Many people have reported using rechargeable NiMH batteries in their remotes with great success. Actually, I haven't seen any problems reported at all. I've been using a set of NiMH batteries in my 550 for almost a month now with no problems. Yesterday my wife calls me at work to tell me the remote is not working. I got home and saw that it wasn't responding to any of the buttons. The "Choose an Activity" screen was up, but nothing happened when I pushed any of the buttons. I took the batteries out and put them back and still nothing. I even tried reinstalling the firmware with no luck. Finally, I called Logitech support and was told to put it in Safe Mode and try updating the firmware again. I tried probably 10 times and could not get it to go into Safe Mode. I took the batteries out, held down the power button and plugged in the USB cable. It would boot up, briefly display "Low Batteries", and then say "USB CONNECTED". Finally, after many tries, I went to go put the batteries back in and saw that there was a sticker in the battery comparment that said something like "4 x 1.5v AAA". Just for kicks and giggles I looked at the rechargeable batteries and they said something like "AAA 1.25v NiMH". Hmm, interesting. I believe all NiMH batteries are 1.25v and that small difference doesn't usually matter (in cameras it generally doesn't, for example). I put in some standard 1.5v alkalines and, voila!, the remote came back to life! Tried the rechargeables again and it worked fine for a little while and then certain buttons stopped responding again. Put the alkalines back in and it worked. I'm going to give it a few days with the alkalines just to make sure my theory is correct, but it looks like my remote doesn't like rechargeable batteries. Not sure why it worked for a month with no problems, but there it is...

Any thoughts?

Sounds like the remote needs 6 volts and you were only giving it 5. Not that hard to understand.

Right, but why are so many people using rechargeable batteries with no problems? And why did it work fine for almost a month? You'd think if 5 volts wasn't enough it would have freaked out immediately...

Just got off the phone with a guy at Thomas Distributing, a major seller of rechargeable batteries. They're pretty knowledgeable about this stuff. I told him what the deal was and he said it doesn't surprise him that a low-drain device would not like NiMH batteries. He said those batteries are designed for high-drain devices and they won't work as well as standard alkaline batteries in low-drain devices.

That makes me feel a little better, but it still doesn't explain why I'm the only one having problems.

I'm sure there is a certain tolerance for low voltage and they were probably on the bubble. Different batteries probably have different voltage characteristics. It's also possible the rechargeables you have were defective.

The batteries I was using were a brand called Power2000 and they were 1000mAh. I just picked up some 900 mAh Energizer rechargeables. Hopefully the remote will like them better. I'd be curious to see what brands other people are using without problems...

All the harmony remote works great with 5V !
Try to power with only usb-port=>it will work without any problem
(I have tested my 675 and my 885).
For my 675: I have 4xnimh 900mA/h (Uniross) which works fine, and I have made a rechargeable base for it too...no problem at all with that.

Yes, many rechargeable batteries have different voltages. They may say 1.25 volts, but that is only an average. I test and computer cycle tons of batteries, and the voltage variance is considerable. Also, NIMH batteries will drop slightly in voltage after a few charges. They will typically level off after that, but they will basically continually get lower and lower on the voltage after multiple recharges. I have seen many NIMH batteries barely make a full vol, and others top out at nearly 1.35 volts. Considering the mass production techniques are pretty lousy, this variance is to be expected.

With any luck the first set was just defective. Here's hoping...

Did you try recharging the nimh batteries that might work, I had a 659 and used nimh batteries successfully, they didnt last as long as akaline batteries bt I recharged them. A month with out a charge is pretty resonable I think my 659 would only go 2 or 3 weeks until they needed charged. At least I didnt see mentioned that you recharged them :)

Yep, I tried recharging them with no luck. I'm guessing they never quite reached the full voltage they had from the factory, despite being charged to capacity.

I just wanted to update this thread in case anyone with a similar problem stumbles across it. My rechargeables just died after another month or so and I had the same problem as I reported in my initial post. After fiddling around for a while I stumbled across a solution that appears to work every time. When the remote locks up all I have to do is take the batteries out, put three fresh batteries back in, then hold down "2" while replacing the last battery. No idea why it works, but it does.

My 659 was working fine until about a month ago. Then, I began using rechargeble NiMH batteries. They only lasted about a week. I put in another set and only got a few days. I then went back to Duracell alkaline batteries, and now even they won't last more than a couple of days! Of course, I don't know the exact time frame for all this, as I wasn't anticipating any problems. The bottom line is that now, no set of batteries, whether alkaline or NiMH, will last more than 2-3 days. Did using the NiMH batteries cause some circuitry in the 659 to fail? Any ideas as to what's going on? TIA.

Nimh rechargeables tend to self discharge pretty quick, usually they are pretty dead in 45-60 days. For high drain uses like camera and flash they are best charged within a day or two of use. There are some new ones on the market now that advertise low self discharge, retaining as much as 85% at the end of a year. A camera store will have "Eneloops" by Sanyo in AA and AAA. A more recent and readily available brand are "Hybrio" by Ray-O-Vac avail at Walmart and most other places that sell rechargeables.

Alkaline batteries typically start at about 1.55 volts and your remote will typically work down to about 1.1 volts. The alkaline drop will be gradual over time. When you put a big drain on an alkailine cell it pulls the voltage way down to like maybe 1.2-1.3 volts. A NIMH rechargeable cell fully charged may read as high as 1.42 volts but will very quickly settle to 1.25 to 1.30 volts. When you put a big drain on an NIMH there is very little voltage drop, they have put out essentially all their useable power when they get to 1.1 volts.

Bottom line here is, with self discharge regular NIMH cells should not last any longer than about 30-45 days. The new low discharge NIMH cells might last a lot longer.

Thanks for your nicely detailed reply, but what would explain the rapid discharge I get with the alkalines now, when I didn't have that problem before? Did my using the NiMHs "break" something in the 659?