TEKIN RX8+BATTERY HELP

[Nas]

Hello ladies and Gentlemen of this forum.

i am in need of help.
I am getting a Tekin rx8 system for my Associated RC8.2E
and i have some Turnigy 4s 4500mah,30C
The turnigy batterys max out at 135amp

and the Tekin esc can do 210amp

Whats the chance of my lipo swelling up?

I can't afford thos £200.00 4s batterys..

Thanks

[shortcoursegoat]

ive used those batteries before on a rx8 1900 with nps, everyone at my old club used them on tekin systems also. ive got a thunderpower 4s an i dont see the money difference unless you have a system that can charge a 4s at 32 amp

[Nas]

Originally Posted by shortcoursegoat

ive used those batteries before on a rx8 1900 with nps, everyone at my old club used them on tekin systems also. ive got a thunderpower 4s an i dont see the money difference unless you have a system that can charge a 4s at 32 amp

Because it doesn't supply enough amps have you ever noticed power shortage?

and you tell me many other racers use this battery,have they had any problems or swelling with them?

my friend says the esc will rarely go to above 135amp just when im doing aggressive throttling?

Thanks

[Rootz]

Righto. One thing we have to get straight: Whatever the battery supplies - via the speedo, it depends what the motor is asking for.

So! Let's say you're balls-out full throttle. The motor will need more power to get up to the speed you're asking for if the car's heavy or the gearing's longer ( lower ). It'll be pulling more current out of the batteries. Conversely, if the car's really light or the gearings high the motor will find it easier to get up to speed and it'll pull less current out of the batteries.

Now! You've got 4500mAh 30C batteries, which means they should be pretty happy supplying 4.5 x 30 = 135 Amperes and the voltage shouldn't sag too much. Let's say less than 15%. So! the amount of power you can supply with your battery is around 135 x ( 4 x 4.2) x 0.85 = 1928 Watts, which is over 2 horsepower.

If you really tax your motor, it'll drag the battery voltage down, which will mean that the battery needs to supply more current to get the same amount of power. It's (just) possible that your batteries are so sluggish that it'll take the current over the limit for the RX8 but it's really not very likely. I think the RX8 has a maximum current limit setting. Use that if you're worried but I'd be surprised if it ever cuts in in a buggy.

Cheerz!

Rootz

[badger5]

Why should the Tekin be any different to the CC you already have in regard to max amp? And what made you change from the CC, I know the Tekin really should be better as it's sensored but just curious.

As for causing Lipo's to swell, well from my understanding this usually happens when the cells are over discharged or over charged. That's not from trying to draw too much current but when you have run the buggy for long enough that the cells dump and the voltage drops below 3 volts per cell.
The theoretical amount of current a battery can deliver is calculated from the C rating, i.e. your Turnigy cells are 30C and 4500mAh. So that is 4.5A x 30C is 135 amps max current that your cells can supply. A lower C rating will result in less punch. The C ratings can also be optimistic in their rating, and/or reduce over time. I suppose the easiest way I can describe it is driving you old nitro buggy with 15% fuel and then with 30% fuel. In 1/10th I don't think that the batteries are being tested the same way as in 1/8th buggy.
So if your esc and motor can handle more current than your cells can deliver you shouldn't have a problem with Lipo's swelling.

Battery types and brands tends to end up as a heated topic, with many people saying that the cheaper ones are just the same as the more recognised and expensive brands. Until their is a real scientific comparison test then at best all you can do is go by advice from people you trust. There has been tests done by people on YouTube etc that are at best seat of the pants valuation. There has also been some better tests done by bigsquidrc.com, you can find them here http://www.bigsquidrc.com/lipo-battery-shoot-out/ and here http://www.bigsquidrc.com/li-po-battery-shootout-2/
But these two comparison 'shoot outs' is filled with US brands some of which we cannot get easily here.

My personal view is that you could of gained more from buying cells that are a bit better, for example these 4S gens ace units from GiantCod http://www.giantcod.co.uk/gens-5000m...-p-406700.html or two of these 2S batteries linked together http://www.giantcod.co.uk/gens-5000m...-p-406697.html or if you really want to fly you could try these Intellect 2S packs from Demon Power Products http://demonpowerproducts.co.uk/prod...hnology-p-5651
As you can see none of these end up being £200 for a 4S set up, but admittedly still more expensive than what you have.

