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Lithium Ion vs NiMh battery



 
 
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  #21  
Old October 23rd 17, 05:37 PM posted to rec.bicycles.tech
Jeff Liebermann
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Posts: 4,018
Default Lithium Ion vs NiMh battery

On Mon, 23 Oct 2017 08:06:07 -0700, sms
wrote:

On 10/22/2017 8:13 PM, Jeff Liebermann wrote:
I recently bought a few of the lowest priced 18650 on eBay. Garbage
in, lumens out. These were suppose to be 5800 and 5000 ma-hr but
delivered 1000 and 880 ma-hr:
http://802.11junk.com/jeffl/battery-tests/18650.jpg
After about 10 charge/discharge cycles, the 5000 ma-hr cell is showing
signs impending failure.


Oh please, did you really expect 5800 mAH from an 18650? There is no
such thing!


Of course not. Notice that I said "bought a few of the lowest priced
18650 on eBay". I wanted to see how the worst possible cells
preformed. These seem to be a fairly reasonable proposition. I
haven't massaged the numbers quite yet, but it seems that a $1 junk
18650 battery, that produces about 1000 ma-hr capacity, has a lower
cost of ownership than a $5 cell 2500 ma-hr from a reputable vendor.
If I buy only junk batteries, I would get twice the capacity for the
same cost, if I'm willing to ride with a bag full of spare batteries.
However, early results from repeated charge/discharge cycles is
showing that the junk cells don't last.

The cheapest way to buy flat top 18650 cells is to buy one of those USB
battery packs. Fry's has a 16,800 mAH model comprised of six 2800mAH
18650 cells for $17. That's $2.83 per cell.

For button-top cells, the source that Barry Beams provided is probably
the best option. I.e. for button-top
https://liionwholesale.com/collections/batteries/products/protected-panasonic-ncr18650b-3400mah-li-ion-18650-button-top-battery?variant=1925834564.


The prices are certainly tolerable, but only if the batteries are not
counterfeit. That's the problem I had buying on eBay. I bought a few
odd high priced cells, that were suppose to be name brand cells, and
ended up with counterfeits. Of course, when I complained, the vendors
refunded my money and claimed they didn't know that they were
counterfeit.

Incidentally, I usually weigh my 18650 cells. For a good battery, I
usually end up with 45 grams/cell. One of the aforementioned
batteries weighted an amazing 72 grams, was advertised as 3500 ma-hr
and measured 800 ma-hr. I couldn't resist opening it up. Inside, I
found what looked like the guts from a 14500 cell and a mixture of
sand and wax to increase the weight.

Another oddity is while 18650 cells are often market with wildly
optimistic ma-hr ratings (much like flashlight lumens), other size
LiIon cells seems to be marked with more realistic ratings. For
example, I bought a pile of SkyWolfEye 14500 (AA size) cells marked
1200 ma-hr. They measure about 1100 ma-hr when tested at the industry
standard 0.2C constant current discharge rate. However, at the 1A
discharge, where I plan to use these cells, the best they could do is
about 450 ma-hr. Still, if you use common 0.2C test method, they
almost meet their advertised spec.




--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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  #22  
Old October 23rd 17, 06:44 PM posted to rec.bicycles.tech
Ian Field
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Posts: 250
Default Lithium Ion vs NiMh battery



"James" wrote in message
news
On 23/10/17 10:42, Sir Ridesalot wrote:

Dynamo hubs are out for me because I use my light on a number of
different bicycles depending on what any particular ride is for. It'd
cost me afortune to a dynamo hub on all of my bikes.


A first world problem of too many bicycles.


I'm down to 2 and one with not a lot missing.

  #23  
Old October 23rd 17, 06:53 PM posted to rec.bicycles.tech
Ian Field
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Posts: 250
Default Lithium Ion vs NiMh battery



"Oculus Lights" wrote in message
...
On Sunday, October 22, 2017 at 1:07:26 PM UTC-7, Ian Field wrote:
"Jeff Liebermann" wrote in message
...
On Fri, 20 Oct 2017 21:40:42 -0700 (PDT), Sir Ridesalot
wrote:

A while back I asked about using an external NiMh battery instead of an
external
Lithium Ion battery on a light that came with a Lithium Ion battery.
Due
to a
problem with the Lithium Ion battery pack of mine not holding a charge
or
for
some other reason battery related for the light suddenly going out I
put a
Tamiya connector onto the light's wire and used my NiMh battery. Guess
what?
It works perfectly and my battery run time is a LOT longer now than
what
it was.
Seeing as I have a few of these 5000Mah NiMh batteries from my RC boats
I
can
now ride VERY FAR at night with no worry about the light going out
suddenly
or dimming drastically at low speeds or when stopped.

