Whats so good about lipos? ----> Noob

[DCM]

A LiPo pack loses runtime each time it is charges, but it is very VERY minimal!!
A NiMH loses voltage and increases IR each charge....

I know which one I would go for.

And to be honest, I wouldn't like to see one LiPo being hammered all day, I have two packs and they get to rest a little, as they still get warm under use.

As for LiPo downside being you got to buy a new charger, you have to buy a new speedo to go brushless, so I don't see it as an issue, and you really don't have to spend that much either to get a GOOD charger.

[dan_kitty]

what classes as a cycle, every time you top it up a bit or every time you have put in the amount of charge of its capacity?

or is it not as simple as that?

[mark christopher]

Originally Posted by Edd

Hi guys,

yes "another noob" who doesent know about lipos. Im asking because I have some "Muchmore" racing saddle pack NIMH 7.2v batteries that are 4500 mah and I've seen the lipos and for example the Trak power lipo saddle pack is only 3800 mah so is the battery i have now better or have i missed something?

sorry, i know questions like these have been asked before

trakpower do saddles in 3200 and 4800 mah
3200 will power a 4x4 buggy for 5 mins, the way the cell delivers its power give you a longer run time from a lower capacity

Originally Posted by sim

Also, they are lighter and they last longer (more charges), have less internal resistance (don't get as hot, and longer runtime compared to NiMH of the same capacity).

But you are right in that the saddle lipos aren't as high capacity as the long brick lipos.

Frankly, saddle pack chassis configurations are designed around heavy (NiMH) batteries and assume that the heaviest(most massive, to be precise) component is the battery pack. They aren't as lipo-friendly as the 6-cell inline chassis in some ways.

4800 sadlle to 4900 stick??

Originally Posted by ashleyb4

That is incorrect A trakpower lipo is good for 100 cycles

I think a better way to put it would be it does not loose performance though its lifespan.

A

ash
the site says

100+ race-worthy cycles, 200+ for practice.

see the 100 plus? that means there saying you can get a minimum on 100 cycles NOT a max!

Originally Posted by ashleyb4

I was informed by neil oliver oswestry regional battery exspert that the cells where onl good for 100 cycles im sure neil will come explain as he confused me.

A

the 100+ life span is on trakpowers site trakpower put this as they were going by the plane/helicopter boys who fully charge a pack and fully discharge the pack in one flight, this is also discharged at max power (one cycle is a full charge from 6 volt then a full discharge)
they did not realize how the car world works where we top them up run for 5 mins and re top up. so you may get "3 car cycles to equal a full cycle, we are also not on full power the whole 5 mins, so the cell goes through less strain.

i can assure you that you will get far more than 100 cycles per pack and 100% at 100 cycles they will not fail just like that, the capacity will simply fall off, the voltage will remain
as tom has said he had a pack off me for trial along with chris long, toms was near 100 cycles old, chris's was nearly new, niether could tell the difference in power and run time.


heres one for you all,
3200 saddle £45 use one pack all day, IF you get YOUR claimed 100 cycles thats 0.045pence per cycle and 16 meetings with 4 qualifiers and two finals, with very little loss in power

can you do that on ONE set of nimh (£45 worth max value) and not notice a drop in performance?

[dan_kitty]

thats awesome long term value for money. even if they were only 100 cycles
thats at least 300+ (at top performance) races with my 4900 trakpower stick pack

[Lee]

Good point mark but.......


Can you take someones eye out with a lipo from 30 yards?


I like the idea of lipo for next year, people say it will be cheaper but in reality we know it wont be as we all know we will have at least 2 packs.

I did try one briefly though and it made the car feel so much more nimble and nicer all round, the hardest part was keeping the front wheels on the floor.

[dan_kitty]

but then it will be much cheaper when you dont have to buy new ones for the next season

[Lee]

Who wouldnt buy new cells for a new season though? just in case

[dan_kitty]

true, i guess the top racers would, but if mine were still running top notch i would just stick with them.

[mark christopher]

Originally Posted by Lee

Good point mark but.......


Can you take someones eye out with a lipo from 30 yards?


I like the idea of lipo for next year, people say it will be cheaper but in reality we know it wont be as we all know we will have at least 2 packs.

I did try one briefly though and it made the car feel so much more nimble and nicer all round, the hardest part was keeping the front wheels on the floor.

well they dont "explode" like nimh and as yet i have not thrown one at anyone

Originally Posted by Lee

Who wouldnt buy new cells for a new season though? just in case

how much as an average racer do you spend on nimh for one season?

my 4900 sticks are comin into thier third year and ill run em at worksop and next year

some may get a new pack or two for each year, but your average racer on a budget wont need to, im sure many racers run old worn nimh because there on a budget (this year is diff due to new list)

[Lee]

agreed mark, but i think everyone gets approx 3 new sets each year, i bought 3 yuntongs for under £35 a pack and they are great. £100 for a years racing aint bad.

