Post by carasdad on Dec 14, 2012 8:25:22 GMT -5
Anyone that uses the AGM batteries.(The following is true ask the manufacturer..they will tell ya. I found this out by tinkering around..then called Batteries Plus and was told..they use a special charger but my method does work)
If the voltage falls below 9.8 volts with an AGM battery the battery charger WILL NOT charge them...it will read as a dead cell or short in the battery. Which is not true. They are NOT dead. Your charger has a built in protection to keep it from charging a shorted battery or dead cell..this prevents the charger from being ruined.Wet cell batteries it will charge when voltage is lower than that..however by design...AGM batteries are an anomaly in this case. Some new chargers are made with AGM in mind..and will charge them..but I have found very few chargers that will except at Auto Zone...Advance Auto and NAPA where they charge and load test them with a special charger. Here is the fix and I assure you it will work on that AGM battery you think has a dead cell or short are about to toss because it won't take a charge. BUT..the battery is still good!!
Step 1. Find a known good battery and connect it to the charger.
Step 2. Take your bad AGM battery (which really isn't bad) and connect it with alligator clip jumpers in parallel with the good battery.
Step 3. Allow it to charge at a low rate..2 amps or less for a few hours.The charger 'reads the first battery as good..and will allow itself to charge it along with the 'dead' AGM battery.
Step 4. Now disconnect your 'dead' AGM battery and test it...and guess what? It's not dead anymore is it?
While AGM batteries do last longer and handle the cold weather better(reason most snowmobiles use them) they have an inherent trait that once the voltage drops too low they read as 'dead cell' or 'shorted cell' So now go try that and report your results back to us.. You are gonna be happy that you do not have to shell out another $70.00 on those expensive AGM batteries.
You all are gonna be so surprised and happy... 
If the voltage falls below 9.8 volts with an AGM battery the battery charger WILL NOT charge them...it will read as a dead cell or short in the battery. Which is not true. They are NOT dead. Your charger has a built in protection to keep it from charging a shorted battery or dead cell..this prevents the charger from being ruined.Wet cell batteries it will charge when voltage is lower than that..however by design...AGM batteries are an anomaly in this case. Some new chargers are made with AGM in mind..and will charge them..but I have found very few chargers that will except at Auto Zone...Advance Auto and NAPA where they charge and load test them with a special charger. Here is the fix and I assure you it will work on that AGM battery you think has a dead cell or short are about to toss because it won't take a charge. BUT..the battery is still good!!
Step 1. Find a known good battery and connect it to the charger.
Step 2. Take your bad AGM battery (which really isn't bad) and connect it with alligator clip jumpers in parallel with the good battery.
Step 3. Allow it to charge at a low rate..2 amps or less for a few hours.The charger 'reads the first battery as good..and will allow itself to charge it along with the 'dead' AGM battery.
Step 4. Now disconnect your 'dead' AGM battery and test it...and guess what? It's not dead anymore is it?
While AGM batteries do last longer and handle the cold weather better(reason most snowmobiles use them) they have an inherent trait that once the voltage drops too low they read as 'dead cell' or 'shorted cell' So now go try that and report your results back to us.. You are gonna be happy that you do not have to shell out another $70.00 on those expensive AGM batteries.
You all are gonna be so surprised and happy... 
Can't do that with an AGM as they are sealed. Also your method with a float charger works as well....since they are not "smart chargers"..which in fact are not really smart at all...the trickle or float charger will bring up the voltage so a regular charger will take over and charge. This takes a few days...but it does work. I just parallel charge cause I don't like waiting so long. I have been given 3 'dead' useless AGM batteries that would not charge on a standard charger. Rejuvenated them and have used them in my scoots for a year now with no problems.Thanks for the input....it is posts like these that help others out and save them money. That is what makes "Team ScootDawg" such a great resource..so thanks again for the input... 