Automotive

Car Batteries - FAQ, General Information, Tips & Tricks

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  • Dec 8th, 2018 9:15 pm
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Sr. Member
May 3, 2008
623 posts
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Markham
blindemboss wrote:
Oct 27th, 2018 2:53 pm
I have a 2012 Mazda 3 with a one-year-old battery (recently replaced) By the dealership.
With a 3 month period away from driving due to injury, I recently tried to start the car. Completely dead.
I had it boosted by another vehicle, and drove around the park for about 40 minutes. The next day, the car wouldn’t start.
I’m guessing your battery had not fully re-charged enough to turn over.

Would connecting a battery charger overnight do the trick?
Once fully re-charged, can I be confident it won’t die out again in a day or week?
3 months is enough to completely drained the battery and sub-$100 charger may not be "good" enuf to revive it and let it charge.
If you drive the car around for 40mins, that should charge the battery properly. Make sure you are driving it for at least 30mins and not just idling, as some cars these days decouple the alternator when idling to improve efficiency. Given battery still wont start the next day, take it to a CanTire etc and they can test whether the battery can accept a charge or not.
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Dec 23, 2003
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Toronto
savemoresaveoften wrote:
Oct 27th, 2018 5:27 pm
3 months is enough to completely drained the battery and sub-$100 charger may not be "good" enuf to revive it and let it charge.
If you drive the car around for 40mins, that should charge the battery properly. Make sure you are driving it for at least 30mins and not just idling, as some cars these days decouple the alternator when idling to improve efficiency. Given battery still wont start the next day, take it to a CanTire etc and they can test whether the battery can accept a charge or not.


I would rather you take it to parts source, kal tire or mr. lube and they can do a free battery test. Canadian tire will charge $25 for the same thing.

As for chargers, don't get anything more than a 6 amp as slower is better. Parts Source has a 3.5 Amp Noco for $71.99 on sale.
Deal Addict
Oct 4, 2006
1470 posts
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Toronto
savemoresaveoften wrote:
Oct 27th, 2018 5:27 pm
3 months is enough to completely drained the battery and sub-$100 charger may not be "good" enuf to revive it and let it charge.
If you drive the car around for 40mins, that should charge the battery properly. Make sure you are driving it for at least 30mins and not just idling, as some cars these days decouple the alternator when idling to improve efficiency. Given battery still wont start the next day, take it to a CanTire etc and they can test whether the battery can accept a charge or not.
Thanks, I was idling for probably half of those 40 min.
Probably worth getting a boost and trying it again, before going the charger route.

@hightech, thanks for the info at MrLube and Part Source.
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Dec 23, 2003
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blindemboss wrote:
Oct 27th, 2018 6:13 pm
Thanks, I was idling for probably half of those 40 min.
Probably worth getting a boost and trying it again, before going the charger route.

@hightech, thanks for the info at MrLube and Part Source.
idling won't charge a battery. You need to rev it to around 2000 rpm to drive the alternator. If the battery is that low, using a charger is better than the alternator as it puts extra strain on it.
Deal Addict
Oct 4, 2006
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hightech wrote:
Oct 27th, 2018 7:17 pm
idling won't charge a battery. You need to rev it to around 2000 rpm to drive the alternator. If the battery is that low, using a charger is better than the alternator as it puts extra strain on it.
So I go to Can tire and sales guy says the opposite.
Says you have to let it idle for 30 minutes...not drive it. Says this way the alternator recharges the battery.

He adds he’s from Winnipeg, so he knows about winter.
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blindemboss wrote:
Oct 29th, 2018 7:48 pm
So I go to Can tire and sales guy says the opposite.
Says you have to let it idle for 30 minutes...not drive it. Says this way the alternator recharges the battery.

He adds he’s from Winnipeg, so he knows about winter.
I think this is old school logic. The best thing is to drive it around town or on the highway.
Sr. Member
May 3, 2008
623 posts
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Markham
blindemboss wrote:
Oct 29th, 2018 7:48 pm
So I go to Can tire and sales guy says the opposite.
Says you have to let it idle for 30 minutes...not drive it. Says this way the alternator recharges the battery.

