What are "normal" battery recharge needs for modern cars?

I just bought a brand new car (Honda Accord Touring 2017). Its battery recharge characteristics are:

``````- loses 1/3 of its charge in 4 days (if the car is resting. See test attached)
- loses 1/3 or its charge even after medium trips (photos in test attached)
(For example: after 28 miles, battery goes from  12.61 V to 12.31 V).
- thus, would require manually-charging nearly every day
(because my daily trips are typically less than 28 miles.
by not charging in one week, I had a flat battery after 1 week of normal driving).
``````

In contrast, I believe (let me know if you disagree) "maximum" recharge characteristics should be to:

``````- lose 1/3  of its charge in ~12 days (if the car is resting)
- lose 100% of its charge in 1 month (T = C/i = 45/0.05 = 900 hours)
- alternator-charging by driving 6 miles every ~4 days, or
- manually-charging once a week or once a month.
``````

My Honda Dealer looked at the car and dismissed the problem by saying:

``````- There is nothing wrong with the car
- This battery discharge amount is normal because the car has many computers
- We would only replace the battery if it was not charging
- We only follow Honda tests which do not show any issues.
``````

MY QUESTIONS IS: In your experience, what are "normal" recharge characteristics of modern cars (are they different or about the same as my belief above)? The answer would indicate if I am stuck with a problem car. In that case, suggestions on the next course of action are appreciated.

My full test steps, methods, and photos are at http://bit.do/BatteryTestAccord2017 .

• You're really over exaggerating the computers in your car. They're, at best, simple microcontrollers that draw a few mA. Nothing even close to rolling a window up and down. I don't see what problem you're trying to solve since voltage isn't linearly proportional to remaining capacity. Mar 28, 2017 at 5:18
• if you are leaving the car sit for long periods and itching to replace the battery look for one that is tolerant of deep discharge. Mar 28, 2017 at 11:10
• Thanks for the help @justinm410 I have added "Clarification" to the post. The dealer (not me) blamed on computers. Thanks for confirming computers are not the likely culprit. In your experience, do you believe the recharge characteristics I listed for the new car are normal? Mar 28, 2017 at 14:47
• Thanks for the help @agentp I have added "Clarification" to the post. I found one that fits and is Dual Purpose: Starting/Deep Cycling. But it does not list its Recharge Capacity (important in this case). That seemed a bit fishy to me. Is it normal for Deep Cycling not to list RC? Mar 28, 2017 at 14:48
• Thanks @Chenmunka. I have added "Clarification" and edited the post. Mar 28, 2017 at 14:49