Replacement Battery for Montana 3761FL

[Sumri]

Battery Died. I think the battery kill switch above the battery is broken and I will replace it also.
What is the standard battery for the Montana? Is it a Marine Deep Cycle Group 27?

[rohrmann]

There is no ‘standard’ battery or batteries in these rigs. They are delivered to the dealers without batteries and the dealers install one or two, depending on their thought on what they will install. With your rig and the residential fridge, you should have at least two batteries, and whether they are RV/ Marine batteries, conventional lead acid deep cycle golf cart type batteries, or AGM’s, or anything else is strictly up to you and how much money you want to spend. There are even some who have solar and have lithium batteries that can run upwards of $1000 each. Our rig originally had two group 24 Maintenance free RV/Marine batteries that the dealer installed and later on I upgraded them to the same type but group 27. We are currently dry camping at Quartzsite and they work great, along with a Honda generator running during the day to charge them back up after each night.

[PeteandJoan]

Yep it should have come with two because of fridge. Not sure what is considered standard but you may as well replace with two larger ones while you are at it. Maybe even AGM so you don't have to service, although they are more$$. Lots of choices out there. But I would get two very good ones or else you may be right back where you are now. I also have the res. fridge and it came with two 27's and when they caused trouble I replaced with 2-6v AGM's which seemed to be the most recommenced from this forum. No more problems. Also install a neg. shutoff switch near battery. Good luck.

[CaptnJohn]

I also have the residential fridge. CW installed 2 group 31 batteries

[Sumri]

If I get a AGM Deep Cycle, do I need to replace the cover in the battery compartment?

[jcurtis934]

No need for the cover and vent hose for am batteries. I use two group 31 agm marine deep cycle batteries and have battery trays and hold down clamps from west marine boat store.

[Arkware]

When you are looking at batteries, look at how they are rated.
look for 'Amp Hours' rating instead of 'Cold Cranking Amps' rating.
This will indicate a 'true' deep cycle battery instead of a hybrid one.

On my unit, the on/off switch above the batteries is only for the inverter.
The switch for the house 12 v. power is in the convience center. (the red key)
There are a few devices that are wired directly to the batteries, so a true cutoff switch on the negative post is a way to be sure...

[mtlakejim]

I saw a winter battery use article in the You may also like section if you see the same thing. I really liked it at it described how to easily calculate basic amp draw and gave a great example, the furnace at 6amps per hour. The way it calculated you could run the Furnace on batteries only all day if you charged them with a generator for about 2 hours. Does that sound right to you boondockers? If that is the case sounds like I could at least use the furnace for short overnights at truck stops and recharge with the truck as we drive to next destination??

[lightsout]

ste your $$$ on 12v batteries period cost per watt with 6v is far more beneficial. You can get more than twice the AH (amp hours) from Two 6v vs a single 12v (group 27 or 31) in almost the same amount of space. Replacing with 6v also sets you up to add solar at some point in the future as you would only want 6v with solar anyway so you are somewhat future proofed. If you have room four 6v's can deliver game changing 12v power to your 5er.

AGM VS Wetcell, that is an individual thing whereas AGM are at or more than twice the cost of wet cell batteries, the biggest difference for RV is the wet cell batteries require you to occasionally add water. If you can afford AGM by all means buy them although keep in mind the biggest drawback they are sensitive to heat so if you use your RV in warm climates that is something to consider as that can reduce the life of the AGM batteries.

What kills me is the manufacturing cost of AGM vs Wet is not a whole lot different even though the retail price suggest there is (more than double). Unfortunately the battery industry is controlled by very few so there is not enough competition to make pricing realistic and on PAR at this time.

I am shopping batteries right now for my 11-month old 2019 3791RD as it has been at the dealer for 2.5 months for warranty work and they let the batteries drain to ZERO and sit for 2 months at zero charge so they are now damaged. I am switching from 2 group 27's to 4 252AH 6v which will nearly triple my AH power I am also adding Solar battery charging as a maintainer as charged batteries are happy batteries and promotes long life.

I mentioned above I will also be adding a Ground disconnect switch and well as a hot switch that will allow me to use each bank of two 6v separately or all together or all off.

I will probably buy Wet Cells we also have a 50' motor yacht that has 8 6V wet cells and for year we have had no issues, they are 6 years old not and still going strong and only lost a small amount of capacity. So I am not apposed to Wet cell they are easy to maintain.

[Dave W]

I use a common Gr 27 or 31 marine deep cycle. I looked at AGMs and decided at over 2Xthe cost that for our needs the flooded lead acid battery was just fine. If we full timed, would probably bite the bullet for AGMs or the entire box of bullets for litium.


