Long term parking and battery discharge

[Tazzieman]

Speaking of age - batteries used to last for a decade. Now, three years is a decent clip. I had to decommission a beautiful Odissey after only 5 years - it will not charge beyond 12.2 V.

That's because they weren't working as hard, and certainly not 24/7 (except for the clock if you had one).
Using a smart charger that conditions the battery greatly extends battery life..
The other thing is to buy a quality battery. Many different labels , but they often are the same low price battery under the skin.

 

[carpetman]

Here you go. Pic from the trend tab.
And it's entirely possible I did the math wrong, I did it a bit quickly in the morning. I'll rerun the math again.
You can see the parked period very well in the graph. Seems to show that the car enters deep sleep fairly quickly.

View attachment 7894607

Hi Parb, I have used the following settings. I have set the current threshold to 0.00A. I can now see ~0.02A as the current after the vehicle has been shutdown. Can you share your voltage trend over the 3 weeks?
The 13.2V Charged voltage is from the Victron smartshunt manual for lead-acid.

Regards,
Carpetman

 

[carpetman]

View attachment 7894615
Hi Parb, I have used the following settings. I have set the current threshold to 0.00A. I can now see ~0.02A as the current after the vehicle has been shutdown. Can you share your voltage trend over the 3 weeks?
The 13.2V Charged voltage is from the Victron smartshunt manual for lead-acid.

Regards,
Carpetman

Actually, the 0.02A I see is a positive current (i.e. charging) so likely a measurement offset.

 

[Tazzieman]

@carpetman The Grenadier battery is AGM type. Does it matter the Peukert exponent is higher than the normal range for AGMs?
These new battery types do my head in.

 

[carpetman]

@carpetman The Grenadier battery is AGM type. Does it matter the Peukert exponent is higher than the normal range for AGMs?
These new battery types do my head in.

I believe the battery is an Enhanced Flooded Battery (EFB) and not a AGM.

 

[TheDocAUS]

I believe the battery is an Enhanced Flooded Battery (EFB) and not a AGM.

Correct it is EFB.

 

[Tazzieman]

I believe the battery is an Enhanced Flooded Battery (EFB) and not a AGM.

I haven't checked mine but early on people were saying it was a Moll 81105. Is that correct?

 

[parb]

I set my peukert coefficient to 1.25.

 

[parb]

Here is my trend over the parked 3 weeks with voltage and current as requested.

And these are my settings.

 

[carpetman]

Latest settings for smartshunt for starter battery.
1. The charged voltage, is the voltage of the charger (i.e. the car) is at when the battery is full. This should be ~14.2V
2. The tail current should be set to ~1.3% (equivalent to 1.365A).
3. The duration of 3mins is fine - Basically the voltage needs to be at least 14.2V with a current of less than 1.365A for at least 3 mins for the smartshunt to determine that its 100% charged.

I have not figured out the correct value for the Peukert exponent or charge efficiency factor yet.

I fully charged my starter battery using solar yesterday - The last 20% of charging the battery takes ~7-8hrs. The SoC on the dashboard was still showing 75% charged. However, if you see the voltage at ~14.2V and the current at 1A the battery is fully charged.

I disconnect the load side of the smartshunt (as well as the BMS negative terminal) and calibrated the zero current state (victron app). When I reconnected the battery, the dashboard SoC read 97%. The load current now shows a draw of ~20mA after 15mins from power down. This seems to be the static current that my car is drawing, however, there is probably still some error in measurement here.

I drove for 45mins to work and at the end both the dashboard and SoC are now at 100%. I made two trips during the day before driving home and the battery was drained to 98% (start-stop was on). It took a drive home of over an hour to bring the SoC back to 100%. So if you end up in the 70-80% charged doldrums, you need to be driving for 7-8 hours to get the battery fully charged.

Here are a couple of observations.
1. Shutdown consumes about ~0.5Ah
2. Opening a door consumes about the same
3. it takes 15 minutes to go to a low current state - 20mA in my case.
4. Having the overhead power switch on consumes ~0.33Ah (my guess this is the power for the USB charger etc). I keep this on when camping!

So basically when camping if you are opening an closing the doors 20 times a day and keep the PWR switch on, you should expect the the battery to get drained in 2-3 days (which has happened to me).

I will let you know how well the two SoC reading stay in Sync.

Regards,
Carpetman

 

[parb]

Nicely written up!