Making a supplemental AA battery pack for a TX

[pruss]

Anybody have ideas on the best way to do it? The charging voltage for the TX is 5v. I suppose that means three 1.2-1.3v rechargeables won't be good enough? I guess four would be just right, but I am worried that I might one day want to stick four alkalines, and then the total 6v will blow the TX. I am really ignorant about these things.

Also, where does one get, or how does one make, a battery holder?

I do have an extra charger cable I can cannibalize.

What made me ask is that I ran out of power stargazing last night. Fortunately, I had enough power to continue using internal memory--only the SD card was inoperative.

Thanks for any suggestions!

[ejtbatchelor]

Current is the more important factor then voltage, too much current will fry your T|X, and I'm pretty sure that your backup battery pack/ power supply will only be able to charge the internal battery, so you will have to wait until the internal battery has sufficient charge and this might not suit your needs, unless you want to do some in depth modifications to your T|X.

[ftwitty]

I have done a custom 4 AA battery charger with a Tx power connector clipped off an extra AC power supply. Nothing fancy. Works well with either rechargable or litium/alkyide batteries with no harm to the Tx.

[kpopgrrl]

I suggest you buy one from Tech Center Labs, they go for as low as $10: http://home.earthlink.net/~gmayhak/catalog.html

I got my mic from them, they make great accessories.

[martinloat]

This thread seems to have everything you need to know :)

http://www.1src.com/forums/showthread.php?t=141716&highlight=batteries

It does move off phones and onto the TX very rapidly before spending a while discussing the number of charges from a set of batteries and then moving on again.
Good luck

[ftwitty]

This thread seems to have everything you need to know :)

http://www.1src.com/forums/showthread.php?t=141716&highlight=batteries

It does move off phones and onto the TX very rapidly before spending a while discussing the number of charges from a set of batteries and then moving on again.
Good luck
Yep, there was a good bit of discussion of available 1 and 2 battery products, but the original question of this thread was about making one with 4 batteries ....... my custom thing still works better than the 1 and 2 battery commercial products. There are some 4 battery commercial units that work just as well as mine. Boxwave makes one. THere are others I'm sure.

[ftwitty]

You can buy the battery holders from Digikey and maybe other places as well.

[Greek]

Alex: as kpopgrrl said, you may want to check this, it's $10 (perhaps you'll end spending the same if you DIY). It's small as it works with one AA battery (I guess they may raise the voltage to 5v).

http://home.earthlink.net/~gmayhak/catalog.html

Regards,

[pruss]

ftwitty: Your 4 cell unit is unregulated?

[kpopgrrl]

Also something else: iGo makes emergency charges that use 2 AA batteries. Since Treos and the Centro use the same charger, iGo sells Palm tips to go on their chargers. It's nice because you can get a wall charger, emergency charger, car charger, the tip for Palms and the tip for your phone and you're good to go. Radio Shack sells them.

[ftwitty]

ftwitty: Your 4 cell unit is unregulated?
Yes, it is unregulated. The Tx appears to have a range of voltage input that works as I previuously indicated.

[pruss]

Thanks for all the responses!

I got a Radio Shack enclosed 4 AA holder with switch for $1.99. My 700P came with a converter cord between central prong and Athena chargers, so I cut that converter in half, and soldered the Athena end to the battery holder (after checking polarity with a volt meter against a standard Palm charger--which, by the way, was producing about 5.3v).

I didn't want to risk my TX and Treo on 6.3v (which is my four alkaline AAs were producing), so I removed one of the AAs from the holder, and put in its place a cut-off Q-tip wrapped in aluminum foil. I now got about 4.6v, and my T5, TX and 700P all recognized it and started charging. Not wanting to waste good batteries, I stopped after the TX charged four percent up.

It seems this is what I need. With 1.2v rechargeables, I'll put in all four, and with alkalines, I'll put in three.

Total project cost: $2.15 with tax, except that my 700P's resale value goes down slightly because I used its charger converter.

Now I won't have to worry that I'll run out of power on my TX in the middle of an observing session.

[ftwitty]

My memory tells me that you are already near the published bottom limit for voltage. It would be interesting to see that the real bottom limit is.

[pruss]

My memory tells me that you are already near the published bottom limit for voltage. It would be interesting to see that the real bottom limit is.

What's the published upper limit?

