HeadAmp Pico Power: Pre-Order Thread - Page 39

Quote:

Originally Posted by Husq2100 

Lithium do have some advantages over Ni-MH as well as some disadvantages.

 

...really I just want to make a good purchase and get the most out of my Pico Power.

Off the top of my memory, Justin, referring to the 9.6 volt lithium ions, said that he would not want to go much higher, i.e. that is pushing the envelope. He also said that the power cut-off circuit cuts in at 6 volts. 

Generally anything outputting in the 7 to 9 volt range is going to work fine. From there you are not going to get a definitive answer as to the best choice. As you said, there advantages and disadvantages.

Quote:

Originally Posted by cooperpwc 

 

 

Off the top of my memory, Justin, referring to the 9.6 volt lithium ions, said that he would not want to go much higher, i.e. that is pushing the envelope. He also said that the power cut-off circuit cuts in at 6 volts. 

 

Generally anything outputting in the 7 to 9 volt range is going to work fine. From there you are not going to get a definitive answer as to the best choice. As you said, there advantages and disadvantages.

Thanks for your reply cooperpwc,

Here is one of Justins comments regarding lithium:

"that would depend how they're charged but most will do 8.4V. 8.2V a little less common. the nominal voltage is 7.4V and they'll spend most of their life around this range, before quickly dropping to 6V and then being shut-off by internal protection circuitry."

Im reading this as the internal protection circuity is in the battery (which I belive all Lithium rechargeables have to have or they are very easily killed)

I guess I cant explain very well what im thinking regarding the actual peak voltage of a "9v"  Lithium (being that a single cell is 3.6v) Given that he said 7.4v is their nominal voltage, Im thinking a Ni-Mh made from 1.2v cells may be able to have a higher nominal voltage without being to high when fully charged.....but could be very wrong..

but maybe 7.4v is fine and no advantage in more volts, but an advantage in the amp hours of the lithium.????

Quote:

Originally Posted by Husq2100 

Sorry for asking some actual tech and when I was given the dont worry about it rather than an actual tech answer, I asked again.  Seems you know all the answers, so if your going to waste your time posting that I am wasting time, how about adding the tech.......

 

Voltage measurements for the PowerEx Imedion 8.4V 250 mAh - actual use.  Fully charged:  11V,  after 4-5 hours of use:  9V,  Pico Power light off after 12 - 14 hours of use.  NIMH batteries stay relatively close to their specified voltage through most of their discharge cycle.  Follow the links to see typical discharge cycles.  NIMH could be a better choice than alkaline as it operates at a more consistent voltage throughout it's discharge cycle than alkaline.  NIMH also appears to operate at a more consistent voltage than Lithium, but the difference is fairly insignificant.

NIMH:

http://www.google.com/search?q=nimh+battery+voltage+curve&hl=en&safe=off&client=safari&rls=en&tbm=isch&tbo=u&source=univ&sa=X&ei=bLVJUZqRNsqayQH3z4GwBg&ved=0CD8QsAQ&biw=1361&bih=916#imgrc=82PYrM-QXG65MM%3A%3BpRzhJcfk0khQlM%3Bhttp%253A%252F%252Ftangentsoft.net%252Faudio%252Fpimeta2%252Fbitmaps%252Fnimh-9v-discharge.png%3Bhttp%253A%252F%252Ftangentsoft.net%252Faudio%252Fpimeta2%252Fps.html%3B833%3B381

NIMH vs Alkaline:

http://www.google.com/imgres?imgurl=http://www.stefanv.com/electronics/using_nimh/nimh_vs_alkaline.gif&imgrefurl=http://www.stefanv.com/electronics/using_nimh.html&h=360&w=480&sz=5&tbnid=VdRJBOHteSKFHM:&tbnh=91&tbnw=121&prev=/search%3Fq%3Dalkaline%2Bbattery%2Bdischarge%2Bcurve%26tbm%3Disch%26tbo%3Du&zoom=1&q=alkaline+battery+discharge+curve&usg=__CKjCsuAtf6ZEv-FI0_iby5D35z0=&docid=zRRLidL16QG8aM&sa=X&ei=NLhJUa76MdPlyAGetYGQBQ&ved=0CEgQ9QEwBA&dur=91

Lithium:

http://www.google.com/search?hl=en&safe=off&client=safari&rls=en&tbm=isch&source=univ&sa=X&ei=ablJUaOGKcnJyQHHj4HwDA&ved=0CDAQsAQ&biw=1361&bih=932&q=lithium%20ion%20battery%20discharge%20curve#imgrc=dQcLQHMvKlYmPM%3A%3BM6nDBBPJoplA_M%3Bhttp%253A%252F%252Fwww.lenrek.net%252Fexperiments%252Fnokia%252Fdischarge.2002-11-09.png%3Bhttp%253A%252F%252Fwww.lenrek.net%252Fexperiments%252Fnokia%252F%3B640%3B480

One remark: "11V" is valid for nominal 9.6V, for 8.4 it's about 10.
 

Quote:

Originally Posted by feliks 

One remark: "11V" is valid for nominal 9.6V, for 8.4 it's about 10.
 

11 volts was measured from the battery immediately after charge using a volt meter.

has it shipped yet for people order in january?

The powerex imedion 8.4v should have a max voltage of 10.08v open circuit fully charged

The powerex imedion 9.6v should have a max voltage of 11.52v open circuit fully charged

Any li-ion 9v size should have a max voltage of 8.4v open circuit fully charged

Justin did mention it's safe with 11.52v per battery when I previously asked, and I assume that is the highest voltage you'll get out of any 9v sized battery.  So it sounds like anything would be safe as long as Justin's comment is accurate. 
 

I'm now running these rechargeables and charger.

They seem to work fine. I'm not sure how long they last compared to other rechargeables however they were priced well, so worth it to me:

http://amzn.to/15tbRq9

http://amzn.to/WF97oX

Thats good pricing, Phototristan. I am using Powerex 9V and a 4 bank charger by Powerex too. This way, when I change the pair, there's a new set thats freshly charged. Got mine from thomas Distributing. Check them out. They also have the Imedion low discharge variety.

Excellent info guys, I appreciate the time given. And yes some more questions. Is voltage the important factor? Will the lower voltage lithium be noticable sound wise compared to the higher Ni-MH? The advantages I like about Lithium are you dont have to fully drain them before charging. You dont have to fully charge them. They have double the amp hrs. And if looked after store well. Im thinking for my use of the Pico Power, sometimes daily, sometimes not. If im not sure of the charge in the battery I can just put them on charge for a bit then go.

cheers

Serg

You don't have to fully drain NimH before charging, for the most part that's a leftover myth from NiCd batteries. There are also low self-discharge NimH batteries which store well.

Quote:

Originally Posted by Nebby 

 There are also low self-discharge NimH batteries which store well.

Which are what the ones I got are (5 posts above). 

Quote:

Originally Posted by phototristan 

Which are what the ones I got are (5 posts above). 

Yup, I saw that. The Powerex Imedion are also low self-discharge but I haven't gotten mine and on general principles I don't like recommending something that I haven't used.

good to know.

So voltage is more important for sound quality, than going for the larger amp hour for run time?

cheers

Serg