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

brucepick · 02-12-2012, 09:17 AM

Well I mapped out my plan of action.

Based on notes from California98Civic, it looks like these Gen 6 Civics draw somewhere around 15A without headlights or other major accessories. We don't have very precise information on this so I'd give it an accuracy of +/- 35% or so. Headlights on would add about 12A. In any case, with this setup I do expect to be able to drive an hour+ to work, hopefully even with headlights on as needed in winter, without exceeding the battery capacity.

I'll use a 40AH 12.8V LiFePO4 pack. The one I've selected has a BMS built into the pack that balances the cells, provides charge and discharge rate limits, and gives a few other protections also. I'll charge it overnight from wall current. It weighs only 16 lb so I should be able to remove it and give it a charge at work if needed, when traveling, etc. A full charge will take about 4 hrs. with the planned 10A charger plus 30 min. for the BMS to balance the cells afterwards.

(I extensively researched using a high end AGM lead cell by Odyssey, ~65AH and 60 lb. However you should only discharge it about 20-25% for optimum battery life. The functionally available ~13-16AH isn't a lot, and running several of those packs gets very heavy and also costly.)

At this point I plan to keep the oem battery in the car, connected ONLY to the alt and the starter. I can disable the alt via switching in the field power wires so I have some control over that.

[EDIT] (This calc was way off when originally posted) I calculated that if the starter draws 100A and it runs at most 2 seconds to start the car, that's about .055 AH of battery capacity per start, or about .55 AH/day if I do it ten times. Mostly I bump start the car after EOC but typically I do use the starter 2-3 time on each commute run, for a total of maybe 0.5AH/day, more if doing lots of EOC in heavy traffic. [/EDIT]

I'm not preserving very much of the Li pack's 40 AH capacity by using the lead pack for starting. I'd rather get a 2nd deep cycle of some type into that location to handle starter + headlights or just to supplement the Li pack in parallel. Of course if wired in parallel, it probably should be a matching chemistry Li pack. Or a simple lower cost lead deep cycle.

02-12-2012, 09:17 AM	#64 (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	Well I mapped out my plan of action. Based on notes from California98Civic, it looks like these Gen 6 Civics draw somewhere around 15A without headlights or other major accessories. We don't have very precise information on this so I'd give it an accuracy of +/- 35% or so. Headlights on would add about 12A. In any case, with this setup I do expect to be able to drive an hour+ to work, hopefully even with headlights on as needed in winter, without exceeding the battery capacity. I'll use a 40AH 12.8V LiFePO4 pack. The one I've selected has a BMS built into the pack that balances the cells, provides charge and discharge rate limits, and gives a few other protections also. I'll charge it overnight from wall current. It weighs only 16 lb so I should be able to remove it and give it a charge at work if needed, when traveling, etc. A full charge will take about 4 hrs. with the planned 10A charger plus 30 min. for the BMS to balance the cells afterwards. (I extensively researched using a high end AGM lead cell by Odyssey, ~65AH and 60 lb. However you should only discharge it about 20-25% for optimum battery life. The functionally available ~13-16AH isn't a lot, and running several of those packs gets very heavy and also costly.) At this point I plan to keep the oem battery in the car, connected ONLY to the alt and the starter. I can disable the alt via switching in the field power wires so I have some control over that. [EDIT] (This calc was way off when originally posted) I calculated that if the starter draws 100A and it runs at most 2 seconds to start the car, that's about .055 AH of battery capacity per start, or about .55 AH/day if I do it ten times. Mostly I bump start the car after EOC but typically I do use the starter 2-3 time on each commute run, for a total of maybe 0.5AH/day, more if doing lots of EOC in heavy traffic. [/EDIT] I'm not preserving very much of the Li pack's 40 AH capacity by using the lead pack for starting. I'd rather get a 2nd deep cycle of some type into that location to handle starter + headlights or just to supplement the Li pack in parallel. Of course if wired in parallel, it probably should be a matching chemistry Li pack. Or a simple lower cost lead deep cycle. __________________ Coast long and prosper. Driving '00 Honda Insight, acquired Feb 2016. Last edited by brucepick; 02-25-2012 at 08:38 AM..