External Battery

[ericw33]

FYI:

I'm running several external batteries to my tablet.

The primary one I use is a rechargeable 9800 mAh @ 12VDC (118 Wh) CCTV battery. The CCTV battery uses it's own plug-in external transformer (mine is 110-240 VAC). You can get them for about 40$. I'm not sure how long it will work for - I can run the tablet with WiFi/Skype/Movies for over 8 hours and still have a 100% charge in the internal tablet battery. They are very small and light.

Example:
http://www.ebay.com/itm/12V-DC-Rechargeable-Li-po-Battery-CCTV-Cam-9800mAh-/280805158576?pt=LH_DefaultDomain_0&hash=item41614aaeb0

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I used this power cable:

http://www.bixmart.com/DC-Power-Cable--55-x-25mm-to-30-x-11mm_p_262.html
* I had to put a tiny bit of aluminium foil in the center-pin as the inside pin is barely long enough. Make sure NOT to 'short-it'. If you do not do this then as you move the wire the power will be intermittent to the tablet.

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I'm not using a DC-DC regulator but thus far the voltage drop has not been an issue (12.6 VDC fully charged, 10.1 VDC near discharge). The tablet charges to 100% then indicates being plugged in. You can get DC-DC regulators if its required.

I just tuck it into the fold-able case. I might use velcro in the future.

Great if you need to run a long time without power - say on a international jet flight or when the power is out (ie: watch some movies during a hurricane). Also as the tablet, the power cables and adapter give off VERY strong magnetic fields when plugged (to about 2' out) into the AC I only use it when running off DC. Great if you're electro-sensitive or would like to avoid that.

Also saves the internal battery as Li-Ion batteries are only good for about 600 charge cycles.

* A full charge is over 15-hours, so get two or three and swap as required if you will use them everyday. Also, make sure to charge in a safe location as sometimes Li-Ion batteries can go "poof". I measured 10.8 VDC on the battery when my tablet began to use the internal battery. As with a full-charge the voltage is 12.6 VDC and near-dead it is 10.1 VDC. It's actually good that it SEEMS to stop at 10.8 VDC as I don't to fully drain the battery.



EW

 

[Icebike]

I had to put a tiny bit of aluminium foil in the center-pin as the inside pin is barely long enough.

This does not sound all that wise....

The potential for a battery short is pretty extreme, here. You also don't specify which end of that cable needs the
tinfoil or how to apply it. It might be safer to trim down the plastic at the base of the connector so that it can
insert farther. If you are relying on the LENGTH of the center pin to make a connection, it indicates you have the wrong diameter center pin.

The cable you mention seems to have a male connector on both ends, but the tablet requires a female connector
on the power cord. So I'm sort of confused here... Help me out.

 

[ericw33]

So far it's done pretty good - but it's not the final version.

The CCTV battery has two DC connectors (although two batteries I have also have a 9 VDC and a 5 VDC USB style connector in addition to the 12 VDC).

One is a 5.5 mm by 2.1 mm female barrel connector which also doubles to charge the battery (connects to an included transformer), the other one is a 5.5 mm by 2.1 mm male connector. The battery is a bit odd in that you have to have it "on" when charging it. The AC Adapter has a "red" and "green" LED light and the battery has one "red" LED light. Basically the "green" is lit until it's fully charged (both the "red" LED on the charger and battery are lit as well on the version I have)- can take up to 18 hours.

Anyways, the one end of the cable plugs into the female DC connector on the battery. In the hollow-center I added a TINY-bit of foil. On a spare cable I'll take it apart next and see if I can't grind it down a bit (which if it works is a longer-term solution). Also I will add an in-line fuse near the positive terminal.
* The 3mm by 1 mm tip which fits into the Acer works fine. A bit long & has no groove but no problems. It's the 5.5 mm by 2.5 mm which was a 'hair-off' (one cable worked fine, one required the mod so possibly a slight manufacturing variance).

Note:
The female 5.5 mm by 2.1 mm barrel coonector on the battery looks like this:
http://www.batteryspace.com/connectoradaptor55mmx21mmbarrelfemalewire35long.aspx

The 5.5 mm by 2.1 mm male connector on that cable looks like this:
http://www.batteryspace.com/connectoradaptor55mmx21mmbarrelmalewire15long.aspx
^--- I put the sliver of foil in the inside of this one and it worked great. As I said, I'll disassemble the spare and see if I can't take it down a hair via my grinder. I have other cables better suited now so it's more out of interest as I'll phase this out.




