Mpg observation today
Checked our mpg while crossing i80 in Nebraska and at 70 mph for long stretched we were at 9.2 rmpg.
Dry camped and used about a 140 amp hours of battery power overnight as we are running the chest freezer under the coach.
Got back on the exact road, same speed, same conditions, no wind.
8.3 rmpg for 70 miles. What the heck?
Hmmmm.
After 70 miles the rmpg slowly raised back to the previous 9.2-9.3.
?
Ah. The alternator replacing the -140 amp hours at roughly 130 amps.
Once the batteries reached full charge and with the roof 270 watt solar adding to the batteries at 13.6 volts same as the alternator it shut off.
That much difference in load to add 3-4 pounds boost to the VPMS display during the 8.3 rmpg.
Most coaches have battery management systems that charge the batteries per the temperature at the cable end.
Our old heart freedom does not have that capability so my guru and I used the lower voltage settings in the link 2000's panel.
Our small solar runs through the refer wire so it's 14.6 panel output drops drops a full volt at the batteries. 13.6
The alternator is also 13.6 as is the hearts charger.
Hesitate to turn it up.
Wolfe mentioned here several times to run 13.6 volts max to charge the batteries versus higher voltage might shorten the service life of all components.
Probably Unnoticeable if the hydraulic radiator fan is jammed on high also from Foretravels selection of a very low temp thermostat.
Also probably not as noticeable without a resonator changeout.
I think the michelins sxs-3+'s ultra fuel efficient design helps as the coach hardly slows down with no throttle since the tire change.
My opinion is all the other draws would have complicated the defining what's going on enough to make it nearly impossible to notice this.
If it repeats then that may be what's going on.
Been thinking of a three step voltage chargin alternator like the heart has.
The additional charge load cost one gallon of fuel approximately.
Too much idle time behind the wheel and having too many neat measuring tools to use from the VPMS. Invaluable tool for a nerd gearhead.
Last thing is to replace the rear axles gear oil with full synthetic if not already done.
Front bearing were already changed.
Fun stuff. Especially if it helps both the power and mpg.
At 65 under good conditions after the battery top off and with sun on the panels to run the normal loads I am getting 10 rmpg.
No wind. No grades
Anyone else want to help and check their long run rmpg with the batteries charging and after just to see.
I,wonder if JOR could calculate the hp necessary to run the alternator at 130 amp load?
Topic: Mpg observation today