Battery question...part 2, group 24 or 27?

[jsms264]

This is part 2....converting to 2 - 12 volt batteries.

The original standard battery was group 24, 12 volt.

Now that I look I can get a group 27 for almost the same price as a group 24.

The group 27 has 105 amp hours per battery verses a group 24 is 80 amp hours. I understand the size and weight difference, but not so sure about the different specs. Is there any reason I cant go with the group 27?

Thank you in advance!

[Jim-Bev-2363]

I don't think it is recomended to combine different batteries. It sounds like you want to combine a group 24 and a group 27 in the same circuit. I think it is because of the different charge/discharge rates of different batteries for the reason not to combine groups. It might be best to have two different systems instead of trying to have one big battery bank.

I'm sure someone will be able to give a better answer.

[jsms264]

Yes, I was not real clear...I apologize.

I will be replacing the one (1) existing battery with two (2) new batteries, identical...same size, brand, spec,...etc.

[GKLarson]

We converted from a pair of group 24 batteries to a pair of group 27's w/o any problems. Needed 2 new appropriately sized battery boxes which just fit in the space provided.

[Jim-Bev-2363]

Then, if you have the room, go for it.

[EMD_Driver]

Originally Posted by Jim-Bev-2363

Then, if you have the room, go for it.

[jsms264]

Thank you, sounds like 27's it is!

[Jim-Bev-2363]

Originally Posted by EMD_Driver

[JohnB]

Hi Joe,,

I added 2, Grp 27's to mine. Had to buy new boxes and make a new battery tray convertor to hold them. I know you are very handy with wood.

See this link to my photo site. Right now I'm maxed out on band width so me linking the pic direct will not show up. But that link will take you right to the sub folder. If it still does not show up, PM me I'll email them to you.

Battery Area pictures by JBarca - Photobucket

Here is the better way on how to connect the 2 batteries so they get equal drain and equal change. See this site and use method 2.

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

It does make a difference and you do not use any more wire then doing the older direct parallel method 1.

Hope this helps

John

[Jim-Bev-2363]

JohnB, Did you do pictures and instructions here on exactly how you did that setup? Sure brings questions to mind. Did you do a picture of the two batteries connected but uncovered? How about the bike rack? Well, I think that is a bike rack.

I've been rounding up parts to do something similar but not sure if I should put the fuse box inside or outside. Outside where yours is looks to have batteries in the way of opening the fuse box. I had even thought of trying to have a third battery box for the fuse box and the main shutoff switch.

More questions than time, LOL!

[JohnB]

Jim,

In addition to the link above on the 2 batteries here are some more I took today to better show the setup.

The Grp 27 battery was wider then my battery rack. I made an adapter kit that drops and clamps in place in the original battery tray. I had to rotate the batteries 90 degrees to get them in there.





A better bottom view then I had in the other picture link


Now to the hook up. Follow this link. See method 2

SmartGauge Electronics - Interconnecting multiple batteries to form one larger bank

Looks like this. This method of paralleling 2 batteries forces the current to come from both batteries more equal. And recharge more equal. I even tested this as I did not have them hooked up like this originally.

The preferred method to 2 batteries



Originally I had them the straight standard parallel method like this.


Then one day I was taking battery state of charge (SOC) measurements and I unhooked the 2 batteries from each other. Sure enough the battery that was first that had both the + and - lead heading to the camper was lower in SOC. Maybe only 0.1 to 0.2 volts but it was different.

Well OK, then I started researching and found that web link. And I changed the hookup to have 1 camper lead on the opposite battery. This then equalized the drain rate and the charge rate. I recharged both batteries independent and hooked them up. Used the camper to drain the bank down some and then went through the process of unhooking both so I could test each one. Sure enough now both are within 0.01 to 0.02 volts of each other which could be some error in my meter.

The wire that joins the 2 batteries has some level of resistance to it, even if it is very low. If you hook them up the older straight parallel way, method 1, the current is gong to come from the easiest path which is the 1st one in the bank. Now granted some will still come from the 2nd battery but the 1st one is working harder over time.

It cost no more to hook them up using method 2 so why not optimize the setup to the best it can be.

Sorry I do not have a pic with the covers off. Those evil battery case straps and I are a love hate relationship. They came with the box and they work but boy are they a challenge to get hooked up. One of these days I'll get disgusted enough to change them to something else. The next time I have the covers off to check the water I'll take some pics for the future.

The bike rack, yes I did a thread on that. See here. Heads up it adds 109# of tongue weight. Make sure your WD hitch and more so the truck can handle that. The bikes ride the best that I have had over the years there it just needs the right truck to be able to use it.

http://www.sunlineclub.com/forums/f6...10sr-9554.html

Good luck and hope this helps

John

[JohnB]

Jim, I forgot one question, you said fuse box. That box on mine
(2004 vintage) only has the truck charge fuse in it. There are auto re-setting circuit breakers in there. I really never need to go in there. One of these days I will add the charge fuse on the outside of the box. I picked that tip up from Art at the Buttonwood M & G.

One battery or 2, if you want into that box the batteries have to come out.

[Jim-Bev-2363]

Thanks John, Very interesting pictures and ideas. I do have a weatherproof box but it is only half the size of what you installed. Might be able to work around that. I don't have a main off/on switch, yet. Soon for that upgrade.

Looking at your batteries and their being placed side by side instead of end to end, it does look like wiring would be simpler/easier that way. And it might even allow for one more battery within that space.

[JohnB]

Originally Posted by Jim-Bev-2363

Thanks John, Very interesting pictures and ideas. I do have a weatherproof box but it is only half the size of what you installed.

Hi Jim,

I myself did not install the box. In 2004 Sunline started to add the battery dissconnect switch. I do not know what year the "box" came. Getting in that box is not simple if dirt is kicked up in the screw holes. I did convert to SS screws on the outside as then little # 4 screws burried way deep inside are a real bear to get out once the phillpis heads strips after you dig the dirt out.

Here is what is in side on my slide camper.




Here is a non slide camper. One less circuit breaker




The battery dissconnect is a really good feature. Unhooking the battery manually each time would get old quick once you knw how simple it is to just rotate the switch.

John

[Jim-Bev-2363]

Thanks John. This can all get complicated if I ain't careful.

[jsms264]

Just returned from a week in the Adirondacks with no hook-ups and the 2 group 27's worked great. Thank you all for the assistance!! Here are a couple of pics.

[Poppy & Nana]

where were you?????

Glad everything worked with the batteries.....did you charge them in between? Leo and I can't get two weeks but we can last a good 5 - 7 days!!!!

[Tod Osier]

Made the change in my batteries yesterday, thanks for the information!

T

[Sunline Fan]

Looks good!

[jsms264]

We were at Rollins pond. I charged every couple days...we had 3 teenagers with us so I didn't want to see how long we could go....it could of got very ugly in the woods with teenage girls and no power. I would rather wrestle a black bear.