Large Scale Central

Taking the Plunge - Li-ion

Electronics Power and Sound
#1

With most of my NiMh batteries starting to poop out on me I’ve taken the plunge into the world of Li-ion. Just purchased two 6700 mAh from RLD to run in my Shay, and in a trailing car I’m still working on. I’ve also purchased a Tenergy TLP4000 charger. I need to do some modification on the batteries since they came with different clips than the 5.5mm x 2.5mm barrel plugs I’m currently using.

The charger says it is for 1-4 cell…not sure what this means. And I’m having a hard time finding the answer…perhaps I’m asking incorrectly. But the two batteries I purchased are the brick style with 8 cylinders…Does anyone know how many cells this is?? And, will this charger work on these batteries??

I’ve researched this forum and it seems that there is information from as far back as 2011…so not sure if there is a huge change in technology. Bottom line I’d like to become better educated with batteries and charging them and am looking for an “Idiot’s” type guide with pictures…

Thanks,

Richard

#2

Following.

#3

Richard, the cylinders are indeed the cells. Each one is a singular battery that is wired up with the others to be a certain voltage and milliamp capacity. I have charged an eight cell battery pack with a charger that is only rated for 1-4 cells, and it seemed to do fine, although it did take a long time to charge.

#4

Hi Richard, you have the correct charger for those pack. With lithium packs there are two values you need to understand.

  1. Total voltage. 4 cells = 14.8V. Each cell is 3.7V x 4 = 14.8V

  2. mAh is Milliamps per amp hour. 6700 milliamps = 6.7 amps. I believe your charger has charge rate of 1amp per hour then expect it will take 6-7 hours to charge these packs.

In actual use it will probably take less unless you completely run them till they stop. It is okay to charge them after each run.

Because these are new lithium packs you should run them till your train stops. It takes three complete cycles for the pack to achieve it full runtime.

Don Sweet

RCS of New England

#5

the 1-4 cell rating is for how many cells are in series… but many packs have batteries in parallel.

putting cells in series raises the voltage, as Don said number of cell IN SERIES times 3.7 volts will equal the nominal pack voltage.

Battery packs can have cells in parallel ALSO. 4 cells total in series is a 4S1P pack… 4 Series, 1 Parallel… if the cells are 1 amp hour capacity, then you would have 4 x 3.7 volts and 1 x 1 amp hour capacity.

The 8 cell pack is most likely 4S2P, 4 cells in Series, and 2 cells in parallel, 4 x 3.7 volts total and 2 x 1 amp hour capacity, or 2 amp hours (2,000 milliamp-hours).

Chargers control the charging voltage to match the number of cells in series.

Chargers can also control the amps, but some just have a maximum rate, so a 4S2P pack would take twice the time a 4S1P pack would, if it was charging at maximum for each.

Greg

#6

This may be a useful reference to help new comers with the terminology quoted by manufacturers.

Simple and effective use of diagrams, there are tabs for charger selection but they may overwhelm newcomers but be useful for more experienced users.

All in all a reasonably useful reference tool.

https://scriptasylum.com/rc_speed/lipo.html

#7

Just purchased two 6700 mAh from RLD

Richard, what you didn’t tell us is the nominal voltage for the 6700 mah packs. RLD sells four packs rated 6700mah ranging from 14.4V to 22.2V.

As you will have gathered by now, LiPo or LiIon cells are rated 3.7V so a 22.2V pack is at least 6 cells in series. 6700mah is a big number for one cell. If each battery is rated 3350mah (more likely,) then 6 LiIon cells in series will provide 3350mah at 22.2V and 2 sets of 6 batteries in parallel will supply 6700mah. As Greg says, a 6S2P pack.

Note that, unlike alkaline cells, Li batteries vary their voltage with the charge state. LiIon and LiPo cells have a protection circuit that cuts the power at about 2.2V to prevent over-discharge, and at 4.25V to prevent over charging. The 3.7V is a convenient middle ground - but the 22.2V pack could be providing 6x4.25V (25.5V) when just fully charged.

14.4V is a more common power pack for Bachmann locos, and that is 4 cells. I have Tenergy charger and it doesn’t automatically work out the battery pack type - you have to set it to a charge voltage (e.g. 14.4V).

#8

The RLD packs do not have the standard nomenclature published.

There is a 14.8v 6700 mah pack, 4s2p

18.5 at 6700 5s2p

and a 22.2 at 6700 looks like (of course) 6s2p

also people “play” with the nominal voltage… for years it was accepted the voltage was 3.6v per cell, now people calculate 3.7… the “fully charged” voltage can be higher, but comes down to 3.7 per cell after running it for a few seconds. All these are the same really.

Also, the max charge voltage is subject to some variation, but generally accepted to be 4.1 or 4.2 volts per cell, and this is the rub, since that voltage depends on the manufacturer. Set this wrong and you damage your batteries very quickly.

#9

Richard, I just bought two Airwire 14.8V 6800 mAh Li-on batteries for two of my USAT GP-9’s and I have the same Tenergy TLP4000 charger as you do to charge them. The combo is working out great for me. I get around four hours of charge/run time, and you should be fine!

#10

Richard,

The OEM cell specification data sheet tells the tale. I’d go therein and ascertain what the specific cell(s) in hand require for charging needs. This will very from OEM cell manufacturer, cell capacity and the specific cells in play

click on link below:

https://cdn.shopify.com/s/files/1/0697/3395/files/LGChem_icr18650f1l_datasheet.pdf?8595214432028904947

I suspect the 6700mAh battery you mention is assembled with LG Chem’s #INR18650F1L, 18650, 3.63V, 3350mAh cells.

