Hybrid Car – More Fun with Less Gas

Any experience with this? - Page 2

register ::  Login Password  :: Lost Password?
Posted by ads on December 8, 2018, 2:57 am
On Fri, 7 Dec 2018 11:01:29 -0500, "Jim Wilkins"

My system is a "Wait until daylight" backup - just enough to not be
out in a thiunderstorm in the dark trying to get a gas gen running.
It's worth the cost for that.  I've also received quite a bit of
education in the process of designing and building it ;-)

If lithium cells were to drop appeciably in price, then the $/KW of a
solar system might become more competitive with grid power, based on
the potential life of good lithium cells even at 80% depth of
discharge.  The AGM batteries I'm using are in the category of 1150
cycles to 50% discharge and probably triple that at 20% discharge.

I did see one example where the cost to get grid power installed
($000US) covered the cost of an offgrid system because of the
distance to the property from the last installed power pole. The
user's estimated costs (distilled water and funding future battery
replacement) were less than $00/year which is cheaper than any
commercial power I'm aware of. There are the issues of being a good
ahepherd of your limited resources but that's true of any non-grid
solution - even a 10,000 gallon tank of diesel will eventually run

My 540AH of AGM batteries can provide 8-10 hours of "switch all the
transfer breakers and let it run" power (still only a small percantage
of the usual usage)  or 24 hours of selective powering of various
things.  Even longer if the inverter can be turned off and no one
opens the fridge during the night ;-)  Again, that's managing the
resources and planning for tomorrow being sunny or cloudy - or running
one of the generators for a while to charge the batteries, at least to
the limits of stored fuel.

At the minimum usage (dorm fridge, a few lights, charging a laptop for
my writing and stored references, etc) I'd have 3 days of autonomy and
the full set of solar panels could replace a day's usage in less than
2 hours.  Not as good as having grid power but better than being in
the dark ;-)

This email has been checked for viruses by Avast antivirus software.

Posted by Jim Wilkins on December 8, 2018, 2:05 pm
<ads> wrote in message  

How long do your AGMs last?

I keep a small stock of replaced-on-schedule used 12V 18A VRLAs to  
rebuild my jump starter and portable power packs as needed, and top  
them all off from the solar panels at least monthly. Typically they  
become too resistive to use after around 5 years or so, whereas I can  
keep U1, car and marine flooded batteries alive and strong enough to  
start an engine (by carbon pile test) for often 10 and sometimes 15  

I weighed its cost against being stuck away from home with a dead  
battery, or replacing them sooner than needed.

The old VRLAs usually appear good by voltage measurement but fail a  
load test, and require 14V~15V or more to force a small charging  
current. I wouldn't notice if I hadn't added volt and amp meters to my  

Flooded batteries are cheaper, too. 12V 105Ah SLI31s from Duracell  
(East Penn) cost me $10 each last year, since my 10+ year old bank  
can barely run the fridge overnight. I kept the old ones for testing  
and traded in all the dead VRLAs.

Their disadvantage is that limiting the charging voltage to below the  
gassing level can extend full recharge time beyond what's practical  
for daily cycling. The ones I have don't bubble significantly at  
13.8V, the recommended long-term float voltage and the setting on my  
solar controllers. One published gassing limit is 14.3V. Clear  
packaging tape over the open vents contains the acid spray while you  
increase the voltage and watch for bubbling. I'm hoping an occasional  
week at 80% SOC or below won't hurt them too much, then I can equalize  
them outdoors.

If the storm that caused the power outage allows me to run a generator  
I can recharge at 27.6V, 20-30A. We've had a couple of storms where  
ice or fallen trees kept me from running it the next day. The higher  
priorities are shoveling or chopping a path to the woodshed and  
covering holes in the roof. New England can suffer every natural  
disaster except volcanoes, though the earthquakes have been mild so  


Posted by Jim Wilkins on December 8, 2018, 8:00 pm
 <ads> wrote in message  

For battery-powered cold food storage I've tried an APC1400 UPS sine  
inverter plus an 18" cube dorm fridge, a 20 liter Alpicool C20 AC/DC  
fridge-or-freezer and finally a new 4.3 cubic foot Magic Chef  
fridge-and-freezer, the best on-grid solution that holds the most food  
and draws the least AC power. Right now a KAWez says it's costing me  
$.70 a month to run, the dorm fridge was $.20.

The Alpicool consumes the least battery power because it doesn't need  
a large inverter running all the time. Its disadvantges are small  
interior size, marginal insulation and uncertain reliability - it  
occasionally throws the F4 fault code and stops working until  
rebooted, or goes berserk and won't shut off, as the reviews mention.  
The one I received had no odor. It worked well in combination with the  
dorm fridge when set as a deep freezer for ice cream but I don't  
normally use it after buying the Magic Chef, other than to bring home  
frozen food.

I made a foam insulated enclosure for it because as-is the compressor  
can't reach its freezer temperature setting in a hot car. The inner  
liner is a yoga mat that doesn't absorb condensation. The C20 was the  
biggest available on Amazon when I bought it and I know nothing of the  
other models. If it was any taller I couldn't carry it on my shoulder  
with one arm and open doors with the other.


Posted by ads on December 12, 2018, 9:01 pm
 On Sat, 8 Dec 2018 15:00:59 -0500, "Jim Wilkins"

I experimented with some Peltier cooling modules and found that while
they do provide cooling, it's at the expense of nearly continuous
power and LOTS of insulation.  I could get a small foam cooler down
near freezing but the power required was greatly out of proportion to
the DC compressor fridges (Engel, ARB, Whynter).  On the other hand,
if I had the extra power, the parts cost would be minimal in
comparison to the Engel.

The best I found in a "normal" fridge was a Kenmore 4.4 cu ft "dorm"
fridge (counter height) that uses 27.5AH/day on the 90% efficient pure
sine wave inverter (in a 78F environment).  That fridge is in the
basement filled with heirloom seeds in sealed containers.  The last I
checked, the Kenmore 99783 is no longer in general availability but
might still be in some stores (those that haven't closed).

This email has been checked for viruses by Avast antivirus software.

Posted by Jim Wilkins on December 10, 2018, 2:53 pm
Clear sky, discharged battery. The sun is low at 9AM in December at 42  
North, so I don't expect the 100% rated power I measured earlier.

The 2s2p array of 100W panels gave 9.7A from a PWM controller, 11.6A  
from this MPPT. That's ~20%, close to the value of adding one panel  
instead, though I'd need two for this 24V bank. It looks like I'm at  
the break-even point where the cost of larger wire and space for  
panels drive the decision whether to buy MPPT or more panels.


This Thread
Bookmark this thread:
  • Subject
  • Author
  • Date
please rate this thread