Battery replacement at dealer or regular auto store?

ANSWER : Hi – your friend is correct. As long as 12v is maintained to the vehicle electrical system, preserving all sort of settings and programming (without shorting cables, etc), yes, you can replace your own battery. There are even specialized accessories just for this task. I would recommend a battery replacement by a mobile, professional mechanic trained in this procedure, such as one from YourMechanic, who will come to your location, and swap your battery for you.

ANSWER : Hi There,
I would recommend having a qualified mechanic from YourMechanic come to your location to replace your battery for you saving you time and money.

ANSWER : As you may yourself have seen, there are many reports of this fault with the Civic, that is a battery or alternator is replaced only to have the warning light fail to extinguish despite checking every conceivable electrical possibility. Your only recourse is to have a certified mechanic go through that exercise with your car and that involves first attempting to "re-set" the light. If the warning light returns, the alternator output has to be carefully measured both loaded and unloaded. All terminal connections have to be verified including all grounds. Fuses have to be checked for integrity (continuity) and the possibility of shorts, in for example dash wiring, has to be checked. To request this repair, simply request an electrical components diagnostic and the responding certified mechanic will seek a resolution to this.

ANSWER : This suggests you may have an alternator that is not working properly. As you may know, the alternator is responsible for keeping the battery charged properly. There is also a unit called a voltage regulator that regulates the charging of the battery by the alternator. Either of these two components, when not working properly may cause the battery to be drained prematurely as you describe. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your charging system.

ANSWER : You may have a failing voltage regulator that could be allowing the alternator to supply too much or too little amperage to the battery resulting in the battery never maintaining a consistent charge as it is designed to. The voltage regulator is a unit that regulates the charging of the battery by the alternator. When the voltage regulator is not working properly, this may result in the alternator allowing too much power to be delivered to the battery resulting in damaging wires and prematurely sometimes destroying the battery. A common sign of this is usually the acid inside the battery boiling causing the battery to swell. You may also smell a bit of smoke due to things potentially getting too hot. In other cases it may result in the alternator not supplying enough power to the battery, resulting in undercharging the battery or not charging it at all. I would recommend having an expert from YourMechanic come to your location to diagnose your vehicle’s charging system.

ANSWER : Taking off the battery cable while the car is running is not a good test of the charging system. In fact, if you do that to a modern car it’s possible to do some serious damage to your alternator and the control modules in your car.. Taking off the battery cable to test the charging system is an old carryover method that dates back to the 1960’s when cars were equipped with DC generators and had no computer systems. That being said, you may never know if you have done any damage until later on down the road when some of the car’s modules start behaving strangely. I would normally expect to see a check engine light after that has been done. Since you didn’t report one, I wonder if the check engine light is working.
If you replaced the battery without having anything on the system to maintain power, there are a number of settings on the car that will have to be re-learned. Many of them will take care of themselves after a period of driving. But if you have persistent problems, you may have to use a few re-learn procedures: procedures that are a little too involved to talk about here. A code read should reveal if any of these settings are a problem.
The noise you have in your engine is a little worrying. Even though you used low-octane gasoline, your car should still run OK except for some spark knock under load. Most of the time you should notice no difference at all. There is a knock control system on your car that should be able to manage the spark knock and I think there might be a problem there. That and the difficulty starting are going to take some diagnostic work.
I expect there are a handful of trouble codes stacked up in the car’s memories. Some will be from the battery change, some will be from the cable being removed, and there may be some there from a previous fault. If you contact Your Mechanic, They can send a technician to your home or office to read the codes on your car and tell you what needs to be done to sort things out.

ANSWER : Hello. A battery saver mode light can sometimes be set off by an issue with the battery, but it is also often set off if a problem occurs with the alternator, such as low or excessive output from a failed voltage regulator.

I would check the alternator to make sure that it is in proper functioning order, as an alternator issue can not only cause problems with the vehicle, it could also cause damage to the battery.

If you’d like to get this repaired, feel free to contact a certified mechanic who can diagnose the cause of the battery light firsthand and replace the alternator if necessary.

ANSWER : The engine idle will relearn on its own and will take a couple days of driving. The a/c door actuators will need recalibrated using a scan tool that can put system in recalibrate mode in order to fix the a/c.