Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

brucepick · 03-14-2014, 11:01 PM

Paul,

Nice project!

Before I ask for your help, one comment/suggestion:
Maybe you've already done this. Your starter doesn't need boosted 13.5 or 14.0 volts. I think you can connect it directly to a lead acid battery, and also connect your boost converter to the same battery and run the rest of the car off that. Higher voltage going to the starter might not be good for it.

I did a similar project but not as evolved, on my '97 Civic HX. That was before the engine blew (as mentioned here in this thread) by California98Civic. RIP my Civic HX.

I still have the two batteries I used for the Civic, and am now driving the '96 Accord. I expect to drive it another 12-18 months. I'm considering doing a similar project again. I hope I can get some input from you (pun??).

Overall plan:
I'm considering powering all the electrical from the two deep cycle (aka deep discharge) batteries, plus the regular starting battery which will only be used to start the car.

I found the car itself ran just fine on my 12.8V 40AH lithium battery. Over the course of a day's driving, about 2.5-3 hours, it would drop to somewhere around 11.8-12V while in use, which was OK.

The headlights didn't do as well, running on a 12V lead acid deep cycle battery. For these, I now want to use some of those Chinese 10A DC-DC boost converters you mentioned. The 2 headlight fuses are under the hood (bonnet); it will be easy to provide power there. I plan to set them at about 13.5 or 13.8V. I don't think I need a full 14V, and any slightly lower voltage will extend both battery and bulb life.

My lead acid battery for headlights was nominally rated about 100AH but really only good for about 40-50AH if you don't want to destroy the battery. After about 1 hour's drive the headlights were getting less than 12V and so were not very bright. If I needed headlights for both to and from work I was out of luck; I would need to hook up the alternator.

Question 1:
How many of those 10A DC-DC booster converters would I need, supporting only the headlights? The car uses 2-20A fuses for headlights, one each left and right. So theoretically 4x10A converters should provide 40A. However I think maybe it's better to provide 50-60A of capacity so as not to overtax the boosters. What do you think? The car uses separate high beam and low beam (dip) bulbs. At approx 10A each, when all four are lit that's 40A. This car lights all four bulbs when using the high beams. I don't think it's practical to reconfigure the circuit to use only one bulb set at a time - even on cars built to do that, there's always an instant when all bulbs are lit, when switching between high/low beams.

Question 2:
What do those boosters do when they get less than the specified 10V required input? Damage to the boosters? Or do they just not provide your specified output voltage briefly, and then go back to normal when the input voltage goes over the 10V minimum? Do you know?

I'm considering also using the boosted battery to power the wipers. The wipers never were very happy on the 12.x volts provided by the lithium pack. Just a matter of routing power to the wiper fuse patching it in.

Again, great project, and thanks in advance for any advice you can give.

03-14-2014, 11:01 PM	#53 (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	Paul, Nice project! Before I ask for your help, one comment/suggestion: Maybe you've already done this. Your starter doesn't need boosted 13.5 or 14.0 volts. I think you can connect it directly to a lead acid battery, and also connect your boost converter to the same battery and run the rest of the car off that. Higher voltage going to the starter might not be good for it. I did a similar project but not as evolved, on my '97 Civic HX. That was before the engine blew (as mentioned here in this thread) by California98Civic. RIP my Civic HX. I still have the two batteries I used for the Civic, and am now driving the '96 Accord. I expect to drive it another 12-18 months. I'm considering doing a similar project again. I hope I can get some input from you (pun??). Overall plan: I'm considering powering all the electrical from the two deep cycle (aka deep discharge) batteries, plus the regular starting battery which will only be used to start the car. I found the car itself ran just fine on my 12.8V 40AH lithium battery. Over the course of a day's driving, about 2.5-3 hours, it would drop to somewhere around 11.8-12V while in use, which was OK. The headlights didn't do as well, running on a 12V lead acid deep cycle battery. For these, I now want to use some of those Chinese 10A DC-DC boost converters you mentioned. The 2 headlight fuses are under the hood (bonnet); it will be easy to provide power there. I plan to set them at about 13.5 or 13.8V. I don't think I need a full 14V, and any slightly lower voltage will extend both battery and bulb life. My lead acid battery for headlights was nominally rated about 100AH but really only good for about 40-50AH if you don't want to destroy the battery. After about 1 hour's drive the headlights were getting less than 12V and so were not very bright. If I needed headlights for both to and from work I was out of luck; I would need to hook up the alternator. Question 1: How many of those 10A DC-DC booster converters would I need, supporting only the headlights? The car uses 2-20A fuses for headlights, one each left and right. So theoretically 4x10A converters should provide 40A. However I think maybe it's better to provide 50-60A of capacity so as not to overtax the boosters. What do you think? The car uses separate high beam and low beam (dip) bulbs. At approx 10A each, when all four are lit that's 40A. This car lights all four bulbs when using the high beams. I don't think it's practical to reconfigure the circuit to use only one bulb set at a time - even on cars built to do that, there's always an instant when all bulbs are lit, when switching between high/low beams. Question 2: What do those boosters do when they get less than the specified 10V required input? Damage to the boosters? Or do they just not provide your specified output voltage briefly, and then go back to normal when the input voltage goes over the 10V minimum? Do you know? I'm considering also using the boosted battery to power the wipers. The wipers never were very happy on the 12.x volts provided by the lithium pack. Just a matter of routing power to the wiper fuse patching it in. Again, great project, and thanks in advance for any advice you can give. __________________ Coast long and prosper. Driving '00 Honda Insight, acquired Feb 2016. Last edited by brucepick; 03-14-2014 at 11:07 PM..