Hurricane... Inverter in car, or generator on balcony

 

I am in Florida and have gone through two years of bad hurricanes with
power outages that have lasted over two weeks. I live in an
apartment/condo with pretty large balconies... and was thinking of
using the Honda EU1000i or EU2000i portable generator on the balcony...
but, this might not be permitted by my condo rules and regs, and I'm
concerned about the safety issues as well... even if I keep my windows
closed, what about the downstairs neighbor!

As an alternative I'm considering a permanent inverter installation in
my car (and running extension cables up to the 2nd floor) after having
great success with a small 150 watt inverter the previous hurricane
season (it was enough to power my laptop (watch movies), a fan and a
couple of fluorescent lights).

I'd like at least 750 watts for the inverter and would like your
thoughts and opinions about a permanent installation of such a unit in
my car (I will probably have a car alarm/stereo place do the install).
Or, should i reconsider the small Honda generators instead?

Thanks!

Cliff in Delray Beach, Florida

 



     I am sure that you will see hundreds of generators running on balconies
afer the next hurricane, but the idea scares the hell out of me and it may well
be forbidden by any given condo Assn.  Another possibility (if allowed) would be
to make a deal with your downstairs neighbor, and share an EU2000 placed down at
ground level.

     I suggest an alternative.  Buy yourself a nice deep-cycle battery, a
battery box and a float charger.  (Be sure it really is a float charger, not
just a trickle charger) Keep the battery charged in your apartment and get
yourself a couple of 12-volt flourescent lamps and a 12-volt fan to run off of
it.  (Don't forget a 12-volt cell phone charger and a 12-volt power supply for
your laptop.  Oh yes, you will also want one of those nifty 12-volt
televisions.)   Buy yourself some monster cable and some big alligater clips to
make a long jumper cable to recharge the battery from your car, or get a little
dolly and lug it down to the car for charging (enjoy the AC in your car while
you are charging your battery).  The inverter is now optional, but I would
discourage it because it is a heluva power hog.

     You can get the charger and many of the 12-volt cords/splitters and other
gizmos at Harbor Freight in Lake Worth.

     Now you have a noise-free hurricane comfort/survival system that (unlike
the genny) you can also use right through the storm.  I set up this identical
system for a friend of mine in Century Village and also for my father.

Vaughn (in Lantana)

 


A bunch of stuff that all works except this:


The line losses and voltage drop going to a second floor balcony make
this a losing proposition.  For a single battery, using a small
handtruck or fold-up luggage cart from the 1970s works well getting a
battery to and from a car.

 



     No, actually I have done it.  With a second floor balcony and assuming the
car is parked near, you are talking about 30 feet of #10 or #8 "monster" cable.
Given the modest loads that I discussed earlier, that setup should allow a
useful charging current.  In fact, the greatest contributor to the overall
resistance of the circuit is likely to be the contact resistance of 4 alligator
clips.  I agree, the battery cart is more efficient.  One would connect the
battery, allow an hour or so for the batteries to equalize, and then start the
car for an hour or two to finish the charge (and to get cool in the car's AC
with the blower on low to conserve juice.)

Vaughn

 



(I wouldn't wait much more than five minutes in this situation, if
that.  You are "jump starting" the deep discharge battery, and if the
voltage was particularly low, you could drop the car battery surface
charge below where it would easily start the car.)


I agree that a long cable sort-of works, enough for a day or two, but
I wouldn't want to use it for much more than that, for fear of
undercharging the battery.  This isn't an absolute, but part of the
trade-offs of battery convenience, lifespan, and use.  The issue I see
is that long cables don't allow enough voltage for an equalizing
charge.  The calculations below are just for example.  

Assume that an alternator puts out 14 volts, and the float charge of a
lead-antimony battery is 2.15 volts per cell, or 12.9 volts.  To get a
full charge, the voltage must reach that or slightly more, and be held
there for at least a brief period.  That allows a maximum 1.1 volt
drop in connector and cables.  On a #10 cable, a single 30 foot run
could deliver about 36 amps at 12.9 volts.  Add in the connector loss,
and the fact that the return isn't a solid huge chassis, and useful
amperage is less.  A #8 cable is significantly better.

Will the battery charge enough to be useful?  Yes.  Will a charge like
that bring the battery up to float charge easily and quickly?  I don't
think so, especially after a few discharge cycles and the battery
begins to age.  If I use a single marine battery while van camping, I
wear it out in a little over a week, even with recharging from a 1000
watt alternator for three or four hours a day.

Common thought is that a lead-acid cell discharged below 10.5 volts is
permanently damaged.  A safer low voltage cutoff is 12 volts, and a
compromise for an emergency battery might be 11.5 volts (in that the
expected useful life of a battery is only about 3 years in Florida
heat anyway).  BTW, the rate of discharge is not linear, so a battery
might last a good while going from 12.5 volts to 12 volts and only a
short length of time going from 12 volts to 11.5 volts.

The voltage drop while charging through a long cable will slow the
recharging and may cause the user to accept lower voltages as
"normal."   That kills batteries - at least that has been my
experience.

None of this takes into account the de-rating of a battery at higher
temperatures, increased wire resistance at higher temps, etc..

Perhaps the user could use the long cables for a day or two and then
bring the battery to the car as a compromise?

By using 12 volt appliances rather than an inverter setup, your
concept does put a lot less drain on a battery, so you might not have
the concerns that I do in keeping a 120 vt refrigerator running.  To
me, if I can't keep the refrigerator going, and a source of ice, I
don't find making my own power that attractive.  My van has a tv, AC,
bed, dorm refrigerator and microwave.  It would be easier for me to
just move into it for a few days.

You can calculate voltage drop here:
<http://www.stealth316.com/2-wire-resistance.htm>