# Observed Li-Ion Battery Limitation and Solution Using Li-Po



## Bret W Tesson (Jan 6, 2008)

I've recently begun the conversion to battery power using the trailing car concept and regulating power with Aristo's Revolution receiver. The batteries I've been using are 14.4V 4400 mAhr batteries from all-batteries.com. I've found these batteries more than adequate for running single engine setups for Bachmann's K-27, Heisler, 3 and 2 truck shays as well as single engine Aristo consists. I also needed a battery car setup for a pair of E-8s pulling and 9 USA streamline cars and attempted to use the same battery and quickly ran into problems. While the speed was acceptable (maybe a little slower than I would have liked), the whole consist came to a quick halt after I hooked up the 9 passenger cars. I assumed I had overloaded the revolution, but that was not the case. Instead, I had tripped a protective circuit on the PCB mounted in the battery pack. After some research and speaking with the folks at All-battery, I found that these batteries (and most other Li-Ion batteries I assume) have such a circuit to protect the pack from too rapid of discharge (can cause fire or at least damage the batteries). It turns out, these batteries are limited to 4 Amps of draw.

After some additional research and talking to the RC battery helicopter guys, I think I've found the answer. Li-PO batteries are used in that hobby due the the massive current draw needed for their flights. I decided to give it a try and so far, I've been impressed. I purchased an 18V 5000 mAhr Li-Po battery, and a new battery charger (which charges all types of Li batteries). The battery is not much different in size than the Li-ion batteries and fits easily into my baggage/trailing car. Run time with this setup should probably be close to 2 hours (engines and sound only..no smoke). 


It turns out you have to be careful with Li-Po batteries as they don't have any type of PCB to protect the battery (and you) from over charging or discharging. I found an inexpensive ($5) alarm that plugs into the battery balancing cable to alert me when the pack or cell voltages drop below the lower limit.


----------



## Paul Burch (Jan 2, 2008)

Bret,
Very good information.


----------



## Del Tapparo (Jan 4, 2008)

The specifications for maximum current draw given on All-Battery.com site is 4.4A for the 14.8V, 4400mah battery. For your big diesel consists you need the 14.8V, 6600mah battery which is rated for 12 amps max current draw. This would still provide you with proper protection, and likely result in more suitable run times.


Do you have a link for your $5 Li-Po device?


----------



## Bret W Tesson (Jan 6, 2008)

Del, 

I didn't realize that the larger mah batteries also included higher current draw capability. I ran my E-8 + 9 passenger cars today using the Li-Po battery and got over 2 hours of run time at about 75% throttle. Plenty fast and great run time. Here is a link to the alarm 

http://cgi.ebay.com/Lipo-Battery-Vo...Control_Parts_Accessories&hash=item3f004e725e 

It's good for various cell configurations and works as advertised. Tells you the specific voltage of each cell as well as total voltage. Looks like the price went up about $2, ($7.99) but still has free shipping from China.


----------



## izzy0855 (Sep 30, 2008)

Bret, 

It's doesn't matter if you decide to use Lithium-Ion or Polymer battery-packs, but what is the most importnat part in any lithium battery-pack is the PCB Circuit Board and the size of weld tabs. Whether it's us (Cordless Renovations) Tenergy, or any other manufacturer the same PCB Boards are use with both types of lithium battery-packs, you will get a higher current draw out of the cells when there manufactured with the .375 nickel tabs. A good rule of thumb when purchasing a lithium battery-pack, is to make sure the PCB Circuit Board can draw at least 2 amps greater then what the combined millimaps of the battery-pack is rated at. For example: we use the LG 18650 2600mah Lithium-ion cells and each cell is rated for maximum discharge current of 3750mah, so when we manufacture our 18.5V 5200mah (5C in series and 5C in parallel) we build each battery-pack with a PCB Circuit that can handle a minimum of 9amps of current on a continuous basis. Because if you times the maximum current draw by 2 = 7500mah and if we build that battery-pack with a 5, 6 or 7amp PCB board then you will never get the full charge or discharge capacity from the battery and it will constantly shut-down. If you would like, send us your 14.8V 4400mah battery-pack and we can upgrade that circuit board to 6.5amps. 

