Author Topic: Sensor 3.6v NiMH batteries (Read 15393 times)

tomwxman · « **on:** November 28, 2008, 09:42:56 AM »

I've had problems with my OA temp/rh sensor "going away" in the WMR968 display whereby I have to re-scan the sensors to get it back. I suspect that it's just far enough away that it misses a few xmission/reception cycles and causes the "---".

My further suspicion is that the solar cell is not keeping the internal 3.6v NiMH battery sufficiently charged to "help out" the AAs alongside.

Has anyone here ever replaced these 3.6v batteries? With what model/type? Has anyone ever taken a battery out and CHARGED it? Requires a special connector/charger of course but I'm thinking I can cobble one of my wireless phones to charge a battery if I can find one that the connector will fit.

Anyone here know anything about this? I've googled "smart chargers" like crazy, and apart from a $120 Tenergy I've not yet found one that will deal with the NiMH aspect at the 250maH (IIRC) capacity, though some of the RC model chargers come very close to meeting these specs.

mackbig · « **Reply #1 on:** November 28, 2008, 10:12:00 AM »

The aa's should work quite a while without the aid of the solar rechargeables.
You could try swapping the solar x-mitter with you rain gauge, or anemoter to see if that changes the behaviour.

Andrew

Anthony · « **Reply #2 on:** November 28, 2008, 10:50:40 AM »

I have to replace a few of mine. At the time Radio Shack was able to order them. But I don't believe thats the case now. The battery information is printed on the pack it's self. What you will probably have to do is. Make your own packs. I think there is a web site call batteies are us or some thing like that. I know there are sites that sell any type of battery you could ever want.

tomwxman · « **Reply #3 on:** November 28, 2008, 02:42:27 PM »

Thanks guys, yeah I can see that AAs alone work (for a few months anyway), but before I buy new NiMH packs I thought I'd zap-em with a real charger and see if I can restore some life to them!

BTW if there are any battery experts here: IIRC these 3.6v NiMH cells are 250maH--does it make any sense, if one is replacing them anyway, to replace them with higher capacity cells? Or would higher capacity cells be somehow a poor "match" for the output of the solar charging cells???

Anthony · « **Reply #4 on:** November 28, 2008, 05:58:23 PM »

I would not recommend using higher capacity cells.

Bushman · « **Reply #5 on:** November 28, 2008, 06:22:17 PM »

If you know the output (in mah) of the solar panels, your cells can be 10x that for reliable trickle charging. That's the ROT anyway.

tomwxman · « **Reply #6 on:** December 06, 2008, 11:07:20 AM »

Quote from: Bushman on November 28, 2008, 06:22:17 PM

If you know the output (in mah) of the solar panels, your cells can be 10x that for reliable trickle charging. That's the ROT anyway.

Thanks for that--I don't know that I can find the solar cell output rating but will keep this in mind as I look!

Bushman · « **Reply #7 on:** December 06, 2008, 11:23:35 AM »

Well, if you know any RC guys or have a radio control hobby shop close by, take in a panel and ask them to hook it up to a Whatt-meter - this device measures current flow and can tell you how many amps a device draws and from there you should be able to determine the panel output. http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LX3605

BTW, what size are these batteries? (length x width)?

tomwxman · « **Reply #8 on:** December 31, 2008, 12:35:52 PM »

Well I had another bout of "----" from my OA sensor and pulled the 3.6v NiMH pack out of it, putting in into a wireless telephone & charging stand overnight. Got warm but I don't think *fire* was ever a possibility.

Measured 4+ volts after and the sensor is working fine for now. Found exactly 1 source on the 'net for these, and they want $30 bucks! For a battery!

I dunno if this will have any lasting impact but thought I'd post & bump my own thread anyway.

Maybe someday when I REALLY don't have anything else to do I will try to measure whether my solar cell is outputting anything!

JOE · « **Reply #9 on:** December 31, 2008, 02:52:47 PM »

Not sure where you're located, but around here (I'm in Illinois) there are places called Battery Specialists and Batterys Plus, that can get about any kind. Or even re-build what you have with new cells.

Maybe that's the $30 place you're talking about....

Make sure your solar panel is clean and facing the proper direction. Duh. Hope you have that right without saying it.

Anthony · « **Reply #10 on:** December 31, 2008, 04:07:37 PM »

When I replaced mine about 3 years ago they were just under $10. I was fortunate and was able to get my ordered at my local Radio Shack. Others have tried recently and have been unsuccessful. Building a pack should be very simple. All you need is 1.2v NMHD batteries rated at I believe 300 mili amps. Should not be difficult to find.

tomwxman · « **Reply #11 on:** December 31, 2008, 06:20:03 PM »

Quote from: JOE on December 31, 2008, 02:52:47 PM

Not sure where you're located, but around here (I'm in Illinois) there are places called Battery Specialists and Batterys Plus, that can get about any kind. Or even re-build what you have with new cells.

What I had done is I Googled on the battery number GP25AAH3BMX and came-up with just one for-sale site:

http://www.buywirelessconnection.com/GP25AAH3BMX_2_p/gp25aah3bmx-2.htm

I also tried to find these by searching 3.6V NiMH and 1/3 (or maybe the 25 in the number means "one-quarter") height AA cells. I realize Google can't find Everything in the universe (some internet databases block it somehow) so if anyone here finds another source by all means tell! I don't have Battery Plus stores anywhere near me or I'd stop there & ask...

