PF Maximum Voltage

[rkkm]

Im new to this forum so hi everyone ;)

i have fun with PF from few months, and i want to buy a li-po and customize it to lego, i got two of real power hungry buggy motors, and i want to feed em' as much as i can :D I only need to know which voltage is maximum for motors, and for reciever, i have maken a research across internet, and ive heard that motors can handle max 16volts , and reciever just 9 volts, but ive heard too that motors can handle max 12 volts and that reciever too, on many forums i have read different numbers, so i have to ask here :) i have found light and small 14,8 volt li po 850 mah, in good price and i like it, but i dont want to burn my buggy motors and rest of PF, im wondering too  about rc unit voltage, if it have 6 aa 1,5v bateries fully charged, it could generate 9v as normal pf battery box but when i compared them, rc unit is way better, and buggy motors are way faster, i hope that someone can help me :)

[syclone]

Welcome to Eurobricks!

Lego 9V motors are actually 12V motors , not sure about the PF receiver. If you need any info on lego electrics/electronics , the best place is Philo's page

[Aventador2004]

Lxf, where did you here that? I heard they were always 9 volts. The rechargeable 8878 battery has 8.4 volts at full.

[Saberwing40k]

When in doubt, go lower. Or, you don't even need a Lipo if you have an SBrick or Buwizz. I've actually got a train controller, and it came with a 12v adaptor, even though the actual output is closer to 9v. But, I've never heard of receivers being useable at 12v. Also, no matter the voltage, you're going to have problems with the thermoresistor.

[rkkm]

What do you think about li-ion 6800 mAh 4,2 volt rechargable AA bateries?  I found em on polish Allegro and aliexpress: https://pl.aliexpress.com/item/4-pcs-lot-Original-18650-Li-ion-2600-mAh-3-7V-Lithium-Battery-18650-Rechargeable/32802038516.html?spm=2114.010208.8.17.nIx74g

 

what do you think about em?

[Attika]

15 minutes ago, rkkm said:

What do you think about li-ion 6800 mAh 4,2 volt rechargable AA bateries?  I found em on polish Allegro and aliexpress: https://pl.aliexpress.com/item/4-pcs-lot-Original-18650-Li-ion-2600-mAh-3-7V-Lithium-Battery-18650-Rechargeable/32802038516.html?spm=2114.010208.8.17.nIx74g

 

what do you think about em?

Hi, What I think is the link shows a totally different battery, not what you were asking about. So it is hard to tell. But to clearify the numbers: Sbrick' limit 10.5 volt. Don' go above. Lego recievers are not even worth to mention with any unique power source, they can overheat even from the regular AA battery box. All the lego motors are 12 v motors, using them on 9 volt is a safety issue for extended lifetime. You've been writing so many numbers that I have vertigo. 14.8 volt Lipo is must be a 4S Lipo (3.7x4) but those on full charge give you (4.2x4) 16.8 volts. That will surely fry everything. I'm using Lipo's, infact I'm using ONLY Lipo's for years now. You don't need more than 2S lipo battery that is 8.4 volt on full charge. What matters is the current it is capable to deliver, and even this "low voltage" solutions are sometimes overheating the buggy motors. The next step would be the 3S Lipo what delivers 12.6 volts, but that is gonna kill your reciever sooner or later and/or the buggy motor. If you have the recource to replace these things frequently (motors and recievers) than go on, otherwise use 2S Lipo's and all your parts will last for years. Or buy a Buwizz that gives you 10.5 volt and this limit is not accidental. That is about the top f safe voltage for lego parts.

[MajorAlvega]

1 hour ago, rkkm said:

What do you think about li-ion 6800 mAh 4,2 volt rechargable AA bateries?  I found em on polish Allegro and aliexpress: https://pl.aliexpress.com/item/4-pcs-lot-Original-18650-Li-ion-2600-mAh-3-7V-Lithium-Battery-18650-Rechargeable/32802038516.html?spm=2114.010208.8.17.nIx74g

 

what do you think about em?

You are confusing battery types. 18650 is not AA size, is much bigger.  AA size compatible LiIon batteries are the 14500. These are rated for much lower mAh (I've been using 600 mAh, I know there are some up to 900 mAh, not more - even if some sites announce more, don't believe).

Both 14500 and 18650 batteries are LiIon, not LiPo. They have very high discharge rates - the 14500 that I use have internal protection that cuts at 4A, I think - that's good to use with the SBrick. But a few models don't have internal protection - and that is very dangerous.

