Battery Question

muerte69 · 03-22-05, 10:38 PM

OK Here Goes,

I have been looking at making a battery pack to take with me from time to time and was wondering if anyone has used any of the NiMH C or D Cell Batterys to do it. I can get them for $10 for 2 at a local store and the holder for a couple of dollars. They are 3000Mah and as of yet I am unsure if I would do just a single setup with them in serial or 2 sets in parallel. I know I can also find some 4500Mah and I think I saw a 5000Mah somewhere but they were close to $10.00 for one. I plan to hook this up thru the charger adapter so it will just plug into that and then that into the Axim. I just want to know if this is feesable, what the best setup is and if anyone has done this. Thanks for the help.

jpmarth · 03-22-05, 10:56 PM

You can buy a battery extender off of ebay that uses AA batteries. Just get some high capactity rechargables to put in it and you are all set.

Ceril · 03-23-05, 02:01 AM

I suppose that you could use C or D batteries if there was such an extender. I personally have only seen AA ones.

The most important to remember though is the voltage. mAh just talks about how much juice can flow but the volts can be problematic. The x50 according to many posts here work about 5-5.4V. As long as you don't pass that, there should be no problem. It would be interesting though how long it would take to recharge a battery with 5000mAh!!!

Rice Lover · 03-23-05, 09:22 AM

Yeah I never thought of this method, but it might probably work, except if the voltage is wrong, it burns up the axim so just be careful about the VOLTAGE not the mAh.

muerte69 · 03-23-05, 10:08 AM

The NiMH C & D Batts that I have seen are the same voltage as the AA's so I think it could be setup just like the AA extenders. But any other opinions let me know.

Ceril · 03-24-05, 01:27 AM

Are you planning to make the unit to fit the C or D batteries

or did you find a company which already makes them?

Out of curiosity, why would you want to use Cs or Ds (which are also heavier and bulkier) than AAs? Just because of the juice (mAh)?

muerte69 · 03-24-05, 01:52 AM

I want it for the extra juice mostly. I have found a bunch of diffrent styles of holders at mouser and digikey's sites and they also have them for AA and AAA's as well. I have only looked in the mouser catalog but I have seen them in digikey before.Most I have found are around $1-$3 for the holder. Here's a link to some of them.

http://www.mouser.com/index.cfm?hand..._pcodeid=01202

http://www.mouser.com/index.cfm?hand..._pcodeid=01202

http://www.digikey.com/scripts/DkSea...236730&Site=US

http://www.digikey.com/scripts/DkSea...sus.dll?Filter

If I do it I may get a small pelican case to fit the holder in and drill a small hole for the wiring and then silicone it back up. Still not sure what I want to do yet. How many NiMH batteries would I need to get the voltages correct. I have read one that said 5 with a led will work. Also if someone could do the math on the total MAH in both the single serial and the doubled parallel circut I would be very thankful. If I get it and get it working i'll let yall know.

radish28 · 03-24-05, 02:02 AM

theres 12,500mAh D cells now

muerte69 · 03-24-05, 02:08 AM

I'll look those up. That would make for a beefy extender.

Ceril · 03-24-05, 04:05 AM

That would be really cool to make one. I would guess that 4 batteries at the 1.3V that the c's and Ds are would be appropriate (like the AAs) - though I would guess that series is the appropriate configuration (solely a guess actually)

I would be very interested in your results. You could even get a huge mag lite casing and have the basis for some REAL fun!!!

seriously, though, I would be interested in the results.

muerte69 · 03-24-05, 08:36 PM

I may try one with and without a parallel set of batteries. It should double the MAH if you run 2 serial sets in parallel. You would have the same voltage output just twice the juice. It would be heavier though. If I get the chance I am going to do this around the firat of next month so I will let you know. If anyone else has any info feel free to share. I was looking at this kit to try if I do do it. Not bad prices but not certin of the quality yet. Have to call them and find out.

http://www.all-battery.com/index.asp...PROD&ProdID=63

IM0001 · 03-25-05, 02:14 AM

aww man. Just get an adapter to lower the voltage of a car batt and plug that thing into the axim. That thing could run for months lol... um ya..

Deimos Anomaly · 03-27-05, 09:16 AM

You would need to use 5-6 c-d batts as they are 1.25v each so to use 4 would only be 5v which in my experience with another pda is not enough. what you need to do is get a 6 batt holder @ 7.5v
and make a voltage regulation circuit. To limit the voltage to 5.5v also I would reccomend a current limiting circuit as well for extra protection, somewhere around 2-2.5a like the dell charger. You need to run all of these batts in series, if you run them in parallel you only get 1.25v total if you wanted more current rating series parallel would work but you would need 12 batts, and that would be huge. As for mA hour rating it would be complicated with the vreg circuit 6 5Ah batts in series would only be 5Ah, but dropping the voltage down a bit would increase that. No way to know without some serious calculations (and I'm to lazy to do that), but I would guess somewhere around 5.5-6Ah.
Which would give you like 5 recharges of the standard batt or like 12-15 hours runtime. Maybe when I get some free time I will develop a vreg circuit for this project although I would reccomend using AA batts for their size. BTW a small car batt would give you over 200hours of runtime thats over 8 days

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