I have other alternatives in the works - some involve soldering which is pretty easy to do but not everyone has a soldering iron. I've seen similar run straight but I strongly recommend an in-line fuse.

For instance, I have a DC-male-connector to a DC female (cigarette) socket. From this I will run it to a DC-DC regulator (delayed as checking out tip sizes). If I don't want a DC-DC regulator I can just use a male-DC plug to a compatible tip (many sockets have fuse already built-in)..

The biggest issue with the Acer is the plug. I can't get "Radio-Shack/The Source" type "G"'s in Canada (discontinued up here in Canada, no stock, and various eBay retailers won't ship 'em here) so I've had to adapt various cables (pretty basic but some soldering and an ohm-meter are required). Fortunately you can source various power cords which fit the Acer. The cable I listed above has a tip which is a bit long - the others I have fit nicer (shorter) and have a 'grove'. No doubt a better fit although I've had one which was defective in the tip.

I also have a 140 Wh universal laptop battery pack I can use - this is more for fun.



EW

 

[Icebike]

You are right, that final female tip to connect to the tablet is very hard to find in the right size. Lots of close fits, but Acer must have
had to hunt for the one they chose so as to make it hard to find.

You might try Digikey or Mouser

The cigarette lighter plug would be very good, and you probably wouldn't need much in the way of protection, a simple inline
fuse should suffice. Automotive cig circuits have pretty consistent voltage, even while starting.

This would be good for travel, and keep the kids entertained for hours, or with some mapping software installed (on-board maps) it would make a great nav panel.

When I looked at the cable you listed in the first post, it was male on both ends. But the acer has the male in the tablet. Are you sure you posted the right cable?

 

[ericw33]

Yes, the cable fits the A500 (or at least my A60) fine.

I have another cable here which looks like this (this one is listed for a A100, but there are similar for the A500):
CAR Charger power adapter FOR ACER ICONIA TAB A100 tablet 8gb 16gb | eBay
^--- I'll plug that into a 5.5 mm by 2.1 male to a female cigarette socket cable. The male-socket if you open it up has a replaceable fuse (which of course makes this option much safer).

Thanks for those two links, I'm checking them out now.


EW

 

[ericw33]

Update:

The "foil fix" might only be applicable to one of my 9800 mAh batteries. I think the female connector on the battery is a 'hair' off spec - probably due to very manufacturing variations. btw, icebike, if you check the cable I listed it's m-m on the cable but it includes a f-f adapter is on the Acer tablet side. The Acer tablet has a male connector.

I have the parts for my (fused) cigarette connector setup & will test this next. The tip on the Acer tablet side is better - it's slightly shorter (good) and has a notch just the OEM connector. I disassembled part of the adapter and it does have a fuse which is better/safer. I'll run tests on this shortly. I'll post the connector later if anyone wishes - this would be the safer & better alternative and doesn't add much cost.

I have another battery type which has 5 VDC (USB), 9VDC and 12 VDC off the same CCTV battery. The energy capacity per hour is a bit less - 7800 mAh versus 9800 mAh both as 12 vDC. That makes it 93.6 Wh versus 117.6 Wh. But as I also own a COBY MID-1125-4G and other various USB devices the 5 VDC USB connector on the same battery is great when traveling. I can charge up my COBY, cell phone, MP4 players and so on AND run my Gateway TPA60 (Acer Iconia A500 equivalent). I run this way now but I am looking for (or will solder) a FUSED 5 VDC USB to adapter plug cable for this application.

As I get about 8 to 10 hours more run-time with the 9800 mAh battery (before it starts to discharge the internal battery). I would imagine each fully charge battery of this type might get me 6 - 8 hours more. While FAA (US) regulation limit how many Li-Ion batteries you can take it should be more than enough to watch movies non-stop. My next flight is just over 23 hours followed by a 8 hour drive home so 2 batteries and a fully charge tablet should do it.



