Author Topic: Bring a deeply discharged AGM battery back to life?  (Read 338 times)

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Offline Underdog1

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Bring a deeply discharged AGM battery back to life?
« on: April 19, 2020, 10:49:00 am »
My bikes been later up for 18months+, the brand new AGM battery that was on it is fully discharged (multimeter reads 0v!).

Got a newish Oxford optimiser 900 which doesn’t recognise it and won’t charge it. To be honest the optimiser was pretty hopeless from day 1 and I wish I never got it.

Is there anyway to kick this back to life? Want to avoid buying a new battery at this stage if possible. I’ve heard some stories about linking it to a car battery and then adding a charger onto the bike battery to ‘trick’ a smart charger into working but to be honest this sounds like a recipe to ruin more batteries haha

Any advice appreciated

Offline scunny

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Re: Bring a deeply discharged AGM battery back to life?
« Reply #1 on: April 19, 2020, 01:41:04 pm »
putting it in parallel with another battery may work. The smart charges look for voltage and wont recognise a dead flat battery. I wont hurt anything.
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Offline scottly

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Re: Bring a deeply discharged AGM battery back to life?
« Reply #2 on: April 19, 2020, 07:43:58 pm »
I've had some luck bringing both flooded and AGM batteries back to life.  :D Typically, the battery is "sulfated", where the sulfur in the electrolyte has come out of solution and deposited on the plates, sort of an electroplating process. If this can be reversed, the battery can sometimes be saved: the trick is getting the chemical reaction started...
Yes, it's OK to jump the bike battery from a car battery, as long as you match the polarity. In order to get any current flow in a sufated battery, you will need more than the voltage from a sitting battery, so start the car. The car's charging system won't allow the voltage to get so high it damages the battery, unless the battery has shorted cells, in which case it's already toast. Once the battery starts to read voltage after disconnecting from whatever charging source, connect a load across the battery ( I generally use a 60 watt headlight) until the voltage drops off a fair amount, then re-charge and repeat. Each cycle should increase the current draw during charge cycles and time to discharge when under load. After only one or two cycles with the jump from the car, your "smart charger" may work?   
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