Converting Roadtrek Agile from Ecotrek to AGM

[booster]

Originally Posted by markopolo

I read it as being aware of the change in the amps in during the absorption phase (14.4V). When it's less than 0.10A per Hr change it's done.

If that's correct then I think I'd watch for that once and note what the amps at the beginning of the static period and then set it based on the amps in seen then. I would not want the batteries held at 14.4V for any longer than necessary.

That very well could be, although I have never heard it of it done that way before. It does make sense, though, and probably would take care of the changes that happen to the return amps as batteries age. And yes, you would want to get the batteries off of absorption as soon as it hit that threshold if that is what they consider full. More time consuming to determine that looking at amps, but could be more accurate over time and life of the batteries. Of course the chargers, at least the ones I have seen, only allow the setting in amps so you would have to convert once tested.

[markopolo]

I'm not really sure of what the -- Charge until change in current < 0.10A per Hr / Max Time: 12Hr -- means. It would be hard to achieve if not impossible if my interpretation earlier was right.

I just looked at an old test log from my Samlex when using a timer based mode (adaptive algorithm). This was charging a single (not exactly new) battery at 14.4V and current limited to 20A for the test. It was steady at 20A in constant current mode for a over an hour until it got up to 14.4V. Then Amps in dropped from 20A to 10A over the next 20 minutes in absorption phase held at 14.4V. Then another 70 minutes to drop from 10A down to 2A. Then it looks like this:

7:30pm 2A
8:45pm done with 1.7A
10:10pm first time 1.5A shows up
after that it was continuously fluctuating between 1.6A & 1.5A

In the example above, charging at 14.4V after 10pm-ish was likely/possibly detrimental. Switching to float at 8:45pm would be near perfect I think.

Ending amps mode is better than timer based modes. Using ending amps mode set at 2A the absorption phase would have ended at 7:39pm and then switched to float at 13.2V. That has to be better than holding the battery at 14.4V for almost 3 extra hours to get to an almost static state.

Earlier I mentioned charging to 1A in or less but Booster's 2A in or less looks better. The 1A in or less in my van reference is at 14.3V.

[MobileCabin]

What is the current thinking regarding equalizing AGM batteries? Lifeline for example recommends it : https://lifelinebatteries.com/2015/1...agm-batteries/ . The OEM AGM batteries in my class B even list the Equalize voltage of 7.3 - 7.3 volts on the battery label. Yet there appears to be companies that prohibit performing the cycle (page 20 in https://www.trojanbattery.com/pdf/Tr...UsersGuide.pdf). Is it simply a vendor dependent case or in general something not to be concerned performing?

[booster]

Originally Posted by MobileCabin

What is the current thinking regarding equalizing AGM batteries? Lifeline for example recommends it : https://lifelinebatteries.com/2015/1...agm-batteries/ . The OEM AGM batteries in my class B even list the Equalize voltage of 7.3 - 7.3 volts on the battery label. Yet there appears to be companies that prohibit performing the cycle (page 20 in https://www.trojanbattery.com/pdf/Tr...UsersGuide.pdf). Is it simply a vendor dependent case or in general something not to be concerned performing?

I think that is a very good question, and I am surprised it doesn't come up more often now that Lifeline says it is OK I even talked to the Lifeline techs about it a few years ago.


I think that the equalizing of AGM batteries is somewhat of a crutch to help battery life if the charging system isn't up to par for the most part. If you start with new AGM batteries and do top line charging on them, equalization shouldn't be needed until the batteries are old and nearly at end of life.


My interpretation of top line charging would be to have all the charging systems base their charging on the measured amps to the batteries at absorption voltage. That would be the .5%C in amps that Lifeline says to use for their batteries or whatever other manufacturers recommend if it is not a crazy high number that some do now to match some of the chargers. It is possible to have all three sources of charging, shore, solar, alternator charge by amps if you take the time and effort to get it all that way. Even having one source by amps, probably shore power or alternator (done manually), and making sure you use that source at least every 7-10 charge cycles, is very good and not all that difficult.


For those with not the best charging setups, they mostly will wind up short charging and not getting the batteries totally full as nearly all the charger manufacturers seem to prefer error to the undercharge side as the wear on the batteries is less than the overcharge side. Repeated undercharging with never getting full all the way will cause the batteries to walk down their capacity over time and that capacity can't be recovered by normal charging. Equalization can recover some or most of that capacity if done soon enough after the short charging. From what Lifeline told me is that careful use of equalization could add significant life to batteries when they are losing capacity regularly from heavy use and/or poor charging. The hard part, I think, is catching the need for an equalization fairly quickly without running capacity tests all the time.


The downside of equalization is that it does do some damage itself in an AGM as it will dry out the electrolyte a bit, so you don't want to do it unless needed. Some manufacturers seem to be adding a mini equalization at the end of their charge cycles, presumably to assure the batteries are full and help recover any lost capacity, but I don't really think doing that every time is the best solution. I would say that you likely will learn how long your batteries can go under normal use before losing capacity and it would be very appropriate to do a short equalize in maybe half that use period as a preventative as damage is almost certainly happening before you can actually see capacity loss easily.


Bottom line though is that equalization should not be needed much or at all if the charging systems are doing the charging well, and you don't kill the batteries to near dead.


With the Magnum and ARC50 remote with BMK, you will be able to set the shore charging to control by amps so no problem at all with that as long as the settings are correct. The built in battery monitor will also allow you to see the amps going to the batteries on the ARC50 (be sure to only use BMK amps screen as the "normal" amp/volt screen is not measured by shunt or accurate) so you can determine and even control manually the charging from your other charging sources like engine or solar, so you will be able to quickly determine how well they are doing.


The Lifeline article in the link you provided is a very good description and much better than the much more vague ones they have had in the past. They are very aware that other manufacturers batteries may or may not be able to handle the same equalization.