Civic EPES: Alternator Delete Project (with additional lithium battery...)
 

[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.

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.

have you looked at LED headlights?

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

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.

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.

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.

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

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

Look at dc to dc converters for EVs. Yes it should output 13.5-14V. The input voltage is rather high because they are designed to be fed by EV pack voltage.
Making a high voltage small capacity pack is easy but for charging it back up you would have to find an acceptable method. ( tapping into the pack by charging leads and use multiple chargers, or get the appropriate high voltage charger etc.)

Here is the first one I found on an ebay search EV DC to DC Converter Electric Car Voltage Reduce 144V volt to 13.8V 35 Amp 480W | eBay

There was also talk about diy converters on this forum too but I did not search for that.

Barna

I looked for LEDs for our Civics [EDIT: I meant LED headlights, sorry, I found the others just fine and have been running them for months]. I did not find them (now watch someone post-up a quick link). I did find LEDs [headlamp] in the old-style round form, but those don't fit the car! I am running HID headlights. I paid extra to get the hi-beam ability. Total was $70. The regular beam wattage is 70w for the pair. It was 110w with the stock bulbs, IIRC. The HIDs work differently: they do not dim at lower voltage but they will cut-out entirely twice if you run the battery down under 11.2volts.

This might help - I didn't take the full amount of time needed to investigate fully.
LED Vehicle Bulb Finder

The site offers various bulbs for any given car. You can see pics and dimensions of the bulbs. I think from what you wrote, it would make sense to get a good look at the bulb housing and try estimate whether the LED assembly would fit the available space.

I'm not going to try look into the HID option; I've read negative reports on beam pattern results with HID conversions. But if you're happy with yours, that's a good thing.

Any other words of wisdom on finding DC-DC voltage regulators?? I'd likely have a battery pack somewhere between 13-18V and would want it to put out a steady 13.5 or so, to mimic a running alternator.

OTOH,
I'm still leaning towards a 4S (four cells in series) LiFePO4 pack that will give a nominal 13.2V. Several of those in parallel. Have them just run the headlights and maybe the heater fan if I can wire that up. Switch the small battery pack in manually when needed or with a clever relay circuit as discussed earlier.

The benefits: I'm making no headway on finding a proper DC-DC converter for this application. And, this method would avoid any losses from the DC-DC regulator that would modify the higher voltage battery pack. I'd be able to start using the battery pack with the number of cells I can afford to get, and add more in parallel later for increased AH. When it gets big enough to power the whole car for 3-2 hours, add battery disconnect switches to switch between the Li Fe Phos pack and the oem starting battery.

Did a proof-of-concept test today. Worked very well. 51 mpg going to work, and 48+ coming home.

No fancy LiFePO4, just a big old second battery (575 CCA rating) on the floor in front of the passenger seat, connected via a couple fat cables snaked out the door frame and under the hood's rear edge to the main battery connections.

Driving in rain, with headlights and wipers and even the fan running on low, I found I could coast with engine off (EOC) for even the longest distances I usually can go - about a mile - and voltage generally didn't drop below 11.5V, once I got past the warmup period.

That's the result I was looking for. With headlights on, EOC is very problematic because the battery voltage drops pretty quickly. With the additional battery capacity, voltage drop was not a problem, so I could EOC as much as the road would allow without needing to spin the engine just to keep the battery happy.

I've looked into building a 10AH pack of LiFePO4 cells, but building a charger for the pack would be pretty serious business.

I'm leaning towards a big Odyssey battery, maybe their PC1500. It's an AGM, about 66AH. Mount it in the trunk and run a fat cable up to the engine bay, like audio guys use to power their amps. I probably could ditch the regular battery that's in the engine bay.

It can be charged via the alternator. Or for a next step, I can build a switch to cutout the alt, and charge the battery off wall current. The battery will use up my budget so I'll have to get creative about funding the charger.

http://i188.photobucket.com/albums/z...0113120741.jpg

http://i188.photobucket.com/albums/z...113120739a.jpg
Hose clamps hold the bare copper strands to the battery posts, plus an assist from Vise-Grips.

Nicely improved numbers. Congratulations! When you compare recent fuel log entries, this certainly seems to prove your concept. The longer EOC is a benefit.

ok confused a little. Bruce what you did (if i read this right) was to add a battery and you got a plus in MPG because the alternator was not working as hard.

Or adding the battery is just allowing you to EOC longer than you where. And thats how you got the gain in MPG?

The second one is what's happening. The two batteries wired in parallel - just like when jump starting - have approximately double the capacity of the single battery. So with no support from the alternator when coasting, they last longer before voltage drops to "too low for comfort". Yesterday I was able to coast whenever I wanted, as long as I wanted, never needing to spin the engine to keep the battery voltage up. Voltage readout is on the dash, of course.

