Try this link to my thread on the Honda Accord forum. You will see the pictures there also.
https://www.driveaccord.net/threads...ce-upgrades-adventure-and-more.570743/page-14
Using LifePO4 battery in my 2024 Honda Accord Hybrid for great mileage. Your thoughts?
- Thread starter PetitFrereArmada
- Start date
https://www.driveaccord.net/threads...ce-upgrades-adventure-and-more.570743/page-14
OVERKILL
$100 Site Donor 2021
Will your insurance cover the total loss if the battery burns your car down? Just curious, since you are using a non-standard battery here.
Honestly, I do not know for sure, but I can tell you that if my car burns down I will file it on my insurance immediately. And I will hope they pay to get the car replaced.
OVERKILL
$100 Site Donor 2021
Might be worthwhile to call and ask.
I am not a soothsayer who sees the future, but I can tell you that I know their answer. They will say NO!
So, I am just hoping the battery does not burn down my car. I plan to keep the battery in my car for a while until I atleast draw a conclusion from my experiment if the battery helps to maintain consistent high mpg numbers or not.
It is a trade off between a large DC->DC converter (with a large capacitor to stabilize the output) or a smaller one with a 12V battery. I don't think they cannot be done, but rather focus the R&D on the more important things and just leave the 12V system alone to reduce risk.
To add to that, there was a claim somewhere along the way in here about weight savings.
What's the difference in weight between the stock lead acid battery and this battery? Would 30lbs be a realistic number if the original is say 40lbs and this one is 10lbs? I'm sort of pulling those numbers out of my rear end, especially as I doubt the original weighs 40lbs and the replacement is as light as 10lbs, but let's go with it for the point(s) I want to make.
Google tells me that depending on the trim, 3,458-3,532lbs is the curb weight of a 2024 Accord Hybrid. I'm actually surprised a modern vehicle the size of an Accord is that light, but I'll go with it. That means that the battery change is less than 1% of the total weight of the car. Somehow that translates to a 10% increase in gas mileage?
Just to go with a few other points:
1. If I let my work backpack get too full, it might push 30lbs. I think my MKZ is about the same weight as an Accord Hybrid, although of course it's a different beast. Still, though, if I claimed I saw a 10% difference in gas mileage on days I didn't have my work backpack in the car, everyone would(rightly) say I was crazy.
2. I'm 6'2" and weigh about 230lbs. I know I'm a bit on the pudgy side, and I'm sure my doctor would be really happy if I was more like 200lbs. If I were to lose 30lbs, would my gas mileage increase by 10%? No, of course not. It certainly hasn't changed notice from when I was more like 280lbs a few years ago. For a lot of Americans wanting to haul 30lbs less regularly in their car, though, losing weight themselves would probably be a better strategy..
3. Offhand, a gallon of gasoline is, what, 6lbs(based on water is 8lbs/gallon and most non-halogenated organics have a specific gravity between .7 and .8)? I'm sure that's close enough. A 2024 Accord Hybrid has a 12.8 gallon gas tank. That means a full tank is ~77lbs, and a 1/4 full tank is 19.2lbs. We'll call it 50lbs difference, or 25lbs difference between half and full. Someone fixated on hypermiling could easily cut about as much weight as this battery by say only filling their tank half full...
This is the odometer of the guy who bought the LifePO4 battery and claimed that after he installed it, he started getting consistently high mpg numbers. Look at the pictures of his odometer.
This thread is my own experiment to see if I will get the same results after installing the LiFePO4 battery. This experiment will last for some months before I can draw my own conclusion.
Look at his pictures below.
It shows he got 61 mpg over 10,000 miles.
It also shows he got 71 mpg over 3,216 miles.
So I bought the battery to also see if I will consistently be getting higher mpg in city driving.
Here are the pictures of his odometer to show the high mpg numbers. Even a Camry cannot claim this. A Toyota Prius cannot easily claim this either.
This thread is my own experiment to see if I will get the same results after installing the LiFePO4 battery. This experiment will last for some months before I can draw my own conclusion.
Look at his pictures below.
It shows he got 61 mpg over 10,000 miles.
It also shows he got 71 mpg over 3,216 miles.
So I bought the battery to also see if I will consistently be getting higher mpg in city driving.
Here are the pictures of his odometer to show the high mpg numbers. Even a Camry cannot claim this. A Toyota Prius cannot easily claim this either.
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An Honda dealer cannot "void a warranty" if that's actually what your 30 plus year honda tech said he's beyond an idiot.
they can and probably will refuse to cover under the warranty an electrical repair that can be related to the battery. That is not even close to the same thing as "voiding a warranty".
People need to stop saying "void warranty" because it makes you sound stupid.
JHZR2
Staff member
Good question.
The HAH battery is used differently than a typical SLI battery. And it’s often allowed to drop real low. Lower than is healthy for a lead acid battery.
LFP drop in.12v replacements are real, and perform well in use cases similar to a hybrid. No high current crank condition, no high rate uncontrolled alternator. Below freezing issues are real. NATO 6T batteries have resolved this through internal heaters. Not sure the run of the mill 12v will have that.
A hybrid with a tiny battery to eat up harmonics and ripple, and keep the keyless entry and a few relays on is an ideal place for li-ion. But it has its issues too.