My guess(tm) is that there is either something wrong with your LiIon
battery pack, or the LiIon battery pack was assembled using cheap junk
LiIon cells. I've seen both, mostly from 18650 cells. Identifying
counterfeit cells is difficult:
https://batterybro.com/blogs/18650-wholesale-battery-reviews/104619270-can-you-identify-the-fake-lg-hg2-18650-battery
I used to weigh the cells and compare them with a known good cell, but
that hasn't worked since the counterfeiters started adding waxes sand
to the cell to increase the weight.


All my 18650s were rescued from discarded laptop packs - if I get any
duds,
there's no point complaining to anyone.

The 3W Tesco headlamp uses one, but my biggest application is my e
cigarette. That's been in service well over 5yrs and I've only had to
swap
out a couple of battery sets.

The one that came with the Tesco unit is only 1800mAh - I get a lot more
running time from salvaged cells.


Laptop battery packs used to be great sources for core cells. The big
laptop battery recall in 07-08 sent case loads of new packs to large
companies. Problem with the packs that was causing fires was cheap
charging controllers, and poor design that put groups of three cells in
parallel without regulating charging between each cell. That resulted in
some cells being forced to absorb power beyond safe charging capacity if
one cell was substandard or dropped off a tenth of a volt after many
charges.
Instructions were given NOT to return old packs, to dispose of locally.
That gave me a huge harvest of 2800 Samsungs and Panasonics from Lenovo
and Dell packs, for my early lights.


I don't get it! - I use a simple DIY charger and never had an accident.
Commercial manufacturers seem intent on comic people cartwheeling through
the air.

There's plenty of spectaculars on Youtube including people blowing up cells
deliberately - I've never set out to do that, but I always "push the
envelope" when exploring a new technology.

Once I ruined an AA cell with my "brute force & ignorance" charger - but it
didn't go exothermic.

  #24  
Old October 23rd 17, 07:01 PM posted to rec.bicycles.tech
SMS
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Posts: 9,477
Default Lithium Ion vs NiMh battery

On 10/23/2017 10:53 AM, Ian Field wrote:

snip

I don't get it! - I use a simple DIY charger and never had an accident.
Commercial manufacturers seem intent on comic people cartwheeling
through the air.


If you're using protected cells you won't have any problem.

It's also very different when you're charging two cells in series at
8.4V or one cell at 4.2V. You already have two levels of protection, the
voltage is correct and the PCB in the battery doesn't let the voltage
exceed 4.2V.

At work, we had been charging unprotected cells with a variable power
supply at 8.4V. This worked just fine. Except when we had a product that
used a single cell and the tech hooked it up to the 8.4V--quite a mess
when it exploded and caught fire on the bench.

Commercial manufacturers are doing high-rate charging while monitoring
temperature. They are also often charging in parallel but discharging in
series, or a in series-parallel combination.
  #25  
Old October 23rd 17, 07:02 PM posted to rec.bicycles.tech
Ian Field
external usenet poster
 
Posts: 250
Default Lithium Ion vs NiMh battery



"Jeff Liebermann" wrote in message
...
On Sun, 22 Oct 2017 21:07:22 +0100, "Ian Field"
wrote:

All my 18650s were rescued from discarded laptop packs - if I get any
duds,
there's no point complaining to anyone.


I have a small collection of such batteries. The problem is that the
spot welded + terminal is flat and is missing the "button top" used in
most removable 18650 cells. I had to buy a few magnetic "button tops"
which work well enough, but are easily lost or misplaced:


Active plumber's flux will allow you to tin the stainless straps, the spot
welds have a fair bit of thermal resistance to the actual battery contact.
Make the solder joint without dilly-dally and you don't cook the cell. The
strong flux will also allow you to tin a M4 nut to solder on the + end. So
far, I haven't had to - but I can if needed.

