Powerex AA discharge after work

50 posts in this topic

#: 1   Posted

I started using Powerex AA for shorter work days. For long days I still prefer the Lithiums.

I searched this forum and the MAHA website and I found that Powerex does not have memory effect.

The last 4 days I noticed that if I charge an almost full AAs I only get 2.5 hours with my SMQV before I see a red light.

I checked if the TX is setup to 250mW but it is not.

All AAs are brand new from the same order coming straight from MAHA.

Anybody experienced something similar?

Also do you guys discharge them before charging?

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#: 2   Posted

I don't discharge them, but I do a "soft charge" as often as possible. Also, they lose about 10% of their charge per day while not in use. Are you using them "hot off the charger"?

Eventually, they will not hold as much of a charge as when they were new.

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#: 3   Posted

I'm all for the Eneloops XX - because they are a great compromise between capacity, and long term shelf life.

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#: 4   Posted

Powerex Imedions. I find them a bit better than the XX. Powerex 2700mah's? I threw them all out.

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#: 5   Posted

I take them off the charger and l put them in my TXs. I don't switch the TXs on till I get to the location.

My Powerex are brand new.

I always charge them after work and if I work a week later I put them in the charger the night before.

I don't discharge them, but I do a "soft charge" as often as possible. Also, they lose about 10% of their charge per day while not in use. Are you using them "hot off the charger"?

Eventually, they will not hold as much of a charge as when they were new.

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#: 6   Posted

I use the same batteries in my SMQV and I get at least 6 hours from it.

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#: 7   Posted

I have found in my SMa's that I get at least another two hours after the red light comes on using Powerex 2700mah. This is the first production I have used them on so they are new.

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#: 8   Posted

I've had my Powerex 2700 mahs for a year and a half and, so far, they've been great. Constant, high charges wich lasts all day. I always soft charge them and always use them within 3-4 days from chargeing. Also I do a "Soft-recycle-discharge" about every third month to keep them fresh.

I seriously doubt they loose 10% per day, Jason, where did you get that number? Atleast thats not my experience with them.

And Rado, remember, battery indicators are not always to be trusted when working with rechargable batteries. Rechargables are measured differently than alkalines.

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#: 9   Posted

I'm all for the Eneloops XX - because they are a great compromise between capacity, and long term shelf life.

I've been using the Eneloops with great success, too... Seem to last a bit longer than my Powerex Imedions.

They're a little newer, too, so that kind of makes sense, doesn't it?

Cheers,

Rich

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#: 10   Posted

Me too from the rest of them.

But the ones I put from the charger in the morning show a red line after 2.5 - 3 hours..

I use the same batteries in my SMQV and I get at least 6 hours from it.

I use the same batteries in my SMQV and I get at least 6 hours from it.

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#: 11   Posted

Well, maybe not 10%/day ::) but the point I was trying to make was that their self-discharge rate is higher than other chemistries.

I would not use a nimh battery (in a Tx) that has been sitting on my shelf for more than 2 days, especially one that has been in use for a couple of years.

I currently use Imedions for all my AA needs and they are solid performers.

I've had my Powerex 2700 mahs for a year and a half and, so far, they've been great. Constant, high charges wich lasts all day. I always soft charge them and always use them within 3-4 days from chargeing. Also I do a "Soft-recycle-discharge" about every third month to keep them fresh.

I seriously doubt they loose 10% per day, Jason, where did you get that number? Atleast thats not my experience with them.

And Rado, remember, battery indicators are not always to be trusted when working with rechargable batteries. Rechargables are measured differently than alkalines.

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#: 12   Posted

Rado,

Do you have a battery analyzer? Perhaps one of the pair is faulty? Any chance an older battery was mixed in with a newer?

Me too from the rest of them.

But the ones I put from the charger in the morning show a red line after 2.5 - 3 hours..

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#: 13   Posted

I do not have battery analyzer.

All batteries are from the same order.

But it makes sense that some of them might be faulty.

The ones that I take out of the SMQV after 2.5-3 hours go in a pack labeled "need charging".

Those are the ones I charge overnight and put in the SMQV in the morning.

Any recommendations for a battery analyzer??

Rado,

Do you have a battery analyzer? Perhaps one of the pair is faulty? Any chance an older battery was mixed in with a newer?

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#: 14   Posted

Are you saying the SMQV does not measure the charge of the battery correctly?

RTFM

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#: 15   Posted

I do not have battery analyzer.

<snip>

Any recommendations for a battery analyzer??