He adds he’s from Winnipeg, so he knows about winter.
he knows about winter, does not know how modern car works...
Deal Fanatic
Jan 27, 2006
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Vancouver, BC
savemoresaveoften wrote:
Oct 27th, 2018 5:27 pm
3 months is enough to completely drained the battery and sub-$100 charger may not be "good" enuf to revive it and let it charge.
If you drive the car around for 40mins, that should charge the battery properly. Make sure you are driving it for at least 30mins and not just idling, as some cars these days decouple the alternator when idling to improve efficiency. Given battery still wont start the next day, take it to a CanTire etc and they can test whether the battery can accept a charge or not.
Driving the car around for 40 minutes isn't enough to charge a battery property especially with these new eco/smart charging systems in cars - they just don't decouple when idling but also in many conditions when actually driving. Even without eco/smart charging, 40 minutes won't fully charge the battery as most car's charging system aren't smart enough to do that. They may get the battery to approx 80% but that will take a lot of driving.
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craftsman wrote:
Oct 30th, 2018 1:24 pm
Driving the car around for 40 minutes isn't enough to charge a battery property especially with these new eco/smart charging systems in cars - they just don't decouple when idling but also in many conditions when actually driving. Even without eco/smart charging, 40 minutes won't fully charge the battery as most car's charging system aren't smart enough to do that. They may get the battery to approx 80% but that will take a lot of driving.
Driving around will keep the battery topped off if the battery is about 70% charged. If it is severely discharged, it should be charged with a charger. This would be the best way to top it off and not put stress on the Alternator.
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Jan 27, 2006
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hightech wrote:
Oct 30th, 2018 1:29 pm
Driving around will keep the battery topped off if the battery is about 70% charged. If it is severely discharged, it should be charged with a charger. This would be the best way to top it off and not put stress on the Alternator.
Yep. I was just making the point that driving for any reasonable period of time won't do much.
Sr. Member
May 3, 2008
623 posts
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Markham
hightech wrote:
Oct 30th, 2018 1:29 pm
Driving around will keep the battery topped off if the battery is about 70% charged. If it is severely discharged, it should be charged with a charger. This would be the best way to top it off and not put stress on the Alternator.
agree, but think need a proper commercial grade charger. Those $50 one or the 1A battery tender wont do the work.
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savemoresaveoften wrote:
Oct 30th, 2018 1:58 pm
agree, but think need a proper commercial grade charger. Those $50 one or the 1A battery tender wont do the work.
LOL, yes. I would suggest a 6 Amp charger as that provides a balance between speed and battery health. Batteries like slow charging but I find for car batteries, anything under 2 amps are really tenders to top off a battery. They don't have enough power to charge it especially in cold weather. The 6 Amp Duracell charger that I got from Princess Auto for $50 can easily charge a battery in a few hours. Keep in mind that the battery voltage needs to be above 9 volts or else the charger won't work. If your battery is that low voltage, even after getting it charged you might need to look for a new battery as most non deep cycle batterys don't do well in these conditions.
Jr. Member
Aug 13, 2003
164 posts
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Calgary
To the car battery gurus on here, what do you think of the claims made by this reviewer on amazon.com.uk about the Noco 3500 vs the CTEK chargers especially in relationship to what he calls the inferior charging algorithm of the Noco and the superior and proper charging algorithm of the CTEK's. You can find the review and statements here: https://www.amazon.co.uk/gp/customer-re ... B00E907PWS
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Dec 23, 2003
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DentDude,

I think that there could be differences in the charging algorithm and every brand has slight variations. For example, the Battery Minder which is another higher end device has a different charging approach than the Ctek, Noco, Battery Tender, etc. Sometimes these companies have patients for the charging profiles (that other brands can't use), and sometimes they have found one charging approach to be better than another.

Personally, I find that all of these devices do a decent enough job and the slight differences really matter mostly for the Engineering/Gear Head types who are fastidious about the specs. Most auto manufacturers tend to recommend the Battery Tender models. If you are in doubt, visit the parts counter of your vehicle manufacturer and ask what chargers they sell and recommend. You can buy that charger from them knowing that it is suitable for your car. Another option is to contact East Penn (the guys that make the batteries) and ask what charger they recommend. You can then purchase that charger, disconnect the battery from your car and charge the battery knowing that the guys who engineered the battery recommended it.

Perhaps Craftsman can chime in here as he has a lot of knowledge on this subject.

I hope this helps to answer your question.
Deal Addict
Mar 16, 2015
1403 posts
217 upvotes
I think somewhere on this thread it was mentioned that it is important to charge your battery time to time using a charger because car's electric system is not able to charge the batter 100%.
I am getting opposite results... I have a NOCO G7200 . I put it to task early in the year , once in Feb and once in April.. then skipped entire spring, summer and fall .. I just put it to battery yesterday... Within a minutes it was showing that the battery is 100% charged.. The battery was bought new in Jan 2018...

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