Perfect 4AA battery pack for the CTR-350

tvBilly · EVDO User Joined: 02 Dec 2007 Posts: 30

I've been playing with my new CTR-350 and experimenting with different battery sources. I wasn't interested in days of power, just a couple of hours would do, so a 4AA pack seemed the best way to go. I started out following this great thread here, with a simple Radio Shack 4AA penlight holder (270-409) and connector ("N" size for my CTR-350), and outfitted it with four RS 2000 mAh NiMH low self-discharge batteries (23-010). This worked great, running the CTR-350 and Franklin CDU-680 (henceforth called "the rig") for about 3 1/2 hours. (And if you don't care about low self-discharge, you can get 2900 mAh NiMH AA cells, for 50% more runtime). Total investment, about ten bucks (five for the holder and connector, five for the batteries). Hard to beat.

Interestingly enough, the NiMH batteries powered the rig way longer than Duracell ProCell alkalines. The ProCells just so happen to also be rated at 2000 mAh at a 500ma discharge rate, which is what the rig generally draws. (Sometimes the rig draws more, btw). It turns out the voltage of the alkalines gets too low for the rig after just half their engergy is used up. This low voltage condition is particularly hard on the CDU-680, which freaks out trying to re-connect before finally giving up. So clearly the RS battery holder method sucks for alkalines (in fact, is a really bad thing to do to the router and the modem). It's OK when using NiMH or NiCad batteries, which keep their voltage up until just before they die.

So I wasn't totally happy with the RS 4AA holder solution. It has no voltage regulation of any kind, and so provides way more than 5 volts when using alkaline batteries, and less than 5 volts when using NiMH batteries. When the alkaline batteries are only half used up, the voltage is so low (just under 4v) that I worry for the router and modem electronics. Also, while it doesn't matter for primary cells that you throw away when they're used up, (like alkaline batteries), it's really bad for secondary cells (like NiMH and NiCad) to keep discharging them beyond a certain point, typically 1.00 volts per cell. Plus the RS penlight holder uses a tiny screw to hold the cover on, which I know I'm going to loose. Still, it only costs five bucks including connector, and it was waiting for me a block away from my apartment when I needed it. (I live in NYC Smile

).

So I did some detective work, and came up with a different 4AA holder that I think is perfect for the CTR-350 (and many other 5v devices). I got it two days ago, and put it through its first two tests yesterday at work. It's made by Tekkeon, and it's called the TekCharge MP1550. It's the perfect 4AA powerpack solution for the rig.

Let me get the two things you may not like out of the way. (1) It's not five bucks, it's twenty five bucks. (2) It also comes with a half dozen connectors for cell phones and the like, none of which work with the CTR-350. If you have no use for the connectors which do come with the MP1550, you probably wasted five or ten of the twenty five bucks. I didn't care about the five or ten bucks, and I made no attempt to buy it without the cable and connectors. (Also, I work with people that come to me six times a year asking if I happen to have a charger for a such-and-such cell phone, so there's some charity work involving having the cables, at least for me).

Now let me tell you about the things you may like.

Its got a 5v voltage regulator built in.
Its output connector is a standard (A) USB connector.
Its got three LEDs to show you how much charge is left in the batteries.
Its got an on/off switch.
It supports alkaline and NiMH and NiCad batteries.

Oh, and if you happen to be using rechargeable batteries, it will charge them in the case. Smile

The input connector to charge the batteries is a separate mini USB connector. And there's a separate red LED to tell you what's going on with the charge, including that you're accidentally trying to recharge alkaline cells. Sweet. Very Sweet. Even works (supplies 5v and allows recharging) using only two batteries (rather than four), though I can't fathom why you'd use it with only two batteries.

And no screws to loose; the sliding battery cover uses a clever latch built into the USB connector!

The MP1550 is almost the identical size of the CTR-350 itself. The CTR-350 sits perfectly on top of the MP1550. The four little "feet" on the bottom of the CTR-350 rest on the curves in the top of the MP1550. There's even a little gap between the two for (not really needed anyway) air flow. I made up a six inch USB to "N" cable which is very solid and works like a champ.

Having your 5v battery stuff on a USB connector scheme is both a blessing and a curse though. You absolutely have to keep in mind that most computer USB power connectors max out at 500ma. You can charge the MP1550 with 500ma, but 500ma is really not enough to power the rig. The rig can get away with only 500ma a lot of the time, but not all of the time. Those of you with USB modems, particularly older ones, already know that 500ma is sometimes not enough (hence the "Y" cable provided with some USB modems). Don't forget the CTR-350 needs power too, to talk to the modem, to run the router, and most of all, to power its WiFi station.

So just remember that having a USB connector on the end of the cable powering your rig doesn't mean you can plug it into any USB socket you find lying around.

The good part is the MP1550 will power anything that plugs into a USB (A) connector. iPods, iPhones, other cell phones, etc. You can also get rid of a couple of "AC to 5v USB" wall warts and other 5v power supplies, and replace them all with one good 5v supply that can provide 2.5 or 3 amps, and use it for everything, including the rig, with the appropriate cable.

