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  1. #1
    RC poster
    Join Date
    Feb 2020
    Posts
    5

    Low voltage detection part two

    I donít know if it is the charge not charging my batteries but whenever I connect a battery the car runs for a few seconds and then low voltage detection is turned off I checked the voltage of my batteries and it said the voltages we about 9 when they were supposed to be 11.1. Any suggestions?

  2. #2
    RC Qualifier Panther6834's Avatar
    Join Date
    Jan 2019
    Location
    SF Bay Area
    Posts
    963
    That's not just "low voltage"...that's, essentially, "dead voltage". "Low voltage" is typically 3.2V/cell. When a Traxxas charger see a battery below that, it might not charge it. If it see a battery at 3.0V/cell (which is where yours appears to be), or below, it considering it a "dead" battery, and will never change it again. Depending on how old the battery is, you have 2 options. If the battery is older than a couple years, you might just want to it away (ie. properly dispose of it at a better recycling center, NOT in the garbage). If the battery is less than 2 years, and is in good condition (ie. it's not "puffy"), you could try 'resurrecting' it, which will require a non-Traxxas charger, and a Traxxas battery lead adapter (since Traxxas uses a proprietary connector).

    Going this route could take wire a long time, as even that charger will have 'difficulty' charging the battery. Also, the trick to making this work is to set the charging level NO higher than 2C...trying to charge any faster could have disasterous results (ie. ever seen a LiPo battery explode, it catch fire?). When initially charging the battery, it will start it's unusual "trickle" charging, ramping up the voltage as is goes. However, after trickle-charging for only a very short period (usually less than a few minutes), the charging will stop, and the charger will give you a "low voltage error" (technically, the error is 'correct'). When this happens, disconnect, then reconnect, the battery, and restart the charging. You'll have to do this at least a few times (possibly a dozen times, it more, depending on how long the battery's voltage actually is when you first start the process) before the battery finally gets to that 3.2V/cell minimum. Once the battery finally reached that minimum 'alive' level, it should continue charging normally, until it reaches peak voltage. Once it's "brought back from the dead", future chargings can be done using the Traxxas charger...well, unless you 'kill' it again, in which case you'll have to repeat the above process.

    I've gone through this process before, and I can tell you that it DOES work...you just need to have some patience. Most ESCs have their voltage cutoff set at 3.2V. some vehicles, sick as the Losi Baja Rey I recently purchased, have the default setting at 3.0V, but the user can change the setting to a higher amount (usually in 0.1V increments). The moral of this story is, if you set your ESC's cutoff at 3.2V, AND you don't continue running your vehicle when the "low voltage cutoff" kicks in, you should never run into this "dead battery" situation. This occurred to me before I knew any better...don't let it happen to you again, and help others understand how it can occur, so that you can help them prevent it from happening to them.

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  3. #3
    Marshal ksb51rl's Avatar
    Join Date
    Nov 2006
    Location
    Northern NJ
    Posts
    20,539

    Low voltage detection part two

    3.5 Volts per cell is a better cutoff level. Itíll make your batteries happier and there is very little runtime and less funtime from 3.5 Volts per cell down to 3.2 Volts per cell.
    Alt-248 on the number pad = į

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