You need a proper charger - common NiMH chargers don't work but there are some models that can charge both NiMh and LiIon.
I've used 14500 batteries with LEGO a few times. Here you can see my 42965 RC Tracked Racer running with 3x14500 - that's 12.6 Volt when full charged so I use some dummy batteries with diodes inside to reduce to a safer value, around 11 Volt:

 

[move5]

An alkaline battery is only 1.5v at the very first moment and the average voltage is around 1~1.2v. And when we say a NiMH or lipo or li-ion is 1.2v, that means the average is 1.2v, and actually, the highest voltage is around 1.4v. So, whatever, It's just my personal opinion, but wouldn't the maximum voltage be 9v? Maybe it can still run over 9v, but maybe the motors are being harmed.

[mocbuild101]

Firstly never go over 12v with any electric Lego parts, and try to keep the voltage as close to 9v as possible

7 hours ago, LXF said:

Lego 9V motors are actually 12V motors

I can confirm this, all Lego motors are 12v inside because it is safer when 9v is used.

6 hours ago, Aventador2004 said:

The rechargeable 8878 battery has 8.4 volts at full.

It is actually rated for 7.4v and only has 8.4 immediately after charging. 

[syclone]

In my experience , Ni-Zn batteries are very good. Delivering 1'6V each , you can use all PF range without problems and with more power. I have these batteries , but to make them work , you need to get a new type of AA battery box ( bright green LED instead of lime) otherwise, it won't work unless the thermal protection is removed.

Edited April 16, 2017 by LXF

[JJ2]

17 hours ago, rkkm said:

Im new to this forum so hi everyone ;)

i have fun with PF from few months, and i want to buy a li-po and customize it to lego, i got two of real power hungry buggy motors, and i want to feed em' as much as i can :D I only need to know which voltage is maximum for motors, and for reciever, i have maken a research across internet, and ive heard that motors can handle max 16volts , and reciever just 9 volts, but ive heard too that motors can handle max 12 volts and that reciever too, on many forums i have read different numbers, so i have to ask here :) i have found light and small 14,8 volt li po 850 mah, in good price and i like it, but i dont want to burn my buggy motors and rest of PF, im wondering too  about rc unit voltage, if it have 6 aa 1,5v bateries fully charged, it could generate 9v as normal pf battery box but when i compared them, rc unit is way better, and buggy motors are way faster, i hope that someone can help me :)

I would not recommend a 4S lips with 14.8V since Lego motors are 12V, a 3s would work fine with 11.1 volts. I don't think the receiver can handle over 9 volts so maybe go with a RC grade ESC and a FLY SKY remote-reciever, I use that remote and its very good for its price. The RC motors internal motor is a 280 size guessing from its size so would use a dual motor ESC like this one, or this one. With those parts you can have really long range and you can control the motors speed better then any Lego IR.

[dr_spock]

I think you can go as high as you dare to go if motor life longevity isn't part of your requirements.

 

[Kelkschiz]

When you replace the PF battery box with with Lipos then the weakest link is the receiver, not the motors. While the motors will happily take 12volt the receiver will not, especially not at high amperage loads. For that reason I would strongly recommend not going over S2 for lipos, 8,4 volts is plenty. Recently I made a LEGO tank with four RC Buggy motors, and 2xS2 Lipos, and it flies on the available power. 

[Cornersruns]

I use 3S1P LiPo packs, but because I use RC speed controllers Ebay link that are only rated at 2S ( I use these because they are the smallest available but they will die with 3S ) I have a voltage reducer Ebay voltage reducer before the electronics.  I adjust this to about 9.6V.  Also important if using LiPo is an alarm to warn if the voltage of the cells gets too low Ebay low voltage alarm.

The ebay links are where I have bought from without issues, plenty of other sellers have identical items as well.

[TimberBrick]

I use regular AA Lego packs to operate both SBrick and Lego IR receivers at 10.8 volts.  In at least 40 hours of operation at high amperage, none have died.  I use 5 NIMH batteries with one LION.  The power increase is substantial.  Other combinations with spacers is possible for weight reduction.

[rkkm]

Thanks for help :) i wont buy lipo, i have bought three 10440 ( aaa size ) 3,6v batteries, ill put only three of them into batbox and three aluminium things in form of aaa baterie ( i found this way on philohome ).

[mocbuild101]

11 hours ago, Cornersruns said:

I use 3S1P LiPo packs, but because I use RC speed controllers Ebay link that are only rated at 2S ( I use these because they are the smallest available but they will die with 3S ) I have a voltage reducer Ebay voltage reducer before the electronics.  I adjust this to about 9.6V.  Also important if using LiPo is an alarm to warn if the voltage of the cells gets too low Ebay low voltage alarm.

That's a lot of stuff just for a bit more power .

9 hours ago, TimberBrick said:

I use 5 NIMH batteries with one LION.

Mixing different types of batteries is not recommended.

[Rockbrick]

i remember putting 9v through the old 4.5v motor system.... never burnt the motor out but wore gearwheels away like crazy

[TimberBrick]

11 hours ago, mocbuild101 said:

Mixing different types of batteries is not recommended.

