Last fall I started buying Nickle metal Hydride batterys because they have such a high ampacity(1300 mah for AA's). They run about $5.00/ea at radio shack. I've since seen the site which has them for about 2.25 ea when bought in 12 packs. AA's that is.That's all well and good with the following exception. The Nimh batterys have a high internal discharge rate!?!? I had 4 of them in a Sangean 404 portable shortwave radio. I had fully charged them in Jan99 and in late Mar99 they were flat. They ran for about 2 hours and quit. Since then I had a friend who is also a ham get me a discussion off one of the usegroups which talks about this very problem. So The question is, where can I get some dense nicads. I've heard Toshiba has them in the 1000mah range along with a few others. Based on my bad times electronics requirements, I need about 50 of them. That's lighting, Night vision, information radio, Communication radiio, entertainment. Anyone have a source for them?

-- nine (nine_fingers@hotmail.com), April 05, 1999

Answers

Nine, have you checked out the batteries at C. Crane Company? These nicad AA's are rated at 850 mah and priced at $2.00 each.

Oh, they also have a solar nicad battery charger that "puts out about 150 mah and about 5 volts" for $14.95.

I'm curious if anyone out there can relate any personal experience with these small solar chargers-- do they work okay, are they worth it?

-- Max Dixon (mcdixon@konnections.com), April 05, 1999.

That's disturbing news about NiMH batteries. I was planning to start testing them out literally next week.

I'll hit the Dimage Quest web site and talk to some of their people this week and see if I can find something out.

I wanted to use them because my Newtons don't seem to like my Nicads and I need them to run my security system post-electrical outages.

As for high capacity NiCd's, Radio shack has them (they're excellent) and Real Goods has them. I especially like Real Good's "D" batteries.

By all means, do not get Everyready Nicads. Anything bigger than "AA" is mostly an empty case with a small cell in the middle - a fraud.

I'm boycotting ALL Everyready & Energizer products because of this blatant fraud.

Jolly

-- Jollyprez (jolly@prez.com), April 05, 1999.

Hi guys,

NiMH batteries are great for high-load devices, such as battery operated drills, bright lights, and other stuff. They don't hold a charge well, but also don't have the 'memory' problem of NiCd's. Charge them, then use them within a few days for best results.

NiCd's don't hold a charge well, either. For charging and forgetting, use the Renewal alkalines from Ray-O-Vac. They need a special charger (max charge rate is extremely critical with alkalines) and they're best used a little, then recharged immediately. But when charged, they hold the charge for years -- well, as long as any other alkaline.

-- Dean -- from (almost) Duh Moines (dtmiller@nevia.net), April 05, 1999.

Keep talkin to me, I'm dumber than a mud fence (and twice as ugly). But I needs to know the status of the apparatus. BTW, I didn't think bob crane has nicads!!!!

-- nine (nine_fingers@hotmail.com), April 05, 1999.

The care and feeding of Nicads

http://www.ccrane.co m/nicad_literature.asp

-- Debbie (dbspence@usa.net), April 05, 1999.

More fun-facts for rechargeables:

• Both NiCd and NiMH are only 1.2 volts (batteries are normally 1.5 volts.
• NiCd and NiMH both discharge after 1-3 weeks (or so). This is normal.
• NiCd (and arguably NiMH too) should be FULLY discharged before charging. NiMH claims otherwise, but some disagree.
• Rechargable Alkaline (rayovac) is full 1.5 volts.
• Rechargeable Alkalines MUST be charged after using only about 30- 50% of their capacity. To fully discharge a rechargeable Alkaline is to KILL it!
• Rechargeable Alkalines hold charge for years.
• NiCd and NiMH can be charged hundreds, if not thousands of times!
• Rechargeable Alkaline can only be charged up to about 100 times.
• NiCd and NiMH can deliver high current (for motors, etc).
• Alkaline can't deliver high current - OK for Radios, but don't use in movie cameras.

...mileage may vary...

-- Anonymous99 (Anonymous99@Anonymous99.xxx), April 05, 1999.

Check out James Electronics, www.jameco.com, I believe. You can order their catalog off their webpage. They carry 'industrial' batteries, metal hydrides, high cap nicads, etc. Another possibility is a 'Battery Warehouse'. These are small businesses in stripmalls that sell only batteries.

I've had mixed luck with batteries. Manufacturing these things is a black art. It's even more like witchcraft, keeping them going.

Nicads will self discharge too. That's why you always have to charge them before use, unlike the rechargeable alkalines.

I'll be using a mix of nicads, alkalines, and metal hydrides.

I have a small, 10 watt solar panel for charging these things.

-- ah6gi cory (cory@you.know.where), April 05, 1999.

Debunking time:

Myth: NiCad's have a "memory effect" that affects their capacity if they are not fully discharged betwwen each use.

Truth: This claim is based on a NASA tech paper back in the late 1970's in which the authors supposedly observed this effect. They misinterpreted their results and printed a retraction years later. Seems they observed this effect when attempting to recharge the batteries when they were below 40 degrees F. Trouble was, NiCad's will not recharge at 40 F or lower. What they assumed was a memory effect was really the cell's not accepting a charge, and appearing to have little capacity. Major duh.

NiCad's do not suffer from a memory effect - period. If you look back far enough, any source who makes this false statement is relying upon the bad data from that old NASA tech paper.

-- sparks (wirelss@home.here), April 05, 1999.

Hi Sparks,

I agree about the 40 degree situation with NiCd's. But I disagree about the memory problem. Perhaps the memory problem isn't as severe as the retracted NASA paper said, but it does exist (based on my ad-hoc tests).

I've had to set up special discharge/charge circuits to convince NiCd cells to supply their rated power. Also, I have a B&D rechargeable drill that has had the NiCd batteries replaced 3 times because they wouldn't take a charge (and I finally gave up on it -- I'm using the new VersaPak battery system, which seems to work okay).

-- Dean -- from (almost) Duh Moines (dtmiller@nevia.net), April 05, 1999.

Hi Dean, well, I can't argue with your observations, if the particular cells you're using do exhibit a memory effect. I've never experienced it myself, and if I can find that NASA paper I'll post it. Conversations I've had with battery manufacturer's reps have indicated that any perceived memory effect in NiCad's is due to the way they are used in a bank, as there can be wide variations between individual cells.

73,

-- sparks (wireless@home.here), April 06, 1999.

Max,

I'm certainly not an expert but I got one of the little solar chargers, put 2 fully discharged D Cells in it, sat it in the sun for about 8 hours, tested cells, seemed ok, buying a couple more.

Nemo

-- Nemo (nemo@nowhereatall.com), April 06, 1999.

OK, But what kind of SOLAR recharger can I buy to recharge Nickel Metal Hydride batteries. I just recieved an email from C.Crane co. saying that their SOLAR charger will only recharge NiCads.

-- Tony Power (power@mail.austasia.net), April 07, 1999.