The alternator has to work just as hard because the car's needs for current haven't changed. Lights, fuel pump, ignition, computer, etc. etc. all the same. The batteries are just a "storage bucket" of sorts.

I have to say that not all the gain is from the increased battery system. Something has changed in the engine and/or computer that's allowing it to be in lean burn mode (an original factory feature of the Civic HX) at lower speeds for longer amount of time. This changed just over the last couple days. I don't know if some EGR piping finally got cleaned out or what. Maybe some rings got degunked and aren't sticking. Maybe the upped battery capacity has something to do with this improvement but I doubt it. In any case, I can do a much higher percentage of my commute in lean burn now, and at lower speeds. I just hope it lasts, because it's a real benefit.

I support the LED idea for ALL lights. I have been researching this for a while starting with night lighting in the house for very little power draw, then starting to target the car lol. In simple terms, Incondesent lights are my base point, fluorescent lights use about 1/4th the power to create the same amount of light, and LEDs use about 1/10th the power. So LEDs are nearly twice as efficent as fluorescent lights. The downside (or upside) of LEDs are that they are effected hugely on angle of light.

Check this out just to get an idea, there are tons of videos like this http://youtube.com/watch?v=y1yqWTU71DM

One thing to point out, when you are hitting 1w+ LEDs you MUST keep them cool, under 160C. I have read the figure of 12 square inches per 3w led running at FULL power.

Another thin to point out, LEDs are most efficent at less power draw compaired to their max. Example is, my 3w LEDs i'm working with are rated 700ma @ 3.2-4vdc (forward voltage), but I'm planning to run mine around 350ma which will probably only loose about 25% brightness.

One final note on useing "raw" LEDs (DIY setups), you must have a curent limiting device, resisters make heat at higher powered LEDs, so a DC to DC converter is ideal since they are 85-90+% efficent.

The LED method should be a LOT cheaper than trying to add a second battery, probably somewhere in the ball park of $30 or so for the headlight conversion, the rest of the lights you could buy from the linke above me for plug and play (built in resisters).


To give a real world example, I'm running 4 small led lights in my bed room as a night light (on 24/7) at 7ma with 13.8v across the series (around 100mw draw + how inefficent the power supply is). It provides as much or slightly more than a typical 7w night light, but the light is spread out over the entire room instead of just by the wall. Remember, 7w lights are a warm light, and LEDs are a cold light, which skews perception of brightness and color.

Good luck in either way you go about your task!

Remember - one feature (as yet unmentioned) of having a second or much larger battery is that I should be able to have it power the car with alternator disabled when headlights aren't needed.

I estimate that a battery of about 50-66 AH capacity should be good for 2-3 hours drive time or more, which would get me through a day's commute. Would also get me through a run in the FE competitions I've been in. In those situations my lights would be off anyway, so converting them to a more efficient light source wouldn't reduce current draw.

Re. LEDs,
I did a due diligence web search for LED headlights.
I've found replacements for most smaller bulbs but not for the headlights. Nice that they can be had for the Harleys.

I'm interested in replacing smaller bulbs with LEDs but it's the 55W x 2 headlights that draw down battery voltage. Four or even six corner bulbs at 5-8W each is a relatively smaller load on the system. I believe I won't escape the need to run the 110W of headlights any time soon. Yes I could run a pair of HIDs for 70W total but it's significant $$ for a savings of 40W.

LED headlights would require a complete reflector/lens/bulb holder assembly to replace the existing one. The YouTube above shows exactly that on the Harley. This is because halogen bulbs are built with a very small filament(s) located at the focal point of the optical system. No LED of that brightness will be as small as the short filament of a halogen bulb. So the optical assembly would have to be built to deal with the particular shape of the LED sources, focusing the light appropriately. It could happen but I haven't found them available - and any set of headlight assemblies is going to cost at least $100 or more. BTDT with a regular halogen-fit assembly for this car about 2-3 years ago.

The alt delete option would be a nice plus, not sure if savings would out weigh the cost involved or not.

LED lights bright enough for head lights cost ~$100 for a pair based on fog lamps which draw 15w x2 and depending on the room, you could ideally gut the back side of the head light assembly and mount the fog lamps inside there, at least that is my plan if my DIY approach is a fail. Here is an idea of what the differences would be, I drive mainly at night (midnight shift) so I need to see well since my trip is 70% along fields and see deer very often and hit one last winter on the express way.

http://www.youtube.com/watch?v=kdl1HW0_vfU

I don't know off hand what kind of draws everything else takes, but your current double battery setup should last your trip if you was 100% converted to LEDs, night or day.

