Beginers guide to LiPos

[Telnets]

Hey guys,
I just wrote an article on my site that focus's on the basics of switching to Lipos if anyone is bored and wants to read. I tried to make it as less boring as I could but still get the information out.

www.telnets.org

take a look if your interested and let me know if it actually helped anyone if your new!

I pan to do a "how to" for painting an RC body, as well as a SC tire writeup with all the ones ive tried out sometime in the near future (after the hummer body project is in production)

[Radiojh]

looks good, good job!

[Cubic]

Thanks! Bookmarked this should I ever make the switch.

[Casadetrevino]

Hey, that is great info, just what I've been looking for. Keep up the good work!

[jwconnelly]

Very well written. That just answered most of the questions I have. thanks

[Hughes500Bob]

Fully charged LiPo cells are 4.2volts and should be run down to the NOMINAL voltage of 3.7v per cell (resting). At 3.7v per cell the voltage dumps rapidly when looking at proper discharge curves.

http://www.rchelicopterfun.com/rc-lipo-batteries.html and http://sites.google.com/site/tjinguytech/home might help you refine your data.

You should have some reference to the 80% discharge rule. Depeleting a pack past 80% of it's listed capacity will shorten it's life.

Pack Low Voltage per cell can differ greatly from vendor to vendor so it is not correct to list a voltage to which packs can be safely discharged.

Kudos on your effort!

Bob

[Spankenrear]

Well written, answered a lot of my newbie questions.
Thanks.

[Telnets]

I can add those couple of points in, thanks!

[elaras]

Not sure if your pro and cons section is accurate.


copy paste link from promatch.
http://www.promatchracing.com/4600.php

3: Maintenance: The newest generation of nimh cells do have a drawback to them in that they self discharge fairly quickly when not being used. ANOTHER ISSUE IS A SUBSTANTIAL VARIANCE IN THE ACTUAL RATE OF DISCHARGE BETWEEN DIFFERENT CELLS IN THE SAME PACK. For this reason it is imperative that you start a regime of maintenance and follow it faithfully if you want your pack(s) to last. One of the most important steps in keeping your packs running strong is to never allow the cells resting voltage drop to BELOW 1.25 volts. It is important to make certain there is always some charge left in the pack after each use. Fully charge the pack if it is not going to be used for more than a couple of weeks and recharge the pack every 30 days when it is not going to be used for very long periods of time. The rate at which the cells self discharge can vary so it is very important to "balance" the cells either before or at the end of the charge cycle. If you charge a pack without equalizing the cells first, you take a chance of damaging them. As a matter of routine I would check the voltage of each cell with a DVM to ensure that no cells are dead first. Then you can equalize the packs using a discharge device such as the Novak Smart Tray*(set the cutoff to 1 volt per cell). Another testing instrument I find extremely useful is an infrared temp meter/gun. You can check the temperature of each individual cell as it is charging to ensure there are no cells getting too hot. One thing you must realize is that virtually all chargers charge the pack in series using some type of delta peak detection. This means the charger only sees what's happening to all of the cells collectively and not each cell individually. If you have one cell in a pack that has reached a full charge before the other cells, the charger will still keep charging as the voltage in the other cells is still rising. The fully charged cell will go into an overcharge condition. Even though these cells are able to tolerate this condition for a short period of time the temperatures will begin to rise very quickly and within a just a couple of minutes the overcharged cell can vent and in rare circumstances explode the positive end of the cell completely off! As the pack nears full charge start checking the temperature of each cell in the pack. Do not let any cell EVER get over 140 F and the lowest temperature cell should be no more than 10 F lower than the highest temperature cell. This will ensure every cell in the pack is fully charged and you will get maximum performance!

From what I read you need to balance Nimh to.

Not sure if you can buy a cheaper discharger but that seems to me like you need more gear then a lipo.

You also said you need a LiPo specific charger. That is only a con if you presume I have a nimh charger. If you go out and buy both set ups from scratch The price shouldn't be much different. So not sure if that should be a con.

Another pro you might want to put in is the charge rate pro match says you can charge there packs at 4-6 amps on a 4600 ENER-G (based on the link above). So up to 1.3 c (ish)

Max amps say you can charge there lipos at 5c, with the right charger.

I know max amps cost more, but its still a faster charge rate. So Maybe a pro, but at a cost

I don't own pro match cells and I never will. This is all based on what they say you should do.

I do like your right up just some thoughts for you to think about.

[Telnets]

Not sure if your pro and cons section is accurate.


copy paste link from promatch.
http://www.promatchracing.com/4600.php

3: Maintenance: The newest generation of nimh cells do have a drawback to them in that they self discharge fairly quickly when not being used.

Not sure if you can buy a cheaper discharger but that seems to me like you need more gear then a lipo.

You also said you need a LiPo specific charger. That is only a con if you presume I have a nimh charger. If you go out and buy both set ups from scratch The price shouldn't be much different. So not sure if that should be a con.

Another pro you might want to put in is the charge rate pro match says you can charge there packs at 4-6 amps on a 4600 ENER-G (based on the link above). So up to 1.3 c (ish)

Max amps say you can charge there lipos at 5c, with the right charger.

