# Li-on battery question



## Madman (Jan 5, 2008)

I am currently using this type of battery for powering my trains 


Tenergy Li-Ion 18650 14.8V 4400mAh PCB Protected Rechargeable Battery Pack w/ Bare Leads


I would like something smaller to power a rail bus. I was looking at this



Tenergy 14.8V 3000mAh LIPO PCB Protected Battery Pack w/ Bare Leads 





What is the difference between Li-on and Li-po batteries? They both use the same charger. Both batteries are from All-battery.com


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## Stan Cedarleaf (Jan 2, 2008)

Dan.... If you are going to charge the batteries on board, I would recommend that you stay with Li-ion. 

If you will be charging them out of the Railbus, the Li-Po should work just fine. Is it necessary to stay with 14.8?????

I've been using the 11.1 batteries very successfully in my Railbusses. 11.1 4400 Li-ion They're smaller and very effective. This is the charger I use.... Charger...


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## Greg Elmassian (Jan 3, 2008)

In general, for the same "type" of use, there is little difference. 

But, in general, the types of packs tend to be quite different. 

I'm talking about what we, as hobbiests, see available. 

Generally, li-ion packs for consumers are general purpose, medium drain, medium charge, packs of batteries with just 2 terminals... good value, light, good life. 

Generally, the li-po packs you find are optimized for the model plane people, which is much higher drain, much higher recharge rate, and usually have the individual cell connnections so you can use a "balancing" charger that does a good job of charging each individual cell in a pack optimally, detecting a weak cell in a pack, etc. 

Some people think this is great, some people (like me) think it's not a great advantage in our applications. 

Originally, li-po was developed because it can be made in flexible packages, and that results in less volume, and more flexibility in design of consumer electronics. 

(I designed them into consumer devices about 10 years ago) 

Regards, Greg


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## Michael Glavin (Jan 2, 2009)

Matters not in the scheme of things which Lithium chemistry your contemplating either will work without issue. Since you noted both batteries have PCB cell protection, choices for either chemistry herein are form factor and cost considerations. 
There is no safety consideration or difference with regard to charging the cells on-board with either chemistry with PCB's fitted, if the Li-Po is equipped with a balancing pigtail all the better when used in conjunction with a balance charger regimen. IMO the balance charger approach offers a precision charge and monitoring algorithm and is more desirable as compared to a typical PCB in lieu of same… 
If space is a premium and the electrical demands are low as in your case halve the battery your presently using will suffice the 4400mAh battery is a 4S2P configuration or two pair of four cells in series wired in parallel, so four cells in series offers 14.8V @ 2200mAh. The typical Li-Ion cell form factor is the cylindrical 18650 cell; these started at 2000mAh many years back and have evolved to 2200-2400 and 2600mAh currently while maintaining the original physical size. 
Li-Ions are capable of delivering 2C or the cell/battery capacity multiplied by two. 
A 4400mAh 4S2P battery calcs out at 4400*2=8800/1000=8.8Amps
Li-Po’s are capable of delivering from 15-45C. 
FWIW:
With the Li-Po's you do not have to use the balance pigtail to charge the battery it merely affords you a desirable cell monitoring attribute. You can charge in the same manner and charge rate as Li-Ion with like capacity and voltage batteries. Yes Li-Po's are capable of higher discharge rates, but they do NOT require high charge rates, the higher charge rates are simply desirable for some modelers with time constraints.
Generally, Li-Po’s are NOT equipped with PCB’s do you have an item # or link for the 14.8V/3000mAh battery your proposing?
You can purchase a 3000mAh 4S, 14.8V, 20C Li-Po for as little $17.00 on up from Hobbyking.com, but these do not have PCB/PCM’s. PCB’s can be added for about $10.00, these batteries do include cell balance pigtails, which used in conjunction with a balance charger mitigate the need for the PCB with regard to charging safely, in fact the balance charge methodology is superior to the PCB’s, which merely open the circuit if cell voltage reaches about 4.35V under charge and 2.15V discharge respectively. Sans a PCB/PCM there is no discharge termination or cut-off voltage safety in play; this isn’t really an issue if you’re not complacent while running your battery powered trains, albeit some like to run them until they stop… If this is your modus operandi, some train controls have low voltage alerts or alarms integral or you can add a noise maker for about $4.00, again from HobbyKing.
Michael


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## Madman (Jan 5, 2008)

I found and purchased this battery, New Li-Ion 18650 11.1V 4Ah battery pack w/ PCB


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