Markuson
SILVER Star
Mark is special didn't you know? Oh and tire pics are his fav
Special Ed, yes.
Oooooh.... Tiiiiires...
Before summer starts top off your battery
- Thread starter SWUtah
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Special Ed, yes.
Oooooh.... Tiiiiires...
Only saying that I power much more stuff in a travel trailer. For longer periods. Yet my battery systems in my trailer are less exotic with less capacity than what is installed in some of these rigs.
I believe these AGM systems are just not performing even at these overklil levels. Point is, it's due to AGM incompatibility in this application.
Markuson
SILVER Star
Ya... It’s just that once I add a fridge & Freezer, charging devices, shower pump, microwave, satalite comms, lighting, electric water boiler and more...I’m basically outfitted to a similar level as a camper trailer...except instead of a battery bank that doesn’t have to retain power to start a 5.7 V8... I’m on just two...without solar.
This is asking a tremendous amount from my two AGMs. At least one vehicle ended up with dead batteries in Baja...but not mine, and I was clearly using the most electrical power, including charging drone batteries for other folks in the group.
This tells me that in contrast to talk of AGMs being “incompatibility with this application,” AGMs actually do quite well.
As to whether AGM is “best?” Meh... I don’t know. But they worked well in Baja under heavy, constant use of heavy-draw equipment and camping.
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Buy a quality charger and charge up/condition/maintain your batteries for a few days monthly or every other month to extend battery life and capacity.
https://smartercharger.com/products/batterychargers/ctek-multi-us-25000/
https://smartercharger.com/2014/04/trucktrend-com-ctek-power-multi-us-25000-tool-of-the-month/
https://smartercharger.com/products/batterychargers/ctek-multi-us-25000/
https://smartercharger.com/2014/04/trucktrend-com-ctek-power-multi-us-25000-tool-of-the-month/
Markuson
SILVER Star
Good advice.
I use a CTEK 7002 to top off my AGMs.
That 25A unit in your link is a beast though! The 7002 is much slower at about 8A.
As to whether AGM is best? Meh... I don’t know. But it worked well in Baja.
You're missing the point. I'm sure they do well, until they don't.
Just that you're killing them softly because AGMs don't like high voltages in hot under-hood conditions.
And no way does an overlanding rig use anywhere near what a family of 4 uses from a camper. With only 2x Group 27 flooded batts. I can go 2-3 days without solar. Potentially infinitely with.
Markuson
SILVER Star
You May be right...
But...
-Until my healthy AGMs reflect the inevitable doom you’ve declared...(and they don’t—despite having discovered having had a faulty IBS booster module for several months...and never turning off my fridge since Moab/LCDC...I use AC power if in my driveway) -I’m inclined to keep using my AGMs despite your dire declarations.
I’ll be sure to crack an egg on my face and post a photo for ya if they die an early death.
Just trying to figure it out, and each use case/habits change the equation to some agree.
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I'll just go by what the battery maker suggests for charging voltages:
Useless. As you cannot set the output of the alternator regulator to match the desires charge profile of an AGM.
Let me put this in specific terms from the manufacturer as to why AGM's are not suited for underhood application.
1) Heat.
I think we agree engine bays are hot places. In overlanding use, it might be hotter still as there's little airflow and lots of hot idling increasing temps at the battery position. For kicks, let's say it's 150F (65 C). I wouldn't be surprised if it were much hotter still as the radiator is right there at engine temps close to 200F (93C).
AGMs in particular don't like hot environments. A similar Victron AGM batt has only an expected life of 2 years, at a barely warm 104F.
2) Thermal Charge Voltage Compensation
All batt's should have temperature compensated charge voltage profiles. NorthStar documents this as -4 mV/cell/*C for AGMs. From 25C.
Assuming 150F (65C).
65C - 25C = 40*C delta.
-4 mV * 6 cells * 40 C = -.96V. So almost a full 1V less at operating temps.
Float 13.5-13.8V @ 25C, or 12.5-12.8V @ 65C
Charge 14.4-14.8V @ 25C, or 13.4-13.8V @ 65C
Yet car alternators are setup for flooded batts, outputting closer to 13.2-14.8V.
