Re: 12V Batteries and charging

[Skywagon]

I have a general battery/charging question.  This happens every time.  I just finished a 325 mile ride today.  Most of it at a pretty good clip.  My battery is pretty new and spins like crazy.  No issues...but......when I park it (everytime) and hook the battery tender (made for agm) it goes into the red/green 75% charge and will charge for several hours....but wait there's more.

 

This happens on every vehicle I have. Yes I am a charger nut case.  When I get out of my boat, I hook up the battery tender 36V to the battery bank and same thing.  I occasionally hook up one to a car and always on the airplane when I'm done.  Same thing.  All my vehicles have agm batteries and all the chargers are agm.  I've checked voltage on all of them when running and they all are in the mid to high 14's.  

 

Is the Deltran battery tender family just that much more capable than modern day alternators....

 

There are no issues with any of the vehicles...just puzzles me why after long usage running hard they all go into 75% mode.

[ESokoloff]

According to this,
“An alternator is meant to maintain a battery, not charge it.”

 

Also my understanding is that alternators are not “tuned” to the higher voltage requirements of AGM batteries. 

[Skywagon]

im no EE but I don't think that is correct.  If you battery was low and all the alternator does is maintain that level, your battery wouldn't last long.  Maybe semantics as suspect they mean get it back to the desired design level...

 

https://en.wikipedia.org/wiki/Alternator_(automotive)

[Paul De]

12 hours ago, ESokoloff said:

Also my understanding is that alternators are not “tuned” to the higher voltage requirements of AGM batteries. 

 

I suspect that if an AGM battery was an original equipment item on your vehicle, then the manufacturer would have the correct voltage regulator for an AGM battery as well.  I think if the vehicle was delivered with a standard flooded lead/acid battery and you  replace it with an AGM battery then the charging system would not likely provide the correct voltage without also changing the regulator to match the AGM battery.

[Skywagon]

Paul...thanks that makes sense.  However I don't remember the original battery in my RT LC....I think it was AGM but memory fade. Regardless it did the same thing.  No matter how long I rode it, as soon as I parked it and put the charger on it would go into the 80% charge by the flashing green light on the Battery Tender Plus...for lead acid or agm.  I rode another 225 today...so 550 miles and when I plugged it in tonight...it is showing charging.  It's been on about 4 hours now. It will be off by morning.