Auxiliary Battery

[Brett0424]

Hey all. I'm ordering the germansupply.com dual battery setup and am deciding which battery to buy to use as the auxiliary. I think I'm going to go with one of the optimas but don't know much about batteries and haven't been able to decide which one. I have searched on here but have had a hard time filtering through the posts to find out the model I need. There is a blue top on craigslist for 100 bucks (a 31M) and I was also wondering how that would compare to the yellow. I am open to other, cheaper batteries that are available in local stores as well. I'm sorry if this has been covered, feel free to direct me to the proper post, I just couldn't find what I needed or much info about the blues at all.

[Dead 1]

Go withe the yellow top (marine battery).
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"I reject your reality and replace it with my own"

"The American Dream - true enough because you gotta be asleep to believe it"
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71, 1776 cc.

[Brett0424]

But is there a specific model I should look for? Don't they make different yellow tops?

[WhirledTraveller]

Actually the blue top is the "Marine" battery.

There is NO difference between an Optima yellow top and blue top with the same group number except the top posts. The blue top has extra stainless steel wing nut studs in addition to the automotive posts.

This web site has a good run-down of all the specs for the Optima batteries:

http://www.1st-optima-batteries.com/index.html

The 31M blue-top looks like a good choice - big, but not so big it won't fit.
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[busfreak_71]

Get an AGM (absorbed glass mat) battery made by Odyssey. Best one you could get. Or, get a Trojan battery. Optimas are overpriced and overrated if you ask me. I've also had good luck with Pow-R-Surge batteries.

I live off grid, and batteries are part of my power system, so I think I have a good opinion on batteries.
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'71 Tin Top Westfalia
'99.5 Bora TDI
'85 Jetta Coupe
'85 Mercedes 300SD

Resident Off-Grid hippie and diesel advocate.

[dbo550]

X2 on the odyssey. Optima batteries are not the same as the ones from a few years ago. The old ones used virgin lead which made them so good but the new ones use recycled lead which is prone to failures. If the odyssey seems to expensive get the deep cycle marine die hard battery instead.
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1985 Westy
2001 Audi Allroad
1999 Volvo v70 xc
1995 Volvo T5-R, Yellow
1998 Jetta GLX

[jmstu76]

Is there a recomended group size for the aux. battery like ther is for the main battery?
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James

'76 Deluxe Sage Green Westy
2258 cc GD case 78mm CW crank, 2.0 H-beam rods 5,325” 22mm pin, JE forged pistons with 15cc dish, JE rings, type 11 clearanced oil pump, CB Eagle 2205 Type-2 “Torque Special” hydraulic cam with matched lifters fed by CB Dual Weber 40 IDF MX with 6” foam air filters, currently 55 idle, 130 main, 200 air correction, 32 mm venturis. 27in General Grabber AT2 All Terrains, Berg Shifter, stock '76 exhaust HPC Ceramic Coated. 11/18/2020

[Bursch]

[itlives]

I run a gell cell 134 amp . It's for uninterrupted power to computers (UPS). I like it alot and paid $89.

[XXX/Rx/RnR]

I learned from an old avation tech that a good way to keep battery acid fumes at bay is to cut out a small section of cardboard and place it under or by your battery to absorb the fumes. This has worked for me.