EW

 

[ericw33]

Update 2/11/12:

I've used the female cigarette socket connector adapter for a while now and it works quite well. Basically it's the CCTV battery to the female cigarette connector then male cigarette connector to Acer Iconia tip. Again I'm using an Gateway A60 which is an Acer Iconia, however, always check your specifications and everything is done at your own risk.

The advantages are: a. fused connection as the male cigarette connector has a fuse in it (much safer if the cable ever shorts out), b. longer cable, c. LED light in the male cigarette socket lets you know power is flowing and d. optionally you can get a DC-DC regulator in there. So a bit better then the single cable (which I still take along), a bit bigger & heavier due to the coupler and an extra connection which could potentially cause issues (ie: pull out when in use). Overall works great for my applications.

Off the 9800 mAH @ 12VDC I get about 8+ hours more before it starts to use the internal battery. I usually recharge them about 24-hours - have more than one and rotate them. Do not charge unattended, follow safety precautions and do so in a safe place in case of fire.

CCTV batteries come in a flexible bright blue plastic "wrap" or a black, hard plastic shell containing the soft, plastic wrap & battery. So far I suggest the hard, black plastic shell versions even if adds some weight and bulk due to he increased durability and protection.

I have some 3-way (12VDC/9VDC/5VDC) batteries I'm now testing. The 5VDC, USB cable included just happens to fit my COBY MID-1125 4G and the 12VDC connector can be used with my existing setup. It's: DC 12V 6500mA, DC 9V 8500mA
and DC 5V 15000mA. I plan to run both the 5VDC USB to my COBY at the same time and to my Gateway A60 (Acer A500) using the 12 VDC - still need to run tests. It's a bit lower capacity but should be fine for most applications.

There's a bunch of other stuff I'm testing them on such as external hard drives which is perhaps the scope of this forum.


EW

 

[ericw33]

Update 2/15/12:

A quick note on the 5V/9V/12VDC, black, hard shell CCTV battery. Rather than use a female barrel connector it has a dual pin setup (12VDC conenctor) which works much better. The capacity as I listed above is less (6500mAh @ 12VDC verses 9800 @ 12VDC) but you gain the flexibility of multi-voltage output, the strength of the rigid plastic case AND a better 12 VDC connector design. btw - You can buy a DC-conenctor to 9V connector, I'll test this in the future as it allows me to run 9VDC items without always having to charge those small 9VDC batteries all the time.

On one of my 9800 mAh CCTV batteries the connector has been the weak point as you have to be careful power flowing (either in charge or discharge mode). I've never had that issue with the other battery so I recommend that version. You can also get a black, hard shell version with the better connector in the 9,800 mAh and other formats.

Again I am using a Gateway A60 which is a re-branded Acer A500 (same company) - always check your voltage specifications, use common sense - you assume full responsibly for what you do with your setup. DO NOT SHORT THE BATTERY - VERY, VERY DANGEROUS!!

I use the same connectors as I listed above for either setup.

Note: I am now testing a 18,000 mAH CCTV battery, 12VDC with the better connectors. Too early to tell but IMO should get 16-hours to 20-hours before the voltage falls to the point the tablet's internal battery must kick-in. Thus a fully charged tablet and external battery would/should yield 24+ hours run-time. Very handy during (say) power outages (ie: hurricanes, snow-storms..), travel, camping and you name it. The battery charge routine is about the same as the others and it also takes about 24-hours for a full charge (uses a 1A charger rather than a 360mA charger). I use the external batteries as portable 12/120V power supplies for power tools & water purification (using an inverter), why I have high capacity units.
* 18,000 mAh (18A) @ 12 VDC = 215 Wh (Watt-hours) --- that's amazing!



EW

 

[kunddizzle]

Hi Nice article.

Im gonna try this battery package as well!

I have the Motorola Xoom and bought a 1800mah 12v cctv cam (only one which was cheap enough to import from outside Europe).

A few questions

1) Will I be able to charge the battery with the Xoom charger (with the right connector of course) ? Its 12v @ 1.5A. Or will the battery explode?
2) If i connect the battery to Xoom and the charger to the battery at the same time. Will the battery be charged, and when fully charged will the tablet only draw power directly from the psu?

Then I would be able to have a fully charged battery all the time and ready to use when leaving for longer trips?

