how much cca is necessary for a truck battery?

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i wanted to ask tho how much CCA do our trucks even need tho?
for example my vehicle has a gm 6.0 lq4 in it and its factory spec is 840cca.
840 seems very high and much higher then other trucks with bigger engines.

correct me if i am wrong but the battery is just for starting the vehicle and once the vehicle is on, the alternator should take over and the battery is essentially not be using correct? however once the vehicle is shut off then obviously the lights, radio, etc etc will run off the battery which would have to do with the reserve capacity. higher reserve capacity meaning more time to use those gadgets

i dont really have any extra mods or anything and nor do i ever listen to music etc when the truck is off. so do i really need 840 cca?

but also on a second hand it seems like 840cca is a good thing correct me if i am wrong because when it degrades etc it will be at about 700cca for example. i am just pulling numbers out of the air.
however if i compare that to a regular 750cca battery, then over the same amount of time in theory the degradation would bring it down to 650 cca.
lets say my truck needs in theory 675 cca to start minimum, and then in this scenario the 840cca would still be able to crank my truck until a certain date while the smaller battery would have already degraded to the point where it cannot start the truck anymore

i do live in alberta and it does get pretty cold here in the winters
so in this case, is it a good idea to get the bigger battery or am i wrong?
 
It's not initial CCA that you need, as much as resultant CCA after it ages and is depreciated by temperature. Get one with lower CCA and all else equal, it'll need replaced sooner.

So yes, the bigger battery of the same type is better, but also because each time you start it using the bigger battery, it discharges it that much less. Starting batteries last much longer if not discharged much. Granted this isn't as big a factor as age and temperature.
 
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Originally Posted by Dave9
It's not initial CCA that you need, as much as resultant CCA after it ages and is depreciated by temperature. Get one with lower CCA and all else equal, it'll need replaced sooner.

So yes, the bigger battery of the same type is better, but also because each time you start it using the bigger battery, it discharges it that much less. Starting batteries last much longer if not discharged much. Granted this isn't as big a factor as age and temperature.

ahnh great i was thinking the same however i heard larger battery has weaker plates or something?
 
Yeah more CCA means weaker plates, but if they make the battery physically larger that's a good thing-- more room for thick plates.

I bought a grand marquis with the 4.6 V8 and its battery was dead as a doornail. I jump started it with my saturn, with its stupid little tiny side post terminals. It chugged over and started, albeit slowly.

It depends on compression, cam profile, oil (!), RVP of fuel, if they use a direct-drive or gear reduction starter, etc.

Seems like the little 4 cyl cars often get batteries 90% as good as the truck ones... not counting the Hondas and Miatas, lol.
 
Here in the states, the ecm will limit the alternators output for cafe standards. I wonder if that "upgrade" is present on Canadian vehicles?
 
Pickups often had an "HD" electrical package with uprated alternator, and uprated battery or batteries. It was for various reasons including in plow packages, etc. Sometimes the battery can help buffer short term high draw loads.

Did this truck have an uprated electrical system either specifically or as part of a plow or trailering option package?
 
The biggest battery you can get, but like others already said, if it comes down to choosing between 2 or 3 get the one with the highest Reserve Capacity.
 
Bigger is pretty much always better, especially in arctic conditions-cranking amps start dropping pretty quickly below freezing, and oil viscosity, battery cables, fuel quality, and starter all make a big difference. For instance, the 7.3 IDI in my sig ALWAYS had issues starting at 32F/0C or below, new glow plugs, new 1000 CCA batteries, even 10W30 oil didn't help. Until I put in the newer style gear reduction starter in place of the OEM direct drive one-now it starts cold with no issues whatsoever. I installed one of the 34/78DT East Penn 1000 CCA batteries from my departed 6.2 diesel Sierra into the 6.0 LQ4 Express in my sig, hopefully it'll be big enough.
 
Originally Posted by eljefino
Yeah more CCA means weaker plates, but if they make the battery physically larger that's a good thing-- more room for thick plates.

I bought a grand marquis with the 4.6 V8 and its battery was dead as a doornail. I jump started it with my saturn, with its stupid little tiny side post terminals. It chugged over and started, albeit slowly.

It depends on compression, cam profile, oil (!), RVP of fuel, if they use a direct-drive or gear reduction starter, etc.

Seems like the little 4 cyl cars often get batteries 90% as good as the truck ones... not counting the Hondas and Miatas, lol.

Yep. Bigger is always better, but, with the right oil in the sump and a good starter, it might not matter.

