What % Of A Battery's Rated A-h Capacity Is Acceptable?

Doing the math, the battery has a capacity of about 20AH. It's done! Costco has a very good battery warranty. I think it's 4 years no questions asked for a free replacement.
I bought my latest battery from Costco. A year later it croaked and they replaced it, no questions asked. I’ll keep buying from Costco.
 
The cheapest battery I've found so far is at Canadian Tire, at around C$180. She's a Costco member (which I'm not), so that might be a better bet.

My booster pack lives in the van. Our garage was around -12 C last night. That may be why it didn't do much good boosting this morning.

I'll keep it in the house, and take it out with me when I think of it.
Those lithium battery backs are hurting once they get down to even -5c.
 
If it were my car, I would. Money is a factor for the owner.
Sometimes salvage yards get vehicles with batteries that are not very old at all. And you can get them really cheap because usually people buy new.

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Group 35 is the same width and length, but it's height is 8 & 7/8 inches, where the 47 height is 7.5 inches. So, is there room for a battery that's 1 & 3/8 inch higher?
 
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I bought my latest battery from Costco. A year later it croaked and they replaced it, no questions asked. I’ll keep buying from Costco.
They pro-rate now is my understanding. Its a new policy.

Walmart does not pro rate. 3 years is 3 years.

 
They pro-rate now is my understanding. Its a new policy.

Walmart does not pro rate. 3 years is 3 years.


OP is in Canada, not U.S.A. COSTCO Canada still has the best automotive battery warranty in the business, probably because they have not experienced the fraudulent/abusive replacement claims that forced them to eliminate the 36 month free replacement warranty in 'Merica. Here is COSTCO's current policy in Canada per the website.

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Is there a rule-of-thumb for when the battery should be replaced?

Before you're wife's friend finds themselves stranded and cold, and your wife puts you in the dog house?

That said a battery with very little capacity can have passing cranking amps especially in warm weather and become garbage when it’s cold out .
If it’s capacity is too low it might have enough winter cranking amps but be found dead from parasitic draw at the end of the day.

Yup, I have an 8.5 year battery ready to be replaced that behaves like this. Charged up, provides plenty of cranking amps, but won't hold that charge for more than a few days. Not such a big deal in a place like Miami, but in the Great White North?

My spiffy new electronic toy? conductance tester rates the battery as "good" and healthy, but that's clearly not the case.

The OEM battery on the Venue is an oddball Group 47 (H-5) size. See if a Group 24F or 35 will fit in the battery space and if the cables will reach the terminals. Those two are the most common sizes which are available in 3 grades from WalMart and any store selling automotive batteries.

H5 is normally stocked as part of the limited range of sizes in Costco's U.S. warehouses. Not such an oddball any longer, nor is the H6 and H7, which used to be mainly confined to Euro applications, but firmly became part of the mainstream once the Asian and American OEMs adopted them in their applications.
 
OP is in Canada, not U.S.A. COSTCO Canada still has the best automotive battery warranty in the business, probably because they have not experienced the fraudulent/abusive replacement claims that forced them to eliminate the 36 month free replacement warranty in 'Merica. Here is COSTCO's current policy in Canada per the website.

View attachment 253953
Good to know, but the person I replied to was in USA.

I guess this means its good to double check warranty terms anywhere before you buy.
 
H5 is normally stocked as part of the limited range of sizes in Costco's U.S. warehouses. Not such an oddball any longer, nor is the H6 and H7, which used to be mainly confined to Euro applications, but firmly became part of the mainstream once the Asian and American OEMs adopted them in their applications.
It looks like the H5 is currently available at the Canadian COSTCO warehouses with the 48 month free replacement warranty for ~$155 CAD. It is rated for 650 CCA, so a substantial upgrade from the OEM battery's 410 CCA.
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I watched an interesting video recently about people living in very cold areas of Russia where it's -70° C and colder at night in winter. They remove their batteries at the end of the day and keep them inside the house so they'll stay warm, then reinstall the warm battery in the morning. They also rig up kerosene forced air heaters to warm up the engine prior to first start. Fascinating seeing how people deal with the environments that they live in.

 
just taking a subjective stab at the OP's question (I know there are more criteria and an algorithnm) I'd say 60%. What concerns me isn't simply the ability to start the engine. It's the fact that the resistance is growing higher and higher and not what the charging system was designed for (V = ir ) .

