LiFePO4 Car Battery replacement Batteries for cranking

[BiGH]

Hey everyone,
Has anyone used a lifepo4 car battery replacement battery? I know it won't save much fuel, but i wonder if you recharged it through the grid, and had a switch to turn the alternator on and off if it would help save a bit of fuel / provide more power.

I'm considering doing some hypermiling mods to my car. (engine off coasting has halved my fuel usage!)

Battery replacements:
similar to these: http://headway-cn.en.alibaba.com/pr...ry_pack_with_petrol_energy_saving_system.html

and these:
http://www.thunder-sky.com/products_en.asp?fid=66&fid2=82


edit: here's a really silly idea: run a small electric motor to turn the serpentine belt or a custom crank belt.

 

[Rassy]

Hi BiGH. Your on/off alternator ideas may be helpful. We have had discussions on the forum about the HF model of the Honda CRX. One of the things they did to help get the 55 MPG was to turn off the alternator when the engine was under load. I think they used an electric clutch similar to those found on air conditioners.

 

[BiGH]

Hi BiGH. Your on/off alternator ideas may be helpful. We have had discussions on the forum about the HF model of the Honda CRX. One of the things they did to help get the 55 MPG was to turn off the alternator when the engine was under load. I think they used an electric clutch similar to those found on air conditioners.

Interesting. I was thinking of going the electrical route - ie using a high amp relay to switch off the output thus reducing drag on the setup. with a switch in cabin to do it.

I was also looking at a engine kill pushbutton

 

[cell_man]

I'm sure no load on the Alternator would reduce the drag significantly. Would be interesting to see how much power it takes to turn an alternator with no load. Word of warning on turning the engine off. My father told me about someone doing this when they were going downhill. It works fine till the vacuum is lost and then you loose your braking assistance not to mention power steering which was lost the instant the engine turned off on one of my previous cars. No brakes and very heavy steering is not a good combo. Take care

 

[BMI]

BiGH I have had my BMI LiFePO4 fuel saving battery in my car for nearly two years now. Same battery as pictured below. I have supplied these in the past to several customers in Europe where they seem to be far more familar with the benefits of these packs.
The battery in my Toyota Camry is great and it has certainly saved me some fuel. I quite regularly drive from Sydney to Brisbane and before with the old lead battery I could not quite make it to Grafton on a full tank from Sydney. Since fitting the LiFePO4 pack I can get to Grafton on a full tank and I have a couple of litres in the tank to spare.
You will probably notice the fuel savings for long distance highway driving but not on stop start city driving.
View attachment BMI LiFePO4 Fuel Saving Battery.JPG
The lithium battery is so much smaller than the original lead acid battery so all I did was use a piece of scrap timer to space out the bracket rather than make up a whole new mounting bracket. It is supposed to be only a temporary solution!
View attachment BMI Fuel Saving battery in Camry.JPG

 

[BMI]

Some more testing results and technical info here-
View attachment Why Save Fuel (Rev1).doc

 

[hydro-one]

Hogwash!! My lead acid battery got me more mpg, after i funneled all the hydrogen/oxygen bubbles, back into the air cleaner. This will recover any efficency lost to higher frequency alternators (voltage swing is absorbed by electrolysis reaction) This futhger increases combustion pressure by way of a hydrogen shock wave, and atomization is increased as well!!! two benefits in one!!! but seriously i would be worried about my engine oil pressure with all that starting and stopping the motor? increased wear? need electric oil pump to keep up the pressure?

 

[AndyH]

You certainly can use a LiFePO4 as a starting battery. The largest benefit will be the weight reduction. The 4S2P (20Ah) PSI pack in my VW diesel weights just under 11 pounds while the Optima red top I used before lithium weighed 38 lbs, and the OEM size chunk of lead was closer to 45lbs. Lower weight and thus lower rolling resistance affects all phases of the drive.

As for other fuel economy numbers...beware of testimonials and the power of suggestion. One example: http://ecomodder.com/blog/one-big-reason-not-to-trust-real-world-fuel-economy-testing/

One US lab that's certified to conduct government tests is Southwest Research Institute (SwRI) here in San Antonio. Here's an overview of their on-road testing: http://www.swri.org/3pubs/BROCHURE/d08/FuelEcon/FuelEcon.htm Note some important points - test and control vehicles on the road at the same time, standardized fuel, weather monitoring, tyre pressure monitoring, vehicle weight standardization, and vehicle operators trained to perform standardized tests. (Note - multiple vehicles on the road - trained drivers - and none of them know which are the 'test vehicles' and which is 'control'...)

Fuel and oil testing done in lab conditions is conducted in accordance with internationally-recognized ASTM procedures. For example - to see how a new engine oil formulation affects fuel economy, it's run against standardized test oil. In order to conduct a valid test, the following parameters are accounted for: (From the ASTM: http://www.astm.org/Standards/D6837.htm)

"This test method covers an engine test procedure for the measurement of the effects of automotive engine oils on the fuel economy of passenger cars and light-duty trucks with gross vehicle weight of 3856 kg or less. The tests are conducted on a dynamometer test stand using a specified spark-ignition engine with a displacement of 4.6-L. It applies to multiviscosity grade oils used in these applications."