I killed the battery in my truck one winter, it wasn't too cold but maybe around freezing? don't remember now but it was below 9V on the battery. Hooked up my car and it cranked right over and started, easy peasy, with just the jumper cables. It starts so easily that it's still running that same battery, which is pushing 10 years of age! Cannot tell me that it has anything close to what it started out with.

Now I'd be wise to replace it sooner than later, but, I don't have a snow plow, a winch nor a thumpin' stereo. A smaller battery will serve it just fine.

I do stick with 0W oils though, so there is that factor (although 5W would serve me just fine too I bet).
 
well my owners manual wants a group 79 but i wont be able to find that at costco. it tells me to put in a 78 which is a little smaller then my 79
but from costco it seems like i am choosing between either a group 78 or a group 65 and it seems like the group 65 is a no brainer since its larger

hopefully it fits tho
 
Originally Posted by apollo18
i wanted to ask tho how much CCA do our trucks even need tho?
for example my vehicle has a gm 6.0 lq4 in it and its factory spec is 840cca.
840 seems very high and much higher then other trucks with bigger engines.

is it a good idea to get the bigger battery or am i wrong?


I'll answer that based on the guidance I had back in the day. However, this was a young engineer with Globe Union ( back then a division of Johnson controls) for Sears and Interstate batteries so its a little "dated" ( OK, a LOT dated) but I don't think the formula for establishing the requirements has changed much. Use this for a historical reference to form a baseline as I doubt the thought process has changed much on how to determine what the requirements should be.

CCA is amps at for 30 second at 0F without dropping below 7.2 VDC for a wet celled battery with a SG of 12.60 ( temperature corrected with a 65/35 mix) and 2.1 VDC per cell in series and OCV at 12.6 VDC

The engine displacement, oil viscosity, compression, number of cylinders and what used to be called magneto ( for older engines) was calculated and given to us to meet.

We took that figure and basically doubled it plus to account for performance degradation from the CA (cranking amps) and loss of estimated performance of a battery plate calcifying for one year.

Reserve capacity was all loads and a discharge of 1 hr.

A car battery has a reserve capacity but not like a deep cycle with denser plates to withstand charging cycles.

I'm sure things are different today and BCI has changed some things but back when that's how a CCA for a vehicle was calculated and given to us to construct against.
 
This thread is a bit old but since it’s battery buying season I thought I’d throw in my two bits since I have a 6.0 like the OP. I’m going into my seventh winter with this AC Delco Professional. My Burb has a full load of electronics and this battery has performed very well. I can get AC Delcos at my local independent Lordco auto parts store, so they’re competively priced. Mine is 770 CCA and 120 RC. It is a 42 month free replacement battery. Hopefully I’ll get 84 months out of it. High temps aren’t an issue here. LOL

BFF0C514-9547-400D-9A9F-2FF9B4B9FA85.jpeg
 
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More CCA in same footprint means thinner/weaker plates. Shoot for what your vehicle came with. Sometimes the only battery available in the group size you need has a lot more than you are looking for. Not much you can do.
 
My starter is rated at 1400 watts Output.

I've measured 1800 watts input, when it was in warm ambient temperatures, but had not been started in 2+ weeks.

1800 watts at 11 volts is 163 amps
1800 watts at 12 volts is 150 amps
1800 watts at 10 volts is 180 amps.

So actual amperage required by the starter, depends on the voltage the battery can maintain during the load of the starter.

This voltage is influenced by battery size, resistance, temperature, health.

Voltage reaching the starter is affected by the above, and the quality of the circuit feeding the starter.
Not just the copper thickness, but the quality of the cable terminations, and not just the +, but the ground too.

Fatter circuit, and one can get away with less CCA.

The Biggest marine battery which fits, is usually a pretty good choice, as long as the CCA(Not MCA) is still above the manufacturer's spec'd minimum.

Marine batteries should be built a bit more robust than a starter battery, and usually have automotive posts clamps, as well as threaded studs to hook ring terminals onto.

But, marine batteries usually have shorter warranties as deep cycling is much much harder on a battery than one that sees starter duty only.

A defect free battery, properly charged/kept at high states of charge, will not require use of the warranty.
Defects usually appear quickly.

Most warrantied batteries were just over discharged, never properly recharged, and quickly sulfated to uselessness.
User error, not the fault of the manufacturer/retailer.
' The consumer is always right', is just so wrong.
The consumer can be a complete halfwit, and the warranty then rewards them.
 
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Also, in spite of the fact that there are a lot of maintenance-free batteries out there, there are still plenty of rectangular capped batteries that need water maintenance. One hot summer can take the electrolyte below the level of the plates.
 
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