i'm getting calls and emails about lipo questions...

here it goes

1) what is the best way to store a lipo for one week

2) how about longer than 1 week?

3)for oval racing what do you suggest for a amperage rate for charging?

4)the pack peaks at 8.44 what kind of drop in lap times should we expect on a 4 minute run with a 17.5 21.5

5) will it hurt the pack to run it 7 times in practice and 4 times in the race(same pack) all day?

6) should i use plugs for racing or solder direct?

7) if i need to use plugs what do you reccomend?

8) should i cycle my pack weekly? monthly?never at all?

9) what happens if my case gets cracked in a wicked crash?

0) what happens to the pack if charged over 8.44 volts?



i'm not going to ask about heating the pack because most tracks/promoters are smart enough to know that this practice should be nipped in the bud now..


11)do you have any tips or tricks to help on track performance with lipos?

12) do i charge balance or discharge balance?

13) what balancer do i need for the smc 3200/5000 packs?

14) how often do i balance the pack?



thanks for your reply

bill

I will try my best to answer these questions. I will reference the number of the question as I don't know how to quote very well on these message boards.

1) A Lipo should not be stored with more than 50% charge which is equal to 7.60 volts. If you race weekly you can keep the pack discharged as the selfdischarge rate of Lipos is very slow. For 1 month to 3 month storage 30% will be fine and for longer time storage I would go with 50%. Keeping a lipo stored with storage charge for long periods of time will drop the capacity a bit and is normal. Storing in a cool place will make the selfdischarge even slower.

2) See answer above

3) I reccomend a 2C charge rate as our Lipos are made to handle up to 3C charge rate and 2C will not deteriorate the pack and takes less time to charge. 3C can start hurting the cycle life.

4) Since I haven't raced oval in awhile I can't answer that one but I'm sure someone who uses Lipos can answer.

5) It doesn't hurt the pack to run it mutiple times per day. The pack doesn't even need to be cool before you recharge or charge it back up. I have charged packs that were at 120 degrees and when they finsihed the charge the temp was down to 80 degrees. Typically when charging a Lipo at 2C the temp of the pack only gains 3-5 degrees.

6) If soldering directly is allowed then I would do so as this drops the IR by 1.5 milliohms plus connectors wear out and increase in IR as they wear out.

7) If rules state you must use a connector I would use a high quality connector such as Deans , 4mm Bullet style and make sure they are copper with gold plating and not brass that looks like gold. The Losi EC3 and Traxxas connectors are also good.

8) You can cycle your pack once in awhile to see how it's holding up but it's not going to improve the pack.

9) If the cells don't get punctured then the pack will be fine. If something happens to the cells and it's an SMC pack I should be contacted as we have a replacement policy at good price.

10) If a pack gets overcharged it can swell up and if it's left to overcharge for a long period of time it can catch on fire. This is why charging in a Lipo sack is a good idea.

11) A couple of things help the packs performance. One is to run it atleast once in practice as the first run after storage seems to be flat. Another tip is to make sure the cells are balanced. We send our packs our balanced but they can come out of balance.

12) Never use a balancer alone as a discharge device as this actually unbalances the pack. The only true way to balance is to balance charge.

13) For those using a GFX a seperate balancer will work well and the Equinox by ElectriFly has the proper harness for our balance connector which is called JST-XH. If your using a charger that doesn't have seperate voltage sensing leads then the pack will kick in to CV (constant voltage) part of the charge faster as the resistance of the balancer will make the charger think the pack is higher in voltage.

There are plenty of good Lipo chargers with built in balancers at a good price so that can be a great option for those who don't have a GFX. A balancer costs 40-60 bucks and you can get a 10 amp Lipo charger for 130-160 bucks.

14) If you have a charger with built in balancer you can balance charge the packs everytime you charge them as it's easy to use and plug. If you have a seperate balancer which needs to be hooked up and will only allow lower charge rates I would blance charge every 20 or so charges.


If there are anymore questions I will do my best to answer.

Great Info! Could be a Great Thread.

What's the part number for the plugs for the SMC Lipos?

JST-XH I believe. The GP Electrifly balancer comes stock with the correct connector.

I've got two more questions:

1) Say you have charged up the LiPo pack with the intention of using it and, for some reason, you didn't. But you know you will get to use it tomorrow, or the next day, or "n" days from now. What is the "n" in days such that that it is better to discharge it for storage (and charge it up again) as opposed to leaving it fully charged until you use it "n" days later?

2) You didn't use enough of the pack to bring it down to the recommended storage voltage. So you want to discharge it some. Does it matter (in terms of long term life and performance) if you discharge it at 30 or 35 Amps vs low amperage (3, 4, 5, or so)?

