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Emergency, safe, alternative low-budget heat for apartment? - Page 2

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Posted by ads on December 3, 2021, 12:23 am
 
On Thu, 2 Dec 2021 09:08:43 -0500, "Jim Wilkins"


If you're knowledgeable enough to build your own from available parts,
LiFePO4 cells can make batteries which are good for 5,000
charge/discharge cycles (about 13 years at one charge/discharge cycle
per day) at prices comparable to AGM sealed lead-acid batteries
(what's typically in the older jumpstart packs).  

I've done that on a very small scale when the manufacturer wanted $0
for a replacement AGM battery for a small UPS - more than twice what
the UPS cost me.  The LiFePO4 cells plus a BMS plus tax and shipping
were under $0 and I spent less than an hour building the battery
pack.  The new battery lasts longer than the original at the same load
and, at my age, it might be a "lifetime" battery ;-)

If you have some hours of sun available, then solar might be your
fallback power source.  No one who has built even a small solar system
would say it's cheap - even the solar-charged LED lighting in the shed
out back was about $00 for parts - but MUCH cheaper than having an
electrician out to run power under a concrete driveway to get lights
out there for maybe 20-30 minutes a day.

That "cheaper than" is the key - what would the other alternatives
cost or are they even available?  I can use a kerosene heater for heat
with zero power needed and I have a place outside to store the
kerosene (that shed with solar-powered lighting) but that won't work
for most apartment dwellers.

There are some nice solar-powered air heaters IF your windows are on
the South side and you're on the ground floor - one design that
outputs 140F air and doesn't need a fan to move that air through the
heat box. Those might work for some during the day, but they're not
any cheaper than solar power unless you can build your own - not
likely for most in an apartment.

The "low-budget" in the title may limit the OP to plastic film over
the windows, tape around the door and extra layers.  You need more
details to work out what will work for someone else.

Posted by Jim Wilkins on December 3, 2021, 4:29 pm
 

On Thu, 2 Dec 2021 09:08:43 -0500, "Jim Wilkins"
...

If you're knowledgeable enough to build your own from available parts,
LiFePO4 cells can make batteries which are good for 5,000
charge/discharge cycles (about 13 years at one charge/discharge cycle
per day) at prices comparable to AGM sealed lead-acid batteries
(what's typically in the older jumpstart packs).

I've done that on a very small scale when the manufacturer wanted $0
for a replacement AGM battery for a small UPS - more than twice what
the UPS cost me.  The LiFePO4 cells plus a BMS plus tax and shipping
were under $0 and I spent less than an hour building the battery
pack.  The new battery lasts longer than the original at the same load
and, at my age, it might be a "lifetime" battery ;-)

If you have some hours of sun available, then solar might be your
fallback power source.  No one who has built even a small solar system
would say it's cheap - even the solar-charged LED lighting in the shed
out back was about $00 for parts - but MUCH cheaper than having an
electrician out to run power under a concrete driveway to get lights
out there for maybe 20-30 minutes a day.

-----------------------
I don't say isolated DIY solar is cost-effective compared to grid power, or  
grid-tied solar, but it's about the only alternate source that's easy to  
experiment with, so I claim what's installed and working on my Form 5695 and  
write off the rest as a hobby or education. I've also built windmills and a  
water wheel and briefly looked into bio and wood gas generation.

Solar certainly does work well enough to be part of a backup plan if your  
area suffers from extended power outages, such as New England's ice storms.  
With full winter sun my batteries recharge to float voltage by ~10AM after  
running the fridge all night. Cold panels are more efficient, the other day  
I saw 440W from the four 100W panels. At float voltage lead acids don't gas  
but revert to a slow taper charge. I've read and tentatively confirmed that  
the battery is at 70~80% SOC when it reaches float voltage. When the grid  
returns I can fully charge and equalize them outdoors.

Wishfully dividing the lower purchase price of flooded marine batteries by  
the longer claimed cycle life of AGMs, the cost of battery depreciation per  
KWH is still higher than my $.18/KWH grid power. Depth of discharge doesn't  
seem to matter if you keep total capacity constant. I've seen a graph of DOD  
vs cycle life that revealed the same lifetime total delivered power for all  
combinations.

The obvious alternative is a generator, if you don't mind running it all  
night for the fridge. I found a small used Honda that I can completely drain  
to store indoors and carry out to a small shoveled patch to quickly recharge  
the batteries if it's overcast, while I struggle to clear the path half way  
around the house to a larger generator in the shed. I already had a  
feedthrough to pass other wiring through the wall. At my age I have to plan  
for injury from falling on ice and thus have an easy to carry backup. I also  
rigged the wood stove chimney so that I can flip open the rain cap and run a  
cleaning brush through it (weekly) while standing on the ground. The unusual  
chimney, handrail and antenna structures up there are painted to disappear  
against the surrounding trees.