Have a great weekend, 
Rick Isard 
Cordless Renovations, LLC


----------



## Greg Elmassian (Jan 3, 2008)

Rick, do you recommend running any of your batteries at a discharge rate of 1.5C, or even 1C? 

If the 6.5 amp limit was to handle occasional surges in current need, I could understand, but what battery life and runtime could you expect of a 4.4 amp hour battery drained at 6.5 amps? 

Regards, Greg


----------



## Stan Cedarleaf (Jan 2, 2008)

Bret........ I'm coming into this post a bit late but I'll share that I've had the same experience with the 14.8/4400 packs when running the FABBA and all passenger cars with the REVOLUTION. The PCB in the battery shuts the battery down as it was designed to do.

My solution has been to use Rick's 14.8 5200 or his 18.5 volt 5200 to run the consist. It's interesting that I can get by with the 4400's during hot weather when the gear grease is nice and warm but when it was below 50 degrees, the 4400's would shut down.

I've recently made some current draw tests by making a "Dynamometer Car" with a 15 amp ammeter and a 30 volt volt meter. Got the idea from Thom Filbert who had built one recently.

The results have been very surprizing and are on The Aristo site under the R/C battery forum. *Pulling Amp Draw on the FABBA * 
The car was made from a Bachmann box car and I can put the roof back on and run it as a regular box car. 


I see you've visited the thread...


----------



## izzy0855 (Sep 30, 2008)

Hi Greg, 

The LG LGDBB31865 2600mah cells all can be discharged continuous at 1.5C (3750mah) and maximum charge current of 1C @ 2500mah. But, I don't believe we will ever use that much amp draw from one battery-pack through one controller (QSI, Aristo, RCS...) because the QSI and Aristocraft boards have a stall speed of 3 - 4 amps. I know our battery-packs (with LG Cells) will handle that much current draw because the PCB boards we manufacture won't let the cells overdischarge past the cells peak... 

But, the reason we use a greater amp draw PCB is because once the board sees any current (peak or continuous) over the PCB boards cut-off rating it will automatically shut-down, so Bret's 4400mah battery-pack with a 4amp current rating won't discharge at the cells top capacity, and I "think" it's around 2350mah (times 4C Series & Parallel) per cells x 4 in parallel = 4700mah...so your loosing 700mah of capacity and I don't think that it's peak either??? Don't quote me because I haven't looked at their chart. 

The Tenergy 18650 2200mah lithium cells will never exceed a continuous discharge of 5amps or more, but could peak at 4700mah; but the reason we would install a higher (6.5amp) PCB board is so Bret could see a higher current limit from his battery without it always shutting down at 4amps. We only manufacture a couple different version of PCB boards with these draw limits...2600mah @ 4amps, 5200mah @ 6.5 or 8amps, 7800mah @ 9, 10 & 20amps. 

Have a great weekend, 
Rick Isard 
Cordless Renovations, LLC


----------



## Bret W Tesson (Jan 6, 2008)

Rick, Thanks much for the information and offer. I've got plenty of other single engine applications I can use the 4400 mah battery Li-Io for and the Li-Po works great. 

It was my understanding that you had to be particularly careful with the Li-Po batteries because they didn't have a PCB (at least that's what I was told by the helicopter RC guys). That's why the need for a balance charger to closely monitor voltage of each cell. Additionally, there's no protection for Li-Po batteries from being run too low. Unlike the Li-Io batteries which shut down at a specific voltage, the Li-PO will run well below their design limits and you will actually damage the battery (shorten the life I've been told). That's why the need for an alarm or careful monitoring of the batteries voltage. 

A question for you. Do your Li-Po batteries with PCB have a shutdown feature to protect them from being run too low? 

Thanks...Bret


----------



## izzy0855 (Sep 30, 2008)

Hi Bret, great questions! 