Anyway, the MP1550 works great with the CTR-350 and CDU-680, and is an absolute must if you're planning on using alkaline cells. Protecting almost $500 worth of router and modem with a voltage regulated 4AA pack for twenty five bucks is a no brainer for me.

I haven't charged any batteries in the MP1550 yet (I have a MaHa C9000 that I use to charge AA batteries), but I'll report any interesting info when I do. Tekkeon says it takes three hours to charge two batteries, and six hours to charge four.

The older Tekkeon myPower Go MP1500 is not the same thing, doesn't have a voltage regulator, and doesn't use a standard charging connector. I would recommend you make sure you are getting an MP1550, not the older MP1500.

Bill S

ps I also recommend that my favorite 3gstore take a look at selling this.

Alex · Posted: Mon Dec 31, 2007 7:21 am Post subject:

WOW! Excellent Post!

Two things that I think a lot of people want to know.

-- how long did this thing allow you to operate your CTR350?
-- can you give us details on the cable you made? and pictures?

thanks again for the post.

tvBilly · EVDO User Joined: 02 Dec 2007 Posts: 30

tz1 · Posted: Fri Jan 04, 2008 7:25 am Post subject: Geekpod

http://www.batterygeek.net/ProductDetails.asp?ProductCode=GeekPod_100_Black&CartID=3

The geekpod might work well too. 6000mAH, and $60 (get $10 if you buy two). 2A, so it could power the CP, my n810, and recharge my BT headset.
3.2x2.3x1 inch with LED indicators

(It probably would work with the KR1 as well)

You would need adapter tips.

(BTW, my old woot closeout ZAP! power packs manage to go for well over two hours)

Update: Then, there's this slightly bigger but more capacious unit with USB connector output:

http://www.tangshop.com/universal-external-battery-3685.html

tvBilly · EVDO User Joined: 02 Dec 2007 Posts: 30

Thanks for sharing those GREAT pointers; both batteries look very interesting. I had a busy week, with no time for testing the TekCharge MP1550 with alkaline batteries yet. If it turns out that its not really very suitable for use with alkalines, then its utility to me goes way down, and both your suggestions are very appealing.

I noted that the batterygeek catalog shows a 0.5" thick 7200 mAh 5"x3" battery called the "PowerPack-B" that would make a perfect base for the CTR-350 to sit on for the 10 to 12 hours it should power it. Smile

Unfortunately, it's not to be found anywhere on their web site. Sad

I sent an email to them asking about it.

The TangShop's battery seems the better way to go as compared to the GeekPod, (more capacity, 5v USB (A) connector and multiple voltages via a co-axial power jack, and only slightly larger and slightly heavier). However, I am not inspired by the TangShop web site, and don't know if I'm comfortable buying from them. Just a feeling, nothing concrete... Do you have any experience with either?

I'm sorta hoping that the BatteryGeek PowerPack is still available, as it seems that it would best suit my purposes. (And I'm disappointed that my TekCharge MP1550 doesn't seem to work well with alkaline batteries).

Bill S

tz1 · Posted: Sun Jan 06, 2008 6:01 pm Post subject:

I got some batteries from battery geek a while ago. Nothing went wrong, and they were hi capacity and quality as far as I can tell.

You might try googling them to see if there were any complaints.

The Tang battery could boost my laptop too, but I would probably just use it with my n810 on the USB chain.

tz1 · Posted: Sun Jan 06, 2008 9:21 pm Post subject:

http://www.tangshop.com/universal-external-battery-powerbox.html

Tang also has this - cheaper, more capacity, a bit smaller, but 5V USB only and I don't know if it has a remaining charge indicator.

Just slightly smaller footprint than the CP.

rjs2015 · EVDO Fledgling Joined: 28 Dec 2007 Posts: 23

I just started using my CTR350 several hours ago and never thought about having batteries as an option. Most of the time my CTR will be next to my desktop with the electrical connection.

Will the Tekkon devise you mention be a good backup source for me? I would use it only when I am out with the CTR and may not have a electrical source.

I am not very technical so I just need to know the basics. Can I hook it up to my CTR350, do I need an adaptor?

Alex · Posted: Tue Jan 08, 2008 9:46 pm Post subject: Re: new CTR350 user

rjs2015 · EVDO Fledgling Joined: 28 Dec 2007 Posts: 23

Thanks. I will wait for the 3GStore.

I bought all my equipment with a bit of "wobbly knees" since I am not a computer person... but this forum, 3GStore, and the equipment is all that people say it is! I got my equipment and was up and running in minutes. No kidding.

CTR350
USB727 Verizon

normalee35757 · EVDO Newbie Joined: 22 Jan 2008 Posts: 6

quote]
3Gstore is deciding upon a battery pack for the CTR350 and should have news soon. stay tuned![/quote]

Alex, has 3Gstore decided on a 12 volt cigarette plug type adapter and/or battery pack yet?

Alex · Posted: Sat Jan 26, 2008 10:12 am Post subject: Re: new CTR350 user