Your 6700mAh battery with “eight cylinders” (cells) suggests you have a 4S2P battery. Said battery is comprised of two sets of four cells wired in series netting 14.52V/3350mAh each. The two sets of four cells are wired/connected in parallel and become the aforementioned 4S2P 14.52V, 6700mAh battery.

click on link below

https://batteryuniversity.com/learn/article/serial_and_parallel_battery_configurations

If I’m correct on the cells in play, LG’s INR18650F1L is nothing special or a low yield battery as compared to other 18650’s. STD. discharge rate: 0.2C/0.65A. MAXIMUM discharge rate: 1.5C/4.875A.

Your 4S2P 6700mAh battery will discharge at 4.875A x 2 = 9.75Amps. Discharge time will be greatly influenced at this level, maybe 20 minutes in my experience with similar cells.

The charger you note is inadequate if you follow the OEM’s standard charge specification. Trinity states MLP-4000 1 Amp Smart Charger is designed for 1-4 cell batteries. In other words, it will provide 50% of LG’s specification for charging their cell(s) i.e., Std charge rate: 0.3C/0.975A. MAX charge rate: 0.5C/1.625A. Anyway, the charger will work but will slow charge your cells in this configuration, which is NOT recommended by OEM’s.

OEM’s of Li-Ion/Li-Po batteries generally recommend a MAXIMUM charge cycle of 3 hours. There is NO need to cycle or exercise said Lithium batteries prior to use. These cells have been engineered to be charged as often as desired from any state of charge or discharge. Discharging these batteries should be keep to a minimum to realize a good life cycle. It’s universally accepted by all OEM’s that running said batteries to voltage cut-out (2.5V) is DETRIMENTAL to the battery’s life span. In laymen speak; charge as often as you like when utilizing the batteries, discharge as little as possible between recharging.

Michael

#11

As a side note, it’s amazing that people “in the business” still recommend charge cycling lithium batteries like old nicads…

#12

Greg,

Misinformation abounds in the train battery world… Accurate information, facts/specs about Lithium Ion 18650’s is readily available (online). Unfortunately, its ill received, much like hitting a wall of disbelief and or closed doors. Much of our heard of battery-operated train enthusiasts is very partisan, objects and places more credence in the local joey’s and battery/charger resellers with nary any experience and or knowledge thereof. I’ve shared my thoughts and made assertions that are supported by 20+ years’ real-word experience with said cells together with the OEM cell specifications. No heresy here, yet those that should know turn the page and continue to espouse misleading and inaccurate information!

On the occasion that someone comments with nothing more than heresy and then conversely ceases to engage in productive conversation or dare I suggest debate finds me at a loss. I was thinking as I’m scribbling my thoughts that this seems all too familiar of late. Fake news has many lives…

Michael

#13

Michael - Your battery posts are always appreciated. I have learned a ton from you; and thanks to that knowledge some of my oldest on-board LiIon packs are still going strong. The number one lesson learned: Don’t wait for the loco to quit running; charge after a few uses or about 80% of expected charge life.

#14

I agree with Jon. What is interesting is that when given data that might not agree, some people get mad and threatened, as opposed to “hey, I did not know that, can you explain further”…

I would think to preserve the investment that would be my top priority. You would love the controversy I am embroiled in with someone wanting to recharge lithiums in a car/loco rolling over the railroad, resetting the charging logic every few milliseconds, when I warned of resetting the charger and dumping more charge into a fully charged battery, the response was that the blue charging light was not on, and it descended to name calling and personal insults the next response.

I should have just given up and sent the gentleman a fire extinguisher.

Greg

#15

Sent who a fire extinguisher, Greg? And would you be specific as to who got mad and felt threatened? You looking for one more guy to argue with on the board? Is that what drives you here, buddy? How come you stopped answering my e-mails and PM’s, Mr. 2-Faced? Did I offend you in some way by talking to you directly via PM as opposed to on the board where you can tag-team with Glavin?

#16

How dare one challenge the man behind the curtain! The tin man became so scared he pissed himself and now he is going to rust!

#17

Now I can see why you two go at it all the time. Noooowww I see. (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-smile.gif)

#18

Ok, gentlemen!! I don’t know any of you personally and I don’t wish my original post to be a sore spot for anyone…I’m just a novice looking for some good information to learn from. And I appreciate all of your comments.

I charged one of the batteries yesterday and kept rough idea from beginning to end of the charge. I had 5 hours and 30 minutes when I checked and saw the green light. Of course it might have been less because was working on other projects and would check periodically on it.

Pete Thornton, to answer your question the batteries are 14.8 volts with mAh of 6700. They are the 4s2p I’m hoping they are strong enough to power my Bachmann 3-truck Shay pulling the 3 AMS coaches at 6lbs each plus the new Bachmann caboose which is also pretty hefty.

I do appreciate some of the technical stuff but I have to read it slowly to gain the understanding…

Michael Glavin you said the Tenergy charger was inadequate…do you have a suggestion for another more efficient one?

Thanks, Richard

#19

Michael Kirrene said:

Now I can see why you two go at it all the time. Noooowww I see. (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-smile.gif)

We do?

I’m been here on LSC and only LSC because I like to model trains as a HOBBY . However my post took away from Richards original question and I apologize.

#20

Don Sweet said:

Hi Richard, you have the correct charger for those pack. With lithium packs there are two values you need to understand.

  1. Total voltage. 4 cells = 14.8V. Each cell is 3.7V x 4 = 14.8V

  2. mAh is Milliamps per amp hour. 6700 milliamps = 6.7 amps. I believe your charger has charge rate of 1amp per hour then expect it will take 6-7 hours to charge these packs.

In actual use it will probably take less unless you completely run them till they stop. It is okay to charge them after each run.

Because these are new lithium packs you should run them till your train stops. It takes three complete cycles for the pack to achieve it full runtime.

Don Sweet

RCS of New England

Thank you Don