First, the RC helicopter enthusiasts don't want to operate their helicopters with a PCB Circuit because if their flying and the PCB Circuit kicks in, their helicopter falls to the ground! Booom! That's why no PCB, and they have to balance the battery-pack each time before reusing. It's less money to replace a battery-packs then a helicopter. Yes, all lithium battery-packs (Ion or Polymer) that we manufcature come with the PCB Circuit built inside, and I will not manufacture a lithium battery-pack without one! Safety first! Yes, the PCB Circuits are designed to shut-down by a low voltage draw, for example; this depends on the voltage of the battery-pack but let's take your 14.8V 4400mah lithium battery-pack, the PCB is designed to shut-down at 9.6V and to stop charging at 4.2V per cell x 4 which is 16.8V. Even though there's 8 cells in your 4400mah battery-pack, 4 are welded in series and 4 are welded in parallel. The PCB Circuit charges all 8 cells at the same time, we run 20 gauge wire leads between each weld connection to charge and monitor each cell in series and parallel. That's why each cell has to be balanced in the manufacturing process before it's shipped to the customer. 

Hope that answers your question? 
Rick Isard 
Cordless Renovations, LLC


----------



## Bret W Tesson (Jan 6, 2008)

Rick, 

Thanks and that helps a lot. So if I understand correctly, your Li-Po batteries do have a PCB and will shutoff at a specific low voltage level. The Li-Po I purchased was also from All Battery and it apparently does not have a PCB (at least one that monitors low voltage for cutoff). I inadvertently ran the cells down to less that 3.5V (2.8-2.9V) which I assume is the lower limit for these types of batteries.


----------



## izzy0855 (Sep 30, 2008)

Hi Bret, 

Unless you tell Tenergy (AKA all-battery.com) not to build a lithium battery with the PCB, I think they automatically do it. It will cut-off at 3V per cell, depending on the PCB and voltage. So, if you take a volt meter and measure the volts of your battery-pack it should read the cut-off voltage, 2.4Volts x 4 cells = 9.6V. It won't read 9.6volts, but just the cut-off voltage per cell. 

Yes, our Li-po's have the PCB Circuit built inside and will cut-off at a specific voltage. 

Rick Isard 
Cordless Renovations, LLC


----------



## Greg Elmassian (Jan 3, 2008)

Rick, sorry to seem to keep "drilling" at a point, but I asked if you RECOMMEND running your packs at 1C or 1.5C. I saw your post where you didn't THINK it was necessary. 

The place I am asking is how many charge/discharge cycles can you get with this type of battery discharging at 1C or 1.5C? 

I can do the research and get the answer, but since you are in the business, I wanted your take. I'm sure it's got to be less than the "standard" 300-400 cycles quoted by most manufacturers. 

Regards, Greg


----------



## izzy0855 (Sep 30, 2008)

Greg, 

The LG cells with our PCB Boards will get 800 cycles at a discharge rate of .2C (500mah per cell). At the rate of .5C discharge (1250mah per cell) you will get between 650 - 750 cycles. At the rate of 1C (2500mah per cell) discharge you will get between 500 - 550 cycles. At the rate of 1.5C (3750mah per cell) discharge you will get around 300 cycles max. Remember, that's times the number of cells in each pack. For example: if Bret's 4400mah battery-pack has 8 cells at .2C x 500mah = 4amp draw. But with a higher discharge rate my recommendation is to run your train for 20 minutes at one time then rest for 10 minutes, but that's drawing 6 amps or more continuous for 20 minutes. 

Rick Isard 
Cordless Renovations, LLC


----------



## Del Tapparo (Jan 4, 2008)

Posted By izzy0855 on 05 Jul 2010 04:59 PM 
Greg, 

The LG cells with our PCB Boards will get 800 cycles at a discharge rate of .2C (500mah per cell). At the rate of .5C discharge (1250mah per cell) you will get between 650 - 750 cycles. At the rate of 1C (2500mah per cell) discharge you will get between 500 - 550 cycles. At the rate of 1.5C (3750mah per cell) discharge you will get around 300 cycles max. Remember, that's times the number of cells in each pack. For example: if Bret's 4400mah battery-pack has 8 cells at .2C x 500mah = 4amp draw. But with a higher discharge rate my recommendation is to run your train for 20 minutes at one time then rest for 10 minutes, but that's drawing 6 amps or more continuous for 20 minutes. 

