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2014 Lexus CT200h
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So I bought CT200h used last year, and recently my MPG has gone to shiz. (Like 28~30)

It usually pull 35~42 MPG, and I realized that EV mode doesn't engage (or engine kicks in over 5 mph even with the slightest press on pedal)

After a brief investigation, I'm assuming it's Hybrid Battery problem.

So I'm thinking to replace the battery pack. Then learned about Lithium-ion Battery.

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One of their sale pitch was the battery pack upgrade increases the car's MPG by about 10~11MPG.

So this is my question.

Is it really 10~11MPG? or is it just a marketing exaggeration?

I would appreciate if anyone could give a real life review on these.
 

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2015 eminent white pearl
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Its would depend of their test conditions, obviously, right? But where are they getting that extra mileage. Its coming from increased battery capacity beyond that offered by the OEM battery. The EV mode has multiple triggers that determines when it come on and off. Pedal input, battery charge state, and speed. The lithium battery holds more energy, can sustain higher output longer and its lighter.

Check this out Rainbow Prius Hybrid Powered by Lithium!
 

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The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside

So I'm not sure how you can get better MPG with a bigger battery. If the energy for the battery comes from the ICE, then it makes no difference whether you are using the ICE to charge or to propel. A bigger battery just means that you have to use more ICE to fill it. The plug ins fix this by adding energy from the grid.
To me, I can only see that to get better MPG, you have to either drive better or add energy from another source ie go down a hill (assuming you didn't use more energy getting up the hill in the first place)
DD
 

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2015 eminent white pearl
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The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside

So I'm not sure how you can get better MPG with a bigger battery. If the energy for the battery comes from the ICE, then it makes no difference whether you are using the ICE to charge or to propel. A bigger battery just means that you have to use more ICE to fill it. The plug ins fix this by adding energy from the grid.
To me, I can only see that to get better MPG, you have to either drive better or add energy from another source ie go down a hill (assuming you didn't use more energy getting up the hill in the first place)
DD
You do realize the car charges when you brake, right? Thats why the needle goe to charge when you step on the brakes and when the battery ia full, the regen is wasted. The lithium has more energy density. You store more with less weight. Having a lighter weight higher capacity battery means less of the regen is wasted, but its stored. Not rocket science. Has nothing to do with conservation of energy.
 

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Yes but in order to get up to speed, you use energy. You cant brake unless you are moving. Hence my comment about hills.
Assuming that you drive up a hill and use a litre of petrol. Going down the other side you wont get that litre equivalent back, you might get about 30% thru the regeneration.
At best, if the battery weighs less, you will use less energy to move hence you will see a better MPG reading.
 

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2015 eminent white pearl
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Yes but in order to get up to speed, you use energy. You cant brake unless you are moving. Hence my comment about hills.
Assuming that you drive up a hill and use a litre of petrol. Going down the other side you wont get that litre equivalent back, you might get about 30% thru the regeneration.
At best, if the battery weighs less, you will use less energy to move hence you will see a better MPG reading.
Suppose you get 30% regen but the battery stop charging after 10% because its full. If you had a battery with greater capacity for same weight, you are able to store more of the regen for use. Its not difficult to understand. Its the difference in CAPACITY that results in greater mpg.
 

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By your own argument, if you extrapolate it out, if you put in a big enough battery, you will never need to charge it and be able to drive for ever. Relying on regenerative energy from braking without using the ICE to charge would put this into the realms of perpetual motion.
 

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By your own argument, if you extrapolate it out, if you put in a big enough battery, you will never need to charge it and be able to drive for ever. Relying on regenerative energy from braking without using the ICE to charge would put this into the realms of perpetual motion.
No one is denying that you would have to be moving to be able to brake. All I'm saying is that a battery with more capacity will be able to capture more regenated energy that a battery with less capacity. But it does sound like you are denying that a battery with more capacity is able to hold more power that a battery with less capacity.
 

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The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a system always has the same amount of energy, unless it's added from the outside

So I'm not sure how you can get better MPG with a bigger battery. If the energy for the battery comes from the ICE, then it makes no difference whether you are using the ICE to charge or to propel. A bigger battery just means that you have to use more ICE to fill it. The plug ins fix this by adding energy from the grid.
To me, I can only see that to get better MPG, you have to either drive better or add energy from another source ie go down a hill (assuming you didn't use more energy getting up the hill in the first place)
DD
you’re using the law in the wrong matter with how the hybrid works.. the ice charges the battery less than you can drain it.. when you pulse and glide you charge battery, when you brake you charge.. when you go down hill you charge… therefore you have more battery than what you use.. so if you have a bigger battery you now have more time in EV hence less ICE use therefore lower mpg. It’s actually not that hard to figure out..
 

