[cajunchrist]

JMT has been kind enough to build an amp for me, and now I want to get good rechargable batteries for it. Conventional wisdom round here suggests the MAHA NiMh rechargable 9v's from Thomas Distributing are the ones to get. I'll also be getting some AAa's for use in my Panasonic 570.

My question is about the charger. There is a $36.97 charger with many smart features and a $13.90 charger that would also charge the batteries I want to buy.

My question is: do the power conditioning features and the other bells and whistles really make a difference in battery performance? The literature indicates the power conditioning features are really only necessary when using NiCd batteries. Is the convenience of not having to remove the batteries immediately after charging the only real reason to pay the extra 20? The cheaper charger has a 15 hour timer that will automatically shut down the unit (great for the 9v's), but will over charging for few hours really damage the AAA's over time?

Please help!

cajunchrist

P.S. 100 posts!

 

[jude]

I only use chargers that detect a full charge and change to trickle charge at that point. Otherwise you can overcharge/overheat the battery (even NiMH), which can damage the battery and shorten its life.

Long story short, I'd highly recommend going with a "smart" charger.

 

[Ctn]

How many volts are those batts?
I found a good one from GP

with very high voltages but its rated at 8.4.

 

[Nezer]

I bought a cheap charger and it trashed one of my batteries on the second charge. I now swear buy the more expensive intelligent chargers. Nothing is more fun then hearing your batteries vent and hoping the vents don't get clogged.

 

[Hirsch]

The Maha is an 8.4 v battery. The highest powered "9 v" battery at Thomas is the Plainview (9.6 v, 170 mAH). This is the only NiMH that I've seen that will actually output a true 9v. If you go that route, the dedicated Plainview charger is "dumb"- you'll have to time the charge (I use a lamp timer).

 

[Eagle_Driver]

Well, smart chargers can be fooled by batteries that have never been charged, as mine is - it all too often stops charging way short of a full charge, unless I charge them a couple of times in a cheap, relatively slow (requiring at least 7 hours to fully charge batteries), timer-controlled charger.

 

[cajunchrist]

What a toss up. Buying a smart charger and 2 of the MAHA 8.4v will be just as expensive as 2 Plainview 9.6v with dumb chargers and a lamp timer.

I think I'll go with the Plainview's.

cajunchrist

 

[Hirsch]

Quote:

Originally posted by jude I only use chargers that detect a full charge and change to trickle charge at that point. Otherwise you can overcharge/overheat the battery (even NiMH), which can damage the battery and shorten its life.

I had some discussions with Thomas Distributing and an e-mail exchange with Plainview on this. Interestingly, Thomas recommends a 20% overcharge on the Plainview, while Plainview recommends a 25% overcharge. The key seems to be heat. The batteries should be slightly warm while charging. However, if they reach the point where they're uncomfortably warm, you're in trouble. With a slow charger, the Plainviews can take a fairly hefty charge before they're in danger (Thomas doesn't recommend too much of an overcharge, but thinks that they're safe in the dedicated charger for up to 24 hours, even though optimum charge time from completely discharged is around 8.5 hours). The real risk seems to be from the "fast" chargers, which are pushing out a lot more current.

 

[gaineso]

I picked up a 6 pack of Panasonic NiMH AA's yesterday at Costco for $12.99. 1600 mah just like the RS ones except they're $17.99 a 4 pack.

Went to RS today and got 23-425 charger which does AAA, AA, C, D and 9V, NiCd and NiMH. Has full auto including discharge for the 1.2 V's but manual for 9V's. Full charge on 1600 mah is about 4 hours.

I'll try the batteries tomorrow in my TA and Kenwood pcdp.

Check out Sam's and Costco. Sometimes great deals and lots of other neat stuff too.

 

[Ctn]

Hi Hirsch,

Have you tried GP batts?
I have one rated at 8.4v but it does 9.6+v on a full charge.

Pretty impressive. Both the GP batts I bought did about 9.6v

Its rated at 150mah.

 

[Hirsch]

I haven't tried the GP's yet...but once my supply of AA alkalines starts running down, I'm going to get a couple of sets of 1800 mAH NiMH with a charger...

 

[gaineso]

Tried out my 1600mah NiMH AA's on my TA and Kenwood pcdp.

The TA sounded just like alkalines on 3 different sources, pcdp, H-K FL8300 line out, and DSP360 on TV. Driving my HD600's like a champ.

On 500 mah NiCd AA's, nothing sounds the same. It all sounds like it's just not right. Hard to describe, but just not all there.

The 1600mah NiMH's really seem to play well. Now to find out about operating times. My TA would go for a week or more on alkalines. My pcdp about 3 to 4 hours. I've used about 1 1/2 hour so far.

I ran them through a charge, discharge, recharge cycle before use.

RS 23-425 charger with Panasonic 1600mah NiMH AA's. 6 pack for $12.99 at Costco.

More on how they last later.

 

[RobertR]

I think that you and others may find the article in "Popular Communications" July 1998 very informative re; the do's and dont's of nimh charging.
You could probably get a copy at your local library. If not let me know and maybe I could send it to someone for general dissemination.