Rick Isard 
Cordless Renovations, LLC 




Sorry, but I don't follow your math Rick: The 4400mah battery pack is 4S;2P is it not? 4 cells in series, 2 sets in parallel. If all 8 cells were drawing 500 ma, that means each series set of 4 cells would be providing 500 mah (at 14.8V). 2 sets in parallel would then produce 1000 mah, or 1 amp. 0.2C draw on the whole battery pack would be 880 mah.


----------



## izzy0855 (Sep 30, 2008)

Del, 

14.8V @ 4400mah is 4 cells is series and 4 cells in parallel. One cell is 3.7v ea. @ 2200mah x 4 in series = 14.8V @ 2200mah x 4 in parallel is 14.8V @ 4400mah. It's 4 sets @ 2200mah. 

Rick Isard 
Cordless Renovations, LLC


----------



## Del Tapparo (Jan 4, 2008)

Apparently, it's easier to connect battery cells with wires than it is with words. How about 2 sets of 4 cells. Each set of 4 cells is connected in series. The 2 sets are then connected in parallel. (That still doesn't explain your math, but I'll quit.


----------



## Greg Elmassian (Jan 3, 2008)

Uhh... Rick... I think you need to proof your posts... 

4 sets of cells in parallel would be 4 times the current of a single cell... 2200 mah times 4 would be 8800 mah... 

I think you are talking what Del said, make 2 sets of 4 cells (in series) and put the 2 sets in parallel, then the current would be 2200 times 2 = 4400... 

Anyway, now that we know how many cells (8) in the pack, and how they are connected.... 

So if you run the pack at 2.2 amps discharge, each cell is only producing 1100 mah, and you should get between 650 and 700 cycles. 

Regards, Greg


----------



## izzy0855 (Sep 30, 2008)

Del, 
The math is correct. We don't call it "sets", it's 4 cells welded in series and 4 cells welded in parallel. There not connected 2-by-2 or as you said; "sets" it's 1-by-4-by 4. If it was 2 sets of 4 cells, then you would have two packs of 14.8V @ 2200mah.

1 cell is 3.7V @ 2600mah x 4 = 14.8V @ 2600mah in series. Weld four cells in parallel then you get 14.8V @ 5200mah which is 1-by-4-by-4.

Here's is picture...











Rick Isard
Cordless Renovations, LLC


----------



## Michael Glavin (Jan 2, 2009)

Posted By izzy0855 on 05 Jul 2010 09:22 PM 


Del, 
The math is correct. We don't call it "sets", it's 4 cells welded in series and 4 cells welded in parallel. There not connected 2-by-2 or as you said; "sets" it's 1-by-4-by 4. If it was 2 sets of 4 cells, then you would have two packs of 14.8V @ 2200mah.

1 cell is 3.7V @ 2600mah x 4 = 14.8V @ 2600mah in series. Weld four cells in parallel then you get 14.8V @ 5200mah which is 1-by-4-by-4.

Here's is picture...











Rick Isard
Cordless Renovations, LLC

Rick, your picture doesn’t make any sense to me???

Industry practice calls out the cell combination as Del noted, 4S2P.

For those that are confused; 3.7V 2200mAh Lithium cell
4S2P = Four cells wired in series x two, or two four cell batteries wired in parallel. Series stacks voltage while parallel doubles capacity. 
3.7 + 3.7 + 3.7 + 3.7 = 14.8V; 2200mAh + 2200mAh = 4400Mah

Cycle life is NOT predominately the issue herein, shelf life from date of manufacture is the consideration… Once the chemical reaction starts the life cycle begins. I have multiple Li-Ion batteries/ cells that expired with nary twenty cycles on them that were four years old or less. These batteries were cycled – stored – cycled – stored many times in an effort to garner some history with them until failure. 