Speaking of AGM batteries, my wallet found out that our Ford Escape Titanium uses them - at a list price of a bit over $200 - and it's about half the size of a Gr 27/31

[jeffba]

The kill switch you speak of in the convenience center is not a kill switch. It just isolates the battery from the converter.

What you need tot do is install a battery disconnect at the negative of your batteries once you replace them. Otherwise, the propane detector and other things running off the battery that the so called kill switch does not block will drain the batteries.

[GreG L.]

I replaced the two 100AH batteries (you should have gotten 2 with a residential frig) that came with the 3561, with two Battle Born LiFe4 batteries. These give twice the amp hours as Wet/AMG batteries at (ouch) 4 times the cost but significant longer life expectancy and no off gas like Wet/AMG's.

[lightsout]

Originally Posted by GreG L.

I replaced the two 100AH batteries (you should have gotten 2 with a residential frig) that came with the 3561, with two Battle Born LiFe4 batteries. These give twice the amp hours as Wet/AMG batteries at (ouch) 4 times the cost but significant longer life expectancy and no off gas like Wet/AMG's.

The Battle Born batteries do not double the amp hours they are only 100AH .ea that is the same as most group 27-31 wet batteries, there is no increase in AH with the Battle Born Lithiums just no maintenance and estimated longer life at $1000 ea that is near triple the AGM and 6 times the cost of wet cell batteries with similar AH.

Much of the cost of the Lithium batteries is the 10 year warranty as there is relatively high risk for the manufacture to warranty for 10 years so they also have to build in cost to cover warranty.

I have no problem with Lithium batteries in fact I was an early buyer of Tesla (we have a 2014 Model S) however that is a different comparison as there is a return on investment compared to their gas counterparts.

@ Battle Born will only provide a total of 200AH at a cost of $2K whereas you can install four 6v AGM for about $1300-$1400 that will deliver 500AH, or for $700 two 6v at 252AH which is still more than two 12V Lithium. AGM batteries should last you 6-10 years Lithium 10-15 years (all depending on use and other factors like ambient temps)

Unless you plan on keeping your 5th wheel 10-20 years there added cost of the Lithiums is a loser. Considering the average life of RV ownership in the US is 7.4 years ultra long term expense not practical especially since lithium battery cost will be coming way down in the next 5 years.

Also note Heat can be damaging to Lithium's and excessive heat also voids the warranty so if you travel in warm climates you need to consider a cooling method for lithium batteries

For those that do not want the Lithium or AGM there is noting wrong with Wet cell batteries as long as you buy decent batteries and maintain them which is really basic maintenance.

for $8-900 you can buy four 6v wets at about 250AH each for a total of 500AH when in series or $400 for two 6v wet at 250AH and should provide 5-7 years of service.

When you compare cost per AH or watt the lithium is a huge loser in the short term (5-8 years). Also keep in mind no one is going to value your lithium batteries when you sell in 7-10 years or more and the productive life is mostly used up.

If you ever planned to have any significant solar you should have a minimum of 600 AH that is $6k with Lithium whereas you really should have 1000AH plus again making Lithium not cost effective.

Frankly for any house power being RV or Boat you should never use 12v they simply cannot deliver the AH that 6V can.

[mlh]

Like Dave said AGM batteries come in most cars with ‘start stop’. Fords 2015 F150 2.7 Ecoboost was their first. Now most Fords have ‘start stop’, the engine stops when the car comes to a stop then starts when you take your foot off the break pedal. I had a AMG battery go bad in my 2015 2.7 F-50 at 3 months. I was going to replace it with a regular car battery. Our Interstate distributor told me not to because a regular car battery would not last with start stop.

My next RV batteries will be Lithium. Yes they are much more expensive but have advantages. If I sell that RV I’ll take them out and replace them with a deep cell.
Lynwood

[jeffba]

Originally Posted by lightsout

The Battle Born batteries do not double the amp hours they are only 100AH .ea that is the same as most group 27-31 wet batteries, there is no increase in AH with the Battle Born Lithiums just no maintenance and estimated longer life at $1000 ea that is near triple the AGM and 6 times the cost of wet cell batteries with similar AH.

100 AH AGM will only give you 50AH usable

Much of the cost of the Lithium batteries is the 10 year warranty as there is relatively high risk for the manufacture to warranty for 10 years so they also have to build in cost to cover warranty.

I have no problem with Lithium batteries in fact I was an early buyer of Tesla (we have a 2014 Model S) however that is a different comparison as there is a return on investment compared to their gas counterparts.