[Gregte]

Pruss,

As has been established 4 AA cells, whether the 1.2 volt rechargeables or 1.5 volt primary cells will work just fine in a holder that puts all 4 in series, no regulation needed. I have bee using one I got in eBay for $2 for over a year.
http://cgi.ebay.com/Battery-Charger-for-Palm-TX-LifeDrive-Treo-650-680-755p_W0QQitemZ150318346869QQcmdZViewItemQQptZPDA_Accessories?hash=item150318346869&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50
http://cgi.ebay.com/Battery-Charger-Extender-For-Palm-TX-Tungsten-E2-T5_W0QQitemZ290284774743QQcmdZViewItemQQptZPDA_Accessories?hash=item290284774743&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50
http://cgi.ebay.com/Battery-Charger-for-Palm-TX-LifeDrive-Treo-650-680-755p_W0QQitemZ150317714394QQcmdZViewItemQQptZPDA_Accessories?hash=item150317714394&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50
Sometimes these ebay adds state that the device has circuitry to keep your Palm from over charging, using an IC chip. One says that it is 'current limited' to protect your Palm. This is all nonsense. I have bought two of these from two different ebayers and they are identical. If you take them apart you will discover they are nothing but a 4 AA cell holder with an on/off switch and a LED to indicate when it is ON. Remove the LED if you want to get maximum life from the batteries.

They are built so that if you put in the AA cells backwards they will not make contact and therefore that is a safety feature.

[pruss]

Pruss,

As has been established 4 AA cells, whether the 1.2 volt rechargeables or 1.5 volt primary cells will work just fine in a holder that puts all 4 in series, no regulation needed.

Is that true for Treos as well as the TX?

[Gregte]

Is that true for Treos as well as the TX?
I don't know from experience because I don't have a Treo but I would not hesitate to use 4 AA Alkaline cells to power a Treo if I did have one.

The battery chargers (as some call them) as shown on the ebay adds in my last post state that they work for the Treo, And as I said, there is absolutely no voltage regulation circuitry in them.

You can operate the PDA with the 4 AA cell device connected to it or you can use the device to charge the batteries while not using the PDA. It is no different than using the PDA with the AC power supply plugged into it.

But by far the cheapest way to go is to use NiMH cells. I recently bought some that are rated at 2700mAh, which is more capacity than most alkaline cells. They can be recharged hundreds of times, making each charge cost a few pennies.

With my ebay battery pack and the 4 NiMH cells I can watch movies all day long and never run out of power. I haven't done any scientific measuring of these 2700mAh cells but I know I have watched as many as four 2-hour movies and still have power to spare, I guess they are not actually 2 hour movies because I do zip thru the commercials with TCPMP.

[rdiheath]

I have one for my T5 that I made with leftover parts from the making of my sons holloween costume last year. Got it all at radio shack
You can get a 4 AA holder that has a 9V plug on the top. This works nice as I can use it to charge the rechargable 2500ma batteries that I use in it and dont have to take them out. I used an old usb charger (for a treo) and attached a 9 volt connector on the end of it. I plug the "pack" onto the 9v portion of my battery charger and plug it in and charge the batteries and then simply unplug it from the charger and plug the connector to the 9v port on top of the "pack" and plug it into my t5
It will run off of the extra power OR charge the internal battery. Batteries were the most expensive at about $10.00 but the rest of the stuff was like 4.00

[MikeB]

I found this at APC for about $15 shipped:
http://www.apc.com/resource/include/techspec_index.cfm?base_sku=UPBX

In the past, I've used similar items from ebay for about $8 for both my T3 and TX and they worked great for long airplane trips. I prefer the ones that use batteries so I can bring extra batteries in my carryon to power my device for as long as I need.

I am ordering the APC unit because it has several advantages:
- a USB connection so I don't need one for my T3, one for TX, one for cell headset, and one for iPod. One size fits all.
- while it does require a specific USB cable, this is an advantage since I can use my longer length cable rather than the short one that comes with the ebay models
- the USB model may allow me to power multiple devices at once (with a mini USB hub)
- it doesn't look like the APC model has an LED, which I used to tell me if the batteries were in need of charging or replacing

[ftwitty]

What's the published upper limit?seems that I remember 5.6 volts.

[Gregte]

ONe thing to be aware of is that AAA cells usually have only about 1/3 the capacity of AA cells but usually cost more than just 1/3 as much. If you have a need for a lot of extra run time as opposed to just a little then AA cells would be a much better value and much less bulk to carry with you assuming you could need 3 times as many extra AAA cells.

