4.35v VS 4.2v 18650 lithium batteries?

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xxllmm4
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4.35v VS 4.2v 18650 lithium batteries?

Hey everyone,

Just curious as to everyone's thoughts on this subject. I started looking around and it looks like we might be missing out on a lot of good batteries. It looks like the manufacturers are pushing towards 4.3v and 4.35v Lithium Ion 18650's 

All the new Sanyo, Samsung and LG batteries I have been looking at are 4.3v or 4.35. I was thinking of having some protected ones made up for flashlight batteries but I wonder how many people would really care? 

My Icharger will go up to 4.3v but but I still can only do 1 at a time. Has anyone ever tested some of these? They might be good in some applications where you wanted to keep the voltage higher?

Hikelite
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xxllmm4 wrote:

My Icharger will go up to 4.3v but but I still can only do 1 at a time. Has anyone ever tested some of these? They might be good in some applications where you wanted to keep the voltage higher?

Interesting indeed.

I wonder if a 4.35 18650 would be better vs a 4.2 18650 when it comes to regulation on a multi led and multi cell setup. Like the DRY. Would the light stay in better regulation because the Vf can be maintained for longer? Or the 4.2's are just fine as the driver starts pulling more amps to compensate the voltage drop?

PilotPTK
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It really, completely, depends on the driver and the Vf of the particular LED.  XML's are pretty famous for having very low Vfs (Low 3V Range for 3A), so for most drivers, the extra voltage doesn't hurt or help.  For a higher Vf LED through, the extra head room may be a very good thing.  Additionally, if the driver is a Buck-Boost (SEPIC, Flyback, CUCK, whatever), then Vin is pretty irrelevant anyway - it can pull more current at lower voltage levels or less current at higher voltage levels, but the output will be the same no matter..

 

The big win is capacity.. Think of it like this, take a normal 4.2V cell, fill it with 'charge'.  Then, keep filling it.  All that extra charge that it takes to reach 4.3 or 4.35 volts is charge that you can then pull out before the cell still has what a 'normal' 4.2 V one would have had to start..

 

PPtk

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fran82
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xxllmm4 wrote:

My Icharger will go up to 4.3v but but I still can only do 1 at a time. Has anyone ever tested some of these? They might be good in some applications where you wanted to keep the voltage higher?

 

What charger is that? 4,3v on Li-ION? I never heard about that. Imprehesive. Also I never heard about 4,35 volt Li batts. I have to google...

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Hikelite
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I wonder if using a 4.35v 18650 with a Nanjg 105 would to any good, or the contrary. It's known that the driver can take 6V but it becomes inefficient. Only 60% efficiency @ 6V input. Lots of heat.

So yeah it depends on the driver and the Vf.

Hikelite
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fran82 wrote:

 Also I never heard about 4,35 volt Li batts. I have to google...

Old has done some battery testing on the Samsung ICR18650-30A  more than a year ago.

fran82
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Hikelite wrote:

fran82 wrote:

 Also I never heard about 4,35 volt Li batts. I have to google...

Old has done some battery testing on the Samsung ICR18650-30A  more than a year ago.

Wow, I have to find the test..

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Stephen Wallace
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fran82 wrote:

xxllmm4 wrote:

My Icharger will go up to 4.3v but but I still can only do 1 at a time. Has anyone ever tested some of these? They might be good in some applications where you wanted to keep the voltage higher?

What charger is that? 4,3v on Li-ION? I never heard about that. Imprehesive. Also I never heard about 4,35 volt Li batts. I have to google...

It's a hobby charger, rather than one of the more consumer friendly cradle chargers. Some of the better brands/models give you some leeway to adjust the termination voltage up to get a little more capacity, or in this instance, to cater for a slightly different type of battery, or down to increase cell lifetime.

I believe that xxllmm4 is using the iCharger 106B+. It's the cheapest - or certainly one of the cheapest - model that Jun-Si make, though still a good deal more expensive than something like an iMax or Accucel-6, but it does have features and adjustments that the cheaper hobby chargers just don't have, along with higher charge rates, higher discharge rates, and a built in fan for cooling. Basically, it's more capable in terms of function and power, but you do pay more as a result.

Hikelite
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There's this charger too, http://www.batteryspace.com/smart-charger-0.5a-4.35v-cut--off-for-ultra-...

I have no experience with it.

 

Hikelite
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Some words on the Samsung 30A by a CPF guy :

"Just an FYI, I tested Samsung 2800 and 3000 mAh cells over the past year. 2 of them I just tested new never used but were produced about 1 year ago.

Large increase in internal resistance, and big drop in capacity just from sitting for 1 year at like 40-50% SOC. These cells were never used. The ones I tested previously (when they were newer) has a nominal voltage of almost 3.8v @ .2C. Now its a nominal voltage of about 3.6v, which means the resistance has increased a lot. Capacity of the 3000mAh cell is now about 2700-2800.

I'm not sure about other companies cells (LG Chem and Sanyo) but so far these Samsungs are disappointing!"

xxllmm4
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Yes, I'm using the Icharger 106b+ as far as I can tell the highest I can go with lithium batteries is 4.3v.

I have often wondered if NOT using lithium batteries could be harder on them than actually using them? Maybe it depends on the brand and model of each battery? 

The more I think about it they would probably have to be unprotected batteries. There is no way anyone would make special protection circuits for a limited run of say 100 batteries.