I am a "newbie" to these LiPo batteries, have been reading some of the threads. How about one for us Newbies? I suspect that there are more battery chargers coming on line (I think a special charger is needed for LiPo's, my Turbo 30 or Reedy charger doesn't do LiPos?), what is a good inexpensive charger to start out with? What are some equivalents to what we are now running? For example: if I was running 4 cell stock and wanted a couple battery packs to prctice with, what LiPo would I get to simulate a 4 cell stock performance? 6-Cell stock? What is the weight of theses batteries (in other words, how would it change my set up with the difference in weight?) Since they are not yet competition approved I would like to have some Looong practice runs. Any other advice for a LiPo newbie? Thanks Ralf 13

As one newbie to another- keep reading.

LiPo's come in 3.7V cells. Your 4 cell pack is nominally 4.8V. No way to get there from 3.7... A 6 cell pack at 7.2V is close to (but inferior to) a 2S (two cells in series) LiPo pack that would give you 7.4V

You Must get a LiPo specific charger. Or one that is designed to do those and others. They do not use a delta V peak detection system. (I think it is thermal but I don't know). To do otherwise is to risk life, limb and certainly your warranty!:)

The only weight spec I have seen was for the Scorpian packs in the latest RC Driver where they said the 2S 3200 pack weighed 7.5 oz or 5.5 less than a Club level NiMH pack. Those wouldn't add to your runtime- just power. Themain threads here seem to be concentrating on 2S, 2P packs that would give you huge run times. But twice the weight. Since they are so much lighter maybe you wouldn't notice. The savings of not stopping in a LONG main would probably offset the extra weight. As would the extra voltage.

I know some oval guys that are now running the 7.4 volt li-po packs instead of the 4.8 volt nickel packs that the li-pos had more voltage, more mahs capacity, were lighter and gave alot better performance along with longer run times. They had to re-gear they cars for the additional voltage.

Hi,

maybe this isn't the right thread to post this but...... I am looking for a 8.4 to 12 volt LiPo pack (s) we will be using them in airsoft (like paintball but with 6mm plastic balls). I'm hoping the size and weight (http://server4.103092804.com/Release3/linkredirect.php?h=42026,378826,1112938014) will be lighter as we play in Close Quarter Battles where speed is paramount. since we are using a full stock M15a4 we need all the help we can get ( we're up againist MP5a's
I'm looking for any place I can buy these cells. I'm also wondering about discharging. what amps, how far your taking the LiPo's down to per cell. etc
one last thing.........I need them to fit into a space the same size as a sub C stick 6.4 volt pack...

Thanks for your help

Dawrench,
Not exactly the right place for your thread but here is what I can tell you.
The Lipos are 3.7v per cell and 4.1v a cell fully charged so my first thought would be see if your gun can handle a 3s (11.1v) I believe it can but not certain of that. Also you may have a problem with using lipos if you are going to jumping around and bouncing the gun all over because there is really nothing holding the battery secure. But if after this you are still interested.
I think the mp5 might be able to fit a 3s4400n
If your gun takes the mini a 3s3100n may work.
Here is a link to my website with all the dimensions if you have any questions let me know.
Keep in mind you will also have to buy a new charger as well. $$$$$$$ :confused:

www.purehobby.com

Are there some inexpensive LiPo chargers out there? I would like to get into it for practice right now as they are still not legal at ROAR races and most clubs I race at. Six-cell dirt oval, I figure two LiPo cells (7.4V) will be close enough to 7.2 that practice with a brushles will be close enough for practice, how much does a couple of LiPo's weigh? What are some good web sites to visit for LiPo information? Thanks Ralf 13

Ralf,
the apache 2500 will run you about $50.00. it can only charge at a max of 2500mah depending on what battery will work for you it may take awhile to charge. I have the astro 109's it is a very nice charger and maybe I can give you a break on the price.
Take a look at our website www.purehobby.com it has all the dimensions and weights and let me know if you have any questions.

Robert
sales@purehobby.com

As far as chargers go, the 1C recommended charge rate and the mah capacity of the battery will help you choose a charger. Example: 8000 mah battery = 8 amps capacity with the charge rate of 8 amps that is 1C or the 1C rate of a 4400 mah capacity battery is 4.4 amps. These charge rates will take a little over an hour to fully charge and peak the battery.

The point being made about the so called "cheap li-po charger" is that if you cut corners and buy a charger with a 2 amp maximum charge rate, it will take you over 4 hours to fully peak charge an 8000 mah capacity battery at the 2 amp rate.

Astro Flight 109 and the Duratrax ICE both can charge at the 8 amp rate.

I have been hearing lipo's are unstable. especially on charging. what is everyones take on that? I guess you got to give a little to get a little. (or lot in this case)

I would not say they are unstable I would however say they do require more attention while charging. I use the protection circuit module (PCM Guard) this limits the charger voltage from spiking above the capabilities of the pack. I have found most incidents to come from charging, but as true as that is they were not the batteries at fault but human error which is usually an overcharged pack, charging a puffed pack, charging a dented pack that may have internal construction damage.
Example: I use an Astro 109 and depending on how charged the battery is at the point when I put it on the charger there is always the possibilty of the charger recognizing the pack to be a higher voltage pack than it really is. This would be very dangerous for any pack but more so for a Lithium Polymer.

Can you give some numbers on that statement? Are you basically saying that repeaking a pack without close attention could be a problem? Do these chargers not have a # of cell's setting like better NiMH chargers do?

