Do AGM's charge quicker?

https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/

My 5+ year old northstar AGM with 1000+ deep cycles is now requiring 5+ hours once 14.7v has been reached, for amps to taper to 0.5% or less of its 90 Ah capacity. The absorption time was much less than this when new, yet it still retains impressive voltage being discharged 45AH at near twice the discharge rate at which it earned that 90AH rating.

Try Lifelines and a charging system big enough to deliver the goods. 13.9 volts is not 14.4 volts. Read It Again, I fully and totally recharge my lifelines with a time limit of 4 hours and change.

When people splay out a carelessly made claim without caveats it is sad and makes everything else they spout, suspect. The Lifeline indeed charges 5X faster. Hong Chow specials don't stand a chance of doing that despite their paper thin plates.

It's the BS factor. No one wants to discipline their comments. Download the Lifeline manual and read reality not regenerated BS. I have duplicated Concorde's claims in everyday charging time after time. It takes one hell of a charger to maintain 100+ amperes at a steady 14.4 volts.

SFVdave wrote:
Read AGM's charge up to 5X faster than flooded. How can that be, converter charger only puts out so much?

5x faster? heck no.

I've been running AGMs in my truck camper for about 3 years. They may charger slightly faster, but not even close to 2x faster than wet cells.

If you want reduced generator run time, upgrade to a smart 3 stage battery charger.

noteven wrote:
If you look at the manual for a PD converter charger it should have graphs showing charging profiles. They will answer your specific questions if you call them.

I thought they detect the battery type automatically...

You can be severely misled by that manual. It does not discuss charging rates, and the PD requires that you keep hitting the boost button to keep it at 14.4v until battery acceptance is down to 0.5a per 100AH with AGMs, if it does drop to 13.6v on you before you get that far.

EDIT: PD says:
"The chart above shows the amount of time it took a PD9155 (55-amp) converter set to three different output voltages to recharge a 125 AH (Amp Hour) battery after it was fully discharged to 10.5-volts.

14.4-VOLTS (Boost Mode) – Returned the battery to 90% of full charge in approximately 3-hours. The battery reached full charge in approximately 11 hours"

So they used a 55 amper on a 125AH which is a 44% charging rate! Took 3 hours to 90% SOC.

And they started from 10.5 volts --which is a "dead" battery! My goodness. So it would maybe stay constant 55 to 60% SOC which is one hour, and now to do the 60-90 (37.5AH) with tapering amps from 55, which they say took another two hours.

So what good is that to know?

If you look at the manual for a PD converter charger it should have graphs showing charging profiles. They will answer your specific questions if you call them.

I thought they detect the battery type automatically...

Wifco's even fail as wheel chocks. But boy do they ever have a heavy piece of aluminum inside. The Ginzu knife of converters.

Another AGM example from ex-member ah64id using his 55 amper on his pair of Lifeline AGM 6CTs 300AH :

A. 18%/80%
A. 28%/65.5% (mine with 56 amps on a pair of 100s)

EDIT--bigfootford has an example where he used 56amps on AGM and amps tapered at 68%, but I don't have his bank size in AH--must be about 200?

Wiring does matter with these, since the R in the wiring, charger to battery and among batteries in a bank, makes the bank look smaller (higher R), so the same amps seem at a higher charging rate in effect, so the SOC will be lower when amps taper.

EDIT--but not so much wiring R that you can't do the charger's rated amps.

Another thought-- if your WFCO can't quite go to boost with Flooded.
EG, on starting, the battery voltage spikes so the WFCO sees 13.3 instead of 13.1 (13.2 is trigger it says) so it stays at 13.6v

Swap to lower R AGM same AH, and now perhaps voltage spikes to 13.1 and the WFCO goes to boost at 14.4 ?

I recharge my Lifelines at full saturation charging of 14.4 volts. But it takes a lot of generator and a lot of charger power. But in the end I end up fully charged meaning the half percent formula in 4 hours and change.

Yes. It doesn't make any difference if they are AGMs. You can use all sorts of chargers at the same time and they will add their amps as long as the chargers' voltages are above the battery's voltage.

When battery voltage rises amps from the lowest voltage charger taper until they stop as battery voltage passes that chargers voltage, then the next one, until only one charger is still adding amps and then its amps taper till battery is charged.

I used to try and get a few extra amps in my old Winnebago Minnie. It had 2 group 24's 82 ah each and it had a PD Intelli-power 45amp. I would be charging in the morning and have 25 amps going into the batteries from the genny powering the converter charger. I would hookup my car charger which was a 40 amp and would get and extra 4-6 amps going in. I had to connect the negative cable to the battery monitor shunt to get the input reading. Is that a do-able option with the AGM's to get higher amps?