 

[ericw33]

kunddizzle:

1. Check the specifications for the Motorola Xoom. With my Gateway A60 (Acer A500 repackaged) it's 12 VDC, + tip, 1.5 A (1,500 mA). You can find the information on your transfomer, possible the tablet, and the user manual. Make sure the battery voltage is the same, the amperage is sufficient and that you have the tip to the correct polarity. Most are + tip, but not all are. It's easy once you get the hang of it.

Note: As specifications can change even within the same tablet family or even model it's vital to always check the specifications on your particular unit & consult your user manual. If you're unsure about electronics then ask a friend whom has the appropriate background to help you.

2. Do NOT underestimate the flexibility of the CCTV batteries - it can run many things not just your tablet. For example:

- with the 12VDC version I have a 12" fluorescent under-counter light I'm taking along. The one I bought at a dollar/discount-store a long time ago just happens to run 12VDC, + tip, 1.5A --- so it works great! It also uses the standard DC connector so I didn't require anything special! Plenty bright for an entire room - I'm sure 12V LEDs would work well too. Handy for power blackouts & bright enough to light up a small room.
- my larger 20,000 mA (20A) battery can power my invertor for powering small tools and recharging my camera on the go. (12V * 20A = 240 Watts). So I can use it for small invertors (DC to AC) to run say a dremmel, or, run my small pump & UVC light for water purification in the developing world (working on this now).
- The 5V USB to small-DC like connector just happens to fit (and be the right tip, voltage and amperage) my power portable, travel AA/AAA battery charger.
- I'm even testing it on other items (at own risk) - for example, my GoFlex 3TB external drive. Can't say yet but might be a solution (for me) on the go when I need my big drives or a media server.

3. Flexibility works well. I use:

a. 170 Wh Universal Laptop Power Supply
b. 5V (1500mAh) / 9V 8500 mAh / 12V 6500 mAh CCTV Battery Pack * Great as I can power USB 5V, 9V and 12 V all at the same time!
c. 12V 9800 mAh CCTV Battery Pack
d. 12V 20,000 mAh CCTV Battery Pack

Items b. and c. use the same small transformer and requires 18 - 24 hours for a full charge. Item d. uses a larger transfomer - it's basically 5 - 12V 9800 put together!, but requires the same amount of time (18 - 24h) to recharge. I use a few so I always have a charged unit - handy in the developing world when AC power isn't too reliable or during emergencies.

USE THE CORRECT, SUPPLIED TRANSFORMER - Do NOT mix and match!! Do NOT use other product transformers to charge them (explosion hazard!!). Li-Ion batteries need to be re-charged a certain way. Consult the instructions! With the versions I have of the CCTV batteries, the unit is turned on (LED lit) and then it's plugged in. Items b. and c. have two LEDS, one RED and one GREEN of which one turns off when the charge is compete. Item d. (the version I have) has only one LED light (green). If used correctly per supplied instructions they are very safe.

I always charge it separately and use a fresh-charged battery to run the tablet. If you use a Gauss magnetic meter (mine is a Trifield) you'll find that there is a powerful magnetic field coming off the transformer, the cable and the entire tablet. Worse yet, it's a pulsed field. For health reasons & to avoid the possibility of becoming 'electro-sensitive) I never, ever use it plugged in. The field can reach close to 100 mGauss up to about 8 - 12" away. So I keep t entire tablet, CABLE! (the ENTIRE length of the cable), plugged in peripherals and transformer at least 2 feet away. But when running off a battery the field is greatly diminished - sometimes around 1 - 5 mG. So for health reasons I am never close to a tablet (or a UPS...) when plugged in.



The 1800 mAh one is pretty small so I don't know how much of a charge it will give it. My guess is a few extra hours. Also I don't know how tolerant your unit is to voltage changes - the battery starts at 12.7 VDC and drops to 10.2 VDC. If sensitive a DC-DC voltage regulator may be required. My other tablet, a COBY MID1125-4G runs off the USB 5VDC output @ 3A, and it's pretty tolerant. It's really trial and error, of course, you do so at your own risk.

TIP: Goto ebay.com and search for the CCTV batteries - they have great deals!