I'm asking that second question because I have found that discharging the SMC LiPos at .8C to a 3.7V/cell cutoff brings them right to the 30% charge level. So is that OK to do, or should the pack be dumped to 6V at 30A and the recharged to 30%?

In my testing I noticed a 10 second drop in performance by keeping a pack fully charged for 10 days. I didn't test every possible combination but I would think if you were going to run your pack the next day it should be fine.

Yes discharging down to a certain voltage is as good as discharging down to 6v then charging back up to 20-30% or 50%. Why are you discharging at a low rate ? You could discharge at 30 or 35 amps down to 7.4 volts and get the same results.

Thanks Danny for the info, looking forward to getting my 5000 pack and joining the Lipo 17.5 oval racing crowd.

Thanks,

Rich Boehmler

p.s. Kat thanks for asking the questions and getting the thread going

Yes discharging down to a certain voltage is as good as discharging down to 6v then charging back up to 20-30% or 50%. Why are you discharging at a low rate ? You could discharge at 30 or 35 amps down to 7.4 volts and get the same results.
I haven't got my GFX updated so I'm using an ICE charger to discharge the LiPos and it won't do more than 10A discharge. (I'm charging with a Hyperion with an integrated balancer and it does the CV mode much faster than the ICE.)

I came up with the .8C discharge by trial and error to leave the battery (SMC packs anyway) at 30% charge. Wouldn't a 30A discharge (to the same cutoff - 7.4V) leave more that 30% in the pack?

I haven't got my GFX updated so I'm using an ICE charger to discharge the LiPos and it won't do more than 10A discharge. (I'm charging with a Hyperion with an integrated balancer and it does the CV mode much faster than the ICE.)

I came up with the .8C discharge by trial and error to leave the battery (SMC packs anyway) at 30% charge. Wouldn't a 30A discharge (to the same cutoff - 7.4V) leave more that 30% in the pack?


I put 30% back in a pack here at home and it was sitting at 7.5 volts.

I think the key is to put back enough charge so the pack doesn't go under 6 volts while in storage. I think 20-30% will be good for a long period of time as I have left packs with no storage charge for 3 weeks or so and they were still fine. Why I reccomend 20-30% is to be safe. I know that leaving to much will drop the runtime some and can cause swelling issues.

we can we expect to see the new 3200's back in stock!!every LHS i have called is out and cant tell me nothing :(

newrcguy2008 Try Maximus rc raceway link on left. I think they still have some

I have a question also.......I see 3200 lipo packs and 5000 lipo packs.....can they be both raced together?....Or will they have to be in seperate classes......I am making the switch over by Jan 1st and no nothing about Lipo....will any of these packs fit in a 4 cell tray for an oval car or will we have to buy new trays or cars for that matter?

Bud, for the most part what we have been seeing in the SouthEast is 21.5 bl run the 3200 lipo and the 17.5 run the 5000 lipo. In 21.5 running 5 minutes on flat ashpalt we are using less than half of the mah of the 3200.

But check the tracks where you run to see what they are doing.

As for the trays, I run the Mavrick car, have been running mostly 21.5 for the last year, I modified the slider trays for the Orion 3200, it has bumps on the bottom of the battery(sort of like a 6 cell pack did) it fit on the trays after a little grinding.

The SMC packs are flat on the bottom, I have run them in my solid cars with no problem, it did shoegoo some old chassis pieces to the bottom of the flat lipo packs to index the packs into the chassis, that way the are installed in the same location every time.

Jump into the lipo pond, it's kool!!!!!

can you really tell a performance difference between a 25c and a 30c pack with the same mah??

can you really tell a performance difference between a 25c and a 30c pack with the same mah??
Depends on what motor you are using. Some people running 1/8th scale electric conversions with motors that draw 100+ amp spikes claim to be able to tell the difference in punch. On an oval track where you run relatively steady amp draws around 20-40 amps, I doubt you would see a difference.

I've got a 1/8th conversions and I can't tell the difference between a 140amp continuous battery and a 100-120 amp continuous battery (they are different mAHr ratings as well as different C ratings, so I multiplied the numbers out to get the actual amp ratings).

I have a question also.......I see 3200 lipo packs and 5000 lipo packs.....can they be both raced together?....Or will they have to be in seperate classes......I am making the switch over by Jan 1st and no nothing about Lipo....will any of these packs fit in a 4 cell tray for an oval car or will we have to buy new trays or cars for that matter?
I have the best way to hold lipo is with Assciated battery cups they fit very snug and have lock bars and are very inexspensive $5.79 at Tower hobbies PN#LN2773 Assciated PN#6773

Markstoy
Thanks for the tip on the associated items. I had forgotten about them until I saw your post.

Jim:thumbsup:

I bought a new SMC 3200 28C about a month ago from Tower and it has been sitting on my work bench. I haven't done anything with it and won't for about 2-3 weeks. Can I just let it lay or should I charge it or something??

nimh or lipo?

