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Battery Size (replacing)

Campinfan
Explorer III
Explorer III
I need to replace my RV battery. It is a 24DC model. I know that does not mean 24 volts DC. I see a 24DC battery I can get but there is also a 27DC that has more MCA (not sure what that means but I am used to CCA--cold cranking amps) So my question is, can I replace it with the bigger battery and if so, is it worth it to get the additional 60 MCA for $4 more? Just not sure if I HAVE to use the same size or is that just the minimum one the manufacturer uses to save a couple bucks.
______________________
2016 F 350 FX4 4WD,Lariat, 6.7 Diesel
41' 2018 Sandpiper 369 SAQB
Lovely wife and three children
42 REPLIES 42

theoldwizard1
Explorer II
Explorer II
valhalla360 wrote:

A few clarifications:
- CCA and MCA are all about starting the engine.

CCA- Cold Cranking Amps (tested at 0°F)
MCA - Marine Cranking Amps

Useless information for your application.
valhalla360 wrote:

- Amp-Hour rating is how long the battery can output power (at an assumed amperage, though much lower than the amperage for starting a truck engine). This would be a good estimate for how long it could run something like a fridge that might be drawing 10amps but for a long time.

Amp-hour is the "best" information you will get (the testing method is convoluted) when trying to compare to different batteries for your application.
valhalla360 wrote:

- Then you have starting, marine and deep cycle batteries. This is the internal structure of the battery. Starting batteries use many thin lead plates as more surface area generates more amps. Deep cycle batteries use fewer thicker plates as thicker plates can hold more stored energy. Marine (aka: Combo) are generally starting batteries that have been relabeled starting batteries that have a wing nut attachment on the studs. It's almost impossible to find true deep cycle 12v batteries. Usually, people will get 6v golf cart batteries and wire them in series to generate 12 if they really want deep cycle.

They also charge more for a Marine/RV battery "just because".

As stated, the "best bang for the buck" is a pair of 6V golf cart batteries. GC2 golf cart batteries typically deliver about 225 Ah. They will tolerate more charge/discharge cycles than starting batteries.

wowens79
Explorer III
Explorer III
I use 2 GC2 (golf cart) batteries. They are 6 volt and a true deep cycle battery. They are also more durable if they get ran down. I run a resi fridge and do not boondock.
The truck does charge the battery on the road, but I don’t think it supplies as much power as the fridge uses. The 2 gc2 batteries have held up to a 16 hr drive.
2022 Ford F-350 7.3l
2002 Chevy Silverado 1500HD 6.0l 268k miles (retired)
2016 Heritage Glen 29BH
2003 Flagstaff 228D Pop Up

wa8yxm
Explorer III
Explorer III
Group24 is about 75 AH give or take a few
Group 27 is the low side of 100
Group 29 is the high side of 100
Group 31 is about 130

You may safely use about 1/4 of a MARINE/deep cycle type battery

GC-2.. I a six volt golf car battery that is about the same size as a Group 24 but a bit taller.. If you have the room then-{6v}+-{6V}+==12 volts at 220 amp hours (Give or take) and you can safely use about half.

LiFePO4.. Not sure how many amp hours they can put in a 24 size (Guessing abourt 100) and of those 100 you can use 90-95 Man need a different converter however.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times

valhalla360
Navigator
Navigator
Campinfan wrote:
I do not boondock but the battery is used to run my inverter to power my residential fridge when driving. I know the truck supplies the power when driving. I guess if it will fit in the box, I will go a little bigger. and thanks for the MCA definition.


Is this the starting battery for a motorhome/truck or is it the house battery for a trailer (or non-engine loads in a motorhome)?

I'm guessing since you mention the fridge, it's the house battery.

A few clarifications:
- CCA and MCA are all about starting the engine. Overly simplified, if you ask the battery to put out as many amps as possible, this is how much it will put out. A big diesel often comes with 2 batteries as it takes a lot more amps to spin the engine fast enough to generate compression ignition vs a gas engine that relies on a spark to ignite the fuel/air mixture. This can easily be in the hundreds of amps.
- Amp-Hour rating is how long the battery can output power (at an assumed amperage, though much lower than the amperage for starting a truck engine). This would be a good estimate for how long it could run something like a fridge that might be drawing 10amps but for a long time.
- Then you have starting, marine and deep cycle batteries. This is the internal structure of the battery. Starting batteries use many thin lead plates as more surface area generates more amps. Deep cycle batteries use fewer thicker plates as thicker plates can hold more stored energy. Marine (aka: Combo) are generally starting batteries that have been relabeled starting batteries that have a wing nut attachment on the studs. It's almost impossible to find true deep cycle 12v batteries. Usually, people will get 6v golf cart batteries and wire them in series to generate 12 if they really want deep cycle.