[pruss]

I've tried four 2000mAh NiMH AAs and couldn't get my T5 above 81% charged (eventually the AA's went down to 4v total). It may be that the batteries weren't fully charged, but I gave them about 14 hours in my RadioShack 13-hour charger, so I thought that should be enough. And they're less than a year old, with only about eight charge cycles on them.

Yesterday, with my 700P, I had the feeling that at one point the external battery pack was speeding up the battery depletion, and I was seeing weird things like the charging light turning from red to green even though the battery was only 80% or so charged.

I've got some new Sony CycleEnergy AA's coming tomorrow, and I'll see if it works better with them.

[Gregte]

I've tried four 2000mAh NiMH AAs and couldn't get my T5 above 81% charged (eventually the AA's went down to 4v total). It may be that the batteries weren't fully charged, but I gave them about 14 hours in my RadioShack 13-hour charger, so I thought that should be enough. And they're less than a year old, with only about eight charge cycles on them.
You got to put a voltmeter on them otherwise you are just guessing.

My battery holder with 4 NiMH cells will keep the TX at 100% for a few hours while watching movies on TCPMP. It does not have any voltage regulation of any kind in it. Just four cells hooked in series and then that plugs into the TX power port, not the USB port.

[pruss]

Seems to be working on the T5 with more fully charged NiMH cells.

Question: Is there a limit on how long a pair of wires, and of what gauge, I can put between the battery pack and the PDA? I think I'd like about 75-100cm, so I can comfortably keep the battery pack in an inner pocket and the PDA out at night outdoors. NiMH performance in cold weather is supposed to be poor. (The battery in the TX is Lithium Ion, I think, and it, too, seems to suffer in cold weather. Last night, when it was about +3C, my TX ran out shockingly fast.)

[raspabalsa]

I don't think you'll have problems with that wire length, if you choose an adequate wire gauge. The TX and T5 draw a little over 0.5A when charging through the adapter. Assuming a current of 1A (added safety factor) you can use AWG 24 wire (according to NEC ampacity tables for the voltage and length).

Some time ago I made an external pack, but I used 8 AAA cells, wired in two groups of 4 cells in series, and both groups in parallel. Total capacity was about 1500mAH, just enough for two charges of the T2 I used back then, or one charge of the TX. But the advantage of the AAAs is that they have much smaller diameter, and placing all 8 cells in a line next to each other makes for a very flat pack. This pack was small enough to fit in the front flap of my T2's leather case.

Eventually I found I needed more power, and not even AA cells had the capacity I wanted, so I built a battery pack powered by six Li-Ion cells. The Li-Ions are connected in series-parallel for a total voltage of 7.2V, so it can't be connected directly to the TX. It uses two voltage regulators, one to charge the Li-Ions from an external supply, one to lower the pack's voltage to 5.2V to charge the TX. The total capacity is about 4500mAH when fully charged. With this pack and with my TX's externally mounted batteries I can spend two weeks away from the power outlets. Or I can watch about 36 hours of continuous video with TCPMP.

[Gregte]

Here's a picture of my external battery setup. I bought the 4 AA cell holder on ebay for $2 new. It has an 8 inch cord that plugs into the TX.

I built the charger device so that I can use four 2700mAh NiMH cells in the holder and just leave them in there for charging. I had to put the power jack inside the holder for plugging my charge circuit into.

My charger is designed to charge the cells up to 1.46 volts per cell and then it shuts off the charging by opening a relay. This is the voltage level where the cells are just starting to rise in temperature signifying they are 'done'.

[philpalm]

Anybody have ideas on the best way to do it? The charging voltage for the TX is 5v.

What made me ask is that I ran out of power stargazing last night. Fortunately, I had enough power to continue using internal memory--only the SD card was inoperative.

Thanks for any suggestions!
Since it seems like you are stationary for a long period of time and it is quite cold maybe you should buy a car battery booster that comes with the car plug outlets. They also come with an air compressor and supplementary lights too.

Just make sure when your TX gets low then connect it for less than 15 minutes because a car plug adapter can overcharge your TX.

My brother usually runs his laptop off of the car battery booster with the 120 volt AC converter because that circuit route has overcharge protection.

[Gregte]

...Just make sure when your TX gets low then connect it for less than 15 minutes because a car plug adapter can overcharge your TX....
The TX will not over charge regardless of what the source of power is. For that matter the TX's regular factory charger does not ever shut off. That is taken care of within the TX.