I edited my last post.

Danny at SMC suggests leaving a 50%-70% charge in lipo's for storage purposes.

Any chance of making the SMC LiPo case with the humps like the other brand? They fit so much better with the humps to fit in the chassis battery slots.

Try Shoegooing a couple graphite or plastic strips onto the bottom of the battery to locate it in your tray. It Works!

Try Shoegooing a couple graphite or plastic strips onto the bottom of the battery to locate it in your tray. It Works!

That's my point, you don't have to do that with the other brand that has the humps.

That's my point, you don't have to do that with the other brand that has the humps.

you also won't win many races with those humpty packs either! :rolleyes:

you also won't win many races with those humpty packs either! :rolleyes:

I beg to differ katfish, dude just set the track record yesterday and won at our local track with a "humpty" pack.:freak: I'm not trying o get into a brand war, I just like the other brand case design, not talking about the performance of them.

I believe if Danny was to add humps it will make the overal height taller and might give folks problems. I am not sure if specs have deminsions but that could also be a problem.

I took some old chassis parts and shoegooged them to be bottom of my 5000's and they have been on there since May with no problems.

I you do it right, and it position the packs nicely.

Kat, quit being a hater, you should know better by now. See ya Saturday.

Gluing on your own strips allows you to shift the wieght of the battery forward or back a bit if you need to.... another tuning option.

That's my point, you don't have to do that with the other brand that has the humps.

I had to grind the end bumps off the Orions to fit my old chassis. Whatever it takes, sometimes you just have to quit whinning and use a little ingenuity.

How is everyone charging lipo's during a race weekend? Do you just keep repeaking or discharge then charge? Should I buy one or two packs? :confused:

I have been just repeaking and had succesfull results so far.. others may differ.. I just run one battery..

Whether you need one or two packs per car depends on how much time there is between each heat you have to run.

we ran 17.5 down here for the first time. alot of us were just repeaking

FlyingFinn,

We've been doing the BL /LIPO thing for almost a full year out west.

The MAJORITY of the racers, CHARGE/RUN/RECHARGE/RUN/RECHARGE/RUN/RECHARGE/RUN

There are a few who discharge to 6 volts or close...and a few who have things to warm the packs as well. MOST never remove the battery from the car.

Myself, for the better part of the year...I've had (1 1/2) batteries PER CAR. My son and I run together, and usually run (4) classes. So we always have (2) Spare packs charged and ready to go..just incase we forget to charge one...or have to repair the car and get behind on the charging.

My personal thougts are - ALWAYS have at least (2) batteries. JUST IN CASE of

Battery Failure (product or due to a crash)
Memory Lapse (forgetting to charge one)
as a LOANER (to help the OTHER guy who may have had an issue)

Thanks Everyone For The Help.......now If We Can Make The Tires Last Forever.

Thanks Everyone For The Help.......now If We Can Make The Tires Last Forever.

Good luck on that one. NASCAR has been trying to figure that one out for years! LOL :)

you can make them last forever but you won't be very fast..lol

now If We Can Make The Tires Last Forever.


JACO did that years ago for VELODROME tires...several of us are still using tires that are OVER 10 years old..and they still run as good as a BRAND NEW Set.

hi guys i have a question about the smc3200 pack. at my local track we have 2 different kinds. one is RED and the other is BLACK! what is the difference. is one better then the other? is one NEWWER then the other? thanks guys. id hate to buy 1 of them and find out i got the wrong one lol also the RED one has GFX numbers on it and the BLACK one does not. thank you guys!

i believe the only difference is the color of the pack and the location of the wires...the new black and red carbon pack is the newer version, the wires come out of the top and for me that makes it easier.

thanks! so there arent any other advantages or differences?

Nope just a different color case and wire location.

.....

Well, after reading through these posts, I've confused myself. So, my question is, do you need a balancer with a GFX or Turbo 35?

Thanks,
Josh


For the best battery maint. yes you need a balancer.

Well, after reading through these posts, I've confused myself. So, my question is, do you need a balancer with a GFX or Turbo 35?

Thanks,
Josh

I run 21.5 and have never balanced my batteries. Numbers are still the same.

when will the 3200's be available again

i am now curious , i have just got my GFX back from lipo upgrade and i bought a team checkpoint inline balencer so can this unit balance charge with the gfx? and if so i hook the sence leads between the battery and the ballencer correct ?
i just got my 1st lipo , a smc 4900 sattle pack, for my (custom) LTO turing car, yes i know but i love turning both dirrections in the summer and this was morefun to make that buying a oval car kit

when will the 3200's be available again


Rc4less, Lefthander rc, and stormer hobbies.

How or when do you know that a lipo is getting weak or not good for racing?