I am going to try and make this simple...
An X factor of Delta T temperature/time gain at a high amperage rate
Is POSITIVELY not the same as allowing the same c/min gain
With much lower charging amperage. The temperature gain per amp/amp hour factor is rather LINEAR, And no this is not a charging regimen. It is a TEST factorial.
Say a battery gains 2c/hour at a 40 ampere charge rate. That is OK
Temperature gain of 2c/hour at a 5 ampere charge rate is absolutely not OK.
Yes electrolyte to ambient temperature Delta T plays a role in this. There is a complex formula written for this that would be absurd to post even if the posting would allow symbology. The very idea of implied braggadocio infuriates me and E=MC2 technobabble would help no one.
Impress the implied correct E (charge absorbsion voltage limit) across the battery. Using a digital thermocouple and clock, arrive at a temperature gain for one hour of charging time. Of course this exercise must be performed on a discharged battery. Keep measuring if your charge source is more than 20% of amp hour capacity but maximum E cannot be reached because of insufficient I (charging amperage). The best record keeping is done in 15-minute increments.
The temperature gain you see now should be the maximum GAIN permitted. If a battery sees a higher amperage going through it and temperature GAIN starts to suddenly ramp upward, STOP! You are over-amping the AGM. Still with me?
You are establishing an amperage/temperature gain profile. Use excel or draw a graph. A dying AGM going over to the Dark Side, will suffer inappropriate amperage temperature relationship.
I love to use the CAKE / OVEN analogy. The don't bake for 5 minutes at 2,000F one.
Similarly with an AGM do not bake the cake for three days at 150F
Chemistry is like math - utterly unforgiving.
And Landyacht, your insufficient charge rate hits the nail right on the head. You understand the need to reduce bulk voltage limit dramatically. This is one of the pitfalls of "only-solar" versus AGM. The 20% minimum is another.
I guess if this was easy for the average person to understand I would have had to find a different career.
