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YOUR RESEARCHReplaced My Puny Battery w/ Much Larger One
Leading reported evidence
Replace interstate mtp-h7
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Performed · outcome unconfirmed
I replaced an Interstate MTP-H7 With a Braille endurance series 7548 AGM battery - direct replacement.
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Suggestion · Original poster
I was under the car late last night cleaning the engine with an old tooth brush (and I enjoyed it) if that makes a difference in your critique of my Porsche dedication.
Leading evidence: 'Replace interstate mtp-h7' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Clean engine' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
Yesterday I replaced a tired 700A battery with this Duralast part number listed above.
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Suggestion · Original poster
I was under the car late last night cleaning the engine with an old tooth brush (and I enjoyed it) if that makes a difference in your critique of my Porsche dedication.
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Suggestion
I put the most powerful recommended battery in mine.
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Clean engine
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Suggestion · Original poster
I was under the car late last night cleaning the engine with an old tooth brush (and I enjoyed it) if that makes a difference in your critique of my Porsche dedication.
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Suggestion
A larger battery (more cell volume) will result in higher alternator peak power and a different, lower, operating frequency for the VR, thus changing the RFI/EMI "pattern".
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Suggestion · Original poster
Remove the cabin air filter plastic cover and there is room to use an open end wrench on a nut under the tray while you tighten the hold down bolt on top.
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Suggestion
Using the alternator to recharge an almost dead battery will put a strain on any alternator and will shorten it's life.The almost dead battery should be recharged by a battery charger and not by driving the car for a half an hour unless that's the only option.
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Rennlist: 1 discussions
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Generation: 20261026T105141Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I think the battery in my car was way too small. It was only 650 CCA, didnt fill up the tray, and showed a little less than 12 volts with engine not running. I went to battery warehouse and got the biggest vented battery that would fit in the tray. I had to move the mount to the extreme end in the unthreaded drain hole and secured it with a nut on bottom. It barely fits but it cranks much faster. Note: I didnt over tighten the clamps. Unfortunately I let the battery guy do that then I fixed the hold down mount myself. It looks worse than it really is because of camera angle.
Tomorrow I change the trans and front dif. oil. Yahoo!
Damn, that thing is huge. "that's what she said" LOL.
Seriously, I just swapped my battery last week and it uses the first bolt hole to hold it. But I do agree with you it does seem small and the battery I just installed was installed under warranty as I bought the original one (Diehard) when I first got the car and it gave up the ghost after 2.5yrs. So, I do think that upping yo a larger battery is a good idea except for the extra weight
https://rennlist.com/forums/996-foru...t-battery.html
I prefer AGM (Absorbed Glass Mat) Gel type batteries
I replaced an Interstate MTP-H7 With a Braille endurance series 7548 AGM battery - direct replacement.
Braille AGM B7548 battery group 48
BCI Group: [?]Group 48
Length:10.9" (277mm)
Width:6.8" (173mm)
Height (without posts):7.5" (191mm)
http://www.braillebattery.com/
http://www.braillebattery.com/index....durance_series
Battery sizes that fit 996 (group 49 will probably need a nut under the last, unthreaded, hole in the tray)
Group Interstate number Dimensions L x W x H Posts
48 MTP-H6 10-15/16 x 6-7/8 x 7-1/5 Top
94R MTP-H7 12-3/8 x 6-7/8 x 7-1/5 Top
49 MTP-H8 13-15/16 x 6-7/8 x 7-1/5 Top
I put the larger vented Bosch battery in, same size, just fits. Like you said, starts faster, stronger, less worry about strain on the alternator or draining battery. Don't care a wit about a little extra weight. DO care a lot if the battery is dead after sitting for a month. I use a smart trickle charger all winter, too.
Size DOES NOT MATTER, REALLY....
With regard to terminal voltage anyway.
Even a smaller than factory standard battery will more than suffice provided it will accept, and is kept fully charged, or almost so.
"..less worry..."
The VR uses PWM, Pulse Width Modulation, to charge and maintain the battery terminal voltage at the proper level. A larger battery (more cell volume) will result in higher alternator peak power and a different, lower, operating frequency for the VR, thus changing the RFI/EMI "pattern".
