Battery choices
 

Hey, folks, I had some questions regarding batteries. (I did do a search, but found only snippets of info here and there, with no detailed discussion of the pros/cons of different brands.) The one that’s dying on me (it came with the car--- a 2001 S---when bought in ’06) is an Interstate “MegaTron Plus”. I considered switching to one of the lighter weight batteries, like Braille (see http://www.tirerack.com/accessories/brand.jsp?brand=Braille), but I started to wonder what the trade-offs would be in dropping a few pounds. It looks like one is warranty: most “standard” batteries are warranted for several years (pro rated after the first 2-3), but Braille’s is only fully warranted for a year, pro rated up to 2 years. Generally speaking, how long do they actually last? Has anyone gone with a Deka (see http://www.remybattery.com/Products/AGM-European-Performance-Battery__9AGM48.aspx) ? What did you think of it? I live in NE Ohio where it gets pretty cold (but not super cold), and I do drive some in the winter. I’m thinkin’ the super-light batteries aren’t going to be a good choice for me. They have one that’s 11.5 lbs that seems like might work well (see http://www.tirerack.com/accessories/detail.jsp?ID=28&cat=Batteries).

If I decide not to worry about the weight, is there much of an advantage to brands like Optima or Odyssey over an AutoZone Duralast or another Interstate? (For example, do they appreciably handle weeks/months of disuse better?)

I guess I’d just like to get input as to what people have used as replacement batteries (specific model where possible) and what were the pros/cons (price, reliability/longevity, ease of installation, weight, etc.)

(BTW, Brucelee---your preference for Costco batteries @ $60 is duly noted. :D )

http://mike.focke.googlepages.com/batteries

Optima all the way.

I replaced mine this summer with a Duralast Gold from AutoZone. Reason? Price, about a hundred bucks and warranty. If ever something happens I have the peace of mind that help is an AutoZone away. BTW, the replacement battery is huge!

In OH I think you'll end up DOA more often than running w/ a Braile especially during the colder months. The OEM Moll IIRC is only 360 CCA so you have lots of options but in colder climates I think the Braille will leave you stranded...

Use Mike Focke's link above as he nicely compiled a lot of options

I wouldn't touch another OEM battery. They weigh a ton and cost twice as much $ as one from Sam's Club.

If you want to go performance check out Deka batteries,they are the ones that make the Braille batteries,but then you have to buy/build a custom mount.

I started with a 11 lb Braille battery, which worked fine for starting the car year-round. But I was also using it to power two outboard amps for the cars stereo and it did not quite have the current when the subwoofer was really booming. I called up the folks at Braille and told them about it and they said no problem, send the battery back and we will send you their 15 lb battery for just the difference in price of the batteries. I was very impressed by their customer service.

The 15 lb Braille works fine both starting the car and driving the outboard amps. The coldest starts I have had have been in the low 20's and it pops right over. I would think if you got their 17 lb battery, which they rate for winter use, you would do fine and save a few lbs. If you are interested in saving weight for your car, it is one of the very cheapest ways to go.

Ed

:cheers:

Before I bought my 98 Boxster, the previous owner installed an AutoZone battery. Its big with lots of cranking AMPs. Your in Ohio, It gets cold..... don't skimp on the size.

And I have AutoZone batteries in all my cars, and they start when its zero or below (this is from someone who owns an ice scrapper and a snow blower).

I replaced my original battery with the big a$$ OEM Moll three years ago...next time I'll do something different. I have an Optima Red Top in my 911, which has been flawless for the last five years.

Quote:

"Optima all the way." Posted by ekam.

Question: Did you have to pick up one of the mounting plates to install? The one in the mike.focke battery discussion site was through an outfit called Yellow Dog Motorsports. It's aluminum and runs $50. I believe I read somewhere that there's a hard plastic one for cheaper, but I haven't been able to locate it yet.



Quote:

"The 15 lb Braille works fine both starting the car and driving the outboard amps. The coldest starts I have had have been in the low 20's and it pops right over. I would think if you got their 17 lb battery, which they rate for winter use, you would do fine and save a few lbs. If you are interested in saving weight for your car, it is one of the very cheapest ways to go."

Posted by edevlin.

Question: Sounds tempting, Ed, but with the shorter warranty, do you think you'll be replacing yours every 2-3 years or so? Was installation simple, requiring any adapter? Where'd you get yours?

"Question: Sounds tempting, Ed, but with the shorter warranty, do you think you'll be replacing yours every 2-3 years or so? Was installation simple, requiring any adapter? Where'd you get yours?"

I got mine directly from Braille. I have only had the car for 2.5 years and have not had to worry about replacement yet. I got mine a couple of years ago and the mounting options were not what they are now. There a number of good inexpensive mounting solutions at the Braille website.

Mine was a bother to mount back when, because those mounting options were not available. I am using parts from a Porsche Turbo in my Boxster, that is the exhaust bracket from a Turbo was modded to hold my battery in place (see photo).

Ed

:cheers:

I bought the same brand but a little upgrade from the stock MOLL.
MOLL M3PLUS 830-85.

Replacing battery in boxster was such as pain especially when I have all the amps in the front trunk, not to mention lack of muscle to lift the battery from the side! I ended up placing the bulk of soft car cover on the top the amps and slowly climbed over with the heavy battery on both hands.

put an AutoZone Duralast in mine this evening.
seemed lighter than OEM one and had no troubles with install.

cost me 89$

The small batteries are nice if your racing and looking for quicker times. But is the trade off worth it? Can you quantify the benefits? Our cars didn't come the size battery it has for no reason.