Mixing batteries is only a problem for charging a whole pack.  In this case the batteries are charged individually in their respective charger types.  The capacities of the LION and NIMH batteries are different, so for discharge the lower LION capacity limits the discharge duration.  My application is battle bot pushing contests typically with four XL motors.  The extra voltage limits the likelihood of stalled motors and makes for great action!

[Epic Technic]

I'm not sure of the exact PF voltage limits, but for the IR receiver, do not go over 9 volts - I fried one at 10V. I learned a lot on lithium Ion batteries when I was making my electric skateboard. When you're buying Li Ion batteries, I would recommend getting brand name batteries (e.g. Samsung, LG, Sony, Sanyo, Enloop, a123), they are less prone to damage. For the cheapest prices in the EU, you should by the cells from eu.nkon.nl . For the most safety, don't forget to balance charge each cell, but many people believe this is unnecessary. !!If you find super cheap Li Ion cells on ebay or aliexpress which claim that they're 10,000mAh with 20A max discharge for only 2 dollars it's a scam. If it looks to good to be true, it probably is!!

Edited April 18, 2017 by Epic Technic

[mocbuild101]

17 hours ago, TimberBrick said:

Mixing batteries is only a problem for charging a whole pack.  In this case the batteries are charged individually in their respective charger types.  The capacities of the LION and NIMH batteries are different, so for discharge the lower LION capacity limits the discharge duration.  My application is battle bot pushing contests typically with four XL motors.  The extra voltage limits the likelihood of stalled motors and makes for great action!

I just said that because I once put 4 NIMH with 2 alkaline in a PF battery box, and both alkaline batteries started leaking after only 10-15 minutes of use.

[rkkm]

On 16.04.2017 at 1:50 AM, MajorAlvega said:

You are confusing battery types. 18650 is not AA size, is much bigger.  AA size compatible LiIon batteries are the 14500. These are rated for much lower mAh (I've been using 600 mAh, I know there are some up to 900 mAh, not more - even if some sites announce more, don't believe).

Both 14500 and 18650 batteries are LiIon, not LiPo. They have very high discharge rates - the 14500 that I use have internal protection that cuts at 4A, I think - that's good to use with the SBrick. But a few models don't have internal protection - and that is very dangerous.

You need a proper charger - common NiMH chargers don't work but there are some models that can charge both NiMh and LiIon.
I've used 14500 batteries with LEGO a few times. Here you can see my 42965 RC Tracked Racer running with 3x14500 - that's 12.6 Volt when full charged so I use some dummy batteries with diodes inside to reduce to a safer value, around 11 Volt:

 

Where do you bought these fake batteries with diodes?

[MajorAlvega]

I made them myself - just wrap tin foil around each diode anode/katode, you can use something like the body of a plastic pen to give it more strength:

Dummy AA battery with diode by Jorge Pereira, on Flickr

The batteries on my photos look pretty ugly but after 2 or 3 attempts you'll have something decent. If you just want a fake battery without diode just wrap enough tin foil around a stick of hot glue or a pencil.

For 3A diodes I used common 1N5401.

[rkkm]

Yea i need those fake batteries which reduce voltage, i got 3 14500 3.7 volt aa bateries, i bought supersonic racer , and i was testing, with all 3 fully charged and 3 fake aluminium bateries, motors works well, but not buggy motor, it gots problem with that voltage when we reverse direction of rotation, when i turn on buggy motor it is ok, not smellining like fired, not act like crazy, but when i change reverse direction it stops... Same with supersonic, i put 3 batteries not fully charged ( one 3,8v and two 3,5 v) and it goes welll till i reverse direction of rotation, it stops buggy motors and servo, and does sound like brrrrrrr grrrr or anything like error sound, i also tested 3 bateries fully charged with ir reciever v1 and it is smelling kinda like from china but also ir controller smells same , but i got crawler 4x4 too and ir reciever v2 and its controller doesent smell anything, im using in rc unit 2 fully charged batteries so 8,4 volt, but i want to use those reducing voltage. How much one fake battery with diode will reduce voltage? if i put 3 of fake diode batteries and 3 fully charged generating 12.6v how much fakes will reduce?

can u do some photos of how to make those fake batteries? i dont really know how to make em from those photos,just if u could do photos of materials needed and little guide please :)

[MajorAlvega]

Each 1N5401 diode drops 0.6 to 0.8 Volt (depends on current). I usually use 2 diodes and one shunt so 1.2 to 1.6 Volt.

If you have enough diodes you can use a pair for each fake battery, reverted, so you don't need to care about polarity when inserting on the battery box.

Take care with heat - 0.8 Volt at 3 Ampere means 2.4 Watt on each diode. Not dangerous for short races but not neglectable.