Lipo's For Dummies....???

[gizmo1]

Hi Guys,

I am new to the FE side of things, but by no means new to the hobby.

I have been in in R/C since 1984.

But i have spent the last 20 or so Years in Gassers, be it land pounders or water.

The last electric stuff i ran was back in the days of NiCad, thus leading to my dilema.

i dont consider myself to an idiot, but maybe a little slow, i guess.
i have read thru many,many posts and the further i read the more confused i get..hence the title of my thread, Is there a Lipo's for Dummies , simple to understand , and comprehend, guide out there.

It is very painfull for me to admit ignorance, but one thing i have learned in my many years in the hobby, better to ask a dumb question , than not ask a question at all....this really cant be that complicated, but untill i " get it " , and that light bulb goes off, i will admit my dumb country a$$ is lost....

Thanks for your help and i look forward to your input, i just ask be patient with me until the light goes off..

Giz.

[jac4412]

Welcome to the board!

Well the real question is... what do you want to know?

Is there an idiot guide? Not in a collective sense... is there a plethora of information? Absolutely... There are countless threads even on this forum that will have everything you need to know about lipos including how to store them, how to run them in series or in parallel, which lipos to buy.... formulas for calculating your battery amp supply....

Here is just a quick look at some info I have on my website that I have picked up from this site and from diesel (a member here)

Here:

"In hobby you mainly have 2 different battery types... NIMH and Lipo. NIMH is rated by 1.2v increments. Lipos are rated by cells (1s= 3.7, 2s= 7.4v, 3s= 11.1v, etc). The lipo packs will also have a discharge rate a "c" rating. This is how fast the battery is discharging... obviously. The higher discharge rates (35-50c) are typically used in racing environments, more current whereas lower rates like 25-20c are for general use. The higher c ratings are the one's you need to care more about. Better performance but need to be careful or poof! There goes your esc.

Now onto the more gritty stuff...

The mah rating of a battery is essentially the storage capacity. Therefore, ESC's like as much current because they will only take as much as they need. Again, less is NOT good.

Now let's work all this knowledge into our system....

Lets say I have a couple 7.4v lipo packs in my Miss Geico, with a 25c and 5300mah rating. There's a formula to see if our setup works.

ah x c rating= amps.

ah in this case is 5300 mah= 5.3ah. 5.3 x 25c = 132.5 amps. Now here is another tip I forgot to mention above... when running lipos you NEVER fully discharge them, they don't like it and it is bad. So since we are only discharging our packs by 80% (a LVC or low voltage cutoff should kick in, you want to stop running your rc before you hit this, use a timer. I have a stopwatch on my controller to monitor my runs.) So 132.5 x .80 = 106. So my Miss Geico ESC is rated at 45 a. So I'm doing great. The trick is the 45a (on the ESC) isn't for the batteries, it's for the motor. The motor is the key, if it requires more than 45a then I'm screwed because thats all my ESC is going to supply. At that point the ESC is going to get hot and burn up. In retrospect, if I'm underpowered then my batteries will get hot and burn up, then the ESC. So make sure you match the esc, batteries and motors!"


There is some basic information for you, if you'll let me know exactly what youre looking to understand I may be able to help better.

[Make-a-Wake]

Here is a great thread of info from Ryan who is quite knowledgable in FE boating, i refer to it every now and then still today. Post #11 discusses lipos..................

http://www.rcuniverse.com/forum/m_9069147/tm.htm

[gizmo1]

jac4412,
thanks for taking the time to post this up it does clarify some things for me...

Make-a-Wake,
I cant thank you enough for that link, it pretty much covers it from top to bottom..it is now permanently stored in my favorites..

Thanks again guys,
Giz.

[ScarabChris]

Welcome to the better way to enjoy RC toys. I too am new to brushless/LiPo. Search my name for the projects I am into here.

I always had big gasoline boats. Once I found out about brushless motors and LiPo batteries I never even gave gas boats another thought.

It takes some research to learn the, what I call "LiPo lingo" but you will.

[GP73]

Great link!

[LiPo Power]

2 on that...

[gizmo1]

jac4412

the math thing is great for me it definately helps out

here is my starting point for play
2- 4s1p ( 4s2p ) 5050mah 35c thru a CC240lv esc to a 1518 1Y 1800KV motor, m447 prop

for race
2-5s1p ( 5s2p ) 5050mah 35C thru CC240lv esc to a 1518 1Y 1800kv motor,m447 prop

can you break down the math on those 2 set ups to show me the amps the motor will draw and approx run time , and how i should set the charger up to charge the packs ?

with that info and your previous post i think i will have a pretty good handle on it

thank you in advance,
Giz.

[ReddyWatts]

http://www.rcgroups.com/forums/showthread.php?t=209187

[jac4412]

jac4412

the math thing is great for me it definately helps out

here is my starting point for play
2- 4s1p ( 4s2p ) 5050mah 35c thru a CC240lv sec to a 1518 1Y 1800KV motor, m447 prop

for race
2-5s1p ( 5s2p ) 5050mah 35C thru CC240lv esc to a 1518 1Y 1800kv motor,m447 prop

can you break down the math on those 2 set ups to show me the amps the motor will draw and approx run time , and how i should set the charger up to charge the packs ?

with that info and your previous post i think i will have a pretty good handle on it

thank you in advance,
Giz.

Alright lets start with your play setup....

You're using a 4s2p setup meaning 2 4s batteries in parallel. Voltage stays the same (14.8) and mah adds. SO that's 5050+5050= 11000mah. So that's 11 ah. 11 * 35 c = 385. *.8= 308a. Your ESC is rated at 240 amps... youre all set. And since this is rated as a "lower setup" we know your race one will be fine as well. What your motor will draw will vary... just know that your esc will handle it and your packs have plenty to give in that setup. Your motor might be pulling every amp it can get at one point, then significantly less at another. For your runtime, no need to look there either, you should be running at a MAX of 5 mins, rarely can you get a highspeed FE to do that anyways... anywhere from 3-5 mins is a safe runtime, otherwise again, your esc and batteries will begin to get taxed... not good. What type of charger are you using? If you have time you want to put in on the lowest setting, that is always the best. Typically, the higher settings can cause the batteries to heat up and at higher cell numbers you need to reduce the charge rate anyways because they cannot handle the charge.