As for numbers I am assuming you are referring to lipo instabilities. My statement is only based on what I have seen in most cases from another forum.
Repeaking a pack does require close attention in the first few minutes of charging because they have no buttons to change they go by voltage to register how many cell pack it is charging and at times may read the wrong cell count. From my experience if I replug the pack to the charger 2-3 times it then reads the proper cells. Can't explain why I will leave that for someone more knowledgeable with the chargers. There are manual chargers which you set the voltage and amps yourself out there and are less expensive but I have not seen one that will charge at 8amps. I am only speaking from my own experience with the astro 109 and this may not be the case with other automatic chargers.

Robert
www.purehobby.com

That depends on the charger. The Astro charger does not allow you to change the number of cells in the pack... it is suppose to autodetect. On the DuraTrax ICE you set the number of cells being charged.

Actually by numbers I was more thinking of voltages. As in if you are reading 3.3/cell (6.6 total) and are in need of a final boost will the charger see it is a 3S that is way low. The answer is yes, maybe. The Ice seems like a nice safe way to avoid THAT particular worry.

In my cases it was always around 8v which yes batteries were already pretty much charged but after sitting for a week or so I couldnt remember how long I used them. I have not had any problems with the astro under 8v and I do like the astro and this mis reading does not happen to often but it does happen and that is the part you have to watch for.

I'm looking to start racing Nitro with my R40. I'm always nervous about my receiver/servo batteries giving out. Does anyone have any experience with how much more runtime you're getting on LiPos?

Also, any perceived differences in transmitter time would be helpful as well. I run a Mars soon to be Spektrum upgraded.

Ballpark figures on how much a setup would cost to run LiPos in my R40, and my Mars would also be appreciated.

Thanks!

Just look at mah. Type of battery doesn't matter. If you get 30 minutes of running out of a 600mah rx pack, then you can get 1.5 hours out of a 1800mah pack of lipoly at a similar size. You have to be weary of running the voltage down too low. I think Novak makes a regulator specific for the task now. For the radio, most have voltage readouts on them these days. Mine will hod a 1900mah 3 cell pack that gives me 3 times the stock capacity. I no some inexpensive packs that could do the job.

What is a good source to read about lipos? Any good resellers in FL or on line?

I was just down in Florida for a show. You can read about Polyquest batteries on the distributors website (www.rclipos.com). I sell them in my online shop.

hello on a 2 cell (7.4v) li-po pack is it better to charge each cell individually or both at the same time?

Normally you charge the pack as a whole. Charging each cell individually is time consuming, but it is the safest and best method when time is not a factor. I recommend doing that maybe every 10th charge or so just to keep the cells in balance.

thanks for the info

some good info here guys. i was gonna post the same kinda thread about lipo's.but now idont have to.because i to didnt know much about them.and was thinking about using them in my mini t.

What about discharge currents? What can LiPo's handle in real racing action as far as amp draw? I race on rather small carpet oval's with off-road trucks converted for left-turn-only.
Should I be looking at packs with 4000 mah capacity?

Depending on the pack, it can handle from 8 amps to over 100 amps. Most decent packs these days can at least discharge at 1C (1 times capacity), so a 4000mah pack could deliver 40 amps continuously. For 1/10 scale on a carpet track, I would be more concerned about brief peaks when getting good traction. A pack that could do 20C burst would be best. I should have Thunderpower 6000 and 8000mah packs in stock on Monday (maybe not posted yet so email). Those will run pretty much any 1/10 setup.

Thanks for the info starluckrc! You are right about the brief peaks when getting good traction. With the added "stress" of a transmission in an off-road truck with foam tires on carpet, I usually have tons of traction which directly relates to amp draw on the battery's.
I'm thinking a 6000mah pack would be safe. Would you have an idea what type of runtime I could expect with that pack?

What motor? 20 minutes shouldn't be a problem with most any motor and maybe closer to 30 minutes with something along the lines of a 19T spec or mild brushless setup.

I'm running a Novak 5800 system. It's pretty close to a 19t.

25-30 minutes should be doable. We get 15-20 on that pack with the Plettenberg Extreme and 30 minutes out of the 8000.....but it's a little too thick for most applications.

So would it be reasonable to expect to run 3 or 4 four minute races on one charge and have the same "punch" in race 4 as in race 1?

Voltage will be down a little as the battery is drained, but punch generally remains right up until the end. There is no reason you can't charge between mains as well to top it off. Craps does that all the time.

I did not know you could "top it off".
Can you recommend a good charger?

There are several depending on your budget. I use a Hyperion EOS7i and will be stocking the more affordable EOS5i(?) soon (@$85) that charges 1-4S as well and up to 14 cells NiCd/NiMH. I can also get and recommend the Astroflight 109D. The Duratrax Ice is a nice unit as well as any of the chargers by Schulze or Thunderpower (in stock later as well). I can special order chargers but will be closing for the holidays Dec 15th and not ordering more stock until the beginning of the year outside of special orders.

I'm not sure what I am willing to spend just yet. I'm thinking two 7.4 cell (6000mah) packs and a decent charger. I'm leaning toward the Duratrax Ice since it'll do NiMH's too. I'll get in touch with you when I'm ready to jump in.

I am going with the Duratrax ICE. I need a second charger anyway. Just gotta figure out which Li-Po pack to go with now.

Anyone know anything about multi battery chargers? Seems like the lipo world is growing by the day as well as a lot of chargers hitting the market.

There is a 4 pack charger in the market right now. You set the charge by the capacity on each of the battery packs. I will get you the manufacturer and model number. I just saw the charger in action yesterday.

OK... our local touring car series has just announced its rules for this year. In the stock motor foam tire class they now allow Lipo's. Does anyone have any real experience running a Top of the line 4200 NiMh verses a Lipo... with equal car weight. Is the Lipo a advantage speed wise and if so, how much?