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Boost a 36V e-scooter from Greece Crete

  1. Jun 29, 2016 #1
    I buy electric scooter in 2005 1000w 36v with 3 batteries of 12v 50ah it's, I was used for 4 years til the batteries finish. Recently I disite to used again but because we have here (Crete) many mountains and became empty the batteries very fast from heaviness to buy half size batteries 26Ah. But I was wrong is weak and fall the volts rabidly in heals. So is possible to boost the motor when it falls to 36v from 41v when is fool the batteries with extra battery 6volt (8v fool) to become 44v to not stop the power the controller.??? This can happen only if the 6v battery is also 26ah? Or it doesn't matter?? Is anybody knows? Thanks....
    Last edited: Jun 29, 2016
  2. jcsd
  3. Jun 29, 2016 #2


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    If the batteries are not matched in discharge characteristics they will not discharge equally and I expect you will not get a good result.

    By discharge characteristics I mean the voltage at the terminals vs the remaining charge in the battery and the load on the battery. All the batteries should be matched.

    If you mix / match just thinking about fully charged terminal voltage, I don't think that will work for you.
  4. Jun 29, 2016 #3


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    Hi Kateridi. smiley_sign_welcome.gif

    So in place of the manufacturer's 3x 12V 50AH batteries,
    you are considering using 3x 12V 25AH in series with 1x 6V 25AH battery?

    Have you thought of emailing the bike's manufacturer and asking them about your proposal? They would be best placed to say whether the controller could handle this without any problem. Though, I'd expect it would render null any manufacturer's guarantee on the bike, so that may be a major consideration.

    The fact that a Pb acid battery voltage is starting to fall away indicates there is not much energy remaining in the battery, so even were you able to fool the controller it would not extend the range by much before the battery was fully drained: meaning you would achieve nothing much. Besides, it is bad treatment for a Pb acid battery to be used until it is almost fully run down, this shortens its life and you'll have to buy expensive new ones sooner.

    Those are my thoughts, meanwhile, we'll see what others think.

    I figured that rabidly in heals = rapidly in the hills :smile:
  5. Jun 29, 2016 #4
    The old charger broken I buy new and gives maximum 41v so I cannot charge them all 4 batteries with the 6v together needs to be separate. I don't know if I will need to buy new charger, in the market after 36 is 46v I ges give 51v I don't know if is good to put 12+12+12+6volts with the 46v charger. If I put all of them is 42v to be full needs I think 47v charge, if I charge them with 46 charger that gives actually I think 51v will be OK?
    Last edited: Jun 29, 2016
  6. Jun 29, 2016 #5


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    If your charger only makes 46V that is 2.19V per cell (46/21=2.19V). That is not enough to fully charge the battery. It might only be 50% full. Lead acid cells need about 2.4-2.45V per cells to be fully charged. So you would need 21*2.4V = 50.4V or perhaps 51.45V.

    This is NOT a good idea. If you use 3*12V batteries and ride until the voltage falls to 36V they will be almost empty. If you then add a 6V battery and continue riding the 12V batteries will become "deep discharged". This can permanently damage the batteries.

    * I recommend you replace 3* 25AH batteries with the correct 3 * 50AH batteries.
    * After you use the scooter put it on charge as soon as possible. The fast way to permanently damage the batteries is to leave them empty for a few weeks.
    * I recommend using a charger with two manual settings "Full" and "Float". You can also get chargers that switch to "Float" automatically when the battery is full. If you know you won't be using the scooter for a few days or weeks leave it on charge on the float setting. If possible use a charger that you can adjust the float voltage. The battery manufacturer will recommend a float voltage.
  7. Jun 29, 2016 #6
    My question is if I can use a 6 volt battery in series with the 3 12v batteries I must have the same Amount of ambers or if I put 10 Ah I will have problems. The batteries are new so I m not wiling to throw them, I have to find solutions with little more money. The batteries how they are now I can go in flat road 15km but in the hill fall the batteries to 37v from 41v in just 100m. So I need for this 100m boosting that actually is the last meters before my house.
  8. Jun 29, 2016 #7


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    This is a bad idea. The 6v battery must also be 25AH. If the 6v battery is only 10AH then it will become empty when the 3*12V 25AH batteries are about half full (15AH). If you keep riding the 6V battery will be damaged.
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