When the original LG 18650’s 2000mAh Li-Ion cells hit the market back around 2004 I was able to load test with a PC docked electronic load @ 4A and +3.0V sustained for approximately 26 minutes if memory serves me. I did lots of tests with varying loads throughout the discharge charge curves too. That said you could not hit them with substantial current draw needs they’d go flat every time. 

Michael


----------



## Greg Elmassian (Jan 3, 2008)

4 times 4 is 16. Rick, does your pack have 16 cells? 

Regards, Greg


----------



## Del Tapparo (Jan 4, 2008)

Michael - Thank you for the complete and accurate diagrams.


----------



## izzy0855 (Sep 30, 2008)

Sorry, but you only have two cells in parallel and not four, it has been and always will be 4 in series and 4 in parallel to give you 14.8V @ 5200mah. Your diagram is not completely accurate, because you will not receive the entire mah draw from the additional two cells in parallel. Because I have four cells in parallel and not two, our lithium packs will last longer between charge times then your design. 

Once again, the members here in this forum have gotten off track from the original question from Bret. Bret's question was asked and answered two days ago and the members here still want to agrue on who's right and who's wrong. 

Rick Isard 
Cordless Renovations, LLC


----------



## izzy0855 (Sep 30, 2008)

In addition, 

When welding the PCB board to your design, where do attach B2 & B3 in parallel. That's how I know your design doesn't work with four cells in parallel. 

Rick Isard 
Cordless Renovations, LLC


----------



## Greg Elmassian (Jan 3, 2008)

Rick, you did not answer my simple question, in the 14.8v pack you mentioned above, how many cells are there in total? 

You showed a picture with 8, but your last post says 16 (4 times 4), but the math does not work. 

FOUR 1300 mah batteries in parallel will give you 5200 mah, or TWO 2600 mah batteries in parallel will give you this. 

No one is trying to give you a hard time, but there is something wrong in the explanation, somewhere. 

So please, just say how many batteries in the pack total. 

Thanks, Greg


----------



## Del Tapparo (Jan 4, 2008)

There are at least two different ways to electrically connect 8 batteries into a battery pack: From what little I know, the most common appears to be 4S2P. Another way, which may be cause for some of the above confusion is 2S4P. This link has some nice diagrams Click Here. Scroll down to "Building a Lithium Polymer Battery Pack". 


As with many posts, it is the questions raised during the post that are far more interesting and educational than the answer to the original question.


----------



## izzy0855 (Sep 30, 2008)

Hi Greg, 

No there's only 8 cells in a 14.8V 5200mah battery-pack, and each cell is 2600mah and the way you get more milliamps is add an additional 4 cells in parallel to the 4 cells in series, like in the diagram. I didn't say 16, I said; 1 by 4 by 4. That's what we call 1 row of 4 cells welded next to another row of 4 cells. Sorry for the confusion. 

Del, I see that but that design is what commonly is used for laptops. Because the cells are welded butt-end to butt-end or side-by-side flat lying next to each other so you can fit the cells in a thin plastic case for laptops. 

Thanks guys, and sorry for the confusion... 
Rick Isard 
Cordless Renovations


----------



## Greg Elmassian (Jan 3, 2008)

no, it's 4 in series and then the two sets of series are in parallel.... 4S2P ..... 

There are NOT 4 cells in parallel... unless you are paralleling pairs of cells.. but then it would be 2P4S .... 

And I just looked that the link (after I typed the above sentences) from Del... so which of the 2 ways shown are you wiring your 8 cell pack Rick? 

This way?








-------------------------------------------------------------------------------------------------------------------------------------- 


Or this way:










In any case, you cannot have 4 cells in parallel AND 4 cells in series at the same time unless you have 16 cells... 

Maybe it's the terminology you are using, I can understand you want a terminology of how the packs are "shaped" or "stacked", but 1 row of 4 cells does not tell what the connections are though.... 

Just to finally clear the confusion, I'l love to know which diagram is what you are talking about.

