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LiPo, the big guide thread *updated March '10* *


Garry

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Newb question. If I was to run 2x2s In parallel how would it effect the mah and c ratings and how would it be effected in series? Also would they have to be the same mah Anschluss ratings or can this be different and not cause any problems?

Edited by groome1
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Newb question. If I was to run 2x2s In parallel how would it effect the mah and c ratings and how would it be effected in series? Also would they have to be the same mah Anschluss ratings or can this be different and not cause any problems?

They do need to be 100% identical, same mah, same C rating, same voltage, same brand, same age & condition.

If you need more runtime, buy larger capacity lipos, unless you have a massive chassis and don't need the higher voltage from running 2 packs in series instead...

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  • 3 weeks later...

Hey folks...

Though I would post this up in this section so it can be useful info once someone answers it...

i bought a 2ndhand 3s from a forum member...but it seems to have one cell reading 2.4 volts...

I would like to know if it is possible to do anything to revive it...as I believe the seller when he says it was fine when he had it....

he has offered a refund but i want to make sure there is no way it can be rectified.

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  • 4 weeks later...
  • 2 months later...

New to lipos and have just ordered this charger

http://www.modelsport.co.uk/orion-advantage-iq240-2s-3s-lipo-charger/rc-car-products/36402

And these batteries for this http://www.modelsport.co.uk/vaterra-kalahari-4wd-desert-raider-rtr/rc-car-products/372836

http://www.modelsport.co.uk/orion-advantage-iq240-2s-3s-lipo-charger/rc-car-products/36402

Also ordered a lipo safe bag with the charger, is the charger ok? Not fussed if it takes 30 mins or 4hours to charge but I will be charging in the house and just want to be safe while doing so

Also if I buy an ec3 to traxxas connector could I use the lipos in my Stampede xl5 brushed or am I safer buying a lipo that already has a traxxas connector on it? Thanks for any help

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New to lipos and have just ordered this charger

http://www.modelspor...-products/36402

And these batteries for this http://www.modelspor...products/372836

http://www.modelspor...-products/36402

Also ordered a lipo safe bag with the charger, is the charger ok? Not fussed if it takes 30 mins or 4hours to charge but I will be charging in the house and just want to be safe while doing so

Also if I buy an ec3 to traxxas connector could I use the lipos in my Stampede xl5 brushed or am I safer buying a lipo that already has a traxxas connector on it? Thanks for any help

That's an insult to lipo chargers to call it one, but it will indeed work fine ( no advanced features so if you ever have issues you'll need a proper ~

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  • 3 weeks later...

higher the cutoff value the better it is for your lipos. less undue stress is put on the chemical makeup of cell etc etc

 

as a rule of thumb i try and keep my cutoff point at around 3.5v -3.8v for each cell.

any lower than 3v and your frying the cell ( chemicals become unstable start to release gas) , not every lipo tester lvc etc etc are very good.

they are an indicator not to be trusted but as a guide. same goes with charging no more than 4.2V anything higher will start a chemical reaction

 

i would say 3.5v for each cell, this way it keeps them in good condition, and it is fairly close to the 3.8v per cell storage voltage.

lipos are not as beefy as nimhs and require care and careful charging.

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higher the cutoff value the better it is for your lipos. less undue stress is put on the chemical makeup of cell etc etc

 

as a rule of thumb i try and keep my cutoff point at around 3.5v -3.8v for each cell.

any lower than 3v and your frying the cell ( chemicals become unstable start to release gas) , not every lipo tester lvc etc etc are very good.

they are an indicator not to be trusted but as a guide. same goes with charging no more than 4.2V anything higher will start a chemical reaction

 

i would say 3.5v for each cell, this way it keeps them in good condition, and it is fairly close to the 3.8v per cell storage voltage.

lipos are not as beefy as nimhs and require care and careful charging.