@ Battle Born will only provide a total of 200AH at a cost of $2K whereas you can install four 6v AGM for about $1300-$1400 that will deliver 500AH, or for $700 two 6v at 252AH which is still more than two 12V Lithium. AGM batteries should last you 6-10 years Lithium 10-15 years (all depending on use and other factors like ambient temps)

At a Rally, you can save $100 per battery. So the premium is less

Just do not let those AGMs go dead or their life will be cut in half

Unless you plan on keeping your 5th wheel 10-20 years there added cost of the Lithiums is a loser. Considering the average life of RV ownership in the US is 7.4 years ultra long term expense not practical especially since lithium battery cost will be coming way down in the next 5 years.

you can also move them to the next rig

Also note Heat can be damaging to Lithium's and excessive heat also voids the warranty so if you travel in warm climates you need to consider a cooling method for lithium batteries

For those that do not want the Lithium or AGM there is noting wrong with Wet cell batteries as long as you buy decent batteries and maintain them which is really basic maintenance.

Any bets how many wet cell batteries are not checked regularly?

for $8-900 you can buy four 6v wets at about 250AH each for a total of 500AH when in series or $400 for two 6v wet at 250AH and should provide 5-7 years of service.

again do not ever let them run down

When you compare cost per AH or watt the lithium is a huge loser in the short term (5-8 years). Also keep in mind no one is going to value your lithium batteries when you sell in 7-10 years or more and the productive life is mostly used up.
Again move them to the new rig. They will be better than what teh dealer will install

If you ever planned to have any significant solar you should have a minimum of 600 AH that is $6k with Lithium whereas you really should have 1000AH plus again making Lithium not cost effective.

Frankly for any house power being RV or Boat you should never use 12v they simply cannot deliver the AH that 6V can.

Can you tell what i am going to buy for my next battery?

[mtlakejim]

Originally Posted by mlh

Like Dave said AGM batteries come in most cars with ‘start stop’. Fords 2015 F150 2.7 Ecoboost was their first. Now most Fords have ‘start stop’, the engine stops when the car comes to a stop then starts when you take your foot off the break pedal. I had a AMG battery go bad in my 2015 2.7 F-50 at 3 months. I was going to replace it with a regular car battery. Our Interstate distributor told me not to because a regular car battery would not last with start stop.

My next RV batteries will be Lithium. Yes they are much more expensive but have advantages. If I sell that RV I’ll take them out and replace them with a deep cell.
Lynwood

Yeah we bought one of those %$&@ "start stop" pieces of *&^% and I am very angry about it. The sales rep. did not mention that the Ford Escape came with that GRRRRRRR......... and apparently from what I have read there is no way to permanently disable that ill conceived tree hugging stupidity! I guess the car manufactures are just desperate to do anything to look like they are environmentally friendly.

[lightsout]

Originally Posted by jeffba

Can you tell what i am going to buy for my next battery?

Look is is your hard earned $$$ spend them as you wish, as should anyone here, however I was simply pointing out the real world comparisons. Lithium is still a relatively young embryonic industry with high AH batteries hence the current excessive cost. I am a fan of Lithium especially since we own a Tesla however Tesla also has a robust cooling system for the Lithium batteries.

One thing that is not discussed is Lithium batteries they cannot be recharged below freezing temperatures without being destroyed and, even worse, rendered permanently and immediately dangerous. This was another thing Tesla had to compensate for they actually warm the batteries before they start to charge.

So for those that use or store in a cold environment they too have to take these considerations into account.

While wet has it maintenance issues (which requires minimal effort), AGM does not like to be over drained, and Lithium has thermal management requirements, none of the battery options are without potential catestrophic failure issues not covered by warranty.

IMO I think AGM is the best current technology for today and I will let Lithium mature a bit longer.

It is one thing to own a car that is engineered for Lithium batteries versus adapting lithium in to a RV that has no thermal management to support lithium in cold or hot environments. For many that is a non issue for us we stay in the Desert in the Summer and Home in Seattle in the Winter so we do see both ambient temperature swings that can be detrimental to Lithiums.

I also own a JL Jeep Wrangler that has that start stop feature however the batteries including the Wet battery are insulated for Thermal management. Most battery compartments on 5ers are not.

There is a lot to consider with this topic, it is not just a plug and play decision.

[jeffba]

Didn't tell him you were in the oil business?

[lightsout]

Originally Posted by jeffba

Didn't tell him you were in the oil business?

Not oil however I am an engineer in the energy business, Commercial electrical conservation and energy management controls.

[jeffba]

Originally Posted by lightsout

Not oil however I am an engineer in the energy business, Commercial electrical conservation and energy management controls.

That was for Jim