9V rechargeable batteries and chargers?

What about Varta?

All batteries will have a limited lifetime. I would say if you got a year or two out of them, your doing good.

Cheers

Those are a bit marginal in capacity. Only 6 cells (so 8.4V) and 200mAh.

Lately it wasn't that great anymore. The newer chargers seem to wear out faster, LEDs lit dimply, and so on. One blew a primary switcher. The batteries don't last as long as they used to, even fresh ones.

So I am looking for something a tad better. Like usual, never really happy with the status quo :-)

"Joke"

Perfect for any radio mic that use a 9V battery.

... Phil

Rechargeable 9v's always seemed to be marginal. But, we had used the Vartas (NiCd) years ago, and they lasted for about a year before they were toast. They are a German company, the batteries are probably made in China.

Cheers

NEXcell seems pretty good for low self discharge. I used a couple AAAs in a TV remote control. Still working today after 10 months on a single charge. I see a 8.4 volt / 200mAh version here:

-Bill

Varta or Vartas?

I thought Varta was owned by Rayovac (Spectrum Brands). I recall reading in one of the Annual Reports that they kept the Varta name around in Europe and 1 or 2 countries in South America simply for reasons of name recognition. Of course, that singular bright idea didn't help Spectrum very much, which has a history of trashing various brands they acquire.

And in SA, believe it or not, carbon-zinc batteries rule (or at least they did at the time!) Probably the economy?

-mpm

Thanks, Bill. I'll check those out but it's a bit confusing. There seem to be four versions that look the same. 8.4V and 9.6V, and then both either with 160mAh (which wouldn't be enough for us) and with 200mAh. And they seem to have screwed up or at least mixed up the data in the technical info tabs :-)

What's your problem you can't refurbish the chargers? If they're not fast charge, they're dirt simple fixed current sources on a timer.

Not these. They are crammed with electronics, all uC controlled with battery diagnostics and the whole enchilada. If I had a schematic I could repair them. And I did repair one where somthing in the primary switcher had blown. But those things don't seem to last and there comes a point where repairing gets old. Also, it is absolutely no fun to find out Sunday morning at 7:30am that all the batteries are dead and worship service begins shortly. This happened three days ago :-(

They might be old NiCd chargers that fail to spot the Delta V on newer NiMh cells, so that they keep charging forever until you switch them off or the safety timer, if any, turns them off.

On 9V cells charge is trickier because you have one Delta V point for cell, which means that if the charger is sensitive it may stop charging when the first cell reaches the charge, and if it's not sensitive it could overcharge the battery, frying it in the long time.

For 9V batteries I'd always go with a current limiter (C/10, max C/5) plus timer.

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If you don't want sudden drop-outs, use conventional top brand alkaline e.g. Duracell + or whatever they're called over there. Plus you really should have some of these for back-up if it's that mission critical. In my experience (in good quality radio mics) they last plenty of time and fail a bit more slowly/gracefully than I would expect a rechargeable to. Plus since your batteries will always be reasonably new, you will get a good feel for how often you need to replace them as part of a regular replacement schedule.

We have them for backup but that gets expensive. Because some mikes are rarely used but must be kept up. Then you remove a $1.50 battery and must throw it out because the voltage won't tell you how much juice has been taken out already.

We had that in our earlier years. They would acutally last less than NiMH and failure in the middle of service was just as bad.

Those are very fancy uC-controlled chargers specifically designed for NiMH. They cost north of $100 each.

Yup, they need to find out the cell number and then count the number of delta-V events, plus time-out if they are too unequal. All not rocket science but sometimes when I see charger designs my impression is that for them a lot is like rocket science.

That's a problem in a church as self-discharge in 9V NiMH is high. You'd have some batteries that are in there 1wk and other maybe 8wks. Trying to get a rotating scheme going is totally not feasible in such a scenario.

Ok, so try Li-Poly. 520mah!

They actually have a good track record from the reviews. BH Photo carries good stuff.

Cheers

Thanks. Yes, BH is a good place, we've bought from them before. But LiPoly is only 7.4V nominal for the usual stack of two. That's a tad marginal for our mikes.

Anyhow, we just ordered this:

If they really hold the 300mAh minus 20% marketing glitz factor or whatever we'd be really happy.

The other thing one has to keep in mind at non-techie places such as churches is the occasional mishap. Like when someone sticks a LiPoly battery or LiIon into a regular charger and *POOF*

I'd like to see how those work out. After the not so good results from the Tenergy batteries. ( I have the D's and AA's) The Tenergy batteries suffer from self discharge from what I see. The D's are working better than the AA's, but they are 9000mAh. The Sanyo Eneloops turned out to be the best. It seems the higher capacity NiMh cells have a higher self discharge rate, and rapidly loose capacity. Which results in a short life.

Cheers

Don't know about 9V batteries, but for 6 cells NiCd or NiMh I've had great success with C/10 then taper to ~C/40 when Vset is reached. I tried some 9V rechargeables way back when and gave up on them. Maybe they're better these days?

Ed

On a sunny day (Thu, 12 Jan 2012 22:56:01 -0500) it happened "Martin Riddle" wrote in :

I can confirm that, I have 6 AAA in use some full discharge / charged every day. They also hold charge, for example the 2 in my wireless keyboard last several month,

Right Duracell AA 2500 mA hr (camera) 'auto discharges' in a few days! Duracell smaller capacity AA lasts many weeks.

I never had a good 9V rechargeable. IIRC the last one was Nicad. These days if I want a new 9V battery I buy a Chinese multimeter... Joerg should try that :-)

What we used to do was to store the mics without batteries, and cram a new one in every time it was used.