Deep Cycle Marine to AGM Battery

[joeclorite]

I am looking to switch from the original Group 24 Marine Battery to either an AGM or Lithium Ion Battery.
Is there anything that I need to do before the change. Do either of these batteries need a different type of Inverter?


Thanks

[powercat_ras]

Lithium would require a new converter/charger. You said inverter but that's not what charges batteries. AGM the current one would be OK. Make sure you get a Deep Cycle battery either flooded lead acid or AGM. The make AGM batteries that are NOT Deep Cycle for marine and auto use.

[joeclorite]

Yes, I meant Converter/Charger.
I will start with the AGM Deep Cycle. It must be better than the house battery.

Thanks for the quick reply Randy.

[BobC]

The charge profiles are different for the different types. I'm assuming you have an inverter/charger. Hopefully it can be set for different charging profiles. Here's a link that discusses charging traditional flooded vs. AGM and Gel Cell batteries.

https://www.westmarine.com/WestAdvis...attery-Charger

In terms of a lithium battery, you want a Lithium Iron Phosphate battery (aka LifePO4), which is a specific (and safer) type of Lithium Ion battery. They are a world to their own.
Here's a link to some info from Battle Born batteries, a widely respected manufacturer of LifePO4 batteries:

https://www.westmarine.com/WestAdvis...attery-Charger

You mentioned that you now have a "marine battery". Typically these are hybrid deep cycle/starting batteries and, since you don't use your's for starting a vehicle, you'd be better served by a "true deep cycle" battery, be it traditional flooded or AGM. A popular, and relatively inexpensive true deep cycle option is to use two 6v "golf cart" batteries in series (negative to positive, positive to negative) to provide 12v. AGM batteries are also available as true deep cycle batteries. The main advantages of AGMs is that they don't need periodic maintenance and can be operated in enclosed spaces. On the other hand, they're more expensive and less hardy than traditional flooded batteries.

LifePO4 batteries are significantly more expensive up front but last longer (lower life time cost), weigh much less and provide more usable power per charge. A 100 amp-hour traditional or AGM battery can only be discharged to about 50%, providing only about 50 amp-hours of electricity, while a 100 amp-hour LifePO4 battery can be discharged to 0%, providing the full 100 amp hours.

You'll probably want to do some significant research before going the LifePO4 route.

Personally, I have golf cart batteries and, although I'm intrigued by LifePO4s, don't use my MH enough to justify the up-front expense right now. Are they in my future, probably, and they'll only get less expensive. I'm sure others will disagree.

[creativepart]

Originally Posted by BobC

I'm assuming you have an inverter/charger.

BobC... it's a travel trailer and he misspoke and meant Converter/Charger. See the 3rd post in the thread.

[BobC]

I recently purchased one of these for my wheelchair van, reasonably priced and 110 Ah vs the typical 100 Ah battery:

https://www.lowes.com/pd/Mighty-Max-...ies/1001401826

[JoeC]

Originally Posted by joeclorite

Yes, I meant Converter/Charger.
I will start with the AGM Deep Cycle. It must be better than the house battery.

Thanks for the quick reply Randy.

A good quality deep cycle AGM would be much better than the cheap dual function batteries that are typically put in the RVs. Lithium batteries are in a whole different class and the electrical system needs to be re-engineered to properly introduce them. You need to have a good reason to go that route but there is no comparison to their great advantages, except cost, which should be coming down some in the next few years. Going solar would be a good case for lithium batteries.

[thataway4]

To do it "properly" with LiFePO4 batteries it would cost in the $2500 to $3000 range. Only worthwhile if you are doing a lot of off the grid camping, and planing to keep the unit for 10 years.

I do want to correct one post above saying that you can discharge to 0%. Battle Born does not recommend discharging to below 10% of capacity--thus their 100 amp hour battery can give 90 amp hours. Actually the BMS will shut down the battery cells when you get about at 9%. I have been using the Battle Born batteries for over 2 years in a boat--same type of application as in a travel trailer.

For the average person a set of good golf cart batteries is best. If you want lowest self discharge then the AGM has an advantage. That is what I used to replace the group 24 FLA which came in my VIA 25T.

