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Second Battery Question


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#1 dharte

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Posted 24 February 2018 - 10:03 PM

Hi folks,

In my recent thread about adding a fridge, I mentioned I would be adding a second battery to my 2015 Hawk set-up which has the 165W solar panel  and one battery.  I have two questions:

 

1.  Is there any harm adding a brand new battery to the 2 year old battery I am using (Exide AGM)?

     The two year old battery has been charged it's entire life with the solar panel and has never been run

     low.

 

2.  Is the camper pre-wired for two batteries, or will I need to add cables from the old battery in parallel to   the new battery.  The battery in use has two connectors on each post, but I think one is from the solar controller and the other set is the main camper power cables.  Not sure though since I don't have a schematic to look at.  One of the positive cables has a built in fuse holder on it but not the other wire.

 

Thanks,

David


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#2 Wandering Sagebrush

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Posted 24 February 2018 - 10:11 PM

My 2¢ worth. It’s not best practice, but it won’t be catastrophic. The older battery might be weaker, and draw down the other. I suspect you’ll have to change them out at different intervals. If you have another use for the existing battery, you might use it there, then install two matched batteries in your camper.
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#3 Ronanmd1

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Posted 24 February 2018 - 11:30 PM

My 2¢ worth. It’s not best practice, but it won’t be catastrophic. The older battery might be weaker, and draw down the other. I suspect you’ll have to change them out at different intervals. If you have another use for the existing battery, you might use it there, then install two matched batteries in your camper.

 

I would agree. If possible, use the original battery in another application. Otherwise, just go ahead and wire in parallel


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#4 ntsqd

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Posted 25 February 2018 - 01:04 AM

I doubt that it is wired for two batteries, but assuming that there is the physical room for the second battery it shouldn't make much difference.

 

Another best practice, but not an absolute, is when wiring two batteries in parallel to make the + connection on one battery and the - connection on the other. If the existing wires allow it, then do it. If they do not, then don't bother and don't fret about it either.


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Thom

Where does that road go?

#5 dharte

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Posted 25 February 2018 - 02:18 AM

Yikes, the original battery (Exide Edge) is $315 on Amazon.  Anyone know a more affordable brand/place to buy a deep cycle rv battery? No luck on the car parts store websites or Sears..  I will not use Optima batteries due to very poor lifespan when I used them in my truck.


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#6 Vic Harder

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Posted 25 February 2018 - 02:26 AM

Hi folks,

In my recent thread about adding a fridge, I mentioned I would be adding a second battery to my 2015 Hawk set-up which has the 165W solar panel  and one battery.  I have two questions:

 

1.  Is there any harm adding a brand new battery to the 2 year old battery I am using (Exide AGM)?

     The two year old battery has been charged it's entire life with the solar panel and has never been run

     low.

 

2.  Is the camper pre-wired for two batteries, or will I need to add cables from the old battery in parallel to   the new battery.  The battery in use has two connectors on each post, but I think one is from the solar controller and the other set is the main camper power cables.  Not sure though since I don't have a schematic to look at.  One of the positive cables has a built in fuse holder on it but not the other wire.

 

Thanks,

David

+1 to what the other's said, and yes, you will need to add wires.


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#7 Trailbob

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Posted 25 February 2018 - 06:00 PM

I also agree with what Wandering Sagebrush (and others) said above.  When you parallel your batteries, consider a minimum of 6 AWG wire for the parallel connections.  If you have enough existing wire in the battery box (and you should), I would follow what ntsqd recommended about using the + on one battery for the camper +, and the neg on the other battery for the camper neg.  This equalizes the load on the batteries.

 

When I went from one to two batteries I bought Exide AGMs from Bi-Mart for a very good price (don't remember what it was, but WAY less than Amazon).  I have also seen them either at Home Depot or Lowes (I think it was Home Depot).


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#8 ntsqd

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Posted 25 February 2018 - 06:42 PM

Suggest searching the type and group size batteries that you want on the whole net. By doing that I found a place where the shipping was included in the price, and they were still way better priced than anything local.


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Thom

Where does that road go?

#9 dharte

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Posted 25 February 2018 - 11:02 PM

Well after a lot of research, I am really thinking about getting 2 6v batteries and connecting in series, I found some that will fit for about $200 each. They have the same footprint as the group 24, but are taller, and my battery cabinet has lots of space above the batteries.  This shouldn't pose any issues for the solar charger should it? 


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#10 smlobx

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Posted 25 February 2018 - 11:23 PM

I applaud your choice of two 6 volt batteries.
We have them in our Hallmark and they have been very reliable so far.
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Eddie
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