Using an H8 instead of an H9 Battery in a 2016 3.8 AWD .Has anyone done this?

[rroyce46]

My 2016 3.8 AWD Sedan has the original Hyundai AGM battery. I'm in Calgary Canada & H9 batteries are in the $478 range for an H9 Interstate.
My car has 53000 Kilometers but was built in August 2015. Battery is fine so far but how long will it last & do I get any warning that it's failing? Our climate is cool & car is always garaged. I can get an H8 Energizer from Costco
for $299 but they don't carry an H9. H8 is 950 CCA Vs 1000 CCA for Interstate.
Will the H8 fit? Am I overthinking this & should I just wait & see when it starts to fail ?

 

[Suburbazine]

You'll lose a bit of fuel economy but other than that it should work.

 

[Andyj]

You'll lose a bit of fuel economy but other than that it should work.

Interesting. Why would the slightly weaker battery affect fuel economy? My 2015 has the original battery as well.

 

[5.0KDM]

You'll lose a bit of fuel economy but other than that it should work.

wait how?

 

[carguy75]

Interesting. Why would the slightly weaker battery affect fuel economy? My 2015 has the original battery as well.

I think the idea of the statement is that the alternator will work harder with the weaker amperage battery by engaging the clutch more to keep it charged and provide more parasitic loss to the engine which in theory would also negatively affect the engine efficiency; therefore less fuel economy.

 

[EdP]

I think the idea of the statement is that the alternator will work harder with the weaker amperage battery by engaging the clutch more to keep it charged and provide more parasitic loss to the engine which in theory would also negatively affect the engine efficiency; therefore less fuel economy.

So instead of 20 mpg, he may get 19.999998 mpg
The electronics, lights, heater fan, etc., will consume the same amount of power and the alternator is capable of putting that out.

He made a claim, he should be able to back it up with facts.

 

[Suburbazine]

So instead of 20 mpg, he may get 19.999998 mpg
The electronics, lights, heater fan, etc., will consume the same amount of power and the alternator is capable of putting that out.

He made a claim, he should be able to back it up with facts.

Interesting. Why would the slightly weaker battery affect fuel economy? My 2015 has the original battery as well.

wait how?

I think the idea of the statement is that the alternator will work harder with the weaker amperage battery by engaging the clutch more to keep it charged and provide more parasitic loss to the engine which in theory would also negatively affect the engine efficiency; therefore less fuel economy.

The energy management system (also known as Hyundai's Alternator Management System) cycles the battery charge level for optimum energy production. The car uses a table in the power management system that equates charge level to battery capacity, basically X voltage = X% battery capacity.

This is important because the car will switch the alternator OFF during cruise and low load conditions and transfer the operational load to the battery until the battery depletes to a certain point. At which point the car re-enables the alternator to bulk charge the battery at the most efficient output. The alternator at low output has more wasted energy than it does at higher output levels.

The massive battery is installed not because the car needs a lot of cranking amps, it's because it needs a lot of reserve capacity for this cycling mechanism to be effective. When the battery loses capacity, the power management system abridges or entirely disables economy cruise so as to not have a condition where the battery cannot start the car. The car doesn't have a feature to reprogram the battery size, so it assumes any under-spec battery is just a battery in poor condition. The system expects a certain range of guaranteed performance based on demand, basically a timer that is used to calculate capacity lost for a certain load over a certain time.

You can watch this process for yourself- plug a voltage meter into the 12v socket and it will bounce from ~14v to ~12.5v while driving.

And like Ed says, it's probably not easily quantifiable or would skate within the standard deviation for fuel economy. But on more fuel efficient vehicles the economy difference is measurable.

 

[rroyce46]

The energy management system (also known as Hyundai's Alternator Management System) cycles the battery charge level for optimum energy production. The car uses a table in the power management system that equates charge level to battery capacity, basically X voltage = X% battery capacity.

This is important because the car will switch the alternator OFF during cruise and low load conditions and transfer the operational load to the battery until the battery depletes to a certain point. At which point the car re-enables the alternator to bulk charge the battery at the most efficient output. The alternator at low output has more wasted energy than it does at higher output levels.

The massive battery is installed not because the car needs a lot of cranking amps, it's because it needs a lot of reserve capacity for this cycling mechanism to be effective. When the battery loses capacity, the power management system abridges or entirely disables economy cruise so as to not have a condition where the battery cannot start the car. The car doesn't have a feature to reprogram the battery size, so it assumes any under-spec battery is just a battery in poor condition. The system expects a certain range of guaranteed performance based on demand, basically a timer that is used to calculate capacity lost for a certain load over a certain time.

You can watch this process for yourself- plug a voltage meter into the 12v socket and it will bounce from ~14v to ~12.5v while driving.

And like Ed says, it's probably not easily quantifiable or would skate within the standard deviation for fuel economy. But on more fuel efficient vehicles the economy difference is measurable.