I see a lot of talk saying the appropriate led headlight bulbs arent avail and you need to modify the lens housing etc.

what happens if I put a pair of these
into my car? wouldn't it work, its 6w that should be equivelant of like50-60w regular headlamp bulb

2 X Car H7 6W SMD LED Super White Headlight Bulb Light | eBay

H7 6W High Power Car Headlight Fog LED Constant Currency Head Light Bulb White | eBay

these are available in h3, h4, h7(in link) etc etc

According to what I have researched so far your figures would probably be closer to the 50w equivalent or a bit less depending how they designed the current limiting methods. Resisters = most inefficient method while constant current drivers are among the best. Just looking at it I would guess resister.

Quick and simple math, it appears to be basically 4 leds, 3 on the sides, and 1 direct out. So according to LED series parallel array wizard ....

voltage: 13.8v
No. LEDs: 4
forward voltage: 3.2v (most whites are 3 to 4v)

The result would be a 2.2 ohm resistor that dissipates 496.375 mW or ~500mw wasted of 6w. In a car that isn't bad at all, house lighting is pretty bad compared to what is out there. Since about 5.5w is converted to light via the LEDs, I would say they would almost exactly match a 55w headlight bulb. Just remember the effects of cold vs natural vs warm lights and our perception of it, if I remember right, cold light looks brighter than warm so it would be a plus :).

I am assuming here TOTAL draw is about 6w, and that it is not 6W at the LEDs only not counting the resister(s).

Either case... 12w vs 110w = savings :D and the LEDs are a great priced!

All in all, I would say try it and see, I know I'm going to be buying some! Thanks for the link share.


EDIT:

Looking at the expected life of 50k hours, I'm going to say that will not be a typical case, since 6w of leds should have (according to my past research) atleast 20 squre inches of AL to cool it. In other words, the life of them will be shorter if you go on long distant trips at night often, short distances and winter driving would allow them to last longer. LED life is directly related to quality and temp ran at. I would expect 10k hours out of them, which I would think would pay for its self in that time :).

I'm not sure I understand you completely. The stock corner bulbs and tail lights on our Civics are 20watts each. For relatively little $$ you could replace just the five tail/brake lights and reduce load by maybe 70 or 75 watts, correct? Of course the demand is not as constantly high as running the headlights. But the brake/tail light mod is what I did first, because I have to use the brake lights all the time, day or night.

BTW, re: raising the funding for it, I'll just share what I do when cash is tighter and I want/need something small like this that I am having difficulty justifying to myself or my wife. I cut something else I routinely budget for. I cut whatever it is for just for a short while, to "defray" the cost of the purchase. Just my method. I hope it helps.

2 X Car H7 6W SMD LED Super White Headlight Bulb Light | eBay

I think those will have an incorrect beam pattern and will bedazzle other drivers at night and might get you a big fine.

u sure?

isn't it the reflector and the back of the lamp housing that's responsible for this kind of thing, not the bulb?

these are made to be used as fog lamps which are close to the ground.
headlamps are higher up but are still directed at the ground.
no?

please correct me if im making a mistake

Well, reflectors don't give the same beam pattern regardless of the shape of the light source. (If they did they could violate the second law.) The short focal length reflectors on car headlamps are very sensitive to the source.

The reflector fact could be a problem, for the ones willing to go more of a DIY route (splitting the head light to install), you could install 4x 3w led in series each with a cone on them (45 degree linked below) and run them at 50~66% rated current. Probably would be best to have 2 at a wider angle, and 2 shorter so the sides light up well.

2pcs LED Lens for CREE Lumens Seoul 45 degree Matte | eBay

Don't forget current limiting in the design or you will burn them out fast, and sites suggest ~10in of heat sink surface area for cooling a fully powered 3w led (700ma) I would be planning to run at around 350-400ma so around 1/2 that should be about right for me.

Now I don't know what I want to try first lol, similar 6w led headlight lamps for my car are around $30 per pair or I already have 40 3w LEDs but not the cones or drivers/1-2w resister. Fun factor and learning experience is priceless though for me :)

Me too, man. A thought I have that is not as adventurous but could still be fun would be to install the Rigid Industries lights in the vid in post #23 above or the $30 ones your refer to AS FOG LIGHTS and then use them for lighting in the early dawn, late twilight, or to keep police off my back when I am rolling slowly and in less need of long range visibility. They seem to illuminate really well, and I think would be useful and power saving in the partial light situations. Would be fun to experiment. I'd have my 35w HIDs for the genuine dark, but the 15w LEDs for the twilight/dawn. What do you think? Would cars like mine and brucepick's still need the heat sink and such you describe or can the manufactured lights/reflectors be installed "plug and play"?