I've been lucky enough to find fairly reasonably priced AGMs for enough of  
my second-hand UPSs, from Amazon or replaced-on-schedule ones from a flea  
market. The dealer told me some had to be swapped out from critical devices  
after 3 months. He has a conductance tester and lets me check the promising  
ones with my HF carbon pile tester. As a favor I tested all his stock and  
found that one of the brands he bought for nearly his selling price wasn't  
worth salvaging while another was excellent.

If you can run a low-cost UPS at greatly reduced load it may be OK with  
larger external batteries, unless it has shutdown timer. A common  
cost-cutting trick is to match the heatsink's thermal mass to battery  
capacity to avoid fan cooling. A larger battery can overheat them. Even my  
originally expensive APC1400 has quirks to avoid or reprogram.

I was a Lithium battery tech and know how to build a BMS, and I keep an eye  
on Lithium prices, but for liability concerns I assembled my solar system  
from purchased power modules and packaged batteries and wired it according  
to published standards. The solar>grid>battery switching was accomplished  
with diodes and careful voltage adjustment, not active control. If there's a  
fire here anything I built is automatically suspect. Although I've been on  
the build teams for prototype electric vehicles I don't have the experience  
or equipment to make a safe plastic enclosure for bare cells, I can only  
fabricate from sheet or "billet" metal.

At Segway we used only the manufactured battery modules to build  
experiments. Mounting them on other than the normal chassis casting was my  
problem. The dimensioned CAD print says "see the pattern" for the battery  
studs so I had to reverse engineer them and cut-and-try the locating taper  
on the old manual metal lathe in my basement, which was easier than getting  
time to fiddle with the CNC machines or learn how to use the CMM.

My wet batteries are in boat boxes and were wired according to boating  
specs, mainly waterproof inline fuseholders on 7" leads, just outside the  
box where they won't ignite hydrogen if they blow. Some of my inline  
fuseholders have needed their Fastons tightened with needlenose pliers. The  
AGMs are replacements in jumpstarter and power pack housings, with added  
PP45 connectors.

I use my homebrew controllers only as temporary battery chargers and  
testers. Much can go wrong in a battery powered system, such as the battery  
backfeeding into an unpowered supply, overheating when recharging a drained  
battery at high current, or failure of blocking diodes, so I overspecify and  
bought the equipment to test components and systems thoroughly.

For example a blocking diode on the input of my HF "45W" controller shorted  
and sent battery voltage to the panels, which fortunately did no harm. I  
have meters everywhere and saw it, and found they had used two undersized  
Schottkys in parallel instead of one with an adequate rating and larger  
package, which is what I installed. Afterwards I added blocking diodes to my  
panel wiring and curve-traced the leakage at night.

The returned Li battery packs (not Segway) I investigated for warranty  
repairs showed a wide range of performance. The BMS recorded their history  
of charges, discharges, temperature, etc. One from a vehicle in hot Arizona  
had deteriorated in less than a year. Many showed significant loss of  
capacity in 3 years, with a wide spread of values between packs and cells. I  
have obtained up to 15 years of useful life from flooded lead batteries at  
half the price of AGMs and 1/4 to 1/10 the price of Lithiums, so my  
new-old-stock of $ tabbed 18650s is reserved for rebuilds.

I've seen similar results from AGMs, including complete failure in 3 years  
though I have one that's still strong after 10. A common fault has been a  
bad cell that caused the other 5 cells to overcharge at 120% of the float  
voltage. I suspect but can't prove that as the reason they swell. I got the  
APC1400 UPS for my solar system for free from a dealer because he couldn't  
figure out how to removed the badly swollen AGMs. Its fairly high idle power  
drain appears to be typical of true sine inverters, so I'm exploring DC  
appliances such as the T60.
jsw  


Posted by ads on December 4, 2021, 5:53 am
 On Fri, 3 Dec 2021 11:29:03 -0500, "Jim Wilkins"


Thank you.  There's a lot of good experience in that post.

I stretched the previous set of used AGM batteries to 9 years and
thought I got a great deal (90AH batteries for$5/each or close to the
salvage price for the lead in the battery when I got them.  I paid a
bit more for the current set - two 100AH and two 110AH for a total of
$05 - but they were only a year old and had seen service a backups
for security cameras.  Unfortunately, the person with the batteries
didn't know that AGMs need to be charged when stored if the voltage
drops to 12.4 or less (depends on the brand).  Although he had 4 more
batteries of similar size and age, they were all at 8 volts and the
likelihood of recovering those is very slim.  I did offer him $ each
for those to use as cores because the core charge on any new battery
of size will be at least double that.

