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

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.

01-06-2012, 11:40 PM	#1 (permalink)
brucepick OCD Master EcoModder Join Date: Dec 2007 Location: Eastern CT, USA Posts: 1,936 Outasight - '00 Honda Insight Team Honda Gen-1 Insights 90 day: 54.18 mpg (US) Thanks: 431 Thanked 396 Times in 264 Posts	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. __________________ Coast long and prosper. Driving '00 Honda Insight, acquired Feb 2016. Last edited by brucepick; 04-28-2012 at 08:41 AM..