Regards, Greg


----------



## izzy0855 (Sep 30, 2008)

Sorry gentlemen, but this has gone on long enough. I have shown both of you how "WE" manufacture a 14.8V 5200mah lithium-Ion battery-pack. I have uploaded a diagram template on how the cells are welded together. Repeatly, I have indicated how four cells in series and four cells in parallel makeup a 14.8V 5200mah battery-pack. Maybe what you should do is go buy a 14.8V 5200mah battery-pack, tear off the heat shrink wrap and see for yourselves, because obvisously words are not enough! 
Greg, your wrong...you can have four cells in series and four cells in parallel. Above, the first design is how laptop batteries are manufactured, the second way will cause a fire. Again, below...you weld four cells in series, then you weld one cell in parallel to each of the four cells in series leaving off the end weld for positive and negative connection to the PCB Board.








This is how we manufacture a 14.8V 5200mah lithium-ion battery-pack, we designed the pack this way is because how we designed the PCB circuit board. Each cross-weld has to receive a connection from the PCB Board to charge and discharge each cell at the same time. Now, please don't over think this...we have tested many different designs and cell layouts before we came up with this. You may think this is not correct, but it is...and in this design we get the most millimaps out the battery-pack. You may not like this design or understand it and that's fine...but what it does do,it works great and it sells! 

Have a great day guys,
Rick Isard
Cordless Renovations, LLC


----------



## Del Tapparo (Jan 4, 2008)

Well Rick, your diagram is incomplete as we cannot see the other side of the pack. But assuming the dark round circle is an indication of polarity, and assuming there are like bars on the other side of the pack for each of the 4 pairs of cells, then you have created one big short circuit. Actually, four short circuits in series, which equals 0 volts at the maximum amps the batteries will put out!

I am sure your products work quite nicely. You just don't seem to be able to communicate with electrical engineers.


----------



## izzy0855 (Sep 30, 2008)

Well Dell, once again your wrong! Below is a 14.8V 5200mah Lithium-Ion battery-pack...top view.


Bottom View


Once again, you guys like to disagree!
Rick Isard
Cordless Renovations, LLC


----------



## rmcintir (Apr 24, 2009)

Perhaps this will help: 










In the lower picture Rick posted, just lay down the two batteries on each side, then spread them center. 4 parallel pairs and 4 in series.


----------



## Michael Glavin (Jan 2, 2009)

It would help if the diagram Rick provided correctly indicated the polarity of the cells as compared to the pictures provided of same. Pictures make sense; drawing is incorrect and or indiscernible. 

I’ve mentioned previously that I have used, tested, abused, cycled and graphed 100’s of Lithium batteries as a Field Rep for many battery suppliers with sophisticated electronic loads docked with PC’s to control discharge curves monitor and or record/graph their specific behaviors on the eload and in flight. I think I might have noted a shortcoming in mAh capacity if I had been doing something wrong at some juncture in my effort. That said my diagram is accurate and provides the rated/calculated numbers. 

Michael


----------



## Del Tapparo (Jan 4, 2008)

Thank you for the photos. They confirm that your diagram was incorrect. The polarities of the bottom row of batteries in your diagram are backwards from those in your photo (which make sense). Of course, we still don't know where you might connect the leads, so your information is still incomplete. There are two ways to connect a 4S,2P pack; 2 sets of 4 cells in series, wired in parallel; or 4 sets of 2 cells in parallel, wired in series. Yours is the latter. I would imagine one way is better than the other in terms of manufacturing (connections, balancing, whatever). That I know nothing about. Basic electricity I do know.


----------



## izzy0855 (Sep 30, 2008)

The diagram is correct, if you look closely you'll see the polarity under the weld tabs which match the photo's. 

Rick Isard 
Cordless Renovations, LLC


----------



## Michael Glavin (Jan 2, 2009)

What happend to the pictures?


----------



## Del Tapparo (Jan 4, 2008)

Posted By Michael Glavin on 06 Jul 2010 09:15 PM 
What happend to the pictures? 
They are off line being corrected so we can observe them more closely !


----------



## Greg Elmassian (Jan 3, 2008)

so you have a series of 4 pairs of cells... 

4 sets of 2 in parallel, then these 4 sets in series... 

not 4 in series and 4 in parallel, this is the statement that is incorrect, and having a devil of a time getting comprehension on. If you had 4 cells in parallel, your amp hours would be 4 times a single cell, not twice. 

