Large Scale Central

So, I'm pretty sure that I screwed the pooch on this one.

Electronics Power and Sound
#21

I told you there was going to be film at 11. But I didn’t tell you which day!

So…….to make a short story long, last night I swapped out my old Tenergy 4400 MaH battery with a new Airwire 6800 MaH battery. Going forward, I will use these particular batteries in my USAT GP9 and F3 A-B battery conversions. I’ll of course use a different battery in my NW-2. It took me four hours to charge up the new battery. Everything looks good so far - engine runs like a top. I then inquired within about the use of my Tenergy Universal Fast Smart TLP3000 1.5A Charger for Li-Ion battery packs and its compatibility with my particular battery pack. According to the gentleman who’s helping me with my installs and who is not only an installer for the BAGRS club (he’s done a few hundred conversions) and is an Airwire distributor and the guy who sold me the Tenergy charging unit. He says the charger I’m using is just fine. Not just happy with one opinion, I asked Mike at Reindeer Pass, the guy who sold me the new battery. He told me the charger I’m using works fine and he sells quite a few of them along with the Airwire and HJE batteries. Then I solicited the advise of Keith Gutierrez, the owner of CVP/Airwire, and asked him what he thought of my using the Tenergy TLP3000 1.5A charger with his new 6800 MaH Airwire battery. He sells these particular chargers too and he also recommends it and says I’m good to go.

So I’m a happy Mike. I musta had a bad battery to begin with. We’ll see what happens going forward. (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)

#22

Michael,

So lets see if I get this right…… The local installer and re-sellers with some experience with Li-Ion batteries/chargers have more street cred than the OEM charger/cell manufacturers and their published specifications are to be ignored? I’m going to politely suggest while your experts are credible individuals they’re uniformed and have limited experience of this battery technology and specifically series-parallel batteries. I know more about this stuff than most and can offer that the OEM cell builders are most definitely savvy! And together with nearly two decades of empirical experience with literally thousands of these batteries in my dust I recommend that you follow all OEM recommendations.

Tenergy’s TLP3000 1.5A charger; specification/description in quotes below:

“Intelligent charger designed for all types of 14.8V (4 cells) Li-Ion Battery packs including Polymer Li-Ion and Cylindrical Li-Ion”.

Ever wonder why the failure rate of the larger capacity multi-cell “series-parallel” batteries is greater than the 4 cell batteries, my assertion is their improperly

charged and maintained.

Does anyone have personal knowledge of someone damaging there batteries because they followed the cell/charger manufacturers guidelines for a specific cell type?

Ever look into your laptop’s charging rate, these use Li-Ion cells too.

If you bought a Tesla Roadster would you charge it at 23% of their recommendation? (23% of 6.5A = 1.5A TLP3000 output)

Michael

#23

A lower charge rate than recommended is not necessarily “best” and can actually accelerate damage/wear.

Look at how many nicad battery packs were damaged by “trickle charging”, and how low charge rates can cause dendrite buildup. This example is nicad, but it’s a good example.

An analogy is shifting a car into a higher gear too soon for speed/load and lugging the motor… many people did this to save gas, only to destroy main bearings.

Greg

#24

Michael Glavin said:

Michael,

So lets see if I get this right…… The local installer and re-sellers with some experience with Li-Ion batteries/chargers have more street cred than the OEM charger/cell manufacturers and their published specifications are to be ignored? I’m going to politely suggest while your experts are credible individuals they’re uniformed and have limited experience of this battery technology and specifically series-parallel batteries. I know more about this stuff than most and can offer that the OEM cell builders are most definitely savvy! And together with nearly two decades of empirical experience with literally thousands of these batteries in my dust I recommend that you follow all OEM recommendations.

Tenergy’s TLP3000 1.5A charger; specification/description in quotes below:

“Intelligent charger designed for all types of 14.8V (4 cells) Li-Ion Battery packs including Polymer Li-Ion and Cylindrical Li-Ion”.

Ever wonder why the failure rate of the larger capacity multi-cell “series-parallel” batteries is greater than the 4 cell batteries, my assertion is their improperly

charged and maintained.

Does anyone have personal knowledge of someone damaging there batteries because they followed the cell/charger manufacturers guidelines for a specific cell type?

Ever look into your laptop’s charging rate, these use Li-Ion cells too.

If you bought a Tesla Roadster would you charge it at 23% of their recommendation? (23% of 6.5A = 1.5A TLP3000 output)

Michael

I have a question;

Is a 4S 2P battery, which I believe is 2 lots of 4 cells in series that that are connected in parallel, regarded as a 2 cell battery i.e. the 4 in series considered as 1 cell or is it an 8 cell battery as it has 8 cells altogether if the latter then would a 4 cell charger not be appropriate?

As for the OEM specs I think that the majority of the batteries used in hobby applications are of Chinese manufacturer (cost being the main driver) and I would take their specs with a grain of salt regarding accuracy.

#25

You cant ever completely treat a multi-cell pack as fewer cells.

Yes, you do have 2 batteries in parallel, sort of. The problem is your 2 batteries are each 4 cells, and thus exhibit much more variation in terminal charge voltage for example.

Bottom line, is you want to be more careful in charging, looking for imbalances developing, thus “balancing chargers” were born. In my opinion one of the saving graces for our hobby is that we do not typically work the cells as hard as the R/C cars and especially the model planes.

All that notwithstanding, if it was me, I would be doing 0.5 C most of the time, and 1 C every so often. Virtually all cells seem to develop imbalances when too lightly charged. Heavy use and charging seems to just wear things out a bit sooner. This is my general observation over 40 years. Can’t give a hard and fast rule.

A piece of information, a lot of people give me their cast-off laptops (I help a lot of people with crashed computers and upgrades), and quite often there is a single weak cell in the series string of batteries, and the rest fine, so it happens.

Greg

#26

GAP said:

I have a question;

Is a 4S 2P battery, which I believe is 2 lots of 4 cells in series that that are connected in parallel, regarded as a 2 cell battery i.e. the 4 in series considered as 1 cell or is it an 8 cell battery as it has 8 cells altogether if the latter then would a 4 cell charger not be appropriate?

As for the OEM specs I think that the majority of the batteries used in hobby applications are of Chinese manufacturer (cost being the main driver) and I would take their specs with a grain of salt regarding accuracy.

A 4S2P = 8 cell battery

A typical 4-cell charger with fixed charging current is most likely Inadequate to charge an 8-cell 4S2P battery if you read the OEM charger and cell manufacturers published specifications. It all depends on the charger in plays charging current output and the capacity of the battery under charge, not necessarily cell count.

If you charge your batteries @ ½ the rated batteries mAh capacity you’ve met the OEM cell builders slow charge specification. 0.5C or ½ the rated capacity is widely recognized by OEM’s as their minimum charge rate while 1C or 1 x battery capacity is the recommended charge rate.

½ / 2800mAh = 0.5C @ 1.4 Amps charge current…

1 x 2800mAh = 1C @ 2.8 Amps charge current…

½ 5600mAh = 0.5C @ 2.8 Amps charge current…

1 x 5600mAh = 1C @ 5.6 Amps charge current…

Yes, there are low quality Lithium-Ion cells out there that exaggerate their potential… That said industry standard charging practice seems to prevail with regard to any given Lithium cell type and cell capacity. I’d suggest reputable battery assemblers/resellers focused on the train market use name brand cells.

Michael