Civic EPES: Alternator Delete Project (with additional lithium battery...) - Fuel Economy, Hypermiling, EcoModding News and Forum

brucepick · 01-06-2012, 11:40 PM

[UPDATE]
This project has been built and is in daily use. Some finishing touches remain to be done.
Circuit drawing, as-built (now shows fuses)
Project circuit notes
(These are .pdf files; you'll need Acrobat or another .pdf reader to view them)
These are a serious circuit diagram and detailed notes. Plan on much more than a quick look if you're interested in building this or something similar.

See this post in this thread for project pics.

[/UPDATE]

This thread is a spinoff from a discussion in the Alternator vs. no alternator thread. I had a few posts there, starting here: http://ecomodder.com/forum/showthrea...tml#post277402

I'm very interested in sometimes being able to de-load the alternator, and in being able to power lights and/or the car from a battery without alternator support. I WANT to run them at 13-14 volts for full brightness, not a paltry 11.5-ish volts.

I think I have a workable solution. A moderate sized (between 5-10 AH) lithium pack will give 13.2V. It can power the headlights. I'll recharge it overnight between commutes.

Bear in mind, I'm in the Northeast US. Our winters are cold and dark. My commute is 55 miles each way, between an hour to an hour 15 minutes. In winter I need to keep the headlights on for the entire ride.

My biggest frustration is that keeping the headlights on interferes with EOC. With the engine off and headlights on, it doesn't take long for voltage to drop below 11.5V. That's not good for the battery, and my nice headlights don't give full brightness either, under those conditions. So I've been limiting my EOC time. Coasting in gear with fuel cut isn't much of an option - you lose speed rapidly. In summer I was EOC'ing roughly 20% of my distance, but right now it's down to about half that.

My plan

Lithium iron phosphate (LiFePO4) cells are probably the best you can get right now. 26650M1's by A123 Systems are about $13 each. 3.3V, 2.5AH. A 4-pack will give 13.2V nominally, 2.5 AH and will cost $52. Multiple 4-packs would give 5, 7.5 or 10 AH. 10 AH would run my headlights for about an hour. A charger + power supply for it will run about $75-100.

With some clever switching I don't expect to need more than about 30 minutes coverage for a full day's commute, or (2) 4-packs. Over time, I can buy additional 4-packs and increase the system capacity.

I use a kill switch to initiate EOC. The same switch can trip a relay that would route power for the headlight circuit from the second (lithium) battery pack instead of the car's starting battery. Once I restart the engine, I can manually activate the relay to run the headlights off the main battery again.

I hope to also wire a switch into the alternator circuit to disable it while driving. With a long commute I think I don't really need to charge the battery at 14V the whole time. If I need to run headlights with the alt disabled, I can power the headlights from the Lithium pack to get full brightness, and have a good long run with the alt. disabled.

Earlier I considered a 14V, 50AH AGM battery. It would run the headlights for about 3 hours without a recharge. It's about the size of a typical automotive battery and weighs 43 lb. However with charger it would be $460. Unfortunately, beyond my budget. To see the battery and charger, search for XS Power D1400 and XS Power HF1415.

deathtrain · 01-07-2012, 12:14 AM

What do the 14v dewalt batteries made from? I had the same thought that you did but using 14v dewalts. they are light and easily carried. just people will ask why you have a dewalt chager and battery in my office LOL.

drmiller100 · 01-07-2012, 12:42 AM

have you looked at LED headlights?

oil pan 4 · 01-07-2012, 02:59 AM

Quote:

Originally Posted by brucepick

I WANT to run them at 13-14 volts for full brightness, not a paltry 11.5-ish volts.

It might be cheaper to build up 11 or 12 cell stacks of NiMH batteries.

brucepick · 01-07-2012, 08:00 AM

Quote:

Originally Posted by drmiller100

have you looked at LED headlights?

I'm interested in LEDs for the tail lights and front corner lights. I looked into LED headlights but my take was they're not yet ready for prime time.

brucepick · 01-07-2012, 08:08 AM

Quote:

Originally Posted by oil pan 4

It might be cheaper to build up 11 or 12 cell stacks of NiMH batteries.

The Li Fe Phos (not the same as regular Li Po, see descriptions below) can be discharged at a very high rate compared with NiMH.
The 2.5 AH, Li Fe Phos cells have Maximum Continuous Discharge 70A.
Two sets in parallel would have max cont discharge of 140A and would power your car's starter motor.
I found a 4.5AH NiMH with Standard Discharging Rate: 4.5A
I found a 3.5AH NiMH with Max.Discharging current 3.5A
NiMH rechargeables

You could look here for comments/discussion: Lithium batteries v/s NiMH batteries the Debate! Battery technologies | V is for Voltage electric vehicle forum

Below is a quote from a r/c hobby message board post RC Groups - View Single Post - Lipo vs. A123 vs. LiIon vs. LiFePO4 vs. NiMH:

Lithium-Polymer (LiPo) - this was an evolution of Li-ion that is used often in the RC hobby today. The packs are flat and somewhat flexible (but don't bend them, it can damage them), though sometimes can be contained within a hard case. They have a large amount of energy that can be delivered at very fast rates (high current) they recharge relatively quickly and are lightweight. They are also relatively easy to damage, both physically and electrically, and can catch fire and explode if mistreated (any battery can, but LiPos can be violent when they go). These are 3.7 volts per cell.

