"House" battery question (Amp Hours and Deep Cycle vs Starter)

[Martinjmpr]

Well I've got most of my dual battery setup installed, at least everything I can do without having an actual battery (have the battery tray installed, the isolator is mounted to the firewall, extended side terminal bolts on the starter battery, and I've made up my cables.) Now I have to get a battery.
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Here's the dilemma I'm in: My truck needs a group 78 battery (with side terminals) and I'm having a lot of trouble finding a deep cycle battery with side terminals. In fact, the only ones I can find are Optima Yellow Top and an Odyssey Extreme. The Odyssey is quite expensive (around $250) but also rated at 62ah. The Optima is less expensive by about $50 - $60 (depending on where I get it) but is only rated to 55ah. For that matter, my starter battery, which is a Deka, is also rated at 55ah.
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Does anyone know of any other deep cycle marine/RV batteries in either Group 78 (side terminals) or group 34/78 (side and top terminals?)
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Given that the primary function of the battery will be to run my refrigerator (Indel B TB-41), should I be concerned about deep cycle vs starter? A "starter" (i.e. non-deep-cycle) would be easier to find and less expensive. The difference in price isn't huge, though (less than $100) and if it makes more sense to get a deep cycle then I'll spend the money to do it right. Just wanted to get some input since this electrical stuff is kind of new to me.
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Thanks in advance. I've been documenting my install and will post up pics once I'm done. It did cost me a bit more than $50 though! :sombrero:

 

[Ducky's Dad]

If this battery is for your Suburban, you may be able to fit a larger battery in the trays. If you don't have the rear A/C, there is probably a spare battery tray opposite the starter battery tray. If you have rear A/C the extra tray is taken up with A/C components. Either way, you are not limited to Grp 78 batteries because you can get a 34/78 or a 34 with top posts and add adapters to accommodate your GM cable ends. Taker some careful measurements and see what else will physically fit, you may find that you can get a Grp 65 in there. I have not looked recently at specs for 34/78s, but Northstar usually has slightly better CCA or ah or reserve capacity than the other brands. I would also recommend getting a battery with marine terminals so that you have an easy way to connect the fridge or other accessories. For the fridge, you definitely want a deep cycle or a dual purpose battery.

 

[Martinjmpr]

If this battery is for your Suburban, you may be able to fit a larger battery in the trays. If you don't have the rear A/C, there is probably a spare battery tray opposite the starter battery tray. If you have rear A/C the extra tray is taken up with A/C components. Either way, you are not limited to Grp 78 batteries because you can get a 34/78 or a 34 with top posts and add adapters to accommodate your GM cable ends. Taker some careful measurements and see what else will physically fit, you may find that you can get a Grp 65 in there. I have not looked recently at specs for 34/78s, but Northstar usually has slightly better CCA or ah or reserve capacity than the other brands. I would also recommend getting a battery with marine terminals so that you have an easy way to connect the fridge or other accessories. For the fridge, you definitely want a deep cycle or a dual purpose battery.

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I actually have the tray in place already. Unfortunately, clearance is very tight and I doubt that anything other than a Group 78 or 34/78 would work. In fact, 34 might be hard to do because there is a fender brace that sits immediately above the battery (I actually had to remove that brace in order to put the tray on, and I will have to remove it again in order to get the battery in.)

 

[Bear in NM]

I put an Optima 34/78 Bluetop in my second battery position (passenger side firewall with factory 2nd tray). It's 55ah, and is only top post. I set my cables up for the posts, so was not an issue for me. The top posts clear the hood just fine. My system is set up to run my fridge when travelling, before I break out the solar.

I am also new at this, but did learn from the folks here that a starter battery in this role was less than optimal. Decided it was better to pick a proper battery, and adjust the wiring as necessary.

Craig

Edit, yup, the brace in my Avalanche had to go.

