Did some driving today with the meanwell disabled. With it disabled, I saw almost +5 MPG with hypermiling (EOC) and almost +10 MPG driving normally (no EOC). Note that my fuel economy is currently around 100 MPG this summer, so these numbers will be less if you are getting lower MPG, and higher if you are getting better MPG. IIRC Nathan, who runs 120-150 PSI in his tires and gets 120-150 MPG noted a +15 MPG gain with the meanwell turned off. So let's say around 10%.
Adding/subtracting load didn't seem to affect economy or power at all, it was just the fact of having the meanwell on that took power and reduced fuel economy.
Suppose base load is 10 amps, at 14.3 volts, that's 143 watts, or 0.2 hp. At full power the meanwell is stealing 1 hp at most, so why is the difference between on and off so noticeable?
The car also accelerated slightly better and had slightly more available power with the meanwell turned off.
But obviously I need charging to the 12V in order for the car to run. After about 12 miles and 20-25 minutes, including 3 starts with the starter, no accessory use besides the radio for 5 minutes, the 12V resting voltage with the car off was 12.4, and under load it varied between 11.8 and 12.2 volts towards the end of my driving. Battery was fully charged before starting. This is just a typical, 500 or 550 CCA 12V starting battery. And yes, I know that wasn't good for the battery, but I just wanted to test it out to see what would happen.
Some things I'm considering doing:
- Turn the Meanwell voltage down to 13.9 volts. Right now voltage is set to ~14.3 volts and varies between 14.0 and 14.6 volts. 12V charging should be above 13.5 to keep a 12V healthy, so with it set at 13.9, voltage should vary between 13.6 and 14.2. That should theoretically reduce power consumption by ~3% (+0.15 mpg if 10 mpg is gained from turning it completely off).
- 80ah Deep cycle battery capable of 20 amp draw for 2 hours without dipping below 50% charge; 40ah might work too if it has at least 1000 to 50% discharge cycles.
- Move the meanwell kill switch so I can disable/enable charging while driving.
- Solar panels in the rear window to keep the battery topped off.
Problem is, my 12V battery is only 8 months old. 80ah deep cycles are close to $200, and a 100w solar panel is close to $100 as well.
Voltage drops under load, so a fully charged battery disconnected from the alternator may read low 12s under load, but it's still fully charged, right? I'm assuming a typical deep cycle battery is the same? If this is the case how can I measure current SOC of a deep cycle battery while I'm driving, other than temporarily shutting the car off, checking the voltage, and then turning the car back on?
I am aware that any MPG gain from disabling the meanwell will result in a MPG loss when the meanwell is reenabled and has to work harder to charge the battery, however my car does sit around for a while and a 100W solar panel should be enough (100W/14.2v = 7A) to keep the battery topped off for anything other than a long highway trip. And even on a highway trip, other than radio and headlights (LED) the car runs at base load - guesstimate 20 amps max, so in full sun I could toggle the meanwell on and off strategically while driving and keep the battery happy.
Meanwell PSU gets very hot to the touch at temperatures above 90 degrees outside, and the fan runs all the time. Voltage dropped slightly during that time, but that was likely due to having to work harder to recharge the battery after draining it with the meanwell disabled. Current setup is stock fan and the meanwell bolted and thermal pasted to an aluminum bar to more than double the contact area for cooling. Meanwell compartment isn't completely closed yet and I haven't added the intake/exhaust fans for the meanwell compartment yet. Thinking of what else I could use as additional heat sinking. Under 90 degrees outside the meanwell fan stays off 70%-80% of the time. Interior temperature is around the same as outside.
It's late, so forgive me if this is all nonsense.