(All tests are run on the same type of engine. Engines are completely rebuilt and run-in with a standard procedure before tests are run -- each test is run on identical equipment in a controlled environment with standardized fuel, a certified process, and as conducted by trained operators. This test protocol can measure effects of moving from 5W-20 to 0W-20 engine oil, for example, or petroleum to synthetic.)

Test Engine Configuration 6.2
Laboratory Ambient Conditions 6.3
Engine Speed and Torque Control 6.4
Dynamometer 6.4.1
Dynamometer Torque 6.4.2
Engine Cooling System 6.5
External Oil System 6.6
Fuel System 6.7
Fuel Flow Measurement 6.7.2
Fuel Temperature and Pressure Control to the Fuel Flowmeter 6.7.3
Fuel Temperature and Pressure Control to Engine Fuel Rail 6.7.4
Fuel Supply Pumps 6.7.5
Fuel Filtering 6.7.6
Engine Intake Air Supply 6.8
Intake Air Humidity 6.8.1
Intake Air Filtration 6.8.2
Intake Air Pressure Relief 6.8.3
Temperature Measurement 6.9
Thermocouple Location 6.9.5
AFR Determination 6.10
Exhaust and Exhaust Back Pressure Systems 6.11
Exhaust Manifolds 6.11.1
Laboratory Exhaust System 6.11.2
Exhaust Back Pressure 6.11.3
Pressure Measurement and Pressure Sensor
Locations 6.12
Engine Oil 6.12.2
Fuel to Fuel Flowmeter 6.12.3
Fuel to Engine Fuel Rail 6.12.4
Exhaust Back Pressure 6.12.5
Intake Air 6.12.6
Intake Manifold Vacuum/Absolute Pressure 6.12.7
Coolant Flow Differential Pressure 6.12.8
Crankcase Pressure 6.12.9
Engine Hardware and Related Apparatus 6.13
Test Engine Configuration 6.13.1
ECM/EEC (Engine Control) Module 6.13.2
Thermostat/Orifice Plate 6.13.3
Intake Manifold 6.13.4
Flywheel 6.13.5
Wiring Harnesses 6.13.6
EGR Block-Off Plate 6.13.7
Oil Pan 6.13.8
Oil Pump Screen and Pickup Tube 6.13.9
Idle Speed Control Solenoid (ISC) Block-Off Plate 6.13.10
Engine Water Pump 6.13.11
Thermostat Housing 6.13.12
Oil Filter Adapter 6.13.13
Fuel Rail 6.13.14
Miscellaneous Apparatus Related to Engine Operation 6.14
Timing Light 6.14.1
Reagents and Materials 7
Engine Oil 7.1
Test Fuel 7.2
Engine Coolant 7.3
Cleaning Materials 7.4
Preparation of Apparatus 8
Test Stand Preparation 8.2
Engine Preparation 9
Cleaning of Engine Parts 9.2
Engine Assembly Procedure 9.3
General Assembly Instructions 9.3.1
Bolt Torque Specifications 9.3.2
Sealing Compounds 9.3.3
Harmonic Balancer 9.3.5
Oil Pan 9.3.6
Intake Manifold 9.3.7
Camshaft Covers 9.3.8
Thermostat 9.3.9
Thermostat Housing 9.3.10
Coolant Inlet 9.3.11
Oil Filter Adapter 9.3.12
Dipstick Tube 9.3.13
Water Pump 9.3.14
Sensors, Switches, Valves, and Positioners 9.3.15
Ignition System 9.3.16
Fuel Injection System 9.3.17
Intake Air System 9.3.18
Engine Management System (Spark and Fuel Control) 9.3.19
Accessory Drive Units 9.3.20
Exhaust Manifolds 9.3.21
Engine Flywheel and Guards 9.3.22
Lifting of Assembled Engines 9.3.23
Engine Mounts 9.3.24
Calibration 10
Stand/Engine Calibration 10.1
Procedure 10.1.1
Reporting of Reference Results 10.1.2
Analysis of Reference/Calibration Oils 10.1.3
Instrument Calibration 10.2
Engine Torque Measurement System 10.2.1
Fuel Flow Measurement System 10.2.2
Coolant Flow Measurement System 10.2.3
Thermocouple and Temperature Measurement System 10.2.4
Humidity Measurement System 10.2.5
Other Instrumentation 10.2.6
Test Procedure 11
Preparation for Initial Start-up of New Engine 11.1
External Oil System 11.1.1
Flush Effectiveness Demonstration 11.1.2
Preparation for Oil Charge 11.1.3
Oil Charge for Coolant Flush 11.1.4
Engine Coolant Charge for Coolant Flush 11.1.5
Initial Engine Start-up 11.2
Coolant Flush 11.3
New Engine Break-In 11.4
Oil Charge for Break-In 11.4.2
Break-In Operating Conditions 11.4.3
Routine Test Operation 11.5
Start-Up and Shutdown Procedures 11.5.8
Flying Flush Oil Exchange Procedures 11.5.9
Test Operating Stages 11.5.10
Stabilization to Stage Conditions 11.5.11
Stabilized BSFC Measurement Cycle 11.5.12
Data Logging 11.5.13
BC Oil Flush Procedure for BC Oil Before Test
Oil 11.5.14
BSFC Measurement of BC Oil Before Test Oil 11.5.15
Test Oil Flush Procedure 11.5.16
Test Oil Aging 11.5.17
BSFC Measurement of Aged (Phase I) Test Oil 11.5.18
Aging Phase II 11.5.19
BSFC Measurement of Aged (Phase II) Test Oil 11.5.21
BC Oil Flush Procedure for BC Oil After Test Oil 11.5.22
BSFC Measurement for BC Oil After Test Oil 11.5.23
General Test Data Logging Forms 11.5.24
Diagnostic Review Procedures 11.5.25
Determination of Test Results 12
FEI1 and FEI2 Calculations 12.1
Final Test Report 13
Validity Statement 13.1
Report Format 13.2
Precision and Bias 15
Precision 15.1
Validity 15.2
Test Stand Calibration Status 15.2.1
Validity Interpretation of Deviant Operational Conditions 15.2.2
Bias 15.3