As for building them, it seems metal leads are somehow crimped onto the battery to combine them. If someone can describe, or knows a site that shows how to build them let us know too. Radio Shack appears not to carry them any more.

SlowModem · « **Reply #12 on:** January 01, 2009, 06:45:21 AM »

Ya know, RS lists the WMR968 in their catalog online (although they say they're out of stock). It seems that they would still support it (althought they probably don't). Anyways, I found a parts list that lists batteries, although the part wasn't listed in the online catalog. Maybe this will help. The parts list is here:

http://support.radioshack.com/support_meters/doc65/65366.htm

Scalphunter · « **Reply #13 on:** January 02, 2009, 01:57:46 PM »

here is another place that carries those batteries http://www.buywirelessconnection.com/category_s/426.htm

Anthony · « **Reply #14 on:** January 03, 2009, 09:20:54 AM »

It's just crazt that anyone would charge that much for that battery pack. I sure wouldn't pay that for one.

tomwxman · « **Reply #15 on:** January 03, 2009, 10:41:36 AM »

Quote from: Anthony on January 03, 2009, 09:20:54 AM

It's just crazt that anyone would charge that much for that battery pack. I sure wouldn't pay that for one.

$30 bucks? Absolutely no way. One post I found from 2006 said RS was charging $10, and even if they can still be had for that price I wouldn't pay it!

I wonder if the Davis system uses more commonly available batteries. Would be another reason to spend the bucks on a Davis when I grow weary of nursing this OS system along.

sam2004gp · « **Reply #16 on:** January 03, 2009, 11:36:25 AM »

Quote from: Slowmodem on January 01, 2009, 06:45:21 AM

Ya know, RS lists the WMR968 in their catalog online (although they say they're out of stock). It seems that they would still support it (althought they probably don't). Anyways, I found a parts list that lists batteries, although the part wasn't listed in the online catalog. Maybe this will help. The parts list is here:

http://support.radioshack.com/support_meters/doc65/65366.htm

I called Radio Shack about some parts from this list about a week or so ago, and their availability to get most of the parts is very limited, so our luck they won't sell them anymore.

Scalphunter · « **Reply #17 on:** January 03, 2009, 04:58:25 PM »

speciality battery

Mark / Ohio · « **Reply #18 on:** January 03, 2009, 08:29:33 PM »

Might check this company:

http://www.dantona.com/

We've used them a few times for camcorder batteries that were no longer made by the manufacture. They seemed to be decent quality.

tomwxman · « **Reply #19 on:** January 05, 2009, 10:30:08 AM »

FWIW my attempt to "invigorate" my THGR968's rechargeable battery by pulling it out and charging it externally does not appear to have helped at all. I got "----" on my displays only a day or two later. Guess I will look at getting another THGR968--at least the solar cell appears to be different (two smaller vs one large on mine) so maybe it's improved.

Or I will apply the $65 bucks toward a completely new system e.g. the WMR200 if not a Davis...

SlowModem · « **Reply #20 on:** January 05, 2009, 10:48:01 AM »

Before you get anything else, might I suggest Oregon Scientific THGR122NX Wireless Temperature and Humidity Sensor with Display? I have one ordered from ambientweather and it's supposed to be here tomorrow (I will get expedited shipping from now on!). It is my understanding that it comes in on channel 1 and, depending on your software, you can substitute that for the normal channel. It takes 2 AA batteries (cheap) but is digital and supposed to be really accurate. I've been through two THGR968s last year and they both died within a month.

Just a thought.

Bushman · « **Reply #21 on:** January 05, 2009, 11:30:17 AM »

In order for a Nimh battery to output 3.6 volts, it would have to be three batteries end-to-end (series). I'm guessing that these are three 250 mah 1/3A batteruies. If someone wants to measure the total battery size/cells and post, I can confirm. If they are such a std. size it is easy and cheap to get tjem custom made

SlowModem · « **Reply #22 on:** January 06, 2009, 07:38:27 AM »

FWIW, you can get the THGR 968 complete for 49.99 on ebay (sensor, solar panel, batteries, etc) and you'd have spare parts.

http://cgi.ebay.com/THGR968-Thermo-Hygrometer-for-WMR968-Weather-Station_W0QQitemZ270326572565QQcmdZViewItemQQptZWeather_Devices?hash=item270326572565&_trksid=p3286.c0.m14&_trkparms=72%3A1205%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

Anthony · « **Reply #23 on:** January 06, 2009, 07:44:14 AM »

FYI The solars transmitters with 1 solar pannel are newer than the ones with 2 small pannels. And a transmitter with a large solar pannel is used for the anemometer only.

SlowModem · « **Reply #24 on:** January 07, 2009, 10:52:27 AM »

OK! I have the THGR122NX up and running and have it substituted for the THGR968. Compared to known stations, it is extremely on the money. I am a 95% happy camper. $\:D/$

I will say that the range is not quite what I expected. The batteries (which were supposed to be included, but weren't) may be weak. When it gets a little more pleasant outside, I need to find a better placement for it. With the clouds and rain, I don't think solar heating is going to be a problem for a few days.

Oh, one more thing. You need a very small screwdriver to open the battery compartment.

From the FWIW Department.

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Author Topic: Sensor 3.6v NiMH batteries (Read 15393 times)