I can view the status of the charge controllers remotely - they're
monitored by an ancient Dell laptop running Win 7 (Ultraviewer is free
and works from XP up  to at least Win 10 and is cross-platform XP-W10
or W10-XP).  I added a smoke alarm and a fire extinguisher within feet
of the shelving holding the batteries, the charge controllers and the
2000 watt pure sine wave inverter.

I've done my own residential electrical work for years, complete with
permit and the city inspector checking it out.  The last time, the
inspector had one question: "Are you an electrician?" so I must be
doing things right.  I'm not a licensed electrician but I plan to
sleep in that house - plenty of reason to get it right.

Grid power here is about $.10/kWH.

Posted by Jim Wilkins on December 4, 2021, 3:21 pm
 .........

Some of my AGMs had charging parameters written on the side. I found I  
didn't have to monitor them if I stayed within those parameters, which  
requires only a voltage adjustable and current limited power supply. The  
home made one that works best for me is based on an LM350 regulator. I added  
a digital voltage+current meter from Amazon and a Schottky diode in the  
output to protect the regulator and its power source from reverse feed from  
the battery. A large discharged cap in the supply could cause a heavy surge  
current from the battery through the regulator's intrinsic reverse diode.  
The caps in my homebrew supplies are 78000uF, bigger than beer cans.

Available meter brands and models change so I didn't reference mine. The 3A  
flavor resolves down to 0.1mA which is nice for other testing, the 10A is  
good enough for charging larger batteries.

The input supply can be a solar panel or an old 19V laptop supply, etc. For  
Dells power is the inner and outer shell rings, the center pin is data that  
indicates the brick's wattage. I made a mating connector from hobby store  
brass tubing to test them non-destructively.

The LM350 self-limits at around 4A which the 3A version of the digital meter  
has survived. I haven't needed adjustable current limiting for this use.  
When the AGM reaches full charge at ~14.7V the current drops below 1% of the  
A-H rating, for instance 180mA for a 12V 18Ah battery. That's from the spec  
sheet, not my experiments. If it doesn't the battery may have a weak cell,  
which will soon show up as <12V if you load it though it might not from  
charging voltage alone.

A sulfated (high impedance) wet battery may respond to charging at 16-17V.  
If so the charging current will slowly rise so a current limit or series  
resistance (brake light bulb) is needed. I've read and seen experimentally  
that this doesn't work on AGMs, but it's greatly extended the life of U1  
tractor batteries. AFAICT the only advantage of pulse desulfating is that  
it's inherently (and cheaply) current limited, whereas DC desulfating  
requires more care from the user. OTOH the pulse voltage can damage  
connected equipment.

An extreme case of this is when a car battery connection vibrates loose  
while the alternator is producing full power. The magnetic field in the  
rotor winding turns into a high voltage pulse of considerable energy.
https://en.wikipedia.org/wiki/Load_dump  
I built a machine to simulate this for GM and watched it quickly destroy a  
prototype fuel injection computer they hadn't hardened well enough to absorb  
the rapidly repeated pulses they had requested from my machine because they  
couldn't generate them with normal lab equipment. That may have been why  
they changed to side terminal batteries. I've built some pretty odd stuff on  
special order, projects the degreed engineers wouldn't risk their  
reputations on.

With practice you can quickly determine the SOC and condition of a battery  
by the charging current it draws as you vary the voltage. I haven't seen  
this in print and am not ready yet to write it up, since I don't neglect my  
batteries enough to encounter all conditions. My neighbors do so I have a  
few data points. I don't think they understand why I'm so happy to mess with  
their dead batteries.

The LM350 charger may revive a discharged NiCd or NiMH power tool battery  
that an automatic charger rejects. I bought a batch of Lithium cell phone  
chargers whose voltage had fallen below the BMS cutoff and used it to  
restore most of them.

An LM317 works pretty well too. They self-limit at around half the current.  
I was once the tech for the test stations Analog Devices used to confirm  
their product met data sheet specs so I know better than to give close  
values, some devices were a little better than spec and others were way over  
it, depending where they were on the wafer.

At Unitrode rejected IC wafers went into a box that was set out like a  
cookie bowl, take what you want. The ink-dotted bad devices formed blotchy  
patterns that hopefully revealed correctable nonuniformity in the  
fabrication processes. I used rejects to practice the delicate skill of  
probing to test them.
jsw  


Posted by SolutionsDIY on December 4, 2021, 5:59 am
 On Thu, 02 Dec 2021 19:23:26 -0500, in alt.energy.homepower you wrote:


Boy, wish I could afford even a small panel but they're too pricey
here.  So will make do with low-tech cheap alternatives.  Better than
nothing.


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