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I was bored last night and decided to look up alternative battery size options, since the 600 CCA Napa Legend battery in my SC400 is slightly under-spec'd and starting a bit sluggishly in sub-30 degree weather. I didn't find any such info for the SC, so I started putting together the attached spreadsheet. Aside from weight savings, there's often a 10-20% price difference for various group sizes with different specs, and more if dropping down significantly in size.
It still has a lot of gaps to fill in, so if you know of any data points, let me know and I'll update it. There's no way to pin down exact weights and CCA specs for each group size, as that will vary by manufacturer, but they seem to track fairly close across different lines.
I ignored powersport sizes, as they don't have a great reputation for holding up to daily driver duties.
I was surprised to see the minimum CCA for the 2JZ being just 450, despite coming with the same 625 CCA Group 27F. That opens up a lot of options for stepping down to a smaller group size. I can confirm that the 2JZ requires a lot less juice to turn over than does the 1UZ.
p.s. I'd never thought about it, but updating the attachment resets the views. So, years from now, someone seeing this with it having only a couple views will know why.
Last edited by t2d2; 01-17-17 at 06:44 PM.
Reason: Chart updated Jan 17th
I picked up a couple AGM batteries the other day, using my handy chart to select the best match among those available used (a wrecker with a battery side business). Store look-ups will only tell you direct fit and will overlook many others that fall within the max dimensions.
I ended up with a Group 35 Optima for each car. At 32.8 lbs and a conservative 720 CCA rating, that's a pretty nice alternative to stock (45-50 lbs); quite strong on the 1UZ and super strong on the 2JZ. I've wanted to try a trunk relocation for a while now, so having AGMs on hand is an essential first step.
The only downside of the Optima 35 is it sits lower than the standard Group 35 dimensions. If I relocate one to the trunk, that's a non-issue. But, for using the stock mounting location up front, it requires some tinkering. A bolt-down battery box is one option, but that would require just as much work to line it up with existing holes (only the 3 for the stock tray) or adding new ones. I chose to leave the stock tray in for its J-hook catch and make do with the lower height, using stuff I had lying around the garage.
Version 1 is a 1-3/8" rough cut piece of cedar, which is the perfect height for the stepped-up hold-down. Wood in the engine bay? Uh, yeah, at least it's cedar... I added a set screw to keep the wood from slipping out and letting the J-hook fall out of place, as unlikely as that may be with that much tension.
Version 2 is a L-channel in place of the stock hold-down. The upside to the Optima 35's downside is it's extremely close to the height of the hold-down's mounting point, so a flat piece is perfect. A shorter J-hook would be useful, as the threads don't go far enough down, but a few spacers work in the meantime. I might add a small bolt at the edge of the battery to replicate the stock hold-down's vertical stops. A U-channel would probably be better still, having a bit more structural integrity.
I had no idea the Optima was so much lighter than a standard battery. That's significant weight savings!
It's listed at 32 lbs in that size, so I knew it would be a nice light option if that's the one I ended up with. It's so much more pleasant to lift in and out! The other AGM I came back with (3 for half the cost of 1 new, and no fear of Optima's DOA reputation of recent years) is a Die Hard Platinum (i.e., Odyssey) Group 35, which is the regular 8.9" height and quite a bit heavier than the Optima. I didn't put it on the scale, but I'm guessing it's closer to the 36 lb range typical of that group size.
I was hoping to get a 51R to try, dropping another 6+ lbs and being right at the 2JZ's 450 CCA spec, but he didn't have any in stock. Oddly, that's only slightly under the weight range for lead-acids in that size, but right in the middle of the CCA range. I wonder why the Group 35 fares so much better for weight relative to lead-acids?
Oh, and back to the previous post... I almost made a Version 1b, using couch feet that are the exact same height as the cedar block. (They came from the couch that donated its luxurious white leather to the seat reupholstering project.) That would do pretty much the same thing while looking much cleaner. I held off on that, though, because it would have required a pretty big hole cut in the hold-down, plus drainage holes cut at the bottom of the six pie slices in the open-topped casters. If I find some smaller ones, I may still give that a try.
