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Thread: Can you run 5s

  1. #1
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    Can you run 5s

    Maybe this is a crazy question but can you use a 2s battery in one bay and a 3s in the other battery bay? If so what kind f speed would be seen would this on a stock 2.0?

  2. #2
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    If they were both 5000mah 35c just one was 2s and the other 3s yes. But I'm not sure it's good on the packs..

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    RC Champion FnFancy's Avatar
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    The battery industry recommends using the same brand, same mah, same discharge and same cycle count for the mismatched batteries. Please be careful, monitor voltage and internal resistance.

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    Thanks guys, don't think I will be doing that then. Either it would be 4 or 6s then.

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    You can run one 2s and one 3s,just make sure mah and discharge rate matches(preferable same manufacture). That's exactly what I run in my summit. I use Traxxas 5000mah batteries,one 2s and one 3s = 5s. Batteries show no ill effects. When I put them on charge all the cells drained equal.

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    Yep you can. As said above make sure they have the same specs. Same mah, c rating, and are the same battery manufacturer. You may want to get a battery monitor/alarm and set the LVC to 3.4-3.5vpc. JMHO’s.

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    I asked this question a few months ago. Finally a good answer!

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    Let us know how the batteries do in the long term if you choose to do it
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    Something worth noting that I post on these topics a few times per year....
    The second battery in the series connection sees a higher stress. It is recommended to label your batteries and alternate which one is battery 2 in the series each time you run it. If you continually run the same battery in postion 2 it will likely see end of life sooner than battery 1.

    -Liberty

  10. #10
    Marshal ksb51rl's Avatar
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    Quote Originally Posted by Peeeenuuutt View Post
    I asked this question a few months ago. Finally a good answer!
    "Good answer" or not, I can see no correct answer above.
    Per the manual:
    Quote Originally Posted by ATTENTION: USING LiPo BATTERIES
    The VXL-6s electronic speed control is designed to operate on 4S or 6S LiPo battery power.
    Also:
    Quote Originally Posted by VXL-6s Specifications
    Input voltage: 4S/6S LiPo (max. 22.2 volts)
    The current stock ESC is not spec'd to run on 5S.
    Alt-248 on the number pad = °

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    Good question ksb51rl. I asked tech support about the VXL-6s. I am not familiar with it. I asked if I could run 5s and if the auto detect would detect 4s,5s,6s and they said it should. Then they said they don't have a 5s. To see how they would answer I asked if I could use one 2s and one 3s battery and his answer was a little "off". The answer was "they would discharge at different rates". That means two 2s or two 3s batteries would do the same thing. Which they don't as we already know. Most phone support are customer support people reading from a generic flowchart or checklist. To get a real specific tech question answered need to talk to their engineer for that product.
    A Lipo battery is made of individual cells. Manufacturer just adds cells to reach the size of the pack they are making. A 2s battery is the same as a 3s battery minus one cell. Think of a flashlight as a LiPo battery and the batteries you put into the flashlight as the LiPo cells. You could have a flashlight that took 2 batteries or a flashlight that took 6 batteries. When the flashlight died all the batteries were dead, not one fully charged and the rest dead. The reason I said yes is because I personally have done it with other ESC's. Both batteries discharged the same wired in series (which is how the bigger Traxxas ESC's are wired they have 2 plugs). Which is why you need to use batteries of same Mah,discharge rate,and manufacturer.

    Now if your worried about the ESC's ability to auto detect, you can turn it off and run a separate Low voltage alarm or manually select cutoff voltage. I set mine at 3.5v per cell which would be 3.5x5=17.5v. The ESC doesn't know how many batteries or LiPo cells are plugged in, only voltage and sets auto LVC based on software installed. I don't see how any ESC is strictly able to run two specific different voltages other than the software installed to detect low voltage for LVC. An example would be(assuming Traxxas settings at 3.2v LVD)4s alarm would be at 12.8v, 6s alarm set at 19.2v, and have no other values set for a different auto voltage alarm. All ESC's I have seen are able to be used in a voltage range. You could use three 2s batteries to equal 6s voltage or six 1s batteries to equal 6s voltage. Castle Creations Mamba Monster(which Traxxas has used) has a range of 2s min to 6s max. Tekin RX8 ESC also has a range of 2s to 6s. The ESC is going to put out the same voltage that is going in.
    For the original question of:
    can you use a 2s battery in one bay and a 3s in the other battery bay?
    Yes you can, just match up batteries of same Mah,discharge rate,and manufacturer.
    Quote Originally Posted by ATTENTION: USING LiPo BATTERIES
    The VXL-6s electronic speed control is designed to operate on 4S or 6S LiPo battery power.
    Only thing I can think of is for auto detect for the VXL-6s.
    Quote Originally Posted by VXL-6s Specifications
    Input voltage: 4S/6S LiPo (max. 22.2 volts)
    Notice how they stated max 22.2 volts not 14.8/22.2 volts only.
    The current stock ESC is not spec'd to run on 5S
    The current stock ESC is spec'd @max 22.2 volts where 5s is under the max of 22.2 volts. The only reason reason why not would be for 5s auto detect for LVC. If you go into Traxxas link app it shows a 5s LiPo setting.