Try the Powerex MH-C9000. It's about $70 list if memory serves, $50 from Thomas Distributing.

mhc9000.jpg

Best regards,

Jim

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#: 16   Posted

+1 for the MH-C9000

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#: 17   Posted

Rado,

Rechargeable batteries operate at a lower voltage. The transmitter LED indicator can show red very quickly, but that does not mean the battery is going dead. Lithium batteries operate at a higher voltage, and may show green right up until they have a sudden drop in voltage.

The best indicator for battery life is simply knowing how they last in your particular pieces of gear. Lectro receivers give you an option to measure time instead of voltage.

I use voltage indicator on the receiver for rechargeables, and have become quite good at knowing when to swap batteries, but I never use the transmitter LED.

Robert

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#: 18   Posted

Thanks Robert.

Very valuable information.

Do you know how accurate is the 9VT display on the receiver for powerex battery?

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#: 19   Posted

Thanks Robert.

Very valuable information.

Do you know how accurate is the 9VT display on the receiver for powerex battery?

I monitor with AA setting on receiver, and swap when they get to about 1.2v.

The best thing to do is test out the performance with your batteries in your gear and get a feel for what you are comfortable with.

I use a slow charge, like others have suggested, and I always top off before use.

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#: 20   Posted

Rado - there is an old thread about this. The red light can light up hours before the battery dies. I actually called Lectrosonics and got into a talk about it. From my memory, the Nimh batteries come in a lot of different capacities. They also have a very slow slope of voltage loss (compared to alkaline and especially lithium). Those capacity options, and slow slope of discharge, means that Lectro can't really make a Nimh setting that will work super accurately for all batteries.

Lectro's suggestion was to figure out the run time of the battery, and use the timer on your RXs.

On a film/reality job I use Powerex AA in my SMQVs and almost always make it till lunch, then wrap. It's a little more sketchy on documentary jobs without set meals/breaks, but I don't get stuck more than I did with any other transmitter.

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#: 21   Posted

Thanks, I meant AA not 9vt

I will buy the analyzer and check my batteries.

It was just strange to have the red light show up after 3 hours on some powerex and after 6 hours on other powerex.

I monitor with AA setting on receiver, and swap when they get to about 1.2v.

The best thing to do is test out the performance with your batteries in your gear and get a feel for what you are comfortable with.

I use a slow charge, like others have suggested, and I always top off before use.

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#: 22   Posted

Unless they have just been taken out of the charger or they are dead, NiMh batteries will measure 1.2 Volts. Further, they measure 1.2 Volts whether the remaining charge is good, bad or indifferent. Neither the transmitter and nor the receiver can give you accurate remaining life values on NiMh. The units will only read correctly with lithium or alkaline batteries. All this is in the manuals.

Get yourself a MH-C9000 from Powerex (Maha) charger as described above because it can analyze your battery and tell you if it is ready for the trash or not. As long as the batteries are both good and 100% charged, the timer on the receiver will tell you when it is time to replace the battery. It will save you both money and unhappy clients.

Best Regards,

Larry Fisher

Lectrosonics

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#: 23   Posted

Thanks Larry,

I will buy the MH-C9000 because all my Powerex are brand new from the same order 2 months ago,

Unless they have just been taken out of the charger or they are dead, NiMh batteries will measure 1.2 Volts. Further, they measure 1.2 Volts whether the remaining charge is good, bad or indifferent. Neither the transmitter and nor the receiver can give you accurate remaining life values on NiMh. The units will only read correctly with lithium or alkaline batteries. All this is in the manuals.

Get yourself a MH-C9000 from Powerex (Maha) charger as described above because it can analyze your battery and tell you if it is ready for the trash or not. As long as the batteries are both good and 100% charged, the timer on the receiver will tell you when it is time to replace the battery. It will save you both money and unhappy clients.

Best Regards,

Larry Fisher

Lectrosonics

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#: 24   Posted

Hi Rado,

The batteries vary a tiny bit as they age and the red to green transition of the transmitter is right in the middle of their nominal 1.2 Volts. One battery may measure 1.21 Volts after a few hours and the next one may measure 1.19 Volts at the same run time, causing the transmitter to cry wolf.

Best,

Larry F

Lectro

[snip]

It was just strange to have the red light show up after 3 hours on some powerex and after 6 hours on other powerex.

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#: 25   Posted

" show a red line after 2.5 - 3 hours.. " + " RTFM " + " Rechargeable batteries operate at a lower voltage. " + " NiMh batteries will measure 1.2 Volts. Further, they measure 1.2 Volts whether the remaining charge is good, bad or indifferent. Neither the transmitter and nor the receiver can give you accurate remaining life values on NiMh. The units will only read correctly with lithium or alkaline batteries. All this is in the manuals. "

::)

It is like Deja Vu all over again... ^_^

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