Honda Insight Forum banner

1 - 4 of 4 Posts

·
Registered
Joined
·
182 Posts
Discussion Starter #1
I just replaced the OEM 12 V battery. The old one was really dead--needed to be charged to start the car if it was left more than about 12 hours. It seems that I'm getting better MPG. It's not a well enough controlled experiment for me to say for sure, but it seems to me that the dc-to-dc was doing just what my charger did when I tried to charge the old battery--continuing to pump current in and never getting up above 12.5 V, and so thinking the battery was still low. It seems like that draw, of perpeturally trying to charge the 12 V battery, makes a difference in MPG.

My recommendation: if you've got an automatic battery charger, try charging the 12 V battery every once in a while. If it never shuts off, or takes a very long time to reach the point where it thinks the battery is full, it's time for a new one. You might get an MPG improvement, and you'll certainly decrease your chance of being stranded.

I got the Optima Yellow Top group 51 (civic size). It's bigger than needed, but the extra capacity is nice for forced autostop at night. Actually got the 51R, with the wrong terminal configuration (since that was all that was in stock) and found that the stock wires could be made to reach, just barely.

Charlie

PS My uncontrolled experimental results are this: I've gotten 103 mpg on a particular ~80 mile trip by going all out--slow back roads, etc. And I've gotten 60-70 mpg taking the freeways at 60-65 mph. This time I mostly stuck to the freeways and went about 55 mph, and got 103 mpg. It seems something must have changed to get the same mpg at higher speed, but it's also possible the back roads weren't as good as I thought.
 

·
Registered
Joined
·
652 Posts
The interstate and freeways are more consistent (cut through the terrain and use fill in low areas) compared to backroads which follow the terrain and have lots of dips and rises. The consistent slopes make it easier to stay in lean burn thus better fuel economy.

Have fun, Rick
 

·
Premium Member
Joined
·
4,942 Posts

·
Registered
Joined
·
182 Posts
Discussion Starter #4
My charging recommendation was meant as a way to evaluate whether a battery of questionable health is in a state where it might negatively impact MPG, not as a way to prolong battery life (although certainly keeping it charged well will help prolong its life).

Thanks for the links to the other threads. I started a new one to specifically address the topic of the impact of the battery on MPG. Although I don't have a controlled MPG experiment, I do have the evidence that the old battery sucked energy continuously from a charger. Presumably it does the same thing on the dc-to-dc converter. How big an effect that is is what I don't know.

I'll put my comments on the "battery exercising" recommendation in the appropriate thread.

In reply to Rick, I choose my back roads with a topo map, and although I sometimes get a wrong and hit a steep grade, there are many back roads that parallel rivers that have less grade than interstates. You can often tell by looking for the routes with parallel railroad tracks.

Charlie
 
1 - 4 of 4 Posts
Top