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    As a note where I said "you need to use batteries of same Mah,discharge rate,and manufacturer" this holds true if you are running two 2s lipo batteries or two 3s batteries. Also you would do the same for any LiPo batteries used in series all the way from 1/16 revo to the X-Maxx. Running mismatched batteries in Mah or discharge rate( C rating ) one battery will discharge alot sooner and lower than the other and if using a low LVC setting it will ruin a battery. Running mismatched manufacturer batteries you take a chance of running different specs on the batteries.

  13. #13
    Marshal ksb51rl's Avatar
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    Again, the documentation is clear. It specifies 4S or 6S, not 4S through 6S.

    Contrast this with the spec of the Castle Creations Mamba Monster 2, which we are familiar with as the MXL-6s:
    Quote Originally Posted by Technical Specs
    Input Voltage Range: MIN: 2S LiPo; MAX: 6S LiPo
    Quote Originally Posted by Application Guidelines
    Intended for up to 6S (25.2 Volt) operation
    Are the specs just described differently or does the fundamental difference in the ESCs require differ input?

    I don’t know whether 5S will cause problems or damage. It is an unusual spec. A wise older man at an engineering company once advised me, “If you see a strange number on a spec or requirement, pay attention to it - there is probably a reason for it.”

    Because you cannot think of a reason why it should not work is a horrible argument. That is dealing from a position of ignorance, as much as I would be dealing from the same position if I asserted that I know it won’t work fine. The difference here is that I have published documentation that supports my advice and that I’m not encouraging others to do something that will potentially damage their property.
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    Okay I just found this thread after trying to run 5S in my 2.0. The LVC kicks on immediately. I turned off the safety just to try it for like 2 minutes and then I lost steering. I'm not sure what that was all about yet. I have brand new SMC 7200 packs (2s and 3s). Can anyone confirm they have been running 5s okay? I don't want to mess anything up.

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    Okay looks like something broke because my steering is out and won't come back. I was just driving, stopped for a second and went to drive again and it wouldn't work. Reset transmitter, re-binded, checked connections. Throttle works fine. This might be due to the 5S.

