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battery backup for modem 2

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young707

young707

Electrical
Aug 11, 2014
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I am seeking battery backup for modem (DSL & cable) for 12VDC 3Amp.

Is there readily available consumer grade 12VDC battery systems so that we can power our modem and recharge our cell phones/tablets when power goes our?

Otherwise, what is the circuit available to regulate & current limiting. Also splite out lower voltages for USB charging outputs.

I prefer using commercially available rechargable 12VDC lead acid batteries.
 
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There are a number of makers of Uninterruptible Power Supplies, also called UPS. They include A/C outlets; I expect that many offer USB style outputs as well.
 
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thank you for your quick replies. Yes, similar, but no need for "uninterruptible". These are industrial grade UPS for office operation, quite expensive units.

just home use for 12VDC battery power the modem and recharge cell phones & tablets.
> have connection for low cost 12VDC lead acid battery
> have both extension to recharge either by 110VAC or car cigarette plug
> have USB to charge cell phones & tablets
> DC female plug to power modem

quite like this mini DC UPS, but use inexpensive 12VDC rechargable lead acid battery

 
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If you're willing to make a few 12Vdc connections, then this would be relatively trivial to assemble yourself.

On one side, the charging options. You could add solar if you wish.
On the other side, the various DC or DC-DC outputs.
In the middle, the deep cycle lead acid battery.

The specificity of your requirements indicates that you're looking for an off-the-shelf solution.

 
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yes, I would rather buy a off-the-shelf item.

but, if needed, I am willing to do some assembling, may be a markatable project and sell on Amazon?
Any comments?
 
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Years ago, I had a somewhat similar unbranded (no name) commercial product. I still have it in my junk box of gadgets. It was intended to address the issue of power failures and cordless telephones. It accepted DC power from the cordless phone's original AC adapter, somehow noted the input voltage (and polarity?), charged up a very small internal lead acid battery, and then adjusted the output voltage to match the noted input voltage. When the power failed, the gadget kept the cordless phone's base unit working for many hours. Of course the cordless handsets have their own batteries.

The only reason that I bought it was that it was on clearance sale dirt-cheap; indication that the market is a tough place. Our ultimate solution was to purchase a desk phone that doesn't need any power other than that provided by the phone line. We may have to walk to the living room during power outages.

Incidentally, our present telephone, internet and one of our TV services, are via fiber optic cable. So the telephone line's power (the 48Vdc power and 90Vac Ringing Voltages) originates in the basement at the Optical Network Terminal (ONT) box. This box has a separate external power supply, and inside the power supply is - guess what? - a 12v 7A-hr lead acid battery to provide back-up so that the optical telephone line still works during power outages.

Like you, I've been eyeing the power supply (conveniently 12 Vdc) going to the connected Internet Wifi Router, wondering if it's worth providing a back-up power supply. Thing is, it's a lot easier to just turn on our smartphone's 'Hotspot' function. So I've not bothered.

Eventually I do plan to set up a 12 Vdc solar power system. But it's quite far down the list.

As I mentioned before, it's a fairly straightforward project. Just be very careful of the risks (e.g. install a fuse near the battery, etc.)

Good luck.
 
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I've actually never seen a 6V UPS. I've probably torn apart 10 random ones and replaced batteries in about 20 and in one case one had a 6V battery.. two of them in series. :/ Two were 24V with 12V batteries in series. A dedicated USB UPS could certainly use a 6V battery effectively.

Keith Cress
kcress -
 
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Thank you for all your helpful replies. Still searching for off the shelf or easy to modify and assemble solutions

When our power went out caused by storms and triple digit super hot days, we desperately want to
1. Recharge the cell phones, tablets and laptops – 5V USB
2. Power the cable/DSL modem + WiFi router + VoIP phones – 12VDC

Only interested in cheap 12VDC rechargeable lead acid batteries – around $15 to $20

Not interested in “Uninterrupted” Power Supplies. Not interested to power 120VAC desktop equipment.
 
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Seems to me that you're underestimating your consumption requirements. If you're planning on actually using two laptops, that's potentially 40W of draw, alone, add in your other items, and your'e looking at less than 3 hours of operation. Let's not ignore the possibly of wanting fans, etc.

I also think that you miss the point of the UPS, which is that they are turn-key solutions for your stated requirements. Moreover, their batteries are ostensibly chosen so that they can tolerate long periods of float charging.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
 
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Hi IRstuff,
You are correct. I always thought those little UPS batteries were 6 volts. Turns out they are 12 volts. The larger UPS used 2 batteries and I thought they were connected in series to make 12 volts. Apparently they are connected in parallel.
I learned something new today.[sup][/sup]

 
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Well, there are laptops and there are laptops.
Microsoft Surface 3 is only 13W, recharge with USB, good for 9 hours. Sorry, no huge massive big screen i7 jobs. We are minimalist.

A $20 12VDC rechargeable lead acid battery at 7 Amp is 84W. Otherwise, get another battery stand by and swap in, meanwhile recharge the used unit in car?
 
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To be more precise, the common cute little 12 Vdc lead acid battery would be 7 Amp-hour, and thus 84 watt-hour. It's worth being precise on that semantic point because it helps to keep the concepts crystal clear.

Just the other week, I went through (charging, testing) four of those 12V, 7A-Hr lead acid batteries to see which were still good and which had died of neglect. Sadly, 50%.

 
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Have you looked at booster packs or jumper packs? Basically a 12V battery in a carrying case with jumper cables attached and some have options such as USB outlets.
 
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12V booster packs or jumper packs: are you talking about 1500 peak amps, 360 cranking amps, to jump start cars? That's hundred of dollars of juice.

For nearly 10 years, I use a 24VDC electric lawn mower. It has two 12V small battery in series. It works well in around up 40 to 50 recharge cycles so far. I have never have to replace it (last chack its cost around $35 replacement battery).
 
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