What battery do you use?

[Paul Crowther]

'87 Carrera: Over the years I have struggled every time I replace my battery(49H8) and need to squeeze it into its spot. What battery is everyone using these days? Does everyone go thru this?

[Noah930]

I use the full size Interstate battery. Yeah, every time I do it I feel it's more of a struggle than I'd be willing to admit.

[spuggy]

The '77 MY had the mounting holes in the tray for the Group 48 aka the 48H6 battery (well, mine does anyway), and that's the battery a PO had fitted.

Seems like plenty of reserve to me, even for winter. Certainly heavy enough... Have never been tempted to fit a Group 49.

Although I did get quite close to buying an Antigravity last time I needed to replace one, because LiFePO4 batteries have worked out very well on the motorcycles - especially the minimal charge loss when not in use..

[Matthew_VA]

I have an '84 3.2 and replaced mine with a Odyssey PC925, saved a good bit of space and shaved about 12 pounds off too.

I've been pleased, it has started right up every time (I do have it plugged on a tender though)...

[schoward]

I hate wrestling with that big H8 Group 49, but my current H8 Interstate is going on 10 years since installed; The one it replaced lasted 12 years, so while I wouldn't mind saving a few pounds, I have a tough time justifying changing to anything else....

[RDM]

I bought an Optima yellow top when I got my SC 13 years ago. Haven't used a battery tender. Still works fine.

To make it big enough for the battery hold-down you have to attach it to a modified cutting board- many threads here on that process.

I like the lead-acid chemistry. I like the fact it's completely sealed and therefore cannot leak acid. I like that it's lasted 13 years.

[dw1]

I also have the "full size" (MTP-93) Interstate battery in my '87 and it is a very tight fit as well as being very likely overkill for the application. It has lasted quite a few years. (It is not driven all that often and I do have it on a trickle charger when I'm not driving it.)

If/when I need a new battery for that car, I would definitely go down a size, probably to the MTP-91 or whatever the equivalent is these days.

Fyi, this has been discussed previously:
https://forums.pelicanparts.com/porsche-911-technical-forum/650911-1987-911-battery-question.html#post6495086

[emac911]

Just checked my stuff, I am using the 48H6 battery in my 88 Cab. IIRC, I had two hold down places for different size batteries. The po had an agm battery in it, so I just got a regular battery the same size. Works fine.

[pmax]

Lift, tilt and slide, still easier than the SUV's boat anchor.

Having said that, 48H6 fits and there's even a pretapped hole for the holddown.

[H-viken]

Odyssey 680. Previously used a Odyssey 925

[ToySnakePMC]

This little guy: https://www.batterymart.com/p-gyz32hl-yuasa-agm-powersports-battery.html

3 yr-old, sits on a modified Walmart cutting board with eBay hold down. Small, 6-1/2” long x 5” wide. Once in a while, he gets fed with a small battery tender. Never had an issue. 500 CCA

[Paul Crowther]

Originally Posted by schoward;
12247986

I hate wrestling with that big H8 Group 49, but my current H8 Interstate is going on 10 years since installed; The one it replaced lasted 12 years, so while I wouldn't mind saving a few pounds, I have a tough time justifying changing to anything else....

The.battery I replaced was 7 years old and fine., but because I’d had weird starting issues over the years that I’ve owned the car (but not battery related), when I realized how old it was I figured I’d play it safe and replace it. Now the new battery is acting weird because….. my battery tender keeps trying to charge it even though it’s fully charged. To the point that I m worried that the steep tilt necessary to get it installed messed with electrolyte levels in it.

[almostordinary]

Optima Red Top with this nice hold down tray from EBay.



https://www.ebay.com/itm/113326603837

[darrin]

Originally Posted by Paul Crowther

The.battery I replaced was 7 years old and fine., but because I’d had weird starting issues over the years that I’ve owned the car (but not battery related), when I realized how old it was I figured I’d play it safe and replace it. Now the new battery is acting weird because….. my battery tender keeps trying to charge it even though it’s fully charged. To the point that I m worried that the steep tilt necessary to get it installed messed with electrolyte levels in it.

Paul - My advice is to keep it simple and go with a H6, Group 48 (G48/h6) AGM-type battery, it encapsulates the battery acid in Absorbent Glass Mats and is unaffected by orientation. Also recommend going with the smaller Group 48 battery as it's both easier to get in/out and your car has a clamp-down post to hold it in place. While a smaller battery will start your car w/o issue, it lacks the reserve power necessary to handle the draw caused when you accidentally leave a glove box light or dome light on overnight. While doing so can completely drain one of the smaller batteries referenced above, the G48/h6 battery can handle such a drain w/o issue.

Also suggest installing a voltmeter (one that fits in your cigarette lighter will work fine for this) and monitor voltage while driving. Our Carreras are notorious for having voltage regulators fail which allow voltage spikes of well over 14v to go through the electrical system and can cook batteries causing premature failure. Do your headlights/dashboard lights seem to "dim" from time to time and/or does your seatbelt warning light randomly illuminate at times? both are symptoms of a failing voltage regulator (as is a sulphur smell from the battery overcharging)

[917_Langheck]

I'm running an IMI 101n starter and a 925 Odyssey in the '84 Carrera. Much lighter and easier to work with.

[bob_cote]

Darrin,

Isn’t the Group 48 an H6 and not an H7?

[darrin]

Originally Posted by bob_cote

Darrin,

Isn’t the Group 48 an H6 and not an H7?

Bob:

Yes! oops, I'll fix my posts above

[GH85Carrera]

I usually just take out my front condenser blower, and the battery is easier to remove and install. I still prefer the huge battery, a glass mat battery from interstate. It is the exact same battery that I put iin my wife's 2017 Macan. Only in the Macan I had to use my OBD2 computer to tell the car the serial number, part number, amp house and if it is a AGM or wet cell battery. In my 911, I only had to rest the clock for a few minutes the battery was disconnected.

On one road trip, I went down to my car in the evening and turned on the dome light on the passenger side and left it on overnight by mistake. The battery did not miss a blink. On one trip to Arkansas, my alternator went to full charge, and I noticed as I was unpacking a funny smell, and the battery was HOT. A small battery would have exploded. I filled it up with more water, and drove with the AC, heater, fresh air fans, headlights and fog lights on and even the rear window defogger and outside mirror heaters on. I had that alternator rebuilt, and I had a voltage meter installed in the tach. Now I know what the voltage the alternator is making.

[shoooo32]

I run an Antigravity ATX-30. Weighs 6lbs and has "restart technology". If the battery voltage drops below 75% it trips a breaker (there's a reset button on top). I've run it for a few years now and it still cranks just as hard as the OEM boat anchor battery (although I have a high torque mini-starter, internally regulated 90a alternator, new engine harness and good grounds).

[myamoto1]

If you're looking to save weight, go with the Battery Tender (or similar) battery, I've had mine for several years with no issues. It's under 4 pounds, so a huge weight savings. Details on Jack Olson's post here