Zoom Gear & Home Recording Forum

This note describes an external pack I made from about $35 worth of parts from Radio Shack. In a non-stop recording test with the internal mics, it can power the unit to record 128kb mp3 for about 20 hours straight [backlight off]. I have not tried run time tests with phantom power enabled. As expected, using the external pack made the 'beep' vanish.

A slow charger and one 9.6v NiMH battery pack are sold together for about $25:



While the charger says 8 hours, I believe that time is for nicads -- with the supplied NiMH, the time is more like 10 hours. Spare packs are currently about $10

Here is the pack shown held to the back with rubber bands:



This is the 'hand held' view:



All that is needed is to make a cable using the cable repair kit and a power plug [note that the tip on mine is negative (black wire) -- be sure to verify the polarity with a volt meter, comparing your AC adapter to the completed pack before attempting to use the pack].



A faster charger is available for about $40, but fast chargers are often known to decrease battery life.

Parts list:

274-1569 Size M Coaxial DC Power Plug (2-Pack) -- $3
23-445 RC 9.6V Battery Pack Connector Repair Kit -- $4
23-432 RC Car Battery Pack and Charger -- $25

Optional:

23-331 9.6V/1600mAh Ni-MH Battery Pack -- $10 [extra pack]
23-433 Ultra Fast Universal RC Charger -- $40 [fast charger]

[the above part numbers are on-line part numbers -- the store version has been known to be different as stock is upgraded along the way.]

Note, I make no representation regarding the suitability of this for your equipment. For all I know, long term use could very well damage the H4. Improper assembly will likely damage the H4. Your mileage may vary.

Great post, I've been using a battery pack almost exactly the same but have been too lazy to post the pics. Still it seems like the capacitor gurus on the other thread have made a breakthrough on the beeping issue with an internal mod...but for extended recordings the 9.6v rc packs are the cheapest option. Thanks for posting.

I'm happy to be corrected, but I have been following that thread, and just re-read it twice, and I don't see a breakthrough on fixing the problem.

Reducing it maybe, but not fixing it.

An external supply is the only way I have seen so far to truly fix the problem. But again, please correct me [and I'll go out and buy the parts immediately].

It a subjective thing obviously, but I thought Rickbos before and after demo were pritty convincing....Although I was at work using crummy headphones

Still it's a big leap forward, to make such a big improvement with one tiny (yet expensive) cap and deserves credit. I feel confident we'll have a low cost solution in a couple of weeks once a few more things have been tested. While I like the idea of longer battery life...I'd be happier with a beepless h4 without an external battery. Depends on your application.

For long recording times the rc packs are the best value option.

Thanks for posting this, especially the pics. Nice job.

sam - thanks very much for the excellent post. I picked up the parts from Radio Shack this morning. I'm not handy enough to crack open the H-4 and play with capacitors, but I think I can handle this little bit of connectivity. Much obliged!

I finally found the time to put this together and it works great!

In the process, I noted that the wall wart that came with the H-4 was putting out 12+ volts. The battery pack puts out about 10v (maybe it is the advertised 9.6v, I can see that clearly.

If the H-4 wants 9v why, do you suppose, the wall wart supplies 12v?

"If the H-4 wants 9v why, do you suppose, the wall wart supplies 12v?"

If you didn't have it plugged into anything then that is the "No-Load" output. If you had it powering a device you'll see the "Rated" voltages.

BTW: I put this one together myself and it does work great, but my charger came set to the wrong type of batteries. You'd thing it should be set to the type it's sold with...good thing I LIKE to read directions:)

Sam, great minds do think alike! I have done exactly the same thing with the Canadian Circuit City version of the 1600 mah pack and charger. The only difference is that I clipped off the r/c connectors and replaced them with trailer hitch pigtail type connectors that seem to take less room and are made of soft rubber rather than the sharp-edged plastic.

With these these I can also keep the pack charged with a solar panel that has the same type of connector (on a sunny day, that is). The solar panel also came with a barrel type connector (which has the rubber type connector at the other end). It can plug straight into the H4 and connect to either the solar panel or the pack. Fortunately, everything is polarized tip negative.

Griff

Geezer, do you have a part number for that Circuit City version of the 1600 mah pack and charger? I've been searching their website but can only find Ni-Cd models at 9.6 volts, 1600 mAh, not Ni-MH.

I did find a 9.6V, 1250mAh Ni-MH R/C battery pack, but not 1600 mAh.

The part number that mine has is: 2300331. I have the feeling that the 1250 and the newer 1600 may have the same number but have been recently updated to higher capacity batteries. If you walk into one of the larger stores, you should be able to find the newer ones.

Geezer

I believe you are correct on that one, Geezer. A Circuit City search using that part number brought up the 1250 mAh, but the accompanying photo showed a 1600 battery pack.

Thanks for that.

And here I thought I was so clever......haha.

Looks like Sam beat me to the punch w/regard to the RC car battery pack solution -- I will concur -- it works great. I also went to radio shack and got a variety of connectors (apparently they are fairly standardized for RC cars) and got the A/C adapter for charging. I went to Ebay, however, for the batteries themselves, and found (2) for around $16.00 -- 9.6v 2300mah. As Sam said, this will give you almost a day's worth of continuous recording. Remarkable......

I went with a longer cord to give my self a little flexibility -- but can shorten it and go with the "handheld" mode if desired.

Here's a pic:














Hmmmm........I've having trouble getting my image url recognized -- if you're curious you can just paste the url into your address bar. Anyone know what I'm doing wrong?

As I have been using 9.6v/2000mA packages on the equipment I rent professionally, I think I came to learn quite a bit about this matter.

1) Get a smart charger like this one:

http://www.batteryspace.com/index.asp?P ... rodID=2378

It tops the battery to its maximum charge and then stops charging it. They are much better than continuously charging types, that may damage the battery due to heat.

2) Try to avoid fast chargers. They do shorten the battery life.

3) When using the standard charger, touch the batteries to see how hot they are.

4) Do not use this battery on the H4 for more than 20 hours. The question is the H4 will work with less than 8v, but that is minimum voltage this NimH should drain to.


Carlos

The cheap radio shack charger included with battery [23-432] in my original post is not a continuous charging type, but, in fact, shuts down when complete. Plus, it is a slow charger. I have seen more batteries damaged by fast chargers -- even 'smart' ones -- than by slow chargers.

Sorry, you seem to be right. There are several LEDs on that charger that must show the current state.

I had seen some RS chargers some time ago, for hobby car batteries, that were not that type. RS got smarter.



Yes, that's why I specified a slow smart charger.


Carlos

30-100 minutes charge time doesn't exactly sound like what I would call a slow charger. On the other hand, they conflictingly quote up to 5 hours charge time. Not sure how they resolve that math.