RC cars

SDK^

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Andybtsn said:
Gents, is there a limit to what kind of battery you can put in a car? Example, could I get a 3s lipo and use it in the Tamiya and my Arrma? I'm wary of what it could do to the Lunchbox..
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You need to be careful you don't discharge a LiPo battery beyond it's low voltage limit (usually around 3.2v) as it might get damaged. Cars with ESC's designed to run LiPo's have an automatic low voltage safety cut off to protect the battery.
 
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Andybtsn

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SDK^ said:
You need to be careful you don't discharge a LiPo battery beyond it's low voltage limit (usually around 3.2v) as it my get damaged. Cars with ESC's designed to run LiPo's have an automatic low voltage safety cut off to protect the battery.
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Yeah I think I’ll keep the battery for mine. I managed to get the floureon one for 25 quid which was good
 

rodders

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The arrmas still take the lipo too low and it's annoying you can't up the cut off voltage.
I always stop and check. Ruined a lipo in my granite letting it go to the cut out all the time.
 

mattyy

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rodders said:
The arrmas still take the lipo too low and it's annoying you can't up the cut off voltage.
I always stop and check. Ruined a lipo in my granite letting it go to the cut out all the time.
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The cut out on the BLX system is set too high in my view. My Kraton cuts off at 3.6v, again non adjustable. LiPo will go down to 3.0v although 3.2v is advised as the lower limit.

In your case it may of been down to a bad cell that was dropping lower than it should. Remember that the ESC will only see total voltage of the pack so if you were running 3s the cut off would be 10.8v (3x3.6v) it doesn’t care how that voltage is made up across the three cells as it doesn’t know. So it is entirely possible to drag one cell down to low while still retaining the cut out voltage of the pack above 10.8v.
Cheaper LiPos will suffer from this.
 

Mr_Clark1000

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Just run a cell monitor / cell voltage buzzer. Used to use those in my custom drones all the time. They display min cell voltages and beep insanely loud when you get to you low cell set point, they are mega small, cheap and just connect to the balance lead. Good bits of kit to have spare.

I've just got myself an Arrma Outcast 4S and am resurrecting my 4S packs from years ago when I had my custom drone fetish. Truth be told, I haven't used the monitor because I don't see the ESC letting the whole pack get down to a point where I would expect a cell to be way out of kilter, I think I saw a 3.35 min cell voltage just after a run when it went into limp mode.

Funny thing is my Turnigy 5000mah packs that I was flying with on my Australia / New Zealand tour about 5 years ago and went into storage for a good 2 - 3 years, are still holding about 4800 - 4900 mah with good cell balance. These packs were not treated all that nicely what with being in Aus in 40+ heat... They have held up really well. Says a lot about being super careful with cell voltages and putting them into storage mode any time they might be sat for a day or two...
 

Yrkoon

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SDK^ said:
You need to be careful you don't discharge a LiPo battery beyond it's low voltage limit (usually around 3.2v) as it might get damaged. Cars with ESC's designed to run LiPo's have an automatic low voltage safety cut off to protect the battery.
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i would highly recommend against 3s in a lunch box, as sdk says you would need a esc with an auto cut off as if the voltage on a lipo drops to much there is a irreversible reaction on the chemistry in the battery, a low voltage cuttoff lvc will cut power to the motor.

there are also low voltage alarms but you wont hear them if the cars not next to you.

when i first got my xxb and xxt i was going nuts having a laugh with 3s lipo's, these things support 3s out the box but it has not been kind to the gears and i got fed up rebuilding them by snapping the chassis etc so i only run 2s now, you will find a 2 cell lipo will have a bit more punch than a 8.4 volt nimh :)

i have a cheapo probably desinged for boats esc in my tamiya tt-01 just so i can use lipos and have a cut off on a brushed motor, i tried a brushless motor and it kept flippin on its roof and it's a road car lol

oh got a pro tip never buy a maverick atom and then put in a 6000kv brushless motor system and 2 cell lipos..... the poor differentials did not like it lol
 

mattyy

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rodders said:
I wish it was a cheap one, it wasn't!
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Sorry I didn't mean to imply that it was. It was meant that in my experience I've noticed it more in the cheaper packs I've bought opposed to the more expensive ones, maybe down to cell matching - I don't know.

