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Battery Life Extention -- Using AA NiMH with NH900?

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etotheix

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I just ordered an NH900 and plan on doing a lot of power hungry PCM live recording. Does anyone here have any experience or know anything about using rechargable AA NiMH with the NH900 (or other recorder with an external battery case)?

1) Is the voltage of NiMH a problem (1.2V vs the 1.5V of regular Alkaline)?

2) Will the NH900 charge a NiMH battery in the external case?

3) How would the life of a high capacity NiMH AA (say 2000+ mAh) compare to an Alkaline?

I know you can get a higher capacity gumstick battery than the one that comes with the NH900 -- Does anybody have any other hints for extending battery life (maybe a homemade battery box hooked to DC in...)?

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Like Latexxx stated, you need an external charger for that AA form factor NiMh because the dry cell pack attachment blocks access to the AC power source connection. I have used alkaline in my old mp3 player (now my wife is using it) and I can attest that the Rayovac NiMh rechargeables gave me at least 2-3 times the playing time at the gym with that mp3 player. I have only used the NiMh AA in the dry cell pack on my NH900 so I don't know what difference the Hi-MD use would produce but I am inclined to think it would be equivalent.

I plan to test the AA alone some more with my NH900. I have noted that you need to power cycle the recorder off for it to recognize the AA dry cell. In other words, if you add the AA while the recorder is playing off the gumstick alone, the battery level does NOT change. If you cycle the power, the recorder's battery level will go up (the dry cell is recognized at the point???) Anybody have insight? I am going to try the AA alone for editing and recording again tonight if I get the chance. The last time, I got the insufficient power warning with just the AA.

When recording shows in PCM, I usually change the gumstick out during set change since I have an extra but usually I have more than enough power on the first to continue but I like to play it safe, that's also why I always use the AA dry cell pack too. I also drain the gumsticks and the AA at least once a month to keep them fresh. It was the main reason I went with the Nh900 over the NH1 but like I stated above, it only supplements the gumstick and does not work alone when recording. Any suggestions are appreciated.

http://www.minidisc.org/himd_2004_comparis...ison_table.html

(check this table for estimates about recording time in PCM with the NH900) Interesting to note it lists recording time with an AA alone. Makes me wonder what I am doing wrong...

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Hmmm... that's interesting mrsoul. So you can't get the HN900 to record with a lone fresh AA NiMH -- have you tried it with a fresh alkaline? I'm still waiting to get my unit (should come tommorow--yay!) but I've looked at the manual and it sure does look like you should be able to record with an external battery alone.

That other thing you mentioned--that you have to power down for it to recognize a new external battery--does seem wierd. What happens if you have the gumstick and a AA in to begin with, then *replace* the AA? Do you sill have to power down?

I'm wondering if these problems might have something to do with the fact that the NiMH AA's are 1.2V instead of 1.5V like alkalines. The manual indicates that recording and editing are especially power hungry so maybe the way the circuitry is set up, when using a lone external battery, you need 1.5V in order to supply enough current to handle recording. That seems kind of dumb though considering the internal 1.2V gumstick works fine. I'd be curious to know what, if any, of those wierd problems go away if you use an alkaline instead.

Hey, thanks for your post mrsoul--very helpful and interesting. Good to know you can use AA NiMH even if they don't seem to work perfectly. Keep experimenting, let us all know what you discover!

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That other thing you mentioned--that you have to power down for it to recognize a new external battery--does seem wierd. What happens if you have the gumstick and a AA in to begin with, then *replace* the AA? Do you sill have to power down?

You can (dis)attach batteries on the fly. The trick is that the power meter just doesn't update.

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I thought I submitted a post last night, well here goes again.

I did test the NH900 with an AA alkaline and the NiMH AA form factor 2000 mAh 1.2v from Rayovac. Really surprised with my results. Nothing like the last time I tried the NiMh AA alone. I guess it had a low charge, I never got a message about insufficient power this time but I confident that I remember it showing 4 bars when just playing in the first test. That is why this 2nd test was so surprising.

1. Power Gold (generic from Dollar store, cheap) AA dry cell alkaline: PCM mode with optical input recording.

Battery level meter showed 4 of 4 bars at the beginning. I recorded the first full Hi-MD (@ 92 mins) and then put in another Hi-MD. I recorded until about 38 min on the 2nd Hi-MD before I noticed the battery meter flashing. Once I stopped and saved to disc, the meter went up to 2 bars. I guess it was calculating what it needed to write the TOC, etc. I was very happy to see my AA test worked. It amazes me that I can get at almost 2.5 hours with a regular AA battery. Can anything else touch that when recording PCM WAV?

2. NiMh AA form factor 1.2v battery 2000 mAh from Rayovac with fresh charge: PCM mode with optical input recording

The battery level only showed 3 of 4 meters when starting the recording, but it did start recording and I stopped the recording after about 15 minutes because I needed to get to sleep. When I stopped and the TOC was written, the meter again went back to 4 of 4 bars. I guess the 1.5v vs. 1.2v makes that a difference for the meter.

Well, I cannot explain the results of my first test that I reported in another post regarding the NiMh. I will have to do so more testing with the NiMh AA when I get some time, I will post the max time with a fresh charge when I test again.

But, I am very pleased to know that I can use just a alkaline AA battery to at least fill a Hi-MD in PCM.If you have to change the disc, why not just change the battery? Just use a gumstick and a AA if you don't want to spend time changing both the disc and the power supply.

Again, is there anything out there that will record this much with just 1 AA battery?

Hope this helps some others looking at the NH900. It made the difference for me in looking at the NH1 and the NH900, now I am really glad I went with the NH900.

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Veeeeerrry interesting... You should definitely test that Rayovac when you get a chance.

Got my new NH900 yesterday. What fun! I'm glad I went with the 900 too. I was this close to getting the less expensive 800 but the versitility of the 900 won me over. The NH1 wasn't an option for me, but even if it was I'd have gone with the 900.

More Battery Questions:

1) While recording, how low can you safely let the battery level get before you need to stop and replace the battery?

2) What happens if you let the battery die while recording? I read somewhere that you're SOL -- the recording won't be accessible. Is that right?

3) Also, when using both batteries, is it possible to safley swap in a new external battery without stopping a recording?

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I think the NH900 will calculate how much battery power it needs to write the TOC and reserve that when recording just so you will have enough to write the TOC, it makes the meter adjustments based on what it needs. You probably have read the many warnings Sony provided about not having enough power, etc. Just make sure you get that TOC written to the MD before losing all power.

If the battery runs down while recording and the TOC has not been written, you may be out of luck. I haven't tried that yet personally.

Yes, you can swap the external out when recording, I just don't think the battery level will change but you should still have the added power if that makes sense.

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