18650 battery

Status
Not open for further replies.

nanZor

Active Member
Joined
May 28, 2009
Messages
2,807
I now own two radios with 18650's - the Commradio CR1a and the Tecsun PL880. I like them for different reasons and are apples to oranges in comparison to each other.

BUT, I love the batteries far better than my stable of nimh's, maha chargers et al ...

The Tecsun 880 uses a 3.7v nominal, protected, button-top cell. Mine was rated at 2000mah. Testing it shows that the internal charger starts out at about 370mah of current which is just fine, only it takes a few hours to fully charge that cell.

The cell comes fully charged out of the radio a *tad* high at 4.22v, but this is still within spec. You don't really need to go this high, but the tradeoff is slightly lower cycle life - however unless you do full discharges daily, the battery will most likely age faster than you can cycle it. :)

I investigated replacements and picked up a Tenergy 18650 protected button top - in silver and black wrapping. It fits fine and has extra capacity to boot - 2600mah vs the Tecsun branded 2000mah.

I also tried using the similar Tenergy 18650 that was inside the Commradio CR1a, but this was a "flat top" and did not make a connection inside the Tecsun.

The beauty about the 18650's is that it changes the way you think about portable radio operation. There is no need to fully-charge it every cycle. It will live it's entire life quite happily in a state of partial-charge.

Note that the Tecsun 880 has a secret low-voltage cutoff you should know about: With power off, and holding down the #4 key for about 5 seconds, and then rotating the tuning knob, you can select anywhere from 3.4v to 3.7v cutoff. 3.4v is practically dead, so I up it to about 3.6v. Your choice on how deep you want to go.

Obviously one can use an external charger like a Nitecore etc, but I'm happy that the internal charger, though even a tad slow, works ok despite being just a hair higher in voltage than I'd like - but still within spec.
 

nanZor

Active Member
Joined
May 28, 2009
Messages
2,807
-- duplicate -- attempted to delete..
 
Last edited by a moderator:

Rred

Member
Joined
Nov 21, 2014
Messages
830
"Lithium" batteries are queer ducks when it comes to charging. There's a "news to most of us" page of this at the Battery University web site. Apparently you can simply charge them by voltage or draw current draw, which are the two most popular [read: cheapest] ways to make a charger. But in order to get the battery fully charged, and to optimize the battery life, the charger may need to sense the charge acceptance of the battery and then do a timed "topping" charge as well as the bulk charge. That means cheap conventional chargers adapted from the conventional battery types, will either damage the batteries (shorten their life) or leave them charged to way less than capacity.

One more mystery to buying "lithium" batteries, invisible to the average buyer.
 

nanZor

Active Member
Joined
May 28, 2009
Messages
2,807
Charging is actually quite simple with a cc/cv charge to no more than 4.2v.

If one really wants to go deep into it, a good resource is here:
Flashlight Electronics - Batteries Included

However the charging circuit inside the Tecsun and the Commradio do a fine job. If one wants external charging, then there are many like the Nitecore and Xtar units.

The batteries themselves should be of the "protected" variety, which contain circuitry under the + positive end of the cap just in case the manufacturer circuitry goes awry.

The only problem I see with 18650's is that there is the temptation to use unsafe / counterfeit JUNK if you get them from a non-reputable source. Most high-end flashlight manufacturers offer decent batteries. I understand now how a radio manufacturer might be swayed to offer proprietary-shape lithium batteries to help prevent this issue, but I commend Tecsun and Commradio for allowing for non-proprietary shaped and easy to obtain 18650 cells.

Other than that, there is an operational simplicity with lithium that may be hard to believe - along with great performance. As a technical hobby, I think we tend to overthink things and delve beyond the practical - like trying to keep an $8 cell alive for 20 years with too much babying. :)

I'm making the switch from AA's powered gear now that I know how to be safe, and purchase them from reputable dealers.
 
Last edited by a moderator:
Status
Not open for further replies.
Top