I have read that, when you add electrolyte and acid to a new battery, it will then be at 80% of max charge. You can put the battery in your bike and it will turn. However, it's highly recommend to tend that battery and bring it up to 100% charge. Is it possible to drop the battery in and take her for a spin (because it's a beautiful evening) then hook her up to the tender anyway and still charge the battery up to 100%?

  • I wouldn't know why not. My suggestion, ride the bike. Apr 3, 2014 at 1:52

4 Answers 4


The reason behind tending it to bring it to 100% vs. just riding it up to 100% is to save wear and tear on the alternator or generator. They're really designed to maintain a battery/do light charging, not do a major charge.

A secondary thing is that a severely discharged battery may vent a lot of hydrogen while charging and you'll need to monitor the cell electrolyte levels. That's hard to do while riding...

  • 2
    from experience of lead acid batteries going bang - its better to not be on the bike in the event of it going bang than on it. If the vents arent fully open and the charge rate is high because the battery is so low then it can create a hazardous situation. Also need to consider why the old battery is being replaced, is the reg/rec faulty and overcharging?
    – Mauro
    Apr 4, 2014 at 13:29
  • Nearly all bikes run 'shunted'. This means that the alternator is running at 100% all of the time. Hard-core drag guys eeking out that last 1% of power will replace a bike's V/R to eliminate CEMF. Obviously, if the alternator is being shunted to ground or going to the battery makes no difference. If the battery is a maintenance free battery, there has to be some pretty crazy engine modifications to cause a rapid enough hydrogen formation to create a hazard on start, but even that would only be on start. Charging via regulator isn't going to create concentrated H2.
    – Paul
    Sep 25, 2014 at 1:34

Hi in my opinion you will be fine to use the battery with 80% charge, your bike will do the rest when you are out for a ride. Also it is a good idea to invest in one of the new SMART CHARGERS that are now on the market, these automatically top up the battery charge and are ideal for protecting your battery over the dormant winter period, when the battery is charged the charger switches off and then on again when the battery requires topping up with charge, hope this helps you Eric Roberts www.batteriesontheweb.co.uk enter image description here


The battery is ready to use after you've put the acid in, and you can charge it on the bike, however, better practice would be to attach it to a charger to complete the first charge... Personally, I filled my battery with acid, and attached it to the battery charger WITHOUT putting the caps on the battery in order to allow the gas to escape. When completed, I'd leave it to stand for a small while, then put the caps on, you'll get better battery life this way.


It should be no problem. An otherwise good electrical system will get you to 100% after a short ride. However, having just dealt with a bad regulator myself, I'd say to check the levels and make sure there is no overcharging (boiling/"cooking") of the battery taking place. "Wet-type" batteries should have a vent and overflow tube. In my experience the main danger of overcharging is ending up somewhere inconvenient with a dead battery that can't be charged. On some bikes, the engine won't function without a conductive, if not dead, battery in place.

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