The 170Wh (unit A) I can leave on a day or two (unplugged, running usual stuff) without issue (I put my tablet on it - kinda like a small tray or in my checked back-pack with a cable to the tablet). I like using female/male cigarette connector option - quite handy! Basically I have a battery DC connector to the female connector, then a *FUSED* male connector to the Gateway/Acer tip. As the cigarette connector is a standard I can plug in other 12V devices I have such as the power invertor or my DC-DC voltage regulator & adjustment unit (for powering (say) laptops).


EW

 

[kunddizzle]

Thx again

The Xoom will trickle charge at around 10.1 and show charge symbol @ 10.3v. It should be able to handle up to 24v I read somewhere.

Think im going for the 5v/9/12v battery, if I can find a seller inside EU.

Btw its this battery:
http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=

will post my results aswell

 

[ericw33]

Update:

1 month in asia & developing world equals great test of batteries in some rugged areas. The ride to the airport is 8 hours, arrival 4-hours early for check-in, and jet time including connections is 23 hours for a total of 35 hours (mostly using Bluetooth, GPS, usb hard-drive, video-players with some wifi).

The 18,000 mAh BIG CCTV battery ran the tablet going there and 80% of the way back. The size is about the same as a 6V SLA lantern battery. No TSA issues or issues at other airports other than asking what is was after the x-ray.

I watched movies from a USB hard drive (1.5 TB Seagate Portable Drive) which takes allot of power. Approximatly 20-hours of video each way (the tablet alone would run about 6-hours video). Tablet was 100% full (internal battery) the way there, 70% full after the journey home. I advise 2 - 18,000 big batteries for very long trips or developing nations where power might be out for days at a time or a massive 30,000 mAh battery (testing one now).

eBay has different sizes of 18,000 mAh Li-Ion CCTV batteries. "mAh" is the power (energy) it can supply over 1 hour and not how much energy is stored in total. Think of mAh as GPH (gallons per hour) - a flow rate and not what is actually held in the resevoir. In general the bigger it is (using the same technology, li-ion) the longer it will last. Most do not give that specifiation so use common sense.

My bix 170 mAh universal laptop battery runs the tablet and 5V USB devices for about 48 hours.

The batteries also run many devices from 5 vdc USB devices( ie: recharge Bluetooth headsets, mp3 players..), 12 VDC LED lights, water purification equipment and so forth. The adapters (for recharging) are 60 Hz, 100-240vac. So watch out in nations with 50 Hz, Japan, used 50 Hz and 60 Hz and bring adapters for nations where the plugs are different. I used the batteries everyday due to the normal everyday 12-hour power failures in some nations, terrible power quality (low voltage aka brownout most of the day) and as the power systems are nuts - bad wires, no ground-plugs, 5000w breakers, non-polarized plugs...) - I'd get buzzed touching stuff plugged in so I charged, put a glove on, unplugged, then ran off batteries. The metallic case of the tablet is a real problem for this as in some nations the whole tablet case becomes a 'live wire - why I use batteries in some developing nations.

Note: After 1 - 3 weeks paid apps may stop working. Many video players, Slide-It and others couldn't confirm the liscence so they stopped working until I got an internet connection at an airport in Japan. Take along "free" versions as well as paid versions may stop working until you can get a wifi internet connection. Not all places in the world have easy access to the internet so this could be a problem for many.

 

[dmtchico]

Thanks to all who shared the info about cctv rechargeable batteries!
Mine should arrive today.

My idea to solve the connector-to-the-tablet problem is to connect the battery to a female car cig-lighter then use my tablet car power adapter to connect to that.
My car adapter has protective circuits (i read) and it has a good connector for the tablet.

OOPS! I just read further on this thread and noticed that my idea is not the first.
HA.

Oh-Well. Thanks again for the cctv battery idea. It should work well for me on an upcoming long plane flight as well as for future backpacking/camping trips.

 

[ericw33]

Good to see this information has been useful. I run a good many items off of my batteries now aside from my 2 tablets. For example, to save electricity I use task lighting using LEDs. The battery supplies both the tablet and the LED light. I have a few LED lights I'm testing (10W LED flood, flexible 5050 LED strip, 12" LED light-bars..), and even added a "watt-meter" (measures power draw - actually for RC use), light-dimmer, a 1 to 5 DC splitter and a few other items as needed like my AC inverter (runs mu hobby tools and water purification system on-the-road).

So it's also help to radically lower my hydro bill as well as improve my health and the versatility of tablet.


EW