  16. #16
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    As I said I haven't dealt with VXL-6s.
    Because you cannot think of a reason why it should not work is a horrible argument.
    I never said I cannot think of a reason why it should not work! The only thing I said was, it is possible Traxxas could have not installed software for 5s setting for auto detect without using Traxxas link. This is the only reason. In Traxxas link it does show a 5s setting for the new revo 2.0 VXL-6s. Why is there a setting if you cannot use it?
    Contrast this with the spec of the Castle Creations Mamba Monster 2, which we are familiar with as the MXL-6s:
    Quote Originally Posted by Technical Specs
    Input Voltage Range: MIN: 2S LiPo; MAX: 6S LiPo
    Quote Originally Posted by Application Guidelines
    Intended for up to 6S (25.2 Volt) operation
    If the VXL-6s is the same as the Mamba Monster 2 it clearly states in the Monster 2 Driver's Ed Guide
    Option 2: Auto-Lipo (Default)
    This setting automatically detects the number of LiPo cells you have plugged in. It will
    automatically set the cut-off to 3.2 volts per cell. It will beep the number of cells in your LiPo
    pack between the initialization tones and the arming tones on initial power up of the controller.
    When you plug in 5s it does beep 5 times indicating 5 cells.
    There is no statement of ignorance, or he said-she said comments. The question of "can I use 5s?" comes up a lot and the answer is yes. I run 5s myself, happy medium between 4s ok-speed and 6s crazy power for me. It is another option besides thinking your stuck with either 4s or 6s.
    The instructions for Traxxas VXL-6s cannot be found anywhere, but the instructions for the MXL-6s are, which is the previous version to the VXL-6s. And in the instructions it states:
    Specifications:
    Input voltage .................................................. .......18 NiCad/NiMH / 6S LiPo (Max 25.2 Volts)
    Supported motors............................................ . Brushed / Brushless / Sensorless Brushless
    On-resistance........................................ .................................................. ....0.0003 ohms per phase
    Battery connector......................................... ......................... Traxxas High-Current Connector
    Motor connectors........................................ ................................TRX 6.5mm bullet connectors
    Motor/battery wiring............................................ ................................... 10-gauge Maxx® Cable
    Case size (l/w/h)................................................ ....... 56mm (2.2”)/ 48mm (1.9”)/ 36mm (1.4”)
    Weight............................................ .................................................. ..................................121g (4.27oz)
    Low-Voltage Detection Setting
    The MXL-6s is optimized to operate out of the box with these battery
    configurations:
    • 7-cell (8.4v) NiMH batteries (2)
    • 2S (8.4v) LiPo batteries (2)
    • 3S (11.1v) LiPo batteries (2)
    Note: The low-voltage detection (LiPo mode) does NOT need to be disabled
    when using 7-cell (8.4v) NiMH batteries (2).
    The MXL-6s electronic speed control is able to use LiPo batteries with nominal
    voltage not to exceed 11.1 volts (3S packs) for each battery (6S total). LiPo
    batteries have a minimum safe discharge voltage threshold that should
    not be exceeded. The MXL-6s electronic speed control is equipped with
    built-in Low-Voltage Detection that alerts the driver when LiPo batteries
    have reached their minimum voltage (discharge) threshold. It is the driver’s
    responsibility to stop immediately to prevent the battery pack from
    being discharged below its safe minimum threshold.
    These instructions say optimized for, not programmed for. And they say not to exceed a 3s battery for each battery. A 2s battery is lower than a 3s battery. So in these instructions you could have one 2s battery and one 3s battery and have not exceeded the nominal voltage of 6s(total). When Traxxas releases the instructions for the VXL-6s it will be worded the same. The only issue you could have running 5s on the VXL-6s would be the autodetect not detecting 5 cells for LVC without using Traxxas link.
    I have provided documentation from the instructions from Castle on the Mamba 2 ("which we are familiar with as the MXL-6s:") it will work. And I also have shown from Traxxas's own documentation from previous version ESC you can use 5s.

  17. #17
    RC Champion FnFancy's Avatar
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    Granted I spend read your post, but nowhere did I see 5s called out, it's a ******* voltage and it's very possible Esc's do not have the ability to recognize it. Don't get me wrong, some do but purpose built Esc's (vxl-6s for example) might not have the capability of recognizing 21v as an option. Hence the low voltage cut of as soon as you plug it in. Aftermarket Esc's would probably be your best ticket for running five cells.

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  18. #18
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    Quote Originally Posted by ksb51rl View Post
    Again, the documentation is clear. It specifies 4S or 6S, not 4S through 6S.
    On the ESC specs for the Revo 2.0 it shows 4s–6s LiPo (max: 25.2 volts) which means 4s through 6s(max 25.2v). If it where to show 4s/6s LiPo (max 25.2volts) that would mean 4s and/or 6s(max 25.2 volts). That is what the symbols mean in the engineering field. Documentation in the owners manual is not clear, it does say 4s or 6s in a sidebar note, and it also shows in the ESC specs as 4s through 6s. I would go with specs because that is how it is listed in more than one place.

  19. #19
    Marshal ksb51rl's Avatar
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    @grizzly03:
    The MXL-6s is NOT the “previous version” of the VXL-6s. They are totally, 100%, wholly different designs from different manufacturers (got that now?) that HAPPEN TO BE installed in different versions of the E-Revo.
    All posting irrelevant specs does is confirm that you really don’t know what you’re talking about. Please stop forcing and twisting facts to support your conclusion.
    Thank you for posting your experience using 5S. Others should remember that their mileage may vary when using batteries outside of the voltage spec, as it has since the days of the original Novak-designed EVX.
    Again, it worked for you. It may or may not work well for others.

    Thread closed.
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