Recover pack cells carefully - pulling the straps off completely can rip the
spot welds out and leave holes in the steel jacket. Tin snips are the proper
job, but scissors will do if you don't need them to cut anything else
afterward.

  #26  
Old October 23rd 17, 07:08 PM posted to rec.bicycles.tech
Ian Field
external usenet poster
 
Posts: 250
Default Lithium Ion vs NiMh battery



"sms" wrote in message
news
On 10/22/2017 8:13 PM, Jeff Liebermann wrote:
On Sun, 22 Oct 2017 21:07:22 +0100, "Ian Field"
wrote:

All my 18650s were rescued from discarded laptop packs - if I get any
duds,
there's no point complaining to anyone.


I have a small collection of such batteries. The problem is that the
spot welded + terminal is flat and is missing the "button top" used in
most removable 18650 cells. I had to buy a few magnetic "button tops"
which work well enough, but are easily lost or misplaced:
https://www.ebay.com/itm/282578704173
My testing, using a West Mountain Radio CBA-II discharge tester,
showed that the cells market 2200 ma-hr delivered 2000 ma-hr at 1.5A.
Good enough.

The 3W Tesco headlamp uses one, but my biggest application is my e
cigarette. That's been in service well over 5yrs and I've only had to
swap
out a couple of battery sets.


Between the eCigarettes, eBikes, LED lighting enthusiasts, power
tools, and radio geeks, it's a wonder that one can find 18650 cells.

The one that came with the Tesco unit is only 1800mAh - I get a lot more
running time from salvaged cells.


I recently bought a few of the lowest priced 18650 on eBay. Garbage
in, lumens out. These were suppose to be 5800 and 5000 ma-hr but
delivered 1000 and 880 ma-hr:
http://802.11junk.com/jeffl/battery-tests/18650.jpg
After about 10 charge/discharge cycles, the 5000 ma-hr cell is showing
signs impending failure.


Oh please, did you really expect 5800 mAH from an 18650? There is no such
thing!


A laptop pack containing 3S1P claimed 5200mAh, but I never bothered
verifying that it actually got that much work done.

A recent find in the recycling was an Ultrafire 3600mAh 18650. It still had
shrink wrap on it that covered the contacts - it was probably binned because
the charger fault LED lit up.

Its in my headlight right now, so I'm in the process of finding out how long
it runs.

  #27  
Old October 23rd 17, 07:38 PM posted to rec.bicycles.tech
Ian Field
external usenet poster
 
Posts: 250
Default Lithium Ion vs NiMh battery



"sms" wrote in message
news
On 10/23/2017 10:53 AM, Ian Field wrote:

snip

I don't get it! - I use a simple DIY charger and never had an accident.
Commercial manufacturers seem intent on comic people cartwheeling through
the air.


If you're using protected cells you won't have any problem.

It's also very different when you're charging two cells in series at 8.4V
or one cell at 4.2V. You already have two levels of protection, the
voltage is correct and the PCB in the battery doesn't let the voltage
exceed 4.2V.

At work, we had been charging unprotected cells with a variable power
supply at 8.4V. This worked just fine. Except when we had a product that
used a single cell and the tech hooked it up to the 8.4V--quite a mess
when it exploded and caught fire on the bench.

Commercial manufacturers are doing high-rate charging while monitoring
temperature. They are also often charging in parallel but discharging in
series, or a in series-parallel combination.


Parallel charging for series use is probably as safe as it gets - I was
considering designing something, but it seems to be one of those projects
that doesn't quite evolve into something tangible.

Series balancing isn't all that difficult - but I haven't quite cracked the
"micropower" bit of the sensing circuits.

  #28  
Old October 23rd 17, 08:09 PM posted to rec.bicycles.tech
Jeff Liebermann
external usenet poster
 
Posts: 4,018
Default Lithium Ion vs NiMh battery

On Mon, 23 Oct 2017 19:02:03 +0100, "Ian Field"
wrote:



"Jeff Liebermann" wrote in message
.. .
On Sun, 22 Oct 2017 21:07:22 +0100, "Ian Field"
wrote:

All my 18650s were rescued from discarded laptop packs - if I get any
duds,
there's no point complaining to anyone.