FOUR in series, and each of the series is TWO in parallel. 

There is NO PLACE in Russ' diagram above there are 4 cells in parallel... 4 cells in parallel means ALL 4 cells with ALL positives connected and ALL negatives connected. 

There is no other way to get your voltage, but 4 cells in series. With 8 cells total you CANNOT have 4 cells in parallel, that would take 16 cells to get your voltage. 

You have FOUR sets of TWO in parallel...... 2P4S .... this is the convention the rest of the world uses and parallel means in parallel as described above... It takes only a few seconds on Google to show dozens of examples. 

And your diagram is incomplete or at least confusing, in that it does not show all the connecting bars... maybe there are more parallel connections BELOW the "top" ones shown, but you CANNOT see that from your diagram. 

A simple schematic is how you show a circuit, like all the other examples above. 

Without confirmation from Rick, I will assume that Russ' diagram/schematic is correct. 

Regards, Greg


----------



## izzy0855 (Sep 30, 2008)

Yes, the pictures are gone. I was very close in giving you to much information with the design of my products, so I have made the decision that if you don't understand the layout and your only on this forum to "Trash Talk," then there's no need for this conversation to continue. 

Del said it perfectly; "I would imagine one way is better than the other in terms of manufacturing (connections, balancing, whatever). That I know nothing about." I like Del's motto, because I would certainly not tell him how to put vinyl lettering on rolling stock. 

Once again, the question on this forum was asked and answered weeks ago, and now the topic has changed because some members can't imagine or even phatham that a different cell design can produce a greater milliamp draw from the same voltage. Just because someone pulls a picture off Google and says; " this is how a lithium battery should be designed," or "your design doesn't work and will "Short Circuit"." Is also the same person that said; "I know nothing about this." There are many ways you can design a lithium battery-pack and just because you may have alot of knowledge in one area doesn't always mean your an expert in another. 

Discussions like this, where the a simple question can't be asked then answered...then turns into "Trash Talk" between members hurts this forum and hurts the hobby. 

Rick Isard
Cordless Renovations, LLC


----------



## Greg Elmassian (Jan 3, 2008)

Rick, with all due respect, I doubt seriously that with an 8 cell pack that you have "invented" a wiring scheme that no one else knows about. I have enough experience in the engineering world to make this statement.

To get 14.4 volts from 8 cells and the amp hours you describe can only be wired 2 ways. Period. 2 paralleled strings of 4 cells in series, or you can put 4 sets of 2 in parallel in series. 

Yeah, you could leave out some of the parallel connections technically. Maybe you play with that to accommodate a sensing circuit that does not match the 4 "cells" in series. 

This is not rocket science, why the mystery? 

And the fact that it was YOU that would not answer a simple question, like how you wired your 8 cells, is unsettling, since you seem to be blaming the lack of answering the question on others. 

I will tell you that this kind of attitude would concern me in purchasing products from you. 

Greg


----------



## izzy0855 (Sep 30, 2008)

Greg, if you have read all my post you would have read this; 

Hi Greg, 
No there's only 8 cells in a 14.8V 5200mah battery-pack, and each cell is 2600mah and the way you get more milliamps is add an additional 4 cells in parallel to the 4 cells in series, like in the diagram. I didn't say 16, I said; 1 by 4 by 4. That's what we call 1 row of 4 cells welded next to another row of 4 cells. Sorry for the confusion." 

So I guess I have answered all the questions? 

Again, here we go with the baggering! 

Rick Isard 
Cordless Renovations, LLC


----------



## Greg Elmassian (Jan 3, 2008)

Not badgering Rick. 

I got the 8 cells long ago. I did surmise the series parallel configuration. 

The thing I think caused the confusion (and I explicitly mentioned this before) is "4 cells in parallel"... adding another set of 4 cells in parallel to an existing 4 cells in series could result in several combinations, and all we were trying to find out is what it was, because technically "4 cells in parallel" would give you 3.4 volts and 10400 mah .... 

