First, thanks for everyone's replies. Appreciated.
The unit I bought is rated for 900w and 1500VA. The specs don't list the
Wh but, again, my guess is around 100Wh.
The idea of hacking the unit and putting in a larger battery is
tempting. Theoretically, if it is rated for a 900w loiad, it seems that
100w or even 200w should be safe continuously. But who knows. And that
assumption has no relation to charging, where the charger is probably
the minimum to safely charge the existing battery.
So, I think I should either be content with what I have or build my own.
I looked briefly at batteries. I can get a 12V 100Ah AGM for about $200,
e.g.
https://theinverterstore.com/product/12-volt-100-amps-agm-deep-cycle-maintenance-free-battery-heavy-duty/
And a 100W inverter continuous for $30. E.g.
https://www.amazon.com/Plug-Car-Power-Inverter-Continuous/dp/B00IJSBFN6/ref=sr_1_7?dchild=1&keywords=car+inverter+100+watt&qid=1621832451&sr=8-7
I don't need rapid charge, just safe charge. Here's a 20A charger, $60:
https://www.amazon.com/12V-20A-Lead-acid-Battery-Charger/dp/B01LP262I0
Would these components work or would I have potential safety issues.
I'd rather have a complete package, off the shelf, with some gages: soc,
power draw, and automatic switch-over. But I haven't found anything
other than chinese (probably with no useful warranty or safety) that
comes anywhere close in price to what I listed above.
Peri
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------ Original Message ------
From: "Jim Walls via EV" <[email protected]>
To: [email protected]
Cc: "Jim Walls" <[email protected]>
Sent: 23-May-21 6:52:30 PM
Subject: Re: [EVDL] small UPS
On 05/23/2021 18:16, Peri Hartman via EV wrote:
Somewhat off topic...
For some time, I've been meaning to get a small UPS to power my router, laptop,
and other electronics in case of an emergency. Well, our power will be off
monday for utility work and so I bought a small UPS. But, I'm disappointed with
it.
Most small consumer UPSes are good for 15 - 20 at their rated load (when the
battery is new). Yes, that varies A LOT. Based on your around 100 WH, that
would make it about right for a 250 - 300 VA UPS (a quite small one). Yes, you
can usually connect a larger battery, but be a little careful. Most of these
consumer UPSes were not designed to operate in inverter mode for long periods
of time. As a result, they can't handle the heat from an extended run time at
anywhere close to rated load. Same problem on battery recharge - it is going
to be asked the charge for a far longer time than expected so again, heat can
be an issue. Heat is generally not that hard to deal with with some forced
cooling, but that may or may not totally mitigate the problem. This computer
is being powered by a 1500VA APC UPS that has about 50AH at 24 volts of
external battery, but under worst cast, the load is only about 300 watts.
There are more professional inverters that will happily run forever in invert
mode For example, we are running a bunch of these in a public safety
environment at work where they run in invert mode 24x7 essentially forever.
These can also run with AC input in either AC preferred or DC preferred. Note,
this is just the inverter. You supply the battery plant (we have 3,600 AH at
48 volts in a bunch of places - that's about 5 tons of lead).
https://www.amazon.com/gp/product/B07C3BKZ2F/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
-- 73
-------------------------------------
Jim Walls - K6CCC
[email protected]
Ofc: 818-548-4804
http://members.dslextreme.com/users/k6ccc/
AMSAT Member 32537 - WSWSS Member 395
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