The lights sold are plug and play, them 15W fog lights are designed to cool in some way I'm sure. They would be good for running lights/just starting to get dark times, but I would think you wouldn't need that much light if your planning to use HID for dark lighting. Maybe look for some ~4w lights (4x 1w led) for cars just for the other people to see you factor + they would give a little light (about 30-35w comparable)

The only time current limiting or cooling is 100% needed is when you build it your self buying separate LEDs (2.5-4v normally each) not led bulbs rated for 12v and plug into car sockets, or the fog lights.

i wonder if this one Motorized BIKE GAS ENGINE parts - LED Head Light blue | eBay is as powerful as a car headlight, if it is near or at a conventional headlamp's power, then two to four of them should do the trick

-with some modifications to make it look normal that is ...

I like the "cut something from regular budget" idea.

Anyway, for my own driving I'm not so concerned about brake lights because I don't spend that much time braking. But my corner lights are on whenever I run the headlights of course, so they are a constant draw, even though they're not 21W bulbs like the brakes..

Brake lights, 21W each (My center brake light is already LED)
Back up lights, 21W each
Front + rear corner lights, 5W each in my Volvo manual
(Looks like Civic front corners might be 8W each)
(I think Civic has 2 bulbs on each rear corner?
Turn signals, 21W each

Anyway, those corner lights are always on so I'm interested. Kinda interested in LED brake lights too; they total about 60W when lit, so they count.

LED Headlights:

I am ignoring the LED headlights discussion. I am ignoring it because there is no way that an array of LEDs can give a properly formed beam when inserted into a system designed for a light source that very nearly a pinpoint in size.

Low beams need to have a severe cutoff above the horizontal plane to avoid blinding other drivers. That's a legal and a moral requirement. Never mind that some inexpensive aftermarket HIDs (different of course from LEDs) violate this daily.

High beams need to have a pencil shaped beam to put light out into the distance.

Neither of these is going to happen when the light source is the size of a Tootsie Roll, inserted in a system designed for a pinpoint light source.

That's not to say that you can't have an LED headlamp. But the housing, reflector and "bulb" have to be designed to work together. Not just be designed to FIT together.

I wouldn't mess with LED low beams.
As far as high beams I say go nuts, just be sure to cut them off as soon as you encounter on coming traffic.

Can we get all the talk about LEDs out of this thread?

these batteries are quite expensive.
i thought of a pair of 6v golf cart batteries wired for 12v would cut the $200 that a decent one costs

Yes they are pricey. Right now I'm considering an Odyssey PC1500 and a 25 amp Odyssey charger; about $275-ish for battery and $150 for charger.

I have some $$ from junking my old Volvo 240 so it will cover a good chunk of the cost.

However I'm not completely decided on this yet. I want to test whether the computer will allow lean burn with the alternator out of the circuit, running somewhere around 12V. If not, I might go with a smaller deep cycle battery that will fit in the standard under-hood location, just to handle EOC without losing as much voltage as my current (sorry for pun) starting battery. The PC1500 is 10.85 x 6.99 x 7.82 inches and 53 lb.; will have to go in the trunk. However, I'm pretty sure it would power the whole car's electrical system for several hours with no help at all from the alternator. I'd keep the alt installed, just switched off unless I need it to support a longer drive. Generally I expect to keep the battery charged from A/C, overnight.

Why get this? First off, it's AGM, so I can have it in the cabin/trunk without concern about hydrogen venting. The trunk is same as cabin as far as that safety issue is concerned.

Second, it gives a bit more voltage than a simple flooded battery due to the high purity lead and strong acid concentration - so in EOC the headlights will be brighter. Not same as when running at 14V with alternator, but better than with a regular 12V battery of any automotive size.

Third, overall quality is unusually high. High purity lead plates and strong, highly concentrated acid. Not made the least expensive way possible. It's a deep cycle battery. There are inexpensive flooded deep cycles but they're not AGM and won't give approx 400 cycles of deep discharge like this one is rated.

If you are worried about low voltage not engauging lean burn why not make a higher voltage battery?
You could find a 6 and 8 volt battery from the same manufacturer that use the same cells just more or less of them in each battery and make your self a 14 volt battery.

I'm trying to avoid that degree of home-brew. I found a nice 14V AGM battery but found only one on the market. XS Power D1400. Rated 50 AH. Cost with dedicated charger would be about the same as the ~12V Odyssey I described above. I hope to test for lean burn at 12V this week or maybe next weekend. Hard to get time for real world stuff; much easier to type on a keyboard :-)

Alternator vs. no alternator thread:

The use of a spare battery to reduce alt loading has merit.
I wonder if you could just manually switch the alt on/off as needed.

Late model BMWs shut off the alt when the battery reaches~80% charge.
Then the remaining 20% gets charged by putting the alt on when the brakes are applied or when the car decelerates.

This has a decelerating effect so you are actually "recovering" energy which goes to the battery.

Maybe you could do something similar - manually with a gauge and a switch???