What to do on Batteries?

[Larryw54]

I like many here, am new to your forum. I enjoy watching the you tube videos, but easy to get overwhelmed with information overload. So let me cut to the chase. I purchased a 28A CA motorhome where the previous owner did many upgrades and one was put in a 1200 Pure Sine inverter. What I don't know is how long will the battery he currently have last, if I boondock? Everything electrical in the 28A is pretty standard EXCEPT the fridge is a 115v residential.
The current House Battery is a Motor Craft 29MH, and seem to be good BUT I have 2 AGM DEKA 8A24 (12v) that was used for my old sump pump backup.
The question is - Am I better of switching my current battery with the older DEKA (Just one I am thinking) Will l get better power for a longer period of time?
Thank you
Larry W

 

[Supervstech]

I couldn’t find much info on the battery 29MH didn’t show in a search.
I am GUESSING the MH stands for motor home, group 29. And as such, marine deep cycle wouldn’t be good for many cycles. Maybe 300 if treated well...
your solar batteries are SLA, and 79Ah, so they can be calculated out to 1896Wh storage.
Now, you could calculate with a watt meter and determine the Wh consumption daily, to know if the batteries will be sufficient.

 

[Pnw_steve]

I run a 10.8 cu.ft. residential refrigerator in my travel trailer from two GC-2 batteries. They are "true" deep cycle batteries. When the were brand new they would run all of my loads, including the refrigerator, for 24 hours without trouble. My battery bank = 12v 215a/h.

I would definitely recommend upgrading your batteries. What you choose depends on a couple of factors.

How much capacity do you need to support your loads? How long do you want to be able to go without plugging in to shore or generator power? How much room do you have for batteries? Are you going to add solar?

One certainty is that the typical "marine/RV Deep Cycle" batteries that you buy at the big box stores are junk. They are a little bit better for this application than an automotive starting battery but not by much.

If you go with a lead acid battery (FLA or AGM) be mindful of your charge source. Too much charge current will boil the electrolyte and can damage the batteries. Not enough charge current and you will sulfate the plates in the batteries. Common recommendations are 8-13% of the C20 rating.

Lifepo4 batteries do not suffer from the same issue but they do have their own needs like a battery management system (BMS) to protect it from under/over charging and to prevent charging at freezing temperatures. I will let others tell you more about the Lifepo4 batteries. I have plenty of experience with FLA in RV's and others off grid applications but Lifepo4 is fairly new for me.

One thing that I would suggest is picking up a "kill-a-watt" meter ($23) and plug your refrigerator in to it for several days of normal use and gauge how much power it actually consumes.

Another random thought..... If you are handy with things electrical, disconnect or put a switch in to control the auto defrost function on the fridge. It really sucks power when it kicks in.

 

[Larryw54]

I couldn’t find much info on the battery 29MH didn’t show in a search.
I am GUESSING the MH stands for motor home, group 29. And as such, marine deep cycle wouldn’t be good for many cycles. Maybe 300 if treated well...
your solar batteries are SLA, and 79Ah, so they can be calculated out to 1896Wh storage.
Now, you could calculate with a watt meter and determine the Wh consumption daily, to know if the batteries will be sufficient.

Thanks I should have included the link for the MotorCraft. They have been bought out by DieHard

Advance Auto Parts - Down for Maintenance

 

[Larryw54]

I run a 10.8 cu.ft. residential refrigerator in my travel trailer from two GC-2 batteries. They are "true" deep cycle batteries. When the were brand new they would run all of my loads, including the refrigerator, for 24 hours without trouble. My battery bank = 12v 215a/h.

I would definitely recommend upgrading your batteries. What you choose depends on a couple of factors.

How much capacity do you need to support your loads? How long do you want to be able to go without plugging in to shore or generator power? How much room do you have for batteries? Are you going to add solar?

One certainty is that the typical "marine/RV Deep Cycle" batteries that you buy at the big box stores are junk. They are a little bit better for this application than an automotive starting battery but not by much.

If you go with a lead acid battery (FLA or AGM) be mindful of your charge source. Too much charge current will boil the electrolyte and can damage the batteries. Not enough charge current and you will sulfate the plates in the batteries. Common recommendations are 8-13% of the C20 rating.

Lifepo4 batteries do not suffer from the same issue but they do have their own needs like a battery management system (BMS) to protect it from under/over charging and to prevent charging at freezing temperatures. I will let others tell you more about the Lifepo4 batteries. I have plenty of experience with FLA in RV's and others off grid applications but Lifepo4 is fairly new for me.

One thing that I would suggest is picking up a "kill-a-watt" meter ($23) and plug your refrigerator in to it for several days of normal use and gauge how much power it actually consumes.

Another random thought..... If you are handy with things electrical, disconnect or put a switch in to control the auto defrost function on the fridge. It really sucks power when it kicks in.

Thanks for the reply - As a Holiday Gift I got a energy 100watt solar Kit, so I was going to use that for charging.

 

[Pnw_steve]

With a 100 watt 12v solar charger you are unlikely to see more than 7-8 amps. If you want to properly charge FLA or AGM I would recommend a battery around 75a/h.

My understanding is that Lifepo4 does not have the same issue. Low charge rate is not a problem.

 

[Supervstech]

Thanks I should have included the link for the MotorCraft. They have been bought out by DieHard

Advance Auto Parts - Down for Maintenance

I did find that battery, but you said MH, not HM...
Anyway, my statement is correct. Marine batteries are not well suited for solar storage and use.