I've recently been running the 4s and 6s Hobbyking HD packs and for the cost, they have been perfect so far.
 

rhysduck

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Yrkoon said:
i would highly recommend against 3s in a lunch box, as sdk says you would need a esc with an auto cut off as if the voltage on a lipo drops to much there is a irreversible reaction on the chemistry in the battery, a low voltage cuttoff lvc will cut power to the motor.

there are also low voltage alarms but you wont hear them if the cars not next to you.

when i first got my xxb and xxt i was going nuts having a laugh with 3s lipo's, these things support 3s out the box but it has not been kind to the gears and i got fed up rebuilding them by snapping the chassis etc so i only run 2s now, you will find a 2 cell lipo will have a bit more punch than a 8.4 volt nimh :)

i have a cheapo probably desinged for boats esc in my tamiya tt-01 just so i can use lipos and have a cut off on a brushed motor, i tried a brushless motor and it kept flippin on its roof and it's a road car lol

oh got a pro tip never buy a maverick atom and then put in a 6000kv brushless motor system and 2 cell lipos..... the poor differentials did not like it lol
Click to expand...

Hi :)

I have a TT01 chassis which I'd like to convert to lipo... I'd be interested in hearing how you've gone about if you wouldnt mind sharing pelase, motor/esc combo etc. Thanks

I also have Baja Champ which is on a TL-01B chassis that I'd like to convert!
 

Yrkoon

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rhysduck said:
Hi :)

I have a TT01 chassis which I'd like to convert to lipo... I'd be interested in hearing how you've gone about if you wouldnt mind sharing pelase, motor/esc combo etc. Thanks

I also have Baja Champ which is on a TL-01B chassis that I'd like to convert!
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just had a look under the shell the esc says model sport sniper, it is one of the water proof ones and probably designed more for boats than cars but it works awesome on 2s and a brushed 17 turn motor :)

resembles this https://www.modelsport.co.uk/modelsport-uk-sniper-rv-20-auto/rc-car-products/31775 but has lvc etc.

linked one is different than mine.

edit: heres a list of them https://www.modelsport.co.uk/index.php?search=1&search_string=sniper

sure i paid less than 20 for it many moons ago :)

edit: meh im drunk and just had a second look at the esc rv-12 assault is the exact one :)

the price seems to off jumped up since i bought it :(

just using a 17 turn or a 21 turn motor brushed with the above esc and 2s lipos :)

i tried a 3000kv brushless motor in it but it never worked out.... i could flip the car from a stand still with that lol

oh use deans connectors, the tamiya style ones suck donkey twangers lol they will melt while deans ones are awesome, just make sure u have a solder iron to switch the connectors :)
 
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Yrkoon

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SDK^ said:
Nice - which Typhon did you go for?
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rhysduck said:
Hi :)

I have a TT01 chassis which I'd like to convert to lipo... I'd be interested in hearing how you've gone about if you wouldnt mind sharing pelase, motor/esc combo etc. Thanks

I also have Baja Champ which is on a TL-01B chassis that I'd like to convert!
Click to expand...

heres some pics of my tt-01 :)

fUkH2O5.jpg

fT2sqZV.jpg

KSh06Os.jpg

oh i changed the shocks and the metal drive shaft came with it, the poor thing was sitting in my local shop for ages, got it fully ball raced and metal prop shaft, guys in the shop kept taking parts and putting in upgraded parts in the box, was a joy to build :)
 

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mattyy said:
Sorry I didn't mean to imply that it was. It was meant that in my experience I've noticed it more in the cheaper packs I've bought opposed to the more expensive ones, maybe down to cell matching - I don't know.

I've recently been running the 4s and 6s Hobbyking HD packs and for the cost, they have been perfect so far.
Click to expand...

No worries, I never took anything from it! Just saying that even expensive batteries can go bad.
 

SDK^

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So both of the steering servo’s in the Revo are dead - no sound or motion from them but the throttle works fine :(
I’ve messaged Traxxas for replacements.
 
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