Thanks for reply.I wouldn't call a 3.8 Genesis a "more fuel efficient vehicle" but I do get 25+ MPG on the highway which is pretty good for a 4500# car.
I'm really looking for someone who has found any drawback to installing an H8 instead of an H9 battery.

 

[Suburbazine]

Thanks for reply.I wouldn't call a 3.8 Genesis a "more fuel efficient vehicle" but I do get 25+ MPG on the highway which is pretty good for a 4500# car.
I'm really looking for someone who has found any drawback to installing an H8 instead of an H9 battery.

There won't be a drawback. It will start and operate the car just fine. It will also work just fine even in very cold weather, as the cranking amps required are still far less than any H8 will provide. Initial amps at 0*C is about 450 to move flywheel and then rotating amperage is about 220. Assuming you don't have any issues requiring a long crank time, there's plenty of capacity available.

If there was a potential drawback, it's that the battery tray will need modification to get the positive terminal close enough to the fuse block to connect, while still being able to lock the battery into place. Some people get around this by building a shoe spacer to take up the missing dimension from the H9.

 

[EdP]

There won't be a drawback. It will start and operate the car just fine. It will also work just fine even in very cold weather, as the cranking amps required are still far less than any H8 will provide. Initial amps at 0*C is about 450 to move flywheel and then rotating amperage is about 220. Assuming you don't have any issues requiring a long crank time, there's plenty of capacity available.

If there was a potential drawback, it's that the battery tray will need modification to get the positive terminal close enough to the fuse block to connect, while still being able to lock the battery into place. Some people get around this by building a shoe spacer to take up the missing dimension from the H9.

Alternative is to drive to the US and buy an H9 at Advance Auto for about $250USD/ $340CDN

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[carguy75]

Thanks for reply.I wouldn't call a 3.8 Genesis a "more fuel efficient vehicle" but I do get 25+ MPG on the highway which is pretty good for a 4500# car.
I'm really looking for someone who has found any drawback to installing an H8 instead of an H9 battery.

I would just use the proper size H9 battery. The cost difference is not that much between the two battery sizes. If both batteries have the same or similar ampere rating then the performance will be similar.

The main hurdle when using an H8 battery would be mostly a fitment issue since the Genesis battery configuration is based on a H9 size including cable length and the power control module mount.

It would be easier to just use the proper size battery.

 

[Genesiswonderer]

My 2016 3.8 AWD Sedan has the original Hyundai AGM battery. I'm in Calgary Canada & H9 batteries are in the $478 range for an H9 Interstate.
My car has 53000 Kilometers but was built in August 2015. Battery is fine so far but how long will it last & do I get any warning that it's failing? Our climate is cool & car is always garaged. I can get an H8 Energizer from Costco
for $299 but they don't carry an H9. H8 is 950 CCA Vs 1000 CCA for Interstate.
Will the H8 fit? Am I overthinking this & should I just wait & see when it starts to fail ?

Been using an H8 in a 2011 4.6 for 3 years now. Not really any issues other than I think the alternator has to work a little harder.

Personally, for the DH, i wouldn’t recommend it as it just has so many electronics. Someone put an H8 in the 2018 G90 we have and some of the electrical things seem to struggle in that car. And I’m sure it can’t be great for the alternator. Other than that car still works fine and we’ve seen 28 mpg on the highway many times. Not bad for a 5.0.

The energy management system (also known as Hyundai's Alternator Management System) cycles the battery charge level for optimum energy production. The car uses a table in the power management system that equates charge level to battery capacity, basically X voltage = X% battery capacity.

This is important because the car will switch the alternator OFF during cruise and low load conditions and transfer the operational load to the battery until the battery depletes to a certain point. At which point the car re-enables the alternator to bulk charge the battery at the most efficient output. The alternator at low output has more wasted energy than it does at higher output levels.

The massive battery is installed not because the car needs a lot of cranking amps, it's because it needs a lot of reserve capacity for this cycling mechanism to be effective. When the battery loses capacity, the power management system abridges or entirely disables economy cruise so as to not have a condition where the battery cannot start the car. The car doesn't have a feature to reprogram the battery size, so it assumes any under-spec battery is just a battery in poor condition. The system expects a certain range of guaranteed performance based on demand, basically a timer that is used to calculate capacity lost for a certain load over a certain time.

You can watch this process for yourself- plug a voltage meter into the 12v socket and it will bounce from ~14v to ~12.5v while driving.

And like Ed says, it's probably not easily quantifiable or would skate within the standard deviation for fuel economy. But on more fuel efficient vehicles the economy difference is measurable.

I always wondered why the voltage would drop in our 2011 when driving when watching the engineering menu, now I know. For proof of your concept, it does not do this anymore since new alternator and H8. It only did it with the H9.

Granted, that car doesn’t get driven much anymore so the battery is probably getting weaker.

 

[rroyce46]

Thanks to all for input.I will stick to an H9 after thinking through the complication of modifying the fitment & the chance of messing with the electronics possibly.