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By your own argument, if you extrapolate it out, if you put in a big enough battery, you will never need to charge it and be able to drive for ever. Relying on regenerative energy from braking without using the ICE to charge would put this into the realms of perpetual motion.
No!… You will always need to charge it because your AC relies on the hybrid to run. The idea of a hybrid is go stay in charging/ev mode more than ice running. That’s why highway is less mpg than city driving. By your logic i bet you drive a hybrid like a regular car so that’s why you get bad mpg.
 

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Yes but in order to get up to speed, you use energy. You cant brake unless you are moving. Hence my comment about hills.
Assuming that you drive up a hill and use a litre of petrol. Going down the other side you wont get that litre equivalent back, you might get about 30% thru the regeneration.
At best, if the battery weighs less, you will use less energy to move hence you will see a better MPG reading.
going down hill and braking will charge your battery more than you think. Do you not drive a hybrid? Yes going up hill takes ice.. butgoing downhill will charge more than it takes going up
 

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2016 Blue Lexus CT200h F-Sport
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Let's please refrain from personal insults, derogatory comments, and belittling. The community is small enough as it is. The argument obviously can be made either way.

The original poster is looking for people with actual experience in upgrading their batteries to lithium ion. It doesn't sound like anyone who has posted so far meets that qualification.
 

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Let's please refrain from personal insults, derogatory comments, and belittling. The community is small enough as it is. The argument obviously can be made either way.

The original poster is looking for people with actual experience in upgrading their batteries to lithium ion. It doesn't sound like anyone who has posted so far meets that qualification.
That’s not what he’s looking for are you blind? Yeah it’s small alright it’s even smaller now. I’m outta here.
 

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That’s not what he’s looking for are you blind? Yeah it’s small alright it’s even smaller now. I’m outta here.
I apologize for hurting your feelings.

Has anyone actually upgraded to Lithium-ion Battery?
I would appreciate if anyone could give a real life review on these.
 

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Adding to the voices that have not tried it - I am keen to grab a pack when I need it. Dr Prius has an enthusiast following in matters hybrid. Lots of car nuts with hybrid cars use his solutions. If they were not up to scratch they wouldn't be recommended in the enthusiast community.

What are your options? In order of cost:
  • find and replace the dodgy cells
  • swap in a checked OK 2nd hand battery pack
  • install the Nexpower lithium battery pack
  • go for a factory replacement
If you are hands-on, the 1st option would be somewhat satisfying.
If not, I see nothing to loose in trying the Nexpower pack.

TLDR: I will grab one when I need one.
 

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Yes, I did purchase the Lithium batteries. They are in transit and I plan to do the swap myself when they arrive. I just pulled out the back seat and cleaned the blower fan to minimize downtime.

I checked my battery and it's at 49% health, which is pretty poor, the difference in voltage between blades is quite high. I expect to get a CEL soon and cant imagine what a strain it has put on my ICE. My options were to replace the bad cell (the #7 blade) and rebalance and hope the rest of the cells last a bit longer, rebalance the whole system (takes 3 days and costs @ $500-900), purchase new NiMh, or upgrade to LiFePo4 (Nexcell). I chose the last option. Why, because LiFePo4 is half the weight, more energy dense, and newer, cleaner technology(from manufacturing to use to recycling). It also has no off-gassing of hydrogen like NiMh. Quite a long list of pro's.
 

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Yes, I did purchase the Lithium batteries. They are in transit and I plan to do the swap myself when they arrive. I just pulled out the back seat and cleaned the blower fan to minimize downtime.

I checked my battery and it's at 49% health, which is pretty poor, the difference in voltage between blades is quite high. I expect to get a CEL soon and cant imagine what a strain it has put on my ICE. My options were to replace the bad cell (the #7 blade) and rebalance and hope the rest of the cells last a bit longer, rebalance the whole system (takes 3 days and costs @ $500-900), purchase new NiMh, or upgrade to LiFePo4 (Nexcell). I chose the last option. Why, because LiFePo4 is half the weight, more energy dense, and newer, cleaner technology(from manufacturing to use to recycling). It also has no off-gassing of hydrogen like NiMh. Quite a long list of pro's.
Can't wait to read your update!
 
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