I do completely understand that 4 sets of 2 in parallel would be 4 sets of 3.7 volts and 5200 mah, and the series combination of the 4 sets is 4 times 3.7 = 14.8... that works 

I do also completely understand that 2 sets of 4 in series would be 2 sets of 14.8 volts at 2600 mah, and the 2 sets in parallel would also be 14.8 volts and 2 times 2600 mah = 5200 mah... 

What I could not understand was "4 in parallel".... and now I think I understand your terminology... One set of 4 in series in "physical" parallel with another set of 4 in series. Physically placed side by side. Geometrically parallel. 

I think you are talking more about the physical configuration, and to electrical engineers and the definition of the words in electronics, parallel and series have very specific meanings. 

So, hopefully I understand your use of the word, and that we are not trying to understand any "secrets" of interconnection, but merely trying to understand. 

Thanks for the comeback. 

Regards, Greg


----------



## izzy0855 (Sep 30, 2008)

Greg, that is correct...thank you!
1 row of 4 cells in series = 14.8V @ 2600mah. Then weld another row of 4 cells in parallel, but you only weld on cell in parallel to one cell in series making it 14.8V @ 5200mah. The reason we weld one cell in parallel to one cell in series is because we found out we can draw more amps from 4 individual cells in parallel then two sets of four cells in parallel. If that makes sense? Here's the picture of the welding diagram so you can see the polarity.









Rick Isard
Cordless Renovations, LLC


----------



## TonyWalsham (Jan 2, 2008)

Assuming the smaller darker circle under the tabs is +, that diagram is still wrong when compared to the pictures. 
If each of the bottom cells are meant to be paired to the top cell immediately above it in parallel, they are actually joined + to - on each pair of cells. A dead short.


----------



## Michael Glavin (Jan 2, 2009)

What Tony said....... The diagram above makes NO sense! 

Rick are you suggesting with your pack assembly; you can discharge at higher amperage numbers, i.e., series battery packs in parallel configuration verses individual cells in series-parallel configuration, I've been down this road in the past and don't recall anything noteworthy? 

I'd like to collect some data that supports this assertion: 
"The reason we weld one cell in parallel to one cell in series is because we found out we can draw more amps from 4 individual cells in parallel then two sets of four cells in parallel." 

Michael


----------



## izzy0855 (Sep 30, 2008)

Holy Crap, your right...slap me in the face and call me Shirley. Here's an updated diagram, sorry...










Rick Isard
Cordless Renovations, LLC


----------



## Michael Glavin (Jan 2, 2009)

Now were talking, the diagram above works for me.... 

Shirley since the diagram is NOW correct and it coincides with the pictures; why not bring back the pictures as it may help others to better understand verses surmise what the back of your battery looks like... 

Michael


----------



## Del Tapparo (Jan 4, 2008)

OK Shirley .... That's what we've been trying to tell you all along. (at least one of the things).


----------



## tom h (Jan 2, 2008)

Wooow, all you electronic wizards sure like to argue







You guys remind me of engineers who design something and think it will work, then you get it in the field and it doesnt because the guy at the desk cant figure out what happens in the field, a lot of common sense goes a long ways.

I have bought and still use products from Del, Rick and Tony, and you know what, they all work with my trains, what just happened here with all you guys talking about sure did give me a headache









Can we get back to trains?

I could not resist tweaking you electronic engineer wanna bees









tom h


----------



## TonyWalsham (Jan 2, 2008)

Thanks for fixing it Rick. 
It is all in the way you say it. 
Assuming of course you have it drawn correctly in the first place.


----------



## Greg Elmassian (Jan 3, 2008)

Now that picture makes sense to me too. 

I could not make sense of the first picture for the same reasons. 

And I would imagine that paralleling the cells by making a series connection of 4 sets of 2 cells in parallel could give you more current, since one string of 4 cells would be "restricted" by the "weakest" cell in the series chain of 4. 

In your configuration, the combination of 2 cells in parallel should "reduce" the restriction if anything. Of course if all cells were exactly the same, then it would make no difference, but cells are never exactly the same. 

Regards, Greg


----------