To generate meaningful numbers for fuel economy due to a battery swap, the tests should be run in this type of controlled environment with a double-blind protocol and trained staff -- not on a road with the vehicle operator (and battery shop owner...) behind the wheel. As you probably already know - one can significantly affect fuel economy simply by making tiny changes in driver behaviour. I can swing the fuel economy in my '97 VW Passat TDI between 0 and 52 MPG (hey - more than 6000 MPG down hill!) thru driver behaviour alone...

Testimonials are not science.

Andy

 

[RPA]

As an ASE certified auto tech I can tell you right now that changing your battery will not significantly increase your fuel mileage at all. I would also be concerned about overcharging these batteries. Most alternators these days put out over 100 amps.

@ BiGH

Your belt driven idea isn't as crazy as you think. GM did the same thing as a poor mans hybrid in the Saturn Vue. Also, instead of putting a relay into the the output of the alternator it would be a lot easier to just run a switch off of one the control wires to the alternator.

 

[patrickza]

Andy or others, how would you do this as a home user. Would you use a 4 cell BMS or just hope the cells never die?

 

[BMI]

If you use matched cells you don't need a BMS (though LVC protection is handy to have).
About a year ago I supplied a customer (and friend) of mine with 8 cells to build a car start pack for his car. He machined top and bottom frames from nylon to hold the cells. He sent me a photo of what he had done.
He was concerned about the cells getting out of balance but has found that since the BMI cells are so closely matched it is not a problem. In fact he was that concerned about cell imbalance occurring that he would check the voltage of each cell every week or two. He got back to me to say how amazed he was to find that the longer he has used the pack the closer the cells would become in balance by themselves.

 

[monster]

well its cirtianly possible to disconnect the alternator and either solar or grid charge the battery when you get home. the disconnected alternator will save some fuel but at the cost of flexibility. taking the wing mirrors off would save substantially more fuel. its worth changing your headlights for LED or CFL Bulbs. we do this all the time in our houses but over-look it in our cars. plus they are more reliyable so you wont get pulled over for a broken tail light.

 

[biohazardman]

Hi BiGH. Your on/off alternator ideas may be helpful. We have had discussions on the forum about the HF model of the Honda CRX. One of the things they did to help get the 55 MPG was to turn off the alternator when the engine was under load. I think they used an electric clutch similar to those found on air conditioners.

Interesting. I was thinking of going the electrical route - ie using a high amp relay to switch off the output thus reducing drag on the setup. with a switch in cabin to do it.

I was also looking at a engine kill pushbutton

If the output wire comes off/gets disconnected, you have a toasted alternator in very short order. I did not make it a half mile before my alt. fried after the output wire broke loose some years back. Possibly, there is a way around this but I don't know it at the time.
Some have used small DC motors to run their water pumps to lessen the constant power loss there. Just another thought in the grand scheme of things.

 

[AndyH]

Andy or others, how would you do this as a home user. Would you use a 4 cell BMS or just hope the cells never die?

Hi Patrick,

I used to think that I could just put 4 cells in series and skip the BMS. I also used to think that a fairly well balanced pack could be managed by routinely under charging and by staying clear of the minimum low voltage point, but that doesn't work very well in the real world. One example is that even though the Thunder Sky TSL charger is set for 3.62V per cell, I'm getting cells pushed routinely over 4.2V during charging when I don't use a shunt or BMS.

A car starter battery is nearly always relatively full, and nearly always on a charger. It's generally not deep cycled but can be from time to time - like when I forget to shut the lights off. I think that with my starter battery, which in my VW diesel is maintained by a 120A alternator and a 14.1V "12V buss", I'll need charge control and shunts constantly and LVC with active cut-off for the ocassional unplanned deep cycle.

I don't enough information yet to 'draw a line in the sand' but this is how it's looking so far.

Andy