Please don't take my comments the wrong way, but perhaps this should be your area to look at next for improving your set up. And please be aware with my RX8 the default set up for low battery voltage was switched off and to reset this you will need to reprogram this to 4S or 12V. I would strongly recommend that you do this. Also when I connected my RX8 with the hotwire it found an updated firmware/software for it, if you do not have the hotwire and I can get up to Slough at some time that I would be more than happy to update it for you.

[Nas]

Originally Posted by badger5

Why should the Tekin be any different to the CC you already have in regard to max amp? And what made you change from the CC, I know the Tekin really should be better as it's sensored but just curious.

As for causing Lipo's to swell, well from my understanding this usually happens when the cells are over discharged or over charged. That's not from trying to draw too much current but when you have run the buggy for long enough that the cells dump and the voltage drops below 3 volts per cell.
The theoretical amount of current a battery can deliver is calculated from the C rating, i.e. your Turnigy cells are 30C and 4500mAh. So that is 4.5A x 30C is 135 amps max current that your cells can supply. A lower C rating will result in less punch. The C ratings can also be optimistic in their rating, and/or reduce over time. I suppose the easiest way I can describe it is driving you old nitro buggy with 15% fuel and then with 30% fuel. In 1/10th I don't think that the batteries are being tested the same way as in 1/8th buggy.
So if your esc and motor can handle more current than your cells can deliver you shouldn't have a problem with Lipo's swelling.

Battery types and brands tends to end up as a heated topic, with many people saying that the cheaper ones are just the same as the more recognised and expensive brands. Until their is a real scientific comparison test then at best all you can do is go by advice from people you trust. There has been tests done by people on YouTube etc that are at best seat of the pants valuation. There has also been some better tests done by bigsquidrc.com, you can find them here http://www.bigsquidrc.com/lipo-battery-shoot-out/ and here http://www.bigsquidrc.com/li-po-battery-shootout-2/
But these two comparison 'shoot outs' is filled with US brands some of which we cannot get easily here.

My personal view is that you could of gained more from buying cells that are a bit better, for example these 4S gens ace units from GiantCod http://www.giantcod.co.uk/gens-5000m...-p-406700.html or two of these 2S batteries linked together http://www.giantcod.co.uk/gens-5000m...-p-406697.html or if you really want to fly you could try these Intellect 2S packs from Demon Power Products http://demonpowerproducts.co.uk/prod...hnology-p-5651
As you can see none of these end up being £200 for a 4S set up, but admittedly still more expensive than what you have.

Please don't take my comments the wrong way, but perhaps this should be your area to look at next for improving your set up. And please be aware with my RX8 the default set up for low battery voltage was switched off and to reset this you will need to reprogram this to 4S or 12V. I would strongly recommend that you do this. Also when I connected my RX8 with the hotwire it found an updated firmware/software for it, if you do not have the hotwire and I can get up to Slough at some time that I would be more than happy to update it for you.

The CC only asked for 120 amps and my batterys give out 135 amps.So that was more than fine
WERE AS the Tekin produces 210 at max and my battery goes to 135amps but as ROOTZ said the you can set the maxium amps you want the esc to go up to with the Tekin Hotwire (programmer)

I understand the batterys i have now are not the BEST. but mainly because the better you want them the higher the price goes.

But you send me this link
http://www.giantcod.co.uk/gens-5000m...-p-406700.html

i must say i do quite like that battery but again it draws 200amps and the Tekin is 210amp
All in all i thing 200 IS MORE THAN ENOUGH and ill set the esc to max out at 190amp.

Thanks

[Nas]

Originally Posted by Rootz

Righto. One thing we have to get straight: Whatever the battery supplies - via the speedo, it depends what the motor is asking for.

So! Let's say you're balls-out full throttle. The motor will need more power to get up to the speed you're asking for if the car's heavy or the gearing's longer ( lower ). It'll be pulling more current out of the batteries. Conversely, if the car's really light or the gearings high the motor will find it easier to get up to speed and it'll pull less current out of the batteries.

Now! You've got 4500mAh 30C batteries, which means they should be pretty happy supplying 4.5 x 30 = 135 Amperes and the voltage shouldn't sag too much. Let's say less than 15%. So! the amount of power you can supply with your battery is around 135 x ( 4 x 4.2) x 0.85 = 1928 Watts, which is over 2 horsepower.

If you really tax your motor, it'll drag the battery voltage down, which will mean that the battery needs to supply more current to get the same amount of power. It's (just) possible that your batteries are so sluggish that it'll take the current over the limit for the RX8 but it's really not very likely. I think the RX8 has a maximum current limit setting. Use that if you're worried but I'd be surprised if it ever cuts in in a buggy.

Cheerz!

