The 12v battery is probably even a bit oversized from Honda....It only has to power up normal 12v items and the ECM / IMA electronics then the IMA system can supply the power. Even during AutoStop, under heavy electrical load, the DC-DC converter can still supply power to the 12v system. The most demand there would ever be on the 12v battery are those very rare occasions (typically cold climate) when the typical starter motor has to crank the engine instead of the IMA battery due to being too cold outside.I know it doesn't directly but some folks on this board go with a larger Civic battery in an effort to down on force regens. I'm not convinced it helps, that's why I stared this thread for discussion.
The 12v battery has to initially power normal 12v items in your car and supply initial power to your ECM / IMA computers until the contact relay kicks in and allows the DC-DC converter to get power from the IMA system and supply 12v power to your battery and the all of the other 12v items in your car....Once the IMA systems power up, the 12v battery acts more or less like a buffer for 12v but the power comes from the IMA system to do so. I tried to say that earlier in a much shorter description.Huh???? The 12 volt battery powers everything but the IMA motor and engine.
If the 12v battery requires a charge, the DC-DC converter will handle that but it also handles ALL of the other 12v needs while it is active. There is an ELD device that will sense high 12v demand (like turning on the headlights for example) and any high 12v demand will keep the DC-DC converter active even if the 12v battery is charged.Gasoline powers the engine, the IMA battery powers the IMA motor and recharges the 12 volt battery. Everything else is powered by 12 volts.
Yes...It does come from somewhere....AS I mentioned earlier, it comes from the DC-DC converter (you call it an alternator). However, your either / or scenario above is incorrect. When regen occurs, it supplies power to the IMA batteries (not to the 12v system directly). The DC-DC converter (what you say is the alternator) takes power from the IMA battery and converts it to 12v when needed. That is why it is called a DC-DC converter because it take high DC voltage from the IMA battery and converts it to a lower DC voltage (12v).That 12 volts has to come from somewhere. Either its recharged when regeneration takes place or when the "alternator" turns on and uses the IMA charge to charge it.
A properly working OEM 12v battery can store enough to crank the engine using the typical starter motor that most people will never (or hardly ever) hear working when starting the engine. Honda had to install a battery that would handle the cranking amps required in that situation but most of the time, even the OEM size that Honda HAD to choose is not really needed.My conclusion is the oem battery cant store much, so its being fed by the IMA battery frequently. This in turns robs assist and causes more regens and less assist. The larger 12 volt battery allows more pause between the system recharging and powering the stuff in the car since it has a larger capacity.
Perhaps they did change some part of the design but what you just described matches what I believe I am saying. I have never said that the DC-DC converter is always active....Here is a portion of my last post:Joe, you are not describing the charging/12 volt system correctly for the i2.
Maybe they changed the design since the first gen? I see by a scanguage that the dc-dc converter isnt always working or charging. In many cases its off and the car is running on 12.x volts. I only see it charge when first fired up for a few minutes, when regening and briefly when the voltage falls below 12.5 volts. Before I replaced my battery it was running constantly for the first few hours of my trips.
The 12v battery has to initially power normal 12v items in your car and supply initial power to your ECM / IMA computers until the contact relay kicks in and allows the DC-DC converter to get power from the IMA system and supply 12v power to your battery and the all of the other 12v items in your car....Once the IMA systems power up, the 12v battery acts more or less like a buffer for 12v but the power comes from the IMA system to do so. I tried to say that earlier in a much shorter description.
I guess that you are not reading my posts as well as I had hoped then...You even include my first paragraph in your posting and it doesn't say that the 12v battery is only used to power up the relay(s).Your first para of your previous post just reads that the 12 volt battery is used to activate the relays, then its all ima.
I personally believe that it is more related to new vs. larger....Joe,
So it's the fact that Cobbs and Chessies batteries are new, not larger that may have contributed to better MPG by eliminating force regens. Do I have it right?
If that's the case, the 12V battery in the Insight has to be changed every 20-30k miles for optimum MPG?
Why not have TWO 12 volt systems? Leave the existing 12 volt Insight IMA charged system as is and have a TOTALLY ISOLATED electrically separate auxillary battery 12 volt system to run all your heavy load equipment. You can plug in and grid charge this aux. system battery every evenimg when you get home and totally avoid using gasolene to charge the heavy load system as you do now. This will truly show an increase in MPG over what you have now because you will have totally removed the heavy 12 volt load off the IMA system...................
I had a group 27 deep cycle battery in the rear of my car for the sub woofers. I noticed almost a year later it had been boiling over and acid had been spilling out in the ima compartment..................
Also, the very act of replacing the 12v battery will reset the IMA controllers and will have to re-learn the IMA battery SOC so that may be a factor as well.
While the battery is connected even when the car is not being driven, a small amount of 12v power still keeps the cars computer / IMA controllers memory area active so each time that you start the car, it does not have to re-learn the current capacity of the IMA battery pack (basically, it doesn't have to figure out the current SOC)....Ooops!
Can you please elucidate a bit more on that?
What happens if you disconnect the 12v battery, for instance in order to change it?