 

[dwh]

Get a deep cycle battery. Cranking batteries are designed to drain just a touch to start the truck (less than one amp*hour normally) and then be immediately recharged. They'll do that 10 times a day for years without a problem.

But when you drain them deeper than that, they won't last anywhere near as long.

 

[KE7JFF]

I was going to say, I run a Costco top post deep cycle in my 2nd position on my '89 Suburban; have no issues with clearence but I at least put a cap on the position terminal for good measure.

I think Exide has a side terminal deep cycle come to think of it....I'll ask the Exide dealer near me..

 

[Martinjmpr]

I was going to say, I run a Costco top post deep cycle in my 2nd position on my '89 Suburban; have no issues with clearence but I at least put a cap on the position terminal for good measure.

I think Exide has a side terminal deep cycle come to think of it....I'll ask the Exide dealer near me..

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Multiple google searches have only turned up a couple of options: Optima yellow top or Odyssey. I realize I could run a Group 34 (top terminals) and use a side-terminal adapter kit but even in group 34 I'm not finding many deep cycle options. I may just bite the bullet and get the Odyssey. If I order from Amazon it will be around $250 and no core charge (since I'm not replacing a battery, I'm adding one, I would get hit with a core charge if I bought one over the counter.) I hate spending money on the same thing twice so rather than go with a starter battery (that I don't want) just to save a few bucks I'll probably spend the extra $$ and get the Odyssey.

 

[DiploStrat]

Have you looked at Lifeline? Not cheap, but we love ours and there is a reason the they are OEM on Earthroamer and others.

As others have noted, Marine terminals are probably better for your camper battery anyway.

 

[Martinjmpr]

Have you looked at Lifeline? Not cheap, but we love ours and there is a reason the they are OEM on Earthroamer and others.

As others have noted, Marine terminals are probably better for your camper battery anyway.

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The problem I'm running into is group size. A group 34/78 battery is 10.3"L x 6.8"W x 7.9" high. It's that last measurement, height, that is the killer.
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Here is a photo of the 2nd battery tray. The battery has to fit into that small space, as you can see there's not a lot of room to expand, especially upward, since the fender/firewall brace sits above the battery:
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And I can't expand in width because of the AC line that runs right in front of the battery tray. Even length wise there's not a lot of room, so for all practical purposes, unless I want to start moving stuff around (and that's way beyond my capabilities and budget) I'm stuck with a group 78 (Side terminals) 34/78 (side and top) or 34 (top terminal.) And from what I've seen, deep cycle batteries in that group size are not common.

 

[dwh]

Try searching for marine in that size instead of deep cycle. There are certainly many more choices in those sizes than just Optima or Odyssey.

I'd search the web sites of Interstate, Exide, Deka and Duracell to begin with.

 

[DaveInDenver]

I thought about suggesting marine batteries, but they are almost always top terminal. They have the super convenient lugs with wing nuts, but still top terminal.

Which brings me to my idea, who says it has to be mounted terminal up? Think three dimensionally. This is the major advantage of AGM & gel, mounting orientation is unimportant.

So maybe there's a marine or other option that shares the dimensions you need when rotated 90 degrees? Don't tunnel vision yourself thinking in terms of automotive battery group sizes. There are tons of odd sizes for race cars, golf carts, boats, motorcycles, etc.

 

[matt41482]

Martin i wouldn't worry about the fender brace from what i've read nobody installs it after installing the battery tray.

 

[dwh]

Yea, there is that. Most AGMs can be mounted sideways.

 

[DaveInDenver]

Or two 6V batteries. Creativity dudes!

 

[Martinjmpr]

Or two 6V batteries. Creativity dudes!

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I'd love to put a couple of 6v golf cart batteries with ~ 200+ AH in there but there's not enough space.
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However, when I redo the trailer's tongue area (going to put on an expanded metal grate) I will put in a bigger battery box with 2 x 6v batteries. Should give us plenty of juice for when we're "off grid."