A real life application. Say your subwoofer blows and your car happens to be a Toyota, and now what should be $80 is $700. BUT, there is no aftermarket available and the resistance is different where the aftermarket is higher. Well, some go with the aftermarket even though the car's amp was not designed for it......I don't like that idea, and I don't like $700, so I get out a tube of silicone lol
 
Often 20 hour tests are used to provide the AH rating spec. 1A for 20H = 20AH.

A faster drain will never work out at 20AH. A good rule of thumb is a healthy battery will show a 20% reduction in AH capacity when drained faster such as a 5 hour test.

Example, a 5 hour test of the 20AH battery will be 16AH. A 1 hour test, even worse.
 
This is my wife's friend's car, a 2021 Hyundai Venue.

It did not come with a block heater, and did not start this morning (or even turn over) even with a boost. It was a chilly -32°C this morning.

I removed the battery, brought it home, thawed it out, and charged it.

It passed the load test (Schumacher resistive tester - 100 A for 10 s - with flying colours.

I now have it on my ampacity-testing rig, drawing about 8 A. Here's the set-up:
View attachment 253915

The battery is original, and is rated at 45 A-h and 410 CCA. In perfect condition, then, it should supply 8 A for over 5 hours.

What if it quits at 4 hours (< 80%)? 3 hours (< 60%)?

Is there a rule-of-thumb for when the battery should be replaced?

Thanks!

P. S. Regarding the absent block heater, I won't install one in this weather, but will lend her my magnetic surface-mount 200 W heater.
Car batteries aren't deep cycle as they pump a whole bunch of electricity into the starter all at once then should be kept topped off by the alternator. It sounds like not enough cca for the cold.
 
I watched an interesting video recently about people living in very cold areas of Russia where it's -70° C and colder at night in winter. They remove their batteries at the end of the day and keep them inside the house so they'll stay warm, then reinstall the warm battery in the morning. They also rig up kerosene forced air heaters to warm up the engine prior to first start. Fascinating seeing how people deal with the environments that they live in.


Before rural electrification (beginning post-war here), it was common for farmers to drain the motor oil and heat it on a wood stove.
 
I can't say this for sure - but when I was looking the "H" designations had the required tabs at the bottom of the lower clamp on mount type hold downs. The "Group" batteries did not. That may have been that specific brand - I don't know?
I just verified that group 47 has the required tabs at the bottom for clamping purposes, and in a Kia of all things.
 
It looks like H5 and Group 47 are different names for the same battery, correct?

Yes, Group 47 is the BCI size designation vs. H5 which I believe is the European (DIN) designation. It is the exact same battery size, regardless.

Common usage of the German DIN designations only came into vogue in the past few years.

Before that, an H6 was commonly referred to as a BCI Group 48/91 (and the H7 = 94R, H8 = 49, H5 = 47). The less common T6 was also listed as an acceptable substitute.

The joke about standards being so great, meaning that there should be many of them, also applies here (no, not kidding), so there's also a European system, where a 48/91/H6 is referred to as an LN3. The Japanese have their own as well.

Coming from a family history consisting of almost entirely European marques, the H6-style battery is quite familiar to me. Regardless of what they're called, they've always had the provisions to be bottom mounted (as well as venting provisions), in a cleat/clamp system, sometimes with multiple positions to accommodate different sizes, allowing a common battery compartment to fit various sizes in accordance with the size of the engine/model.

So the dinky fours would get the smaller H5, and the honking V8s get the H8, etc. Top brackets would make appearances only on the family members who strayed and bought Japanese cars.

All for a bucket of electrons.

Edit: Forgot to add, yeah, absolutely take the suggestion to check the battery tray/compartment to see if it will take a larger battery that a different-engined model may have used. For whatever marginal difference in cost, the additional capacity of an H6 might be worth it, if the car will take the larger size without the need for any mods.
 
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