Rootz

Great help matey cheers

[DCM]

Originally Posted by NASIR

The CC only asked for 120 amps and my batterys give out 135 amps.So that was more than fine
WERE AS the Tekin produces 210 at max and my battery goes to 135amps but as ROOTZ said the you can set the maxium amps you want the esc to go up to with the Tekin Hotwire (programmer)

The RX8 doesn't produce the power, more directs it in the right direction. So the Tekin can cope with more power than the CC. If your cells can only give 135amps, thats all they will give, the RX8 has no way of sucking more power.

[JabberingJimbo]

I have seen the reduced affect of a lower C rating battery like yours, compared to my 50c ones, mainly towards the end of a run.

But it was still way quick enough and may actually of helped control the wheelspin Think of it like a slightly rich nitro down the straight.

This should not lead to any swelling and I would just use them until you can afford a better quality (and C) battery.

Note if your planning on doing the 1/8th electric Nationals you WILL need hardcase.

[Nas]

Originally Posted by JabberingJimbo

I have seen the reduced affect of a lower C rating battery like yours, compared to my 50c ones, mainly towards the end of a run.

But it was still way quick enough and may actually of helped control the wheelspin Think of it like a slightly rich nitro down the straight.

This should not lead to any swelling and I would just use them until you can afford a better quality (and C) battery.

Note if your planning on doing the 1/8th electric Nationals you WILL need hardcase.

oh bloodly hell! hardcases are over £180.00!!

think i'll do the nationals when im like 30 and have a job lol

[Nas]

Originally Posted by DCM

The RX8 doesn't produce the power, more directs it in the right direction. So the Tekin can cope with more power than the CC. If your sells can only give 135amps, thats all they will give, the RX8 has no way of sucking more power.

I understand. Thanks for the help sir

[JabberingJimbo]

£180!!! Your being ripped off then.
I paid £85 for my 5600mah 50c 4s intellects in hardcase.
Will swap to 2s pairs so I can swap between cars and they will be about £40 each for 6000mah.

Shop around a bit!

+1 on getting the RX8 setup and reduce the current down to about 75% and then drive it.
Will have my Hotwire with me if required

[Nas]

Originally Posted by JabberingJimbo

£180!!! Your being ripped off then.
I paid £85 for my 5600mah 50c 4s intellects in hardcase.
Will swap to 2s pairs so I can swap between cars and they will be about £40 each for 6000mah.

Shop around a bit!

+1 on getting the RX8 setup and reduce the current down to about 75% and then drive it.
Will have my Hotwire with me if required

£180.00 for the team Orion batterys and lets be honest to be in the Eletric nationals you want the best batterys right?

[badger5]

+1 on the intellects, bloody good cells. And how says that Team Orion are the best cells? They maybe good but so are several other packs.
If it was me I'd start with something like the Gens Ace pack to get started with and then use them for qualifying etc, then have a good higher mAh pack for finals.
But you don't really have to spend mega bucks to get good kit, just do your research and look a bit beyond the claimed ratings.
Have you looked at the Lipo reviews on the ultimaterc.com channel on YouTube yet? Well worth a look.

[JabberingJimbo]

Originally Posted by NASIR

£180.00 for the team Orion batterys and lets be honest to be in the Eletric nationals you want the best batterys right?

This will be the 1st year the Nat's have ever been held + I'm only an average club driver with a very spread out budget (4 classes!) and I would rather have 1or2 spare batterys I know are OK than 1 super batt that cost a fortune....

Sure if I loose by 0.1s then I made a bad call, but I'm likely to be 2 laps behind and having fun

Spend the money saved on a spare battery for practice or TIRES they will make you quicker (unless your on astro).

[Nas]

Bit of an update

I am keeping my Turnigy batterys.

The seller of the batterys said if they die because there low amps or something he will refund me. He said he tested this system and car and it will NEVER go up to 210 amps.

He tested the car+Tekin esc with a amp meter and it never went above 125amps,even at maximum attack.

MORE MONEY FOR SHINY PARTS!!! lol

Thanks

[VillageIdiot]

Originally Posted by NASIR

Bit of an update

I am keeping my Turnigy batterys.

The seller of the batterys said if they die because there low amps or something he will refund me. He said he tested this system and car and it will NEVER go up to 210 amps.

He tested the car+Tekin esc with a amp meter and it never went above 125amps,even at maximum attack.

MORE MONEY FOR SHINY PARTS!!! lol

Thanks

least you can afford that serpent now

[Nas]

Originally Posted by LIP

least you can afford that serpent now

Jesus christ!

AE for the win! Not Serpent LOL