For your use, the $4 upgrade is probably fine but don't expect much difference in amp-hr. Reality is your truck will keep the battery topped up and the battery will power the inverter, so it doesn't make much difference. For that use, I typically buy the cheapest battery available as there is negligible difference.

If you start boondocking more (aka: no shore power), that's when bigger and better battery banks become useful.
Tammy & Mike
Ford F250 V10
2021 Gray Wolf
Gemini Catamaran 34'
Full Time spliting time between boat and RV

Grit_dog
Navigator
Navigator
RLS7201 wrote:
Marine/RV batteries are compromise batteries. They were developed for marine trolling and engine start. They do not excel at either.
For you application a standard lead cell starting battery is your bet choice.

Richard


You’re right about the first part, sort of. They’re actually just fine for starting and will take the short term high amp loads just fine but they’re a compromise for deep cycle/ house battery use like trolling motors and campers because they have more/thinner plates to accommodate the high amp loads.
Second part you’re completely off/backwards. A dedicated starting battery while it will do the same job as a deep cycle, it won’t do it near as long before it’s worn out. That’s why true deep cycles aren’t suitable for high amp starting loads. They have thicker plates that last longer under discharge conditions that a good operating starting / charging system keeps from happening.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

Grit_dog
Navigator
Navigator
Find it hard to believe that big ole camper only came with one battery. That’s largely useless if the camper is being used for more than a couple hours tops off of shore power.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

RLS7201
Explorer II
Explorer II
Marine/RV batteries are compromise batteries. They were developed for marine trolling and engine start. They do not excel at either.
For you application a standard lead cell starting battery is your bet choice.

Richard
95 Bounder 32H F53 460
2013 CRV Toad
2 Segways in Toad
First brake job
1941 Hudson

Grit_dog
Navigator
Navigator
Campinfan wrote:
I do not boondock but the battery is used to run my inverter to power my residential fridge when driving. I know the truck supplies the power when driving. I guess if it will fit in the box, I will go a little bigger. and thanks for the MCA definition.


Your truck doesn’t directly supply the “power” when driving, and unless you’ve done considerable charging modifications, it supplies only a very low amp charge to your trailer battery if everything works Ike it should.
Not even close to what the inverter pulls off the battery to keep the fridge going in the dead of summer. Maybe winter too.
Now if you only drive a couple/few hours between being plugged into shore power and plugging into shore power again, yes you can continue getting by with a little single battery.

But do/will you ever drive all day long, maybe have a 24hour lapse in shore power? If so your setup even with a bigger battery won’t cut it.
I only mention this because the battery(s) are the biggest part of the equation you mention and if it’s time to get a new battery, it’s the best time to think about whether what you have will continue to work well for what you need.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

MFL
Nomad II
Nomad II


After having many different brands of this size battery, this is the one I'd recommend. Good power, and very long lasting.

Jerry

Campinfan
Explorer III
Explorer III
I do not boondock but the battery is used to run my inverter to power my residential fridge when driving. I know the truck supplies the power when driving. I guess if it will fit in the box, I will go a little bigger. and thanks for the MCA definition.
______________________
2016 F 350 FX4 4WD,Lariat, 6.7 Diesel
41' 2018 Sandpiper 369 SAQB
Lovely wife and three children

nickthehunter
Nomad II
Nomad II
You can replace with any 12volt battery you want. You should first determine the physical size of the battery and if it fits within the space it will reside in.
MCA = marine cranking amps Clicky

Grit_dog
Navigator
Navigator
Buy the biggest battery(s) you can cram in there if you want more capacity. Not difficult to measure your battery compartment and then compare to the published dimensions of different batteries.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold

enblethen
Nomad
Nomad
Group 27 has a little more capacity then a Group 24
Battery size depends on what style of camping you do. If just overnighting, a Group 24 will do. Couple of days then a Group 27. Longer periods you may want to switch to two 6-volt golf cart batteries.
It all depends on you on which is best!

Bud
USAF Retired
Pace Arrow


2003 Chev Ice Road Tracker

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