The alternator is going to have the same draw when the car is running regardless of battery size because the electrical devices that consume power don't care if the battery has 250cca or 750cca. Technically you don't need a battery to run the car. It's only necessary to start the car. Once you have it started you could remove the battery, wrap the unconnected terminals in electrical tape and as long as you don't need to shut the car off you're fine. Of course 99.9% of people aren't going to remove the battery completely. So once the voltage regulator recharges the starting battery the alternator provides the power for the electrical load. So other than starting the car (and providing a power reserve to run electrical items while the engine isn't running) having the smallest battery possible to start the car is going to save weight and reduce alternator load due to faster recharging times.
Last edited by inuvik; 05-02-2019 at 06:27 PM. Reason: clarification
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View my fuel log 2015 Mirage ES 1.2 automatic: 40.5 mpg (US) ... 17.2 km/L ... 5.8 L/100 km ... 48.6 mpg (Imp)
The amount of power required to start the engine is independent of the battery size.
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View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)
Please don't tell people this, a battery is required on our computer controlled cars as it acts as a shock absorber / capacitor for changes in electrical loads. If you run a modern car without a battery, the voltage spikes from the regulator trying to change for electrical load may / will fry sensitive equipment (EG ECU, Dash, ATC, etc ) it can't act fast enough.. Also since some alternators are computer controlled, if the battery is missing it may result in many drive ability issues, codes etc. I wouldn't tell this to anyone, especially on an Internet form as someone may try it to gain a few MPG & toast his dash / computer etc...
Just My Opinion,,, Roger
Last edited by klroger; 05-02-2019 at 09:53 PM.
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View my fuel log 2018 Mirage GT 1.2 automatic: 37.3 mpg (US) ... 15.9 km/L ... 6.3 L/100 km ... 44.8 mpg (Imp)
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View my fuel log 2018 Mirage GT 1.2 automatic: 37.3 mpg (US) ... 15.9 km/L ... 6.3 L/100 km ... 44.8 mpg (Imp)
I'm pretty sure that trying to competitively autocross my Mirage is going to shorten the life of many various components of the car vs. not doing so. You've clearly missed the whole point of this exercise.
I swapped the battery for one reason and one reason only: To reduce weight with the goal of being more competitive in autocross.
If I blow an alternator, I can get a used one for $50. I'm not worried about it.
To put that into perspective, I've burned through $500 worth of tires in the past 6 months. It's a hobby, it costs money.
Simplify and add lightness.
Fummins (05-03-2019),LetItMarinate (05-07-2019)
Might have to move post #11 to the first page?
Attachment 14511
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View my fuel log 2014 Mirage SE wussie cvt edition. 1.2 automatic: 37.7 mpg (US) ... 16.0 km/L ... 6.2 L/100 km ... 45.3 mpg (Imp)
You didnt address the point I was making. Having a dead battery over and over and jusmp starting it requires the cars charging system to charge that dead battery. It's hard on the system and will shorten its life. But Loren stated he doesn't car as this is his hobby car so no harm no foul.
And I know a car runs and drives without a battery. I had my battery crap out in my old Mustang gt so I disconnected it and had a buddy push me and popped the clutch and drove the 15mi home.
I think this thread is about someone using a motorcycle battery to start their car. They are interested in reducing the weight of their car for racing purposes & not much else. If you aren't interested in racing your Mirage or seeing it shed a few pounds, I don't see the point about arguing about all this?
Personally, I hate motorcycle batteries. Motorcycles, UTVs, & ATVs all have them. They can be expensive for what they are, but some are surely better than others. Personally, I've considered going the other direction with my Kawasaki Mule. The next time the motorcycle battery dies in my Mule I want to replace it with a cheaper, larger riding lawnmower battery. These batteries are typically $25-40 and available most anywhere for that price.
My 2006 Mule and 1993 John Deere (Kawasaki engine) riding mower have very similar engines. I've heard of others making some adaptations & going with lawnmower batteries on their UTVs , too.
I once kick started my Honda ATV for two years straight, because I got tired of replacing the battery every couple years. Adding a motorcycle battery to my Mirage is of no interest to me. Thus, I shouldn't even be here commenting!
I'll move on to another thread now.