Not sure if it matters, just saying.
I was not concerned at all about the slight increase in weight. What concerned me much more was the capacity of the smaller battery. It was obvious the smaller battery was weak if you were in the car cleaning it or whatever and opening closing windows, roof, or using other accessories with the engine off. Also cranking speed seemed a little slow to me. These are high compression engines your trying to start. I dont drag race or track my car so weight simply was not an issue in the decision. I was under the car late last night cleaning the engine with an old tooth brush (and I enjoyed it) if that makes a difference in your critique of my Porsche dedication. My engine is now nice and clean.
What you need to look at is the Cold Cranking Amps CCA. It looks like you went from a CCA650 to a CCA850. Sure it will crank faster because you have a whole lot more amps. You can still find a CCA850 in the smaller foot print.
Nominal terminal voltage for both will be EXACTLY the same. So it will only crank faster if there is a need for more current than a charged CCA650 battery can supply, which would be virtually NEVER.
Sorry WWest, I disagree. As I said in the first post, the voltage was less than 12 with engine not running. I suspected the old smaller battery was getting weak. Engine cranking speed much better now.
The voltagewas lower because the battery was on its way out. If you would have gotten a new, same size one, it would have the same voltage as this bigger one.
Yes, but as I posted earlier, I wanted the extra capacity for operating the windows, sunroof, radio, accessories, etc. while I clean and detail the car. The few extra pounds are of no concern because everytime I get in it the 50/50 weight distribution is way off anyway. If a larger battery was not an option for replacement, why is the battery tray so large????? Never heard of people not wanting more battery reserve capacity but thanks for the opinions.
But is it not also going to put more strain on the alternator when it does need a big charge?
Its a 200 CCA difference.
The car will not take 650cca to turn it over, your battery probably had dead cells and therefore could not supply 650cca and it will only draw the Amps required even if you put a 1000000cca battery in there.
If its not been used for a month or if there an un-attended drain eg: Lights left on.
Probably ok when the alternators only topping off the battery but when its got to give it a good charge?
Anyone?.
I think the Porsche alternator is a big one and puts out 90amps
that's why it is so freaking expensive.
I think it can handle charging the bigger battery.
Using the alternator to recharge an almost dead battery will put a strain on any alternator and will shorten it's life.The almost dead battery should be recharged by a battery charger and not by driving the car for a half an hour unless that's the only option.
I'm sorry but 90A is not considered a large alternator my any means. Actually it's quiet the oppsite. Also, if you need more power when detailing the car, that extra power now has to be recharged by the alternator. Bigger is not always better in a gasoline engine. Diesels on the other hand, need all the CCA they can get when thenyemls are extremly low. Unlike gas engines, they need to spin around 650rpm just to start.
Have to agree with that,90Amps is normal 150Amp would be more like BIG.
And yes a big charge should be done on a charger, but if it cranked and started you wouldnt know and could still require a fair amount of charge.
I reckon the alternator will spending a lot more time at 14v
KrazyK, how did you get the nut under the tray, tighten down the battery, and then manage to bolt down the tray? The nuts for the tray are under the battery itself on the driver side, so you need to get the tray in first, then the battery, so I didn't think this could be done.
I replaced my 8 year old Optima battery (after making a custom hold-down tray) 2 weeks ago with a Duralast (Autozone) H7 AGM battery -- 800 CCA, 140 minute reserve, no drain tube because it's fully sealed.
I really wanted to get the H8 -- 850CCA, 170 minute reserve -- but there were no threads on the furthest last hole for the clamp. I thought about buying a nut and then epoxying it to the bottom to create a thread, but I decided to skip that and just buy the H7.
Oggie, look at the second photo. Remove the cabin air filter plastic cover and there is room to use an open end wrench on a nut under the tray while you tighten the hold down bolt on top.
Yesterday I replaced a tired 700A battery with this Duralast part number listed above. Perfect fit.
I don't remember the car turning over this fast since I've owned it.
Yes, my Optima battery was around 16 pounds lighter. Oh well. Now what to do with that nice Optima battery adapter tray that I have no use for anymore.
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