level shows 75%. One bar away from full.
 
Read

which basically says to ignore all they internet experts. Just use on of the cheap battery analyzer. It will tell you the SOC and SOH. Its close enuff.
My "cheap" battery tester (photo above) showed only 25% SoC (12V measured), that's were this discussion started. Similar results with an (exact) DVM. Besides, this marine battery article was quite helpful as it proved that the difference between battery voltage under significant load deviates only 0.2V from the "ideal" no load measurement. So I will go on and check the idle voltages in the morning after driving the car the day before (w/o charging over night and no opened door or hood before measuring) and come back...
 
You most certainly won't get 13V with the battery connected and in the car.
 
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