[Big Al]

I been burning in my SR-71 and 325i for about a week and half now using Powerex rechargeable 9v batteries and what I noticed on the last two battery swap outs is that one battery is completely exhaused while the other battery still has about 85-90% charge left in them.

I'd say I get about 7-9 hours from a set of batteries. The sound either drops out completely or sound quality and volume is very low when the batteries start to exhaust. But again one battery still has 85-90% charge left???

Has anyone experienced this with thier SR-71?

 

[Xoton]

That doesn't sound right.

 

[Big Al]

I know. I still have the 2 - 9v alkaline batteries from Walgreen's before I switched over to the rechargeable Powerex and they show a even discharge.

 

[Graz]

Send an email to Ray. I'm sure you'll get a fast answer. Beats me though why one would discharge faster than the other...I'm totally at a loss.

Peace,

Graz

 

[Big Al]

Quote:

Originally Posted by Graz Send an email to Ray. I'm sure you'll get a fast answer. Beats me though why one would discharge faster than the other...I'm totally at a loss. Peace, Graz

I just sent Ray an email on this. Isn't the 71 using (1) 9v battery for each channel?

 

[maxxfell]

Quote:

Originally Posted by Big Al I just sent Ray an email on this. Isn't the 71 using (1) 9v battery for each channel?

Ray isn't a big fan of using NiMH in the 71, so expect to hear about why he isn't!

 

[Dimitris]

I am using the IpowerUS batteries and they show completely parallel exhaustion. Most of the times after one channel goes down it takes a couple of seconds for the other one to shut down as well. I like rechargeable batteries. You save money and they are more environmentally friendly than the alcaline ones.

 

[Ray Samuels]

The rechargeable batteries are never reliable, they could be from the same manufacturer & the same model # but act very funny in holding charge & in loosing it evenly. You can charge them the same amount of time & find out that one holds better voltage than the other or gets charged faster than the other, that said, if one of your batteries drops the voltage faster than the other then you have one that has some problem, this causes the amp to shut off as it needs both voltages to be present from both batteries in order to work right.
Cheers.
Ray Samuels

 

[Big Al]

I agree with you Ray, rechargeables are not as consistent as alkalines. What do suppose the 71 is doing here? Is the 71 drawing off of (1) 9v and maybe some off the 2nd 9v because of the inconsistency? I hear no sound degradation in the 71 after 5 hours off the rechargeables. Is the 71 using one 9v battery for each channel?

 

[Jahn]

Methinks the SR71 is made to draw from both batts equally at the same time, so it's the fault of the batt, not the amp, that one is losing charge quicker (bad conditioning, just sucky, who knows) - it's cheaper just to test it by getting two duracells, popping them in, playing them a bit, then testing them. if they are even, it's your batts.

 

[kunwar]

What I have noticed with my amp and the 2 pairs of plainviews that I am currently using with it is that after a discharge the batteries usually are down to rouondabout 6.6 V. fully charged (I use an Energiser charger which does a gr8 job, perfect for these batts) the 2 pairs show 10.89 V. Every single time I have checked it is the same. Now I haven't thought very hard of how i would test the current but does anyone have quick pointers for how to do it using a multimeter.

Kunwar

 

[thatopampguy]

Hi,

I just got 2 Rayovac NIMH 8.4 volts for use in my SR-71. I've been getting good sound a good life out of these, 10+ hours and no problem yet. However, one battery usually takes ~1 hour to charge and the other takes twice as long. Does it matter what kind of charger I use? I have a rayovac 1-hour charger and a cheap XG fast "smart" charger from Fry's.

If regular alkalines last 40 hours (in my experience with the SR-71), does that mean that NIMH will also last 40 hours? In digital cameras, NIMH last 3-4x longer than alkalines. Is this also true for 9volts rechargeables in the SR-71? If not, then what is it about battery/cell chemistry that makes it different?

Also, if 8.4 volts works in the SR-71, why is everyone out there getting these 9.6 volt Plain View and maha Powerex rechargeables for their SR-71?

Thanks!

 

[Graz]

Quote:

Originally Posted by thatopampguy ...one battery usually takes ~1 hour to charge and the other takes twice as long...

Is it possible that your charger charges one battery at a time? That would account for the timing...one hour to charge one battery, and then an additional hour to charge the second one. Just a thought...

Peace,

Graz

 

[atx]

Quote:

what I noticed on the last two battery swap outs is that one battery is completely exhaused while the other battery still has about 85-90% charge left in them.

If you have 2 sets, mark the "good" battery and the "bad" battery (the one that's exhausted). Then switch them so that you're using 2 good batteries and see if you still get the uneven discharge.

I have powerex 9Vs also and I noticed that if you've ever accidentally short circuited the battery even for a few seconds, it will cut the battery life significantly.

 

[tigger]

Quote:

Originally Posted by Big Al I been burning in my SR-71 and 325i for about a week and half now using Powerex rechargeable 9v batteries and what I noticed on the last two battery swap outs is that one battery is completely exhaused while the other battery still has about 85-90% charge left in them. I'd say I get about 7-9 hours from a set of batteries. The sound either drops out completely or sound quality and volume is very low when the batteries start to exhaust. But again one battery still has 85-90% charge left??? Has anyone experienced this with thier SR-71?

I'd wager you have a faulty battery here. It should have a warranty for such eventualities.
The general rule of thumb with NiMH batteries in a headphone amp is they last approximately 25% as long as an alkaline. If you get 40 hours with two Duracells in an SR71, you can expect 10 hours with two 9v 170mA NiMH batteries.