Is there a complete kit available to swap the battery into my 1992 SC300 trunk: box, clamps, wires, blah?
I've seen battery relocation kits at Summit and Jegs, but I imagine you'd get better quality for less money, and a better fit, by piecing it together yourself. There are lots of threads here on how people went about their relocations, what they used and how much wire length, etc.
You can go even smaller and still have plenty of CCA to start a SC300. I ran a Yellowtop 51R (or it might have beena normal 51) for years with my SC. No problems unless I let my car sit parked for more than 2 weeks.
Here's a pict of it. Sorry it's giant. Oh, and this pict is from 10 years ago lol
You can go even smaller and still have plenty of CCA to start a SC300. I ran a Yellowtop 51R (or it might have beena normal 51) for years with my SC. No problems unless I let my car sit parked for more than 2 weeks.
It's highlighted in the chart and mentioned in post #4 as the one I was hoping to try. The 51R is a common Miata size, so I was curious how it would fare with a bigger engine. That's good feedback, thanks.
Too big a battery, if alternator is not upgraded, the battery often will be under charged.
I don't see that being an issue. The size limitations of the stock location pretty much maxes you out in the 800 CCA range. And if you're not concerned with the stock location, i.e. a trunk relocation, then this thread isn't applicable in the first place.
I don't know at what point you'd be approaching that concern, but I'm guessing it's a pretty big percentage over OEM CCA spec, since the SC300's minimum is 72% of the SC400's, yet they come with the same size battery from the factory. That's a big margin of error to work with.
This is veering slightly off topic, but since I highlighted the Optima Group 35 as a good option, here's what I came up with for the eventual battery relocation to the trunk. I knew I wanted to use the amp/cd changer mount somehow, but it seemed a bit tipsy and too small of a platform to mount the battery on top. I took some measurements and, as luck would have it, the inner dimensions of the mount (ignoring the top panel) are like 1-2mm bigger than Group 35 specs!
Optima's Group 35 is a bit smaller than spec, so I'll fill it out with adhesive pads or something. A rectangular Group 35, as opposed to Opima with the rounded corners, might not fit as I assembled the box, as the screw heads holding the back piece would interfere. You could do without that back piece, but it wouldn't be as solid and you'd lose the ability to put a J-hook hold-down on width-wise. But, you could do a length-wise hook using the ends of the amp mount.
My tool bag still fits in behind it, but we'll see if that works once the battery and cables are in place. The ABS in the background is a vent delete I had done previously on that side.
Oh, and I found some 7" J-hooks today with deep enough threads to do away with the spacers for an engine bay mount. 6" to 6.5" would be perfect, since you need a deep well socket or wrench to thread the nut that far down otherwise. Not that it's something that has to be done often enough to be annoying.
Looking good man!! As long as it has a solid base to sit on without wobbling around you're good.
i didn't want to post this in the other thread, but yeah it's a kill switch which can be turns off and on
Looking good man!! As long as it has a solid base to sit on without wobbling around you're good.
i didn't want to post this in the other thread, but yeah it's a kill switch which can be turns off and on
Gotcha, thanks. I'm still filtering through the various inline fuse vs kill switch options... I have a negative terminal disconnect I could use with it, maybe in conjunction with a fuse near the battery? Then again, if it's got a fuse, is the disconnect really necessary? It's not like the stock location has one. This is where I go round and round in circles with the various recommendations.
I haven't placed one of the Optimas in yet, but the cage itself feels very solid, so I don't anticipate any problems there. I'll put some adhesive pads down to level the spot it sits on, since I don't have a perfect tray like your design.
Originally Posted by Bankswood
Can you use a ventless battery like an optima and not worry about venting?
Can you use a ventless battery like an optima and not worry about venting?
Yes. This is correct. It's a sealed lead acid battery. Sealed lead acid and dry cell batteries can be mounted in any position you want/need.
There's no holes to let gases out, so there's no dangerous gases that need to be vented externally (like normal 'wet' batteries)
01-13-17, 02:15 PM
battery size options