Combine the high temps with the high alternator voltages... killing softly or murdering? These batts are prone to dry out in these conditions. As they are sealed, cannot be watered per @SWUtah 's excellent suggestion for flooded batts.
And consider that the other thread is talking about adding diodes to increase AGM charging? Hrmmm.
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Markuson
SILVER Star
Our alternators put out barely 13 after running for a few minutes. -Higher before that...and only continues past a few minutes if there is a heavily depleted battery...which is when AGMs want those higher voltages. With a resistor tweak, that can be increased/improved a bit for deeper discharge due to camping and power needs.
Without a tweaked alternator? Hitting over 14 is rare. Heck, even hitting 13.5 is rare unless (again) the battery is very depleted.
Charge voltage is very easy for me to monitor in real time, by the way, as my in-cabin IBS status indicator shows how much charge voltage is being applied at any given time and I can see it while driving. So I’m telling you actual voltage being sent from the alternature rather than generalizations about what alternators’ ranges may or may not be.
Without a tweaked alternator? Hitting over 14 is rare. Heck, even hitting 13.5 is rare unless (again) the battery is very depleted.
Charge voltage is very easy for me to monitor in real time, by the way, as my in-cabin IBS status indicator shows how much charge voltage is being applied at any given time and I can see it while driving. So I’m telling you actual voltage being sent from the alternature rather than generalizations about what alternators’ ranges may or may not be.
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Hey, your car, your choice. I've laid out the information in simple terms. What you do with it is your prerogative. As this is a forum, hopefully others may appreciate the data to make their own informed decision.
Markuson
SILVER Star
Accordibg to Oddysey (my 2nd battery is extreme series type 35), they do not suffer diminished moisture via pressure valves until they exceed 176 degrees F. My batteries are not getting that hot. Wet cells lose water more easily.
Odyssey also notes that vehicles that are driven often/or daily are able to maintain battery health much better than batteries only used occasionally as RV or boat batteries tend to be...and are less vulnerable to heat. In contrast, occasional use batteries are far more susceptible to heat due to water loss.
Oddysey’s Extreme Series AGMs (like my type 35) are “specifically designed for high heat” and designed for 10-12 years service life. While heat has an adverse effect on all batteries, Thin Olate Pure Lead (TPPL) AGMs are far less susceptible to heat damage.
So...in my case, and likely others here...perhaps it’s not quite so deadly as you suggest.
Read for yourself here:
FAQ: How to protect your battery against the summer heat
Heat matters, yes. No doubt. But it’s not always “murder.”
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I've had Oddysey's before, and is where I cut my teeth on this issue.
1) Note that Oddyssey Extreme series is specifically designed for high heat over typical AGM models.
2) Not all Oddysey models are created equal, and only some specific models (with metal jacket) are capable of operation to 176F MAX, before they vent.
3) Even if they can handle the high heat, there is significant additional wear and tear when used in this application, causing useful service lives to be greatly impacted.
4) Voltage too high. AGMs do not like extraneous charge voltages.
1) Note that Oddyssey Extreme series is specifically designed for high heat over typical AGM models.
2) Not all Oddysey models are created equal, and only some specific models (with metal jacket) are capable of operation to 176F MAX, before they vent.
3) Even if they can handle the high heat, there is significant additional wear and tear when used in this application, causing useful service lives to be greatly impacted.
4) Voltage too high. AGMs do not like extraneous charge voltages.
Markuson
SILVER Star
Right. So their 10-12 year designed service life might be cut in half or more.
I can live with that.
Real question is...can you live with me ...living with that.
I can live with that.
Real question is...can you live with me ...living with that.
RET2
SILVER Star
Holy crap Batman, what is is and no there there have infected Mudd?
Markuson
SILVER Star
gaijin
GOLD Star
Back at ya!
Sorry if in my brevity was out of line. Was trying to point out that if an AGM were to be tied into the stock electrical system, it would not matter as there's no tailoring if voltages there.
Apologies to you too @Markuson.
You don't have to accept any of my interpretations, so the data is copied here for your own judgement. I think you both know my only intent as a professional engineer is to wade through complexity to highlight the pertinent points. But we also know there's many ways to skin a cat. Choose your own poison.
