AGM for weekenders

Off-grid charging AGM is challenging and expensive;  doing it as a weekender can be easier and less expensive since we can ward off battery-murdering sulfation with vigorous and timely charging just before/after the weekend outing.


  1. make it through the weekend outings with power for light-to-medium loads
  2. without murdering AGM batteries due to undercharging, by using a minimum of C/5 (40A) charging.

Scenario:  camper has 200A of AGM and 200w of panels.  The panels are not intended to fully charge the batteries, only to support the batteries over the weekend and get them back to at least 12.7v during the day.  Vfloat would be nice.   Campground is an hour away from the house.   Batteries are fully charged at the house just before leaving and immediately upon return.  When not camping (ie, not cycling), 200w of panel will keep the house batteries maintained.


  • there is a huge cost difference between fully charging lead batteries to manufacturers specs in the field and keeping them alive in the field and fully charging at home.   We aim to exploit that difference.
  • Configurations with B2B (aka DC-DC chargers) can be fed at home with 12v power supplies, since they will step up voltage.    Configs with isolators will require a smart converter.

From most to least expensive, not including battery costs:

Continue reading “AGM for weekenders”

the problem[s] with 1:1 solar charging

this is a draft

1:1 rule of thumb

There is a rule of thumb that says a 1:1 ratio is the minimum amount of solar needed to charge a deep cycle bank.  The long form is 1w:1ah, which means 1 watt of solar panel for every amp-hour of lead chemistry deep cycle battery capacity under good insolation.  So if you had 150w of panel and 100ah of battery it would be 150w:100ah, or 1.5-to-1.  Yes, I know the case on the unit abbreviations is wrong but it’s easier to read.

As with all rules of thumb, it serves as Continue reading “the problem[s] with 1:1 solar charging”

idiot permanence

Object permanence is the understanding that objects continue to exist even when they cannot be seen, heard, touched, smelled or sensed in any way. — wikipedia

I propose idiot permanance, which is the understanding that idiots and jerks continue to be idiots and jerks even when they are out of your direct observation.  That swervedriving guy who just cut you off in traffic with no blinker?  Probably not the first time he’s done that today, or even in the last 5 minutes.

Continue reading “idiot permanence”

laptop cooling update

The thermal paste fix has made a huge difference.  I played Minecraft in 92F ambient the other day (hottest day in Twin Springs just before I bailed).  No issues.

Normally I use the chromebook because of the low power consumption, but I’m getting such good sun here in Boise NF that I am running the laptop this morning.  This means I can do some extra stuff:  Continue reading “laptop cooling update”

field mouse

I picked up a field mouse in the Twin Springs area.  I saw some of them running around on the ground.   About the size of a domestic mouse, but more intelligent-acting and with a furred, tuft-ended tail like a gerbil.

not actual sizeThe easiest way in would be to jump about 10″ up to the stepstool, then another 10″ into the van.  Good job, buddy, but ya gotta go.

Walmart didn’t have the normal metal “cheese pedal” ones like this:

and only had this bit of heresy:


The holding mechanism is iffy at best.  One could not be set at all.  The second one in the package could be set with only a few false positive snaps.

I placed the trap and caught the mouse within an hour.

BN:  I’ve used this style before in rat traps and they worked fine.  Never used the mouse sized one:

Twin Falls, ID

It was scheduled to rain last night, so I gathered up the campsite.  Since I was planning to head out in the next couple days anyhow, I topped off water from the campground and headed out.

The historic bridge as one crosses the Snake River and enters the city:

Stopped at Wally World for provisions.   Sunday morning, which is Continue reading “Twin Falls, ID”

a walk to the west

I’ve been wanting to walk up the hill to the west but an attentive bull has been hanging around the last several days, trolling back and forth on this side of the hill, vocalizing softly but constantly.   First day he appeared he looked straight at me and now he’s been hanging around.

Today he wasn’t there so I grabbed the daypack, the dog, and the Multipurpose Walking Stick and headed out.

The other day when I was looking on Google Maps I saw what appeared to be irregularly-shaped denuded spaces but thought it was an artifact of image stitching.  But I saw today they are really there:

looking south

digital zoom of the above: Continue reading “a walk to the west”