Lithium Iron Phosphate (A123/LiFePO4) - A123 is a brand-name for the LiFePO4 cells. These are technically Lithium-Ion batteries, but they're a specific subset, so they are considered different. They're generally available in two cell sizes in our hobby, 1100 mAh and 2300 mAh. They are round cells with hard cases. Because of the different chemistry, they are slightly heavier and slightly lower voltage than a comparable LiPo pack. However, they are showing to be much more durable than a comparable LiPo, being able to take more physical as well as electrical abuse. They can be discharged/recharged at higher rates than LiPos. These are 3.3 volts per cell.

Nickel Metal-hydride (NiMH) - slightly older technology that uses a completely different chemistry than Lithium-based batteries. It's heavier and less energy dense than LiPo, and ~1.2 volts per cell. You'll find these in hard round cases. They can be discharged/recharged relatively quickly. They are also quite durable and have been used for years, and still used today.

jakobnev · 01-07-2012, 08:27 AM

Having the switch be a relay that is controlled by the no-charging (or no oil pressure) light seems simple enough.

Did you see this thread: http://ecomodder.com/forum/showthrea...uce-16992.html

An alternative is to have the extra batt supply current to your main batt trough a voltage regulator. That way it just regulates the voltage the same way the alternator does, and automatically increases the current when the alt drops out.

brucepick · 01-07-2012, 08:40 AM

Quote:

Originally Posted by jakobnev

Having the switch be a relay that is controlled by the no-charging (or no oil pressure) light seems simple enough.

Did you see this thread: http://ecomodder.com/forum/showthrea...uce-16992.html

An alternative is to have the extra batt supply current to your main batt trough a voltage regulator. That way it just regulates the voltage the same way the alternator does, and automatically increases the current when the alt drops out.

Good ideas. I don't know enough about voltage regulators; I see a new research venture coming on.

3dplane · 01-07-2012, 10:14 AM

I saved 3.6 amps on my parking lights by going all led.
I did not do a "how to" on the process because it is a bit on the redneck side the way I did it but so far works flawless and I can put it back to original in a few minutes if I ever had to.
Before when I turned on the parking lights it had a 5.3 amp draw. Now it is 1.7 amps. An additional amp can be saved if I dim the interior illumination (cluster,a/c control head and a few switches).From full bright to full dim exactly one amp difference almost to the milliamp.

Nice to sit at a long red traffic light at dusk only pulling 800 milliamps with the exterior lit up.
The headlight on my car pulls 7.5 amps with the engine off and I'm looking into doing something about them.

2 taglights,2 rear side markers,2 tail lights,2 front corner lights are the main savings (3.6 amps) additionally I did my brake lights(all 3),dome light,trunk light but they are not on very often.

For your case where YOU need to see with them I would look into a DC to DC converter to keep your car battery voltage up and you could supply power to it with your custom lithium pack that you would charge later.

For my case the only part bothers me is sitting at redlights with engine off having to keep the headlights on when I really don't need to see with them (until I get out of town) so they are just sucking my battery for nothing. I will just put some diffused white low power leds in there to make people think I have a headlight on so I can keep the real headlight off until needed.

BTW I recommend you look at the smaller a123 cells on ebay! ($ / A/h cheaper than what you mentioned) 1-1.1 A/h rated 18650 cells. 30C continuous rated,I believe 60C burst. I have quite a few of them for projects/testing and testing 2 random cells shorted I got 137amps out of one and 128amps out of the other!!! (just long enough to get a reading.about one second)
I built a "micro" jump box out of 12 cells (4s 3p). Smaller than 3 packs of cigarettes and it will start a car!

Just some thoughts!
Barna

brucepick · 01-07-2012, 02:34 PM

Barna and Jakobnev

Maybe you can give me some info on DC-DC voltage regulators. Some places that sell them where I'll find the needed information posted?

I looked at some DC-DC v. regs that I found, and they were rated for 12V output. So I don't know if that's a true 12V or is it really 13.x so it will charge your 12V battery?? Really I think I need a DC-DC regulator that outputs about 13.5V and quite a few amps, correct?

And I believe it will need at least 14V input? Maybe will need 16-18V input???

Thanks, friends