Baring in mind storage voltage is 50% charge/capacity, setting the cutoff for 3.5v means you are only able to use around ~60-70% of the total capacity which is seriously shortening the potential runtime for no good reason. 80% discharge is the industry norm which equates to 3.2-3.4v per cell and has been what is recommended for years. Below this the voltage level drops off sharply so setting the LVC any lower than 3.2v is certainly nto a good idea, but setting it much higher is just wasting runtime ( also bare in mind plenty of packs have been saved when the voltage dropped down as low as ~2.5v, so lipos aren't quite as fragile as nimhs which them selves are very easy to destroy by running too low as well & often only have a couple dozen uses before professional racers relegate them to practice use only...). 

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  • 2 weeks later...

New to lipos and have just ordered this charger

http://www.modelsport.co.uk/orion-advantage-iq240-2s-3s-lipo-charger/rc-car-products/36402

And these batteries for this http://www.modelsport.co.uk/vaterra-kalahari-4wd-desert-raider-rtr/rc-car-products/372836

http://www.modelsport.co.uk/orion-advantage-iq240-2s-3s-lipo-charger/rc-car-products/36402

Also ordered a lipo safe bag with the charger, is the charger ok? Not fussed if it takes 30 mins or 4hours to charge but I will be charging in the house and just want to be safe while doing so

Also if I buy an ec3 to traxxas connector could I use the lipos in my Stampede xl5 brushed or am I safer buying a lipo that already has a traxxas connector on it? Thanks for any help

That charger you put a link up for if you buy it chuck cable away that plug has no fuse i.n it

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  • 3 weeks later...

hi jyst recieved some second hand lipos and the 2s lipos seem to have 8.4v instead off 7.4v which is staded on the battery.

should i be worried about this?

thanks 

joe

Noob.  :002: 

 

Lipos are 4.2v per cell fully charged, 3.7v is the nominal voltage ( ~half charged ), and ~3.2v discharged ( or, set or LVC to this voltage if it is adjustable- don't ask what an LVC is or I will cry.... ).

 

A 2s lipo will therefore be 8.4v fully charged, so nothing to worry about. To learn about lipos and chargers / charging, click the Tutorials link in my sig and read the Lipo chargers & charging section, along with the lipo battery section to get yourself upto speed. :)

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  • 1 month later...

Quick question if you don't mind - I've started using a lipo battery and I'm using a buzzer to tell me when the voltage has dropped to 3.3 volts (Just as a stop gap before getting an ESC with a LVC)

 

However, once the voltage gets to around 3.5 volts, after a short time, the buzzer will go off - I think when I'm punching the power down, the voltage is dropping below 3.3 temporarily, then by the time I've got to it to look at, the voltage has levelled back to about 3.5. Does this sound correct?

 

I've stopped using the car as soon as the buzzer has gone off and re-balance charged it, just to err on the side of caution - but should I carry on until the voltage actually properly drops to 3.3, just not keep pushing the trigger down so hard?

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Quick question if you don't mind - I've started using a lipo battery and I'm using a buzzer to tell me when the voltage has dropped to 3.3 volts (Just as a stop gap before getting an ESC with a LVC)

 

However, once the voltage gets to around 3.5 volts, after a short time, the buzzer will go off - I think when I'm punching the power down, the voltage is dropping below 3.3 temporarily, then by the time I've got to it to look at, the voltage has levelled back to about 3.5. Does this sound correct?

 

I've stopped using the car as soon as the buzzer has gone off and re-balance charged it, just to err on the side of caution - but should I carry on until the voltage actually properly drops to 3.3, just not keep pushing the trigger down so hard?

 

Perfectly normal, voltage will dip lower when pushing it hard(er). I would just say to go easier on the throttle when the buzzer starts to go off, will extend the run time a few more minutes. Mashing the throttle isn't th best idea no matter what as that's how to heat up the electronics faster and damage the drive-train....

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  • 1 month later...

What is the acceptable "off balance" in a LiPo?

