Civic VX MPG project (Delete Alternator, add solar)

[California98Civic]

Originally Posted by ecomodded

I have not heard/ read about ah losses due to low amp charging. I am still under the belief that slow/ low amp charging is superior to fast / large amp charging. In short the fast charge is reported to dissipate faster. Could you enlighten me with some information or a link ?
I seem to have a gap in my knowledge bank.

Here's the content of my conversations with the Odyssey factory people, the three substantive calls with Bruce (plant manager) about my charging strategy, my alt on/off switch, and my driving pattern. He recommended a 25amp charger--instead of their 6amp charger--because the lower amp charger on the 40 amp hour battery I bought will not, long term, be able to fully charge the battery even if I only discharge 20%-25%. Over time, sulfation builds up more quickly and cannot be as easily corrected by the charger. It also cannot be rectified by the alternator, which has modestly too low voltage for effective charging of a 40ahr deep cycle battery. He also recommended I modify or swap my alternator for either higher voltage (to 14.7 or so instead of 14.3) or higher amperage (from 40 to maybe 70 or 90). The latter is only if I cannot have the alt modified for higher voltage. He told me about a rule of thumb he applies: assuming appropriate charging voltage up around 14.7, then the charger should be rated for amperage not less than 40% the amp hour rating of the battery. Lastly, the 25amp charger has three stages: charging, "finishing," and float, which apparently means different amounts of current and voltage.

Probably most things are debatable, so what do you think might be wrong, partly or entirely, in that set of recommendations?

[VXmpgRacer]

This road trip was 400 miles of hills in cloudy and rain. I didn't let the voltage go below 11 volts to prevent damage to the standard car battery. The results were impressive as I only had to run the alternator for 30min to charge the system before parking the car for the night. Olive averaged around 55mpg at 70mph on I-81 in Virginia which is mostly mountain driving.

[ecomodded]

California98civic

I think the 25 amp charger will knock the sulfation off the plates as well, also it may be useful with a battery to have a high amp charge if it needs to be fast charged before being put back in duty, much like the alternators do to our conventional car batteries.
Trickle chargers are for low duty maintenance , a high amp charger is more of a necessity with high drain battery systems.

I have read that you can change the voltage regulator instead of the alternator.

[VXmpgRacer]

With 5000+ miles of testing on consistent routes, the results of this experiment are in.

The alternator belt was NOT removed.

Running the entire electrical system on only the solar system resulted in statistically insignificant mileage increase. (not expected)

[MetroMPG]

Ouch!

Since we know taking the electrical/alternator load off the engine is absolutely going to save fuel, I would say those savings were off-set by increasing other loads:

1) the weight of the solar/battery system (probably a relatively small impact), plus,

2) the added aerodynamic load of the panel mounted on the roof which increased frontal area (A) and drag coefficient, (Cd).

Aero losses were probably a relatively larger impact compared to the weight gain.

It's discouraging to do all that work and not see the effect you were hoping for (been there, done that!).

Thanks for reporting unexpected results though. It'll help the next person considering this type of mod.

[California98Civic]

Agree completely with Metro, and also want to thank you for writing in the results even though they were frustrating to you. Much integrity in that and very helpful to the community as a result. I'm sorry the mod didn't work.

[oil pan 4]

Try this mod with the belt off the alternator.

With my suburban 100w should only make a difference of about 0.1mpg, which is impossible to track. I am going to guess a car that gets twice the fuel milage of my truck would see about twice that milage increase.

[JRMichler]

Originally Posted by California98Civic

Agree completely with Metro, and also want to thank you for writing in the results even though they were frustrating to you. Much integrity in that and very helpful to the community as a result. I'm sorry the mod didn't work.

+1

It is just as important to report negative results as positive results.

The idea is good, though. My opinion: Your solar panels are much larger than you need given the size of your deep cycle battery. I suggest looking for thin film panels that could be glued to the original top of the car. That would maintain the original aerodynamics.

[Cobb]

You said connecting a charger to the battery was optional, however have you tried precharging the battery since taking ownership or checking its current SOC?

Have you tried charging the battery before driving the vehicle?

Hondas have something that turns the alternator off and on as needed to aid in mpg, its called an ELD. Having said that, myself and a few Insight owners have noticed a signnificant increase in mpg whe precharging the 12 volt battery before driving on short vs long trips. After 7 miles or so the charge is worn off and mpg starts todecline vs increase.

For the Insight it cuts on the charging of the 12 volt battery when the power falls before 12.5 volts and off when it hits like 14.5 volts.

If you consider this a fail, get yourself a grid tie inverter and use it to supplement your power needs in your home. I have 6 panels and 2 converters and they save me 50 bucks a month on my power bill.

Or if you like, Ill take the panel off your hands. You anywhere near 288 and Hull St?

[brucepick]

Originally Posted by ecomodded

That is a serious solar panel. It must put out 5 or10 amps on a sunny day. If your car uses 10 amps to run , lets say your panel is putting out 6 amps, your battery would only have to carry 4 amps. 4 amps an hour is not going to drain the battery. I have complete faith in your Solar charging system. Adding some high output led spot lights flush to the grill block would be a nice feature. One that i plan on doing to my Beetle. Its headlights are weak and suck amps.

I agree withthe math above - My HX with alt delete does seem to need about 10A to run the car, as long as I'm not running headlights or fans. Headlights take another 10-12 amps.

I like this project. Nice job. I'm concerned about the aero losses from the roof panel but you may be improving that situation.

4A draw (after adding in the 6A from the solar charger) won't have much effect on your large deep cycle battery's state of charge, if you only do that for an hour or two. However if you've read into these batteries' behavior, you already know they last longest if kept well charged up. So top it off if you draw down more than 5-10 amps, is my advice. If you can top it off daily that's nice but I wouldn't go, say, a week, drawing it down 50A or more, and then recharge on weekends. If you want it to have a long life, recharge more often than that.

Kudos for building it with a large deep cycle. Mine is also pretty large, a Group 29 from WalMart; I estimate it at about 100AH by standard measurement. Enough to do the job without getting drained down much.