I have a small collection of such batteries. The problem is that the
spot welded + terminal is flat and is missing the "button top" used in
most removable 18650 cells. I had to buy a few magnetic "button tops"
which work well enough, but are easily lost or misplaced:


Active plumber's flux will allow you to tin the stainless straps,


The strips are nickel, not stainless. Some are nickel plasted steel.
http://www.ebikeschool.com/how-to-differ-between-pure-nickel-strip-battery-tabs-vs-steel-core/

the spot
welds have a fair bit of thermal resistance to the actual battery contact.
Make the solder joint without dilly-dally and you don't cook the cell. The
strong flux will also allow you to tin a M4 nut to solder on the + end. So
far, I haven't had to - but I can if needed.


An M4 nut seems to be too thick for the purpose. The magnet is only
0.85mm thick.

Recover pack cells carefully - pulling the straps off completely can rip the
spot welds out and leave holes in the steel jacket. Tin snips are the proper
job, but scissors will do if you don't need them to cut anything else
afterward.


I use diagonal wire cutters. I'll admit to ripping holes in the steel
battery jacket, but I just plug them with solder.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
  #29  
Old October 23rd 17, 09:07 PM posted to rec.bicycles.tech
Ian Field
external usenet poster
 
Posts: 250
Default Lithium Ion vs NiMh battery



"Jeff Liebermann" wrote in message
...
On Mon, 23 Oct 2017 19:02:03 +0100, "Ian Field"
wrote:



"Jeff Liebermann" wrote in message
. ..
On Sun, 22 Oct 2017 21:07:22 +0100, "Ian Field"
wrote:

All my 18650s were rescued from discarded laptop packs - if I get any
duds,
there's no point complaining to anyone.

I have a small collection of such batteries. The problem is that the
spot welded + terminal is flat and is missing the "button top" used in
most removable 18650 cells. I had to buy a few magnetic "button tops"
which work well enough, but are easily lost or misplaced:


Active plumber's flux will allow you to tin the stainless straps,


The strips are nickel, not stainless. Some are nickel plasted steel.
http://www.ebikeschool.com/how-to-differ-between-pure-nickel-strip-battery-tabs-vs-steel-core/

the spot
welds have a fair bit of thermal resistance to the actual battery contact.
Make the solder joint without dilly-dally and you don't cook the cell. The
strong flux will also allow you to tin a M4 nut to solder on the + end. So
far, I haven't had to - but I can if needed.


An M4 nut seems to be too thick for the purpose. The magnet is only
0.85mm thick.

Recover pack cells carefully - pulling the straps off completely can rip
the
spot welds out and leave holes in the steel jacket. Tin snips are the
proper
job, but scissors will do if you don't need them to cut anything else
afterward.


I use diagonal wire cutters. I'll admit to ripping holes in the steel
battery jacket, but I just plug them with solder.


There's probably an electrolyte contamination issue there, but i'm no
chemist - so I'll leave if for you to look it up.

Whatever the straps are made of - plumbers flux gets the job done.

  #30  
Old October 23rd 17, 09:49 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 3,345
Default Lithium Ion vs NiMh battery

On Monday, October 23, 2017 at 11:01:42 AM UTC-7, sms wrote:
On 10/23/2017 10:53 AM, Ian Field wrote:

snip

I don't get it! - I use a simple DIY charger and never had an accident.
Commercial manufacturers seem intent on comic people cartwheeling
through the air.


If you're using protected cells you won't have any problem.

It's also very different when you're charging two cells in series at
8.4V or one cell at 4.2V. You already have two levels of protection, the
voltage is correct and the PCB in the battery doesn't let the voltage
exceed 4.2V.

At work, we had been charging unprotected cells with a variable power
supply at 8.4V. This worked just fine. Except when we had a product that
used a single cell and the tech hooked it up to the 8.4V--quite a mess
when it exploded and caught fire on the bench.

Commercial manufacturers are doing high-rate charging while monitoring
temperature. They are also often charging in parallel but discharging in
series, or a in series-parallel combination.


All of my speedos use 2032 cells. I used to just buy a card of them and insert new ones. Then I realized that they are Li-ion. Do these things charge up again?
 




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