[Pianotuna]

My Next bank will be from SiO2 about 1/3 the price of LI but can be used and charged down to -40C

[MrBill]

I just rebuilt the electrical system in my 40 year old Winnebago and I have 4 AGM 100 amp hour deep cycle marine batteries this seems to be good I can run my a/c with a 5000 inverter not sure how long it will run before the generator kicks in still rebuilding the motorhome

[macnut]

It might run the AC, but not very long. If you get 200 amp hours from the AGMs, and it takes roughly 120 amp hours per hour to run an AC unit on a 12 volt battery, you would get less than two hours. That does not include any efficiency loss for the inverter. I’ve seen folks run an AC off a lithium battery, but I don’t recall running it off an AGM battery. My understanding is AGMs don’t do as well for large, quick power drains. I’m sure the battery experts with add more info,

[MrBill]

My idea was to only use it for A/C in an emergency, I have a friend that gave me a smoking deal on the AMG batteries paid 200 for 4. Also doing solar panels on the roof to help with keep batteries charged was looking at lithium batteries but couldn't pass the price on the AGM. I really do appreciate the advice.

[Tomakazie]

Purchased a 2010 Winnebago Tour, 40’ last year. I was all happy to see the 4 house batteries were only 2 years old. Come to find out they were Enterprise starting batteries, not deep cycle. These took a crap last month. Ended up purchasing from Sam’s Club 4 Duracell AGM 31DT deep cycle for $179.00 each. I have 380 watts of solar currently. Looking to place one more 190 watt panel the get the most out of my Go Power GP-PWM 30 controller. The Dog House....

[BobC]

Originally Posted by Tomakazie

Purchased a 2010 Winnebago Tour, 40’ last year. I was all happy to see the 4 house batteries were only 2 years old. Come to find out they were Enterprise starting batteries, not deep cycle. These took a crap last month. Ended up purchasing from Sam’s Club 4 Duracell AGM 31DT deep cycle for $179.00 each. I have 380 watts of solar currently. Looking to place one more 190 watt panel the get the most out of my Go Power GP-PWM 30 controller. The Dog House....

These are hybrid starting/deep cycle, not true deep cycle batteries.

https://www.samsclub.com/p/duracell-...gm/prod3590232

[MrBill]

This 1981 Winnebago 26 foot came with one house battery and it was not a deep cycle marine battery it's a battery you would find in a bus. So I'm thinking the upgraded electrical system and all the AGM deep cycle marine batteries I put in it has got to be an improvement.

[Pianotuna]

Originally Posted by MrBill

This 1981 Winnebago 26 foot came with one house battery and it was not a deep cycle marine battery it's a battery you would find in a bus. So I'm thinking the upgraded electrical system and all the AGM deep cycle marine batteries I put in it has got to be an improvement.

Going to a Marine AGM battery is, imo, a poor choice. For house loads one needs a true deep cycle battery. They also need to be wired in a ballanced manner.


This is what is balanced and best for twin twelve volt batteries.





As it often doesn't cost a dime more to do this, I think it is worth the trouble.


If you wish to understand the "why" surf here:


correctly interconnecting multiple twelve volt batteries

[Pianotuna]

Originally Posted by MrBill

This 1981 Winnebago 26 foot came with one house battery and it was not a deep cycle marine battery it's a battery you would find in a bus. So I'm thinking the upgraded electrical system and all the AGM deep cycle marine batteries I put in it has got to be an improvement.

Going to a Marine AGM battery is, imo, a poor choice. For house loads one needs a true deep cycle battery. They also need to be wired in a balanced manner.


This is what is balanced and best for twin twelve volt batteries.





As it often doesn't cost a dime more to do this, I think it is worth the trouble.


If you wish to understand the "why" surf here:


correctly interconnecting multiple twelve volt batteries

[Hatrock]

I switched from my original equipment Group 24's to two 12V Full River AGMs and tripled the amp hour capacity. I also installed 220W solar on my roof and have an onboard ONAN propane generator. No inverter change required. I just had my first dry camping experience with this setup. As long as the solar gets enough sun I will be comfortable running minimal 12V stuff for as many days as I want. In a pinch, I can run the generator. Seems to work very well.

[BobC]

It's too bad the battery industry keeps advertising their "Marine/RV" batteries as "deep cycle". They should be up front and advertise them as dual purose starting/deep cycle. It's very misleading.