How can I check a rechargeable battery to tell if it needs recharging?

I want to buy a UPS battery to leave in the detached garage to charge my phone while working on the mower and other things. I don't have much luck with batteries. Years ago I used a lot of ups batteries for portable power and had problems keeping them charged. I'd think one was charged and it'd be dead when I needed it.

Will a trickle charger do a good job of charging it without over charging? There isn't any power in the garage so I'll have to bring the battery into the house to charge. It's to far to run an electric cord. I listen to a lot of Internet radio out there.

Maybe you can can suggest some other setup?

Thanks

On Thu, 07 Apr 2016 20:41:40 -0500, "Austin Davis"
wrote:

How can I check a rechargeable battery
to tell if it needs recharging?

It depends on the chemistry. The only sure way is to use a discharge
tester. However, that doesn't tell you if it needs a charge. It
tells you that your charging method is successful. There are also
some tricky ways of measuring SoC (state of charge) by putting a load
on the battery for a short period of time, measuring the slope of the
discharge curve, and using that information to guess the SoC. APC
uses this method in some of the SmartUPS designs. However, it's more
of an indication that you're battery needs replacement, than a SoC.
Another is a coulomb counter. That's common with LiIon battery
systems. In effect, it's a data collector that tabulates the current
going in and out of the battery. If the battery charge efficiency is
known, the SoC can be calculated.

I want to buy a UPS battery to leave in the detached garage to charge
my phone while working on the mower and other things. I don't have
much luck with batteries.

Let me guess(tm). You were trying to float charge a gel cell or AGM
battery with a crude charger? Gel and AGM batteries do not like being
overcharged, varying temperatures, or sitting discharged for any
length of time. In other words, they're quite easy to kill.

Years ago I used a lot of ups batteries for portable power and had
problems keeping them charged. I'd think one was charged and it'd
be dead when I needed it.

Offhand, I would guess that would be overcharged, and dead fairly soon
after. It might also be that you discharged the gel or AGM battery
too much. Discharge below about 50% SoC can kill off batteries rather
quickly.

Will a trickle charger do a good job of charging it without over
charging?

No, although that's controversial. My contention is that trickle
charging without a full charge cutoff is guaranteed to put a thin
coating of lead sulfate on the plates, which if discharged further,
will kill the battery. My favored method is the usual 3 stage
charger.
https://www.batterystuff.com/blog/3-stages-of-smart-chargers.html
with a total turnoff when at 100%.

There isn't any power in the garage so I'll have to bring the
battery into the house to charge. It's to far to run an electric
cord. I listen to a lot of Internet radio out there.

Solar power perhaps?

Maybe you can can suggest some other setup?

Google for "portable power station".
https://www.google.com/search?q=portable+power+station&tbm=isch
Get the one that has the biggest battery (heaviest weight on the
specs) and claims to have a decent battery charger circuit. This may
not be the best, but will probably be the cheapest. It can also be
used for other things in the garage. However, don't just leave it in
the garage. Bring it into the house and keep it charged to prevent
sulfation. The bad news is that if you use it regularly, the typical
battery life is about 5-7 years.

Also, if all you want is more runtime from your smartphone, get a
LiIon external battery battery for the smartphone. I have several and
find them quite handy for 5V (USB) power:
https://www.google.com/search?tbm=isch&q=smartphone+external+battery+back up
They come in different sizes and battery capacities. I can't tell how
big a backup you need without knowing your smartphone current drain.
There should be an app for determining that on the phone.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Il giorno venerdì 8 aprile 2016 03:41:44 UTC+2, Austin Davis ha scritto:
How can I check a rechargeable battery to tell if it needs recharging?

I want to buy a UPS battery to leave in the detached garage to charge my phone while working on the mower and other things. I don't have much luck with

Maybe you can can suggest some other setup?

buy a small solar panel.

Bye Jack

On 7 Apr 2016, Jeff Liebermann wrote
(in ):

Google for "portable power station".
https://www.google.com/search?q=portable+power+station&tbm=isch
Get the one that has the biggest battery (heaviest weight on the
specs) and claims to have a decent battery charger circuit.

How about the €œblue toaster€�? (c;

http://www.amazon.com/PowerOak-Gener...-Refrigerator-
AC160S/dp/B00SR4HQ62

Li-ion.

On Fri, 08 Apr 2016 09:32:47 -0700, DaveC wrote:

On 7 Apr 2016, Jeff Liebermann wrote
(in ):

Google for "portable power station".
https://www.google.com/search?q=portable+power+station&tbm=isch
Get the one that has the biggest battery (heaviest weight on the
specs) and claims to have a decent battery charger circuit.

How about the “blue toaster”? (c;
http://www.amazon.com/PowerOak-Generator-Deepfreeze-Refrigerator-AC160S/dp/B00SR4HQ62
Li-ion.

Overkill. He's trying to power a lousy smartphone, not power the
entire garage.

Also, I have my doubts about using a LiIon battery for backup power.
The problem is that LiIon batteries deteriorate if left at 100% charge
full time:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
http://www.mpoweruk.com/lithium_failures.htm
Some laptops have a "battery saver" profile, that charges the laptop
battery to 50-60% SoC in order to extend the battery life.

APC does offer a LiIon UPS (BG500). I haven't dug into their design
yet to see what they're doing:
http://www.apcmedia.com/salestools/GHSA-97F4WW/GHSA-97F4WW_R0_EN.pdf
http://www.amazon.com/APC-BG500-Back-UPS-Pro-500/dp/B00DW2J7SY
It has a 3 year warranty.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558