I know max amps cost more, but its still a faster charge rate. So Maybe a pro, but at a cost

I don't own pro match cells and I never will. This is all based on what they say you should do.

I do like your right up just some thoughts for you to think about.

Thanks for the comments,

Your right that NiMHs do require some maintanance/care I just decided to leave it out and just focus on the basics of lipos since the reader is probably already using NiMHs and is looking to switch.

Regarding your suggestions -

You really dont need more gear for lipos though? For example, i dont own anything but a balance charger and my batteries. But I do explain that if you dont have stuff like a balance charger you would require a balancer, so i think i have that covered? unless maybe i need to make that more clear?

As for the con of buying a lipo charger, i have included that its only a con if you dont already have one, but your right its not really a con if you have one.

as for the pro's on the discharge rate you mention - I was thinking about adding the whole "rule" of 1C charging under the section on balancing.. Though i dont want to start getting into lists of manufactueres that claim they can do more then another, i could always mention that its the general rule for charging, and check with thier manufacturer if they can safely be charged higher.... something ill think about if i add that section..

thanks!

[jperry]

Very cool site, great info and delivered so us non techie bashers could handle it.I bookmarked the site and plan to check it out a lil bit more. thanks .

[castorriv]

Nice work on the write-up. btw I have a venom pro charger which has a lot of useful features and it wasn't that expensive. What I like you can program all your charging rates/functions for lipo's nimh etc... It also will discharge/charge up to 5x times to bring back nimh batts when they've been abused. You can also balance lipo's with it and the charger comes with about 10 connectors for different set-ups. And the cooling fan is adequate and quiet.

[Telnets]

Yeah there are a lot of cool chargers out there.. mine will charge through the balance plug (its only 3A though) but it does each cell individual so they are always perfectly balanced in the end.. it can also do 5 separate batteries at one, no programming required for anything.. its a great little charger.

Thanks for the comments guys, my next one will be a painting "hot to" basics.. so hopfully Ill get that online soon.. just waiting on the CNC guy for my custom slash body to finish that project then i can do this writeup.

[lilNiTRO]

awesome write being a noob to electric found this very useful even though my first car came with a lipo it help me understand why now all i need to find is a write up on speed controls and motors! any one has any useful info let me know...thanks

[slcpunk]

now all i need to find is a write up on speed controls and motors! any one has any useful info let me know...thanks

Agreed! I have so many questions about brushless systems. I hope someone can do as great of a job on that as he did on that Lipo write-up.

Great stuff, thanks!

[Out of Sight]

Nice write up Telnets!!
It's good to see an effort to actually bring people and 'open up' their minds on the advantages of Lipos, rather than scaring them away, thinking they are running a small atomic bombs. I've always been very supportive about using atomic bombs...err I mean Lipos, in our RC cars.

Two thumbs up man! I would've given three, but I was born with two hands only

[Telnets]

esc / motor write up sounds interesting :P

let me see how much time at work i have this week hehe

[Jarbo44]

Thanks Cleared up some stuff for me!!!

BUt on the C rating ( mah x c= / 1000) can u go over the amps your esc is rated for or not suppost to go under???? little confused on that,,!!!!

THANKS

[Telnets]

You can go as much over as you want, but shouldnt go under.. the ESC draws power from the battery and will draw it at whatever it wants/rated to. so getting 80c batteries for a 30a esc is just fine.. theres not much of a point to do it, but you can with no problems ;P

when you go under the recommended C rating, then yoru esc is asking more from your battery then your battery is willing to give... this can lead to damaging your batteries, or the ESC itself

[Ree-vo]

Awesome article! Anyone know where to find one on how to charge lipo's, for newbie's? I have two new ones coming in and I'm not to lipos!

[Federally]

All of this battery stuff is great and all but I was looking through your site and your paint jobs are ridiculously better then anything I could do. How do I convince you to paint a body and sell it to me?

[muddybuddy]

This is still one of the best threads I've read on here. For anyone who has questions about Lipos, this is a must read.

[pakratt]

excellent-- I have been LiPo leery since I travel and my batts charge in the hotel while I'm gone--- this will help- will read

[Federally]

Pakratt I'm also on the road constantly and take my slash with me and I would suggest LIFE batterys to you. They are a middle road between Nimh's and Lipo's, they have several of the pluses of Lipos without the added precaution Lipos require. They are a little heavier and produce a little less volts/cell. A 3s life pushes 9.9v, but they don't need balanced and they don't start fires if you run them down too far. They also can be handled by most hargers that are lipo capable.

[pakratt]

Pakratt I'm also on the road constantly and take my slash with me and I would suggest LIFE batterys to you. They are a middle road between Nimh's and Lipo's, they have several of the pluses of Lipos without the added precaution Lipos require. They are a little heavier and produce a little less volts/cell. A 3s life pushes 9.9v, but they don't need balanced and they don't start fires if you run them down too far. They also can be handled by most hargers that are lipo capable.

Awesome-- thank you-- will check them out right away