smc lipo help questions
 

hi my first tme having lipos.

i have the 7.4 volt lipo 2 cell. well when i was charging it the pack out put says 8.4 volts is this correct? will that hurt my esc? packs are 5200 mAh. pack seems to be normal and runs fine. it charges normal but the out put voltage is 8.4

It is fine. This is something I have never understood as well. The fully charged voltage of a battery is different from the voltage on the label. The voltage on the label is the "nominal" voltage, where the battery tries to keep its voltage level at.

LiPo batteries have a fully charged voltage of 4.20V/cell (8.4V for a 2S pack).
The nominal voltage is 3.7V/cell (7.4V for a 2S).

When you put the battery under load (motor) it will drop close to the nominal voltage.

Go have fun!

thank you for the reply!! now i can charge it up fully and run tomorrow. it does haul ass.

SMCs are supposed to be handled a little differently than other lipos - be sure to read and follow the instructions that came with them.

There is another voltage to worry about with lipo - they shouldn't be discharged nbelow about 3v/cell, so a 2S shouldn't be discharged below about 6v. Use a low voltage cutoff - either in the esc if it has one or a separate add on type lvc to protect your lipo.

yes my ESC has a voltage detect when it gets to low i believe it cuts off.but it has low voltage dection. lipos seem to be faster than then nihm pack i have.

i cant wait to race with it.

This is what we've been told by the SMC rep, Bryan, that used to be on these forums. SMC recommends charging only when you're going to use them. At all other times they recommend storing them at 3.6v/cell (2S would be stored at 7.2v). This is different than most other lipos and you should be aware of how SMC recommends their lipos be treated.

There have been several who did not know how to treat them properly and they have had their packs swell up (puff).



What you're seeing is how much better lipo holds voltage under discharge than NiMh.

how can i get it down to 7.2 volts just run it down in my car then check the voltage on my charger? once it hits 7.2 volts its okay for storage?

Som,e chargers have a discharge mode where you set the voltage and the charger does it. Running down in the car is better since you're actually getting use from the lipo. Then put on charge and watch voltage. When its back to 7.2v, its time to stop charging til you're ready to run them again.

SMC LiPos are no different than any other LiPos. They have a different (and perfectly reasonable) set of guidelines for handling the batteries, but you can use them for any batteries.

Storage voltage from most manufacturers is 3.85v / cell

Can't imagine why theres would be different, same chemistry

Cheers

Unfortunately they are. The SMC rep Bryan had a reply in the elect offroad thread telling someone whose SMCs had just puffed from storing them at 100% they were supposed to be stored at 3.6v/cell.

http://www.rctech.net/forum/electric...standards.html


I'm decently informed and I don't seem to be seeing a one size fits all storage voltage out there. Care to post some links?


These Hyperion G3s have a pretty good rep - they specify storage as "packs are in the range of about 60%~70% capacity (3.78V~3.92V resting voltage per cell)"

http://media.hyperion.hk/dn/g3lipo/

Here's Thuinderpower's take on storage - "If storing longer than one week; batteries must be stored at 3.8V/cell to 3.9V/cell (approximately 50% charged)".

http://thunderpowerrc.com/PDF/THPSafetyWarnings.pdf

The two manufacturers you quoted seem to agree on 3.85v

3.78 - 3.92 is the middle of that range not 3.85v ?
3.8 - 3.9 again the middle 3.85v ?


So the chemistry in the SMC cells is different to every other manufacturer ?

Sounds like a lot of waffle

I've left all my lipos (cheap zippys to more expensive 45c discharge boost's) fully charged for weeks with no issues

All of them have over 50 cycles on them

Only now that I have a charger that will discharge / charge automatically (to storage voltage) that I even bother

I use the following chargers and they both store at 3.85v

fmadirect Cellpro 4s Gold
icharger i106b

So according to the SMC rep I cant use storage mode with SMC batteries on my chargers because it leaves them at 3.85v ?

Never heard of a lipo fully charged puffing (unless it was over-charged) while in storage

I'm not bagging SMC dude, never used their batteries and have heard good things

I'm all for using any batteries that are good bang for buck

Cheers

I don't own SMCs but after witnessing what several have been thru with theirs and trying to get warranty support, you really shouldn't be propagating info that will cause damage claims to be denied due to what SMC considers improper handling.

Don't care if they are really diff or not, thats not the point.

SMC LIPO BATTERY THREAD
 

Superior Matching Concepts (SMC) has been a leader in the R/C battery industry for close to 20 years. With numerous IFMAR world championships and national titles under our belt, our track record as both a leader in the field and an innovator in the industry is well known. SMC's philosophy has always been to provide everyone from the competitive R/C racer to the backyard novice the highest quality battery money can buy. We spend countless hours testing on the track and at the shop in an effort to extract the most performance out of our packs. Every step is taken to formulate a battery that not only outperforms our competition, but is durable under even the most demanding conditions.

With the advent of the internet, the whole landscape of our industry has changed dramatically. No longer do racers and enthusiasts simply purchase items from a brick and mortar store. Parts and supplies are ordered from all over the world with a click of the mouse. Competition is fierce and pricing can be extremely competitive. The battery business has been particularly affected by this new way of doing business. Packs are available from China at prices that seem too good to be true. This environment makes it extremely difficult for a small company like SMC to compete selling product through the normal distribution/dealer network. For this reason, we have decided to launch our new website as a way for us to counter these companies that seem determined to undermine the industry. We have slowly been introducing all of our batteries, along with some other R/C related items over the last few months, available directly from our site....at amazing prices. So now you will be able to purchase the highest quality SMC packs at incredibly competitive prices and have them shipped directly to you.

I posted the above message from the home page of Danny's site.
He has alot of new things on the horizon.
His new Factory spec packs are all available on the web site www.smc-racing.net
I will be very interested to hear how everyone buying them up likes them.
His new shorty packs are in as well but it was a little disappointing to see they did not meet his specs, they were suppose to come in at 4600MAH 70c, when he tested them they were coming in at 4200MAH so what does he do, he slashed the price.

Those I have talked to that have ordered the new Factory Spec packs love them, I know I can hardly wait until mine arrive.

Anyone that has gotten them in post up and let us know how you like them.
I am sure Danny will be checking in from time to time on this thread as well.

Also if anyone has questions about Lipos that need answering you might check here http://www.hobbytalk.com/bbs1/showthread.php?t=357870, I know it's a different forum but Danny has some very good info posted here about Lipos, I know I have learned alot and had alot of my questions answered by reading through these posts. Would be nice if there was an easy way to post up all that info over here as well. If I get time maybe I will see what I can do about transfering some of the good posts over.