I do see the advantages of lipo but we both know that the technology is advancing so fast and the cells you buy now probably wont even be sold 12 months down the line

[mark christopher]

Originally Posted by Lee

agreed mark, but i think everyone gets approx 3 new sets each year, i bought 3 yuntongs for under £35 a pack and they are great. £100 for a years racing aint bad.

I do see the advantages of lipo but we both know that the technology is advancing so fast and the cells you buy now probably wont even be sold 12 months down the line

true

but my cells from near 3 years ago are the same as you get now, oh sorry there not, mine are 20c and you get 25c for the same price now

[jim76]

what's all the 20c and 25c stuff about? sorry for bod question!

[sparrow.2]

Originally Posted by jim76

what's all the 20c and 25c stuff about? sorry for bod question!

1C on a 5000mah lipo would be 5 amps. 20C would be 100 amps and 25C would be 125 amps. It is the continuos discharge rate they are capable of safely. Obviously 1C on a 3200mah lipo would then be 3.2 amps and 20C 64 amps.

Geddit

[Chrislong]

Originally Posted by jim76

what's all the 20c and 25c stuff about? sorry for bod question!

20c & 25c is the discharge rate. 1c of a 4900mah pack = 4.9amp hour continous discharge

So 20c of a 4900 = (20 x 4.9) 98ah
25c 4900 = 122.5

20c 3200 = 64
25c 3200 = 80


I could be wrong. But the maths is right, basically for 2wd I would choose a 3200mah 20c pack as this gives the lowest discharge rate, therefore the power of the motor is as good as very first charge of very best Nimh packs (controllable with same motor as used with Nimh cells)

Whereas anything such as 25c 4900 (I use these in truck) is completely mad power compared to Nimh, so I run a 7.5R Novak and its still freekin' quick and punchy too.

I hope the manufacturers realise that we require lower C rating, not higher, and don't go to 30C. That'd be bonkers.

Chris

[Richard Lowe]

It's to do with how much current they will give. xxC x capacity gives you the current the battery can give.

20c x 4.9 (4900mAh) = 98 amps
25x c 4.9 = 122.5 amps

Jimmy lent me a trakpower 4900 stick and 3200 stick to play with at Southport last week, the 3200 had a lot less punch than the 4900 - even with a 7.5 in 2wd and it being a lot lighter.

:::EDIT::: Just beat me to it Chris
The 3200 (not sure if it was a 20 or 25c, Jimmy!) felt very similar to a NiMh pack to drive.

[Chrislong]

Hi Rich,
That 4900 pack I leant you was 20c, thats the pack which squared your diff balls!

[jim76]

so the higher the rating the punchier the cells? that seems a bit odd to me.
I understand about the sustainable amp draw bit, but do brushless motors reach 80-100A draw? if so then i suppose it makes sense that the higher cells will give more punch. also what would happen if you use a motor that wants to draw more than the cells can sustain, will it simply limit the motor to lower performance or will it knacker the cells?

sorry, bit slow with all this Lipo syuff!

[Lee]

I would think a 4.5 woulf probably draw somewhere in the region of 130A+ from a standing start, i know i had brushed motors that would show 140+ on a dyno.This is only for milliseconds though.

I think the cells would give the motor what it wanted within reason, just remember that it is only a spike and not a constant current. The speedo will also limit the motor to about 120A depending on the profile used.

[cjm_2008]

I love my trakpower 3200's - so much that I bought 3 sets. and I'll probably buy another so I can have 10-15 minute practices

even if it means never scoring any points in regionals this year, I'll never go back to over-priced & poor performing nimh.

[RURC]

I track all my lipos., which is all I use and have for almost 7 years in cars. I have packs with over 300 cycles. Now I cannot say for the first couple of years because they did not have chargers that recorded mah imput but I still have 2 packs that I have been running since the beginning and I still use that pack for practice. Not because of a drop in performance but because it is a soft pack, no one made hard packs back then and this is one of the many I made myself because no one even made car packs then either. These 2 cells after 6 minutes of practice are still with in 7% of original (as I can tell) mah rechargeing. I have Core RC 5000 packs with 137 and 144 charges on them respectively anad they act and respond the same as new within 2%. Now dont get me wrong I have had a lot of packs that have fallen off after a while but none that have gone beyond 15% over 150 cycles.

I am refeering to only those packs that I have owned since new and not ones I have tested for other manufacturers.

The Core RC 5000 are proving themselves to be very good packs. I my work I have found that they are the best bang for the buck. If you have to have the absolute top then Tanic is it. They hold better voltage under high loads better than any battery I have ever used, and last for well over 100 cycles. Just to clarify to me well over 100 charges would be around 150 or more. The Max Amps batteries do very well also in longevity but lack in voltage stability.