You’re an engineer, with a PhD, and understand batteries better than anyone.
Was my BTU to watts to amps math correct?
How much does it take to charge/maintain a typical LA battery in normal use?
The sustained load on most cars is dozens of amps to run things like fuel pump, ECU, injectors, blower motors, headlights, and infotainment, with momentary loads like windows, ABS module, perhaps, brake lights.
For the 12V system, not the hybrid system, I just don’t see how a battery chemistry change makes much of a difference - the 12V system is there to start the engine, and provide some capacity for momentary surge load like window operation, brake lights, whatever, while the alternator sustains the steady state loads.
Most of my cars have a 140 Amp alternator. Fairly typical.
I just don’t see how you can gain a reduction of 250 amps load to explain the fuel efficiency increase when we are not changing the load on that alternator, and that load is created by running accessories.
JHZR2
Staff member
TBH I hadn’t even read through that far in the thread when replying.
My first gut reaction is that charge control, and use of the battery, and provision of the power for a range of things is done differently.
It’s not uncommon for the HAH battery to be maintained at 12.5V in use (less than 100% SOC), and sit at 11.9-12V after parked a while.
My point was that it isn’t reliant on the battery the same way. Sitting at low SOCs is damaging to a lead acid battery, but not to a Li-ion. In fact, it’s favorable for the Li-ion.
Regarding math, the battery is either charged or it isn’t. My HAH has a group 51 battery. Call it 55Ah. And let’s say it sits between 0% SOC and 95% SOC every single trip. That’s about 650Wh.
How much fuel does it take to make 650Wh? Well, the inverter is probably 97% efficient, the motor and drive is probably 95% efficient, and the engine is about 30% efficient at best. So that’s the math.
If it is fully charged, then I’d call it <0.5A. If not, see above.
Note that the Li-ion requires zero, it can sit at any SOC it desires. It will charge slightly more efficiently, but it will take about the same Wh overall to fully charge from zero to full. But there could be a scenario where the HAH maintains at 12.5, the Li-ion couldn’t care less, maybe the charge control doesn’t even invoke a charge, while the lead acid would absorb. I don’t know. But it’s Wh…
All of that is handled by the hybrid battery and motor generator. The 12v battery may clean up power quality a bit. Not much else.
I tend to agree. Unless the car is short tripped and the parasitical are high enough that it does a real number on the lead acid, but less of one on the Li-ion. We do see that sometimes. But it’s going to be a difference of watt-hours, not massive, IMO.
I’m not either. At least not at the level that is being claimed. We know “smart” alternator charging is a thing, and can offer incremental mpg benefit. But that’s fractions of a MPG, not huge amounts, IMO.
And the batteries are small. The Li-ion will be half the weight. But half of a small amount is a small amount.
So it doesn’t add up, IMO.
How much was the final purchase price with shipping ?
https://www.driveaccord.net/threads...e.570743/page-12?post_id=6974359#post-6974359
Posted by @X686016
Reading through that thread and, wow...
Apparently it was $350 total, bought from a seller on Alibaba. That would instill me with a lot of confidence...
Also, apparently the battery is a touch over 20lbs. Per the OP, the stock lead acid was 27lbs. So much for one of the claimed benefits being weight savings-7lbs...
They also added a full sized spare. How much does that weigh? A lot more than 7lbs I'm sure.
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This what I wrote on my Accord blog and it answers your question.
"I paid $345.XX for the battery. That includes a whopping $150 for shipping!!! The Battery itself was about $160 and then they added tax and shipping. I was ok paying the total amount of $345.XX."
Very correct.
The new battery weighs 20.8 lbs. The oem battery weighs 27.2 lbs.
I bought the battery from a seller on alibaba. They shipped the battery and it was held by US customs for inspection for some days or say more than a week before it was released.
Yes, my car did not come with a full size spare. I bought and installed a full size spare. It definitely added some real weight. I think maybe if I removed the spare tire, I may gain atleast 1 more mpg on my number.
As of today, I am averaging 65 mpg after 372 miles. This is 50% city and 50% highway with a top speed of about 60 mph. My tires are set at 36 psi.
I do not know if the LiFePO4 battery is making it easier for me to maintain this mpg, but I will see as time goes by I still have many months before I draw any conclusion if using this battery helps me easily get higher mpg numbers.
I do not know if the LiFePO4 battery is making it easier for me to maintain this mpg, but I will see as time goes by I still have many months before I draw any conclusion if using this battery helps me easily get higher mpg numbers.
JHZR2
Staff member
What is your AC set at? Ive read thst HAH has ideal efficiency with ac set at 70, Econ mode, and of course don’t let it change into heating mode…. But ac use will be a big factor.As of today, I am averaging 65 mpg after 372 miles. This is 50% city and 50% highway with a top speed of about 60 mph. My tires are set at 36 psi.
I do not know if the LiFePO4 battery is making it easier for me to maintain this mpg, but I will see as time goes by I still have many months before I draw any conclusion if using this battery helps me easily get higher mpg numbers.
I drive only in ECON mode. My ac js set at 60. In Econ mode, the ac is not as cold as in normal mode.
When I hypermile, I turn off the ac any time I feel I can live without it. Also, I almost always run my ac only at 60. I never chose any other number because at 60 in econ mode, the ac is dialed back a little bit. It is not as cold.