 

I have myself a few LiPo batteries, but my 3s seems to have a cell quite out on balance charge. It's taken about 5 charges, and today it has finished charge with the cells at:

4.194

4.191

4.174

 

Battery is a Turnigy 5.0 3s charged at 4a (max current for charger) with the balance board connected.

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What is the acceptable "off balance" in a LiPo?

 

I have myself a few LiPo batteries, but my 3s seems to have a cell quite out on balance charge. It's taken about 5 charges, and today it has finished charge with the cells at:

4.194

4.191

4.174

 

Battery is a Turnigy 5.0 3s charged at 4a (max current for charger) with the balance board connected.

 

Generally speaking, +/- 0.02v is fine- you have to bear in mind that chargers themselves aren't always 100% accurate in terms of the voltages they read ( calibration may or may not be done precisely with high end

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  • 2 weeks later...

Ok so maybe i'm being a bit thick, but I just cant work out what lipo to buy for this.

http://www.modelsport.co.uk/?product_id=34310

 its going in a 4wd 1/10 buggy, help ??

 

2s ( 7.4v ) lipo, anything around ~3500-5000mah & rated for 30C or higher ( continuous ). Check dimensions on lipos vs your buggy though, otherwise the lipo may be too wide or long to fit the battery tray..

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  • 3 weeks later...

So I've just upgraded to this set up:http://www.modelsport.co.uk/etronix-photon-2.0-1-10-brushless-system-12.0r/rc-car-products/368727

Niw I'm looking to go lipo, what are the downsides of getting a 3s 11.1v rather than a 2s 7.4v? Would it damage anything? Is it designed for 3s?

I've been looking at this one:http://www.modelsport.co.uk/overlander-sport-11.1v-5000mah-30c-lipo-pack-no-con.-/rc-car-products/377046

Can you tell me if this would be suitable for an upgrade in battery time and also speed? Thanks

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So I've just upgraded to this set up:http://www.modelsport.co.uk/etronix-photon-2.0-1-10-brushless-system-12.0r/rc-car-products/368727

Niw I'm looking to go lipo, what are the downsides of getting a 3s 11.1v rather than a 2s 7.4v? Would it damage anything? Is it designed for 3s?

I've been looking at this one:http://www.modelsport.co.uk/overlander-sport-11.1v-5000mah-30c-lipo-pack-no-con.-/rc-car-products/377046

Can you tell me if this would be suitable for an upgrade in battery time and also speed? Thanks

 

Read the spec of the esc & motor on that page- it actually tells you they are rated for upto 3s lipo.

 

Nothing will be damaged by running 3s as such, but expect higher temps / possible overheating if you don't alter gearing ( higher voltage = gear down ). Not sure how durable the carnage is so do some research into what other guys run with it.

 

Runtime and speed with be more than fine with that lipo, though there are better value options about ( there are ten billion threads asking about lipo choices- a quick search is all it takes.. )- depends if you want to order from inside the UK and get faster postage, or if you don't mind ordering from overseas ( hobbyking have a UK warehouse but postage speed & stock levels aren't always great )...

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Read the spec of the esc & motor on that page- it actually tells you they are rated for upto 3s lipo.

Nothing will be damaged by running 3s as such, but expect higher temps / possible overheating if you don't alter gearing ( higher voltage = gear down ). Not sure how durable the carnage is so do some research into what other guys run with it.

Runtime and speed with be more than fine with that lipo, though there are better value options about ( there are ten billion threads asking about lipo choices- a quick search is all it takes.. )- depends if you want to order from inside the UK and get faster postage, or if you don't mind ordering from overseas ( hobbyking have a UK warehouse but postage speed & stock levels aren't always great )...

When u say gear down, I have a 17t pinion gear at the moment, what would u recommend changing it to if I get 3s lipo?

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When u say gear down, I have a 17t pinion gear at the moment, what would u recommend changing it to if I get 3s lipo?

 

That's why you need to do some research; I don't own that model, so I can't recommend specific or ideal gearing- it's just a general rule of thumb ( higher voltage / kv rating on the motor needs lower gearing to keep temps in check ).

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