Fullriver batteries

[AJMike]

Originally Posted by creativepart

I know many use them and feel they are adequate. But that's exactly what AJMike did initially - Marine/ RV AGMs - and he's unhappy with their performance.

I'd always recommend true deep cycle batteries for a RV house battery bank.

Most of the 115AH AGM batteries I have seen run around $325 each, some name brands like Lifeline quite a bit more. Not knowing anything about battery construction or design I am lost in all of the "market-speak" and subject to sales pitches. It always pays to know something about the subject you are thinking about buying so I have been trying to learn what I can before I actually buy something.

It seems clear to me (given my current state of understanding) that I either need as large a pair of AGM batteries as I can get or a pair of Lithiums. My assumption is that I need to be able to supply perhaps 100-125 AH of power over 2 days without much in the way of solar supply given how much foliage there is where we camp and given that it is in a valley with mountains on both sides. The "daylight", such as it is, does not really start until the sun crests the mountains and stops when it sets on the other side, and that only provides about 6 hours.

Perhaps the battery monitor will help me figure out what I really need.

[BigWoods]

If you have a good quality, modern MPPT solar charge controller then I would recommend the BIM. If you have a cheap controller then I’d upgrade with a DC to DC.

[creativepart]

BigWoods... I can't understand why a solar charge controller would have anything to do with alternator charging of Lithium batteries.

MPPT charge controller for SOLAR charging... you bet.

But I totally fail to see any impact on engine alternator charging profile.

[bobmac]

AJMike
With regards to your comments on the relationship ship between battery voltage and "state of charge". There is a very direct relationship between the charged voltage and the health of the battery. A new full capacity battery will read about 12.8 volts when fully charged and maintain a higher voltage over time than an older "experienced" battery.
An older battery will likely achieve that level but when the charger is disconnected, the voltage will drop. The difference between a new and an older battery is how fast the voltage drops when disconnected from the charger. When the voltage drops, it is also telling you the capacity of the batteries has also decreased.
With your solar connected to charge your house batteries and connected to divert a portion to your chassis batteries thru a Trik-L-Start, my grp 31 AGM batteries lasted 7 years. I installed a Res Fridge and those same batteries power it thru an inverter when we boondock overnight so the get regular "heavy exercise". Good luck,

[Lefler39]

I hope this solution helps you.
AGM versus Lithium descision. An AGM can only go to 1/2 capacity which is 11.5 V or 50AH before it shuts down. AGM can last <4 years before you purchase a new one fro discharge rates.

I have a 2018 Winnebago Navion. I have two Group 24 NAPA 35AH lead acid batteries when purchased. I just found out I can replace them both with one Group 31 Lithium and get 100 AH and it fits nicely into the cabin battery step. The Lithium offers a fast charge, 90% discharge to 5% and 10 year life expectancy within my small battery compartment. This idea appears to be a common sense low cost solution for our unit.

I plant to change them fout before our summer road tour.

[AJMike]

Originally Posted by Lefler39

I have a 2018 Winnebago Navion. I have two Group 24 NAPA 35AH lead acid batteries when purchased. I just found out I can replace them both with one Group 31 Lithium and get 100 AH and it fits nicely into the cabin battery step. The Lithium offers a fast charge, 90% discharge to 5% and 10 year life expectancy within my small battery compartment. This idea appears to be a common sense low cost solution for our unit.

I plant to change them fout before our summer road tour.

I wonder if your Group 24 Napa batteries were the same as those that came on our 2018 Fuse. Were those maintenance-free? Or did they have caps on the top?

Whose Lithium battery did you install? And do you have a battery isolator or DC-to-DC charger installed for your Lithium batteries?

[BigWoods]

Originally Posted by creativepart

BigWoods... I can't understand why a solar charge controller would have anything to do with alternator charging of Lithium batteries.

MPPT charge controller for SOLAR charging... you bet.

But I totally fail to see any impact on engine alternator charging profile.

Hopefully I can explain this way.
I put in solar with AGM. I used a Renogy 40a MPPT controller. I later decided to switch out the AGM for two Battleborn. I checked and my stock converter was perfectly fine for the BB batteries. The only issue was charging from the alternator. I could have replaced the Renogy controller with a DC to DC, or I could switch out the BIM for the one BB sells for $172. I decided the easier and cheaper way was to switch out the BIM. It took less than 30 minutes. Does that make sense?

[Lefler39]

Originally Posted by AJMike

I did not seriously consider Lithium because I understood that they needed to be charged to a higher voltage and that my current alternator would not supply the 14+ volts that they needed to get fully charged. Since you have Lithium what did you do about that? Or is my understanding wrong?

https://www.youtube.com/watch?v=Ci9w5kqhz-I

Upgrade the charge controller

[creativepart]

Originally Posted by BigWoods

Hopefully I can explain this way....
Does that make sense?

No actually. Not at all. The Solar Charge controller has zero to do with the alternator on your RV charging your lithium batteries.

Neither does your converter/charger have anything to do with your Solar Charge controller.

These are all totally and completely separate things.

1. The solar charge controller- charges your lithium batters from the output of your solar panels. It does nothing else.
2. Your converter/charger powers your 12v appliances and charges your batteries when on shore power. It has nothing to do with your solar panel charging.
3. You alternator charges your Lithium batteries while the motorhome engine is running. It has nothing to do with your solar charger, nor your converter/charger.

Three totally separate things doing three totally separate jobs, but all charging your batteries just not usually all three at the same time.

So, you still must have a solar charge controller. You still must have a converter/charger. And your alternator... well it has a BIM which has no bearing on the other two.

Still hoping you can explain your statement because I'm lost to see how they are related.