Portable jump starter

Discussion in 'General Chat' started by MrXT, Nov 13, 2016.

  1. MrXT

    MrXT Active Member

    Messages:
    534
    I found a portable jump starter battery pack in the cark park at work, no one claimed it for 4 weeks so its mine.
    No charger tho and cant find any on ebay.
    I Made my own charged using an old lithium charger that was designed to charge a 12volt lithium battery pack used to jump start cars and bikes and managed to find a connector that fitted the batterys ac port and that seems to charge the battery a bit but i suspect the voltage isnt quite high enough for a SLA battery type as i know the charger needs to output around 14-15 volts for the battery to charge properly.

    Do you think i could just connect a normal lead acid battery charger to the jumper cables on the battery pack to charge it?
     
  2. Tamiyacowboy

    Tamiyacowboy Pippa's Owner

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    possible it has a backflow zener diode , stops power flowing from whatever is being started back into the battery.

    SLA battery requires a voltage charge of NO MORE than 14.4v any higher and you run the risk of boiling of the electrolight jel and frying the battery ( sla stands for sealed lead acid), you must remember its a sealed unit but does have some vents and when charging will produce unwanted fumes/gasses like a normal car battery would.

    my local hobby store sells chargers for SLA batterys ( we use them in our large scale boats and to start our gas airplanes ). link below to give you an idea what your looking for. those ones are 700mah to 1amp chargers ideal for sla batterys and would be the same thing you get with jumpstarters to charge them up.

    http://www.pegasusmodels.co.uk/prod...es&id=Lead+Acid&filter=RS&subF=1#.WCjA9Knxpv0
     
  3. MrXT

    MrXT Active Member

    Messages:
    534
    Its a portable jumper battery pack the terminals are not exposed so its unlikely they have the right charger for it.
     
  4. Tamiyacowboy

    Tamiyacowboy Pippa's Owner

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    Piaggio Skipper
    do you have a picture of the pack.

    I am betting its a Lipo ( lithium polymer battery) , if so they have to be charged with great care.
    i use them in my hobby stuff and keep my lipo's stored in a 50cal metal ammo box as they are a fire risk and prone to exploding/catching fire if mistreated or charged incorrect or discharged to much/to fast or punctured.

    lipos come in flavours of 3.7v - 7.4v - 11.1v - 14.8v ( 1s - 2s - 3s -4s )
    each pack will be a set of envelopes each one is 3.7v and depends if they are wired parallel or serial .

    closest to 12v would be what we call a 3s battery and thats 11.1v
    each seperate battery is 3.7v but when they are fully charged the voltage is 4.2v, they also have a C rating a discharge rate the ones i run have a 30c discharge rate and can dump around 140amps in a 10s burst ( anything over that your into unknown danger of the pack giving up)

    To charge them i use a smart charger , its a chip based charger that feeds them a certain voltage via PWM (pulse width modulation) with a fair few safety features, but even then we charge them in fireproof bags. a 11.1v 4000mah lipo would be charged at 11.1v and with a current of 4amps ( it takes a hour to charge and the charger would ramp down the input feed as the battery nears its full capacity)
     

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