Do AGM's charge quicker?

SFVdave wrote:
Now I’m really confused! Am I correct in assuming that I am limited to how quickly AGM’s would charge in comparison with my existing regular flooded batteries because of my PD intelli-power 55 ah. Converter charger? From what I’ve read regular flooded are limited to 25% of battery’s total capacity and AGM’s are 40%. But because I can’t adjust the ah charging rate, there wouldn’t be much difference in charging time.

That's right.

None is actually limited, you just have to start Bulk at a lower SOC to get the battery to accept the higher amps. The amps will taper almost right away, so you get no time at the high amps. Waste of money buying the higher amp charger. 30% is about optimum for saving gen time and not overdoing it. If you want the batteries to last forever and are on shore power, 10% is recommended, being easier on the battery. --Except AGMs as noted in that article--they want at least 20% from a low SOC start every so often to keep them cleaned out. (They don't have their electrolyte where it can bubble like Floodeds do)

You cannot get more than 55 amps from a 55 amp charger just because it is on AGMs. The charger is "current limited". Actually you might get a few more amps from it using very short and fat wires to either kind of battery, but the point remains.

Now I’m really confused! Am I correct in assuming that I am limited to how quickly AGM’s would charge in comparison with my existing regular flooded batteries because of my PD intelli-power 55 ah. Converter charger? From what I’ve read regular flooded are limited to 25% of battery’s total capacity and AGM’s are 40%. But because I can’t adjust the ah charging rate, there wouldn’t be much difference in charging time.

time2roll wrote:
BFL13... was that charging graph you had into flooded or AGM?
Maybe you could repeat it for AGM with similar capacity and charging rate.

It was for Flooded and had its own particulars, so it was an example ballpark for other chargers and batteries. It did come out close for other chargers and battery types I had.

Here is a list of examples of that guy's and mine. (F = flooded, A= AGM) of percentage charging rate and percentage SOC when Bulk ended:

A. 40%/63% (his)
F. 32%/65% (mine)
F. 25%/72% (mine)
A. 20%/77% (his Lifeline 31)
A. 19%/72.5% (mine,not Lifelines,plus my wiring zoo charger/batt)
F. 16%/80% (mine)
A. 15%/75% (his other one at the end there, but it was used so the charging rate was higher than 15% --as indicated by the lower SOC)

So allowing for all sorts of things, pretty much the same for Flooded and AGM and also same pattern. Which is expected, A and F both being lead -acid batts.

EDIT--that guy did mention how charging efficiency goes down past 80% SOC but I didn't see in his article where he used any number for his calculations. Mine using Trimetric has a built in fudge factor for charging efficiency but it is fixed for all SOCs. Even so, the examples are close.

BFL13... was that charging graph you had into flooded or AGM?
Maybe you could repeat it for AGM with similar capacity and charging rate.

When I was in a similar situation I went Lifelines for the rapid bulk acceptance and a PD9280. A pair of GPL-6CT would give you 300 amp hours.

SFVdave wrote:
Will a Trimetric system provide the necessary charging specifications to charge the AGM's quicker My neighbor who has the system seems to think so.

The Trimetric "shows" things, it does not "provide" anything. I use mine with my AGMs to note when amps to the battery get down to 0.5a per 100AH, and also to confirm the battery voltage has reached the Absorption voltage set on my adjustable voltage charger.

You solar controller shows the amps from the controller, not amps to the battery. Other 12v loads come first, then the battery gets any amps left over. So the Trimetric showing just your amps to the battery is valuable information.

EDIT--that 0.5 doesn't count with any loads though. That could be just what's left over, not what the acceptance is down to. Your RV has small loads all the time, so to get a true 0.5a reading on the Tri, you have to shut down any other 12v things.

Will a Trimetric system provide the necessary charging specifications to charge the AGM's quicker My neighbor who has the system seems to think so.

THree answers:
LIFELINE (Specific to that brand) Does reocmmend a much faster charge than other companies do.
IT only affects total charge time by a small amount
And only if you change (Serious upgrade) the converter.

NOt many RV converters can do the "Fast" that LIfelien wants if you have Much
more than 200 amp hours of battery.

Ductape wrote:
What are your present batteries and what converter?

2 Exide Natilus dual purpose deep cell group 27 3.5 years old came with new MH and PD Intelli power 55 amp converter charger with built in charge wizard and 300 watts of roof solar.

What are your present batteries and what converter?