Think of your battery as a bucket of water and the alternator as a small facet. Now all of electrical components all take some "water" out of that bucket and the facet tries to keep it full. I don't know about your car but I have heated seats, Bose amp, electric windows/mirrors and seats, deployable spoiler, all the electronic hardware (ECU, ABS, PSM, fuel pump) and the convertible top. I'm sure I missed a few things but thats allot of drain on a battery. It's all about electrical capacity. Don't forget your putting a strain on the alternator trying to keep up...if you have a small battery.

I feel if you want to save some weight in your Boxster, go on a diet. Don't sacrifice you car.

No need to go on diet...I bought midtronics PBT-300 to test the battery just to avoid having to go through a diet. That way you'll know for sure how much electricity that your system eats and how much power that the battery has.

Porsche Tequipment charger also seem to do its job everytime I leave the car in the garage for more than 3 days. It gives me a peace of mind and I don't think I can live without it!

Amazing! People want to install a light weight battery, then they install 200 pounds of stereo upgrades: amps, speakers, head units. Probably drive with the golf clubs in the trunk too.

Hey, go ultra light weight and Sears will sell you a lawn mower battery. It will start the car, but will be fried in 6 months... but you'll save weight.

I agree, you'll never notice the weight difference. I didn't notice any change in lap times in my Formula Ford racer after losing 10 pounds. This car only weighs 1100# with driver, so that's equivilent to a 25# change on a Boxster. (And yes, I run competitive lap times, so it's not because I'm slow!)
Steve

A small correction... the battery is used to start the car. Once running, the alternator supplies *all* the current to run the car, and it also recharges the battery. The battery is simply a storage device used for starting and for supplying power when the alternator isn't spooled up.

Having a smaller battery will not put a bigger strain on the alternator. After all, it still takes the same amount of energy to start the car, so the alternator has to replace the same amount of energy back in the battery after the start. And it's already sized to handle all those electrical items you listed.

If you add big amps for your stereo, and you run them at loud, thumping levels all the time, you may exceed the alternator's output capability. The fix there is to upgrade the alternator. A bigger battery is a patch at best. If you're exceeding the alternator's output capability on a nearly constant basis, the battery will eventually be drained, but that's an extreme case.

"Amazing! People want to install a light weight battery, then they install 200 pounds of stereo upgrades: amps, speakers, head units. Probably drive with the golf clubs in the trunk too."


To each his own. I like my stereo and a light car. My outboard amps, subwoofer, head unit and lightweight battery weigh less than the factory battery. That way I save a few lbs and still have the audio rig I want.

Saving weight does make our cars quicker and more responsive, but how much weight is necessary to lose, and what are each of us willing to go through to save it? I dont know, seems like I can notice 40-50 lbs weight savings on how the car handles, and I can easily feel 100 lbs. Try putting a 50 lb bag of dogfood in the passengers seat a see if you can notice a difference in performance.

If someone is autocrossing and has an older car, to put a lightweight battery in and if they lose their spare tire, thats about 50 lbs savings that most could feel. Is it worth the bother and expense, depends on the owner. Owning these cars is a hobby/passion for many of us, and messing around with them is part of the game.

Is it cost effective to try to increase performance by losing weight? Mostly it is not, a battery is probably the cheapest way to lose a fair amount of weight. Most of the ways available to save weight are quite expensive and would not make sense to many:

Lose spare-if you have one 0K 25 lbs

Light weight flywheel 1K l5 lbs

Full exhaust system 4K 25 lbs

Lightweight seats 2.5K 48 lbs

Lightweight battery <0.2k 20+ lbs


Looks like you could pretty much put a larger engine in the car for the cost of all of those mods. But hey, if thats what floats your boat, so be it.....


Ed

:cheers:

If I was ever to race / autocross, I would make the car loose weight:

As small of a battery I could install - yes, a lawnmower battery
Remove the easily pulled carpet - including engine covers carpet (no tools req'd)
No spare or tools
1/4 tank of fuel - max
Only a drivers license and insurance card
One key
Pull the wind deflectors (un-clip)
Nothing in the pockets, doors or trunks
Remove the radio display

And I feel like wrenching: no Pass seat (4 bolts, need a star socket set)

The battery would take the most time to set up, everything else could be stripped in an hour. When you race, weight is everything.... if you don't race, set the car up to be comfortable. You have decide on which side of the track you want to live.

True, as part of a greater weight loss program it would make sense. 50-100# is worthwile.

Jack,

I totally disagree with everything you wrote and stand behind my thread. The car does not run off of the alternator, it pulls power from the battery. The battery is a constant, large capacity source of ~12 volts of electricity. The alternator does nothing more than recharge the battery at 13.5-14.5v. Anything less than 13.5v and the battery will not recharge ("Alt" idiot light). The alternator produces A/C power thats converted to D/C through diodes and the voltage regulator does just that, it regulates the flow of current to the battery. Flow starts when battery volts fall below 13.5v and shuts it off at 14.5v.

So as I said;

"It's all about electrical capacity. Don't forget your putting a strain on the alternator trying to keep up...if you have a small battery." That's because the alternator is not meant to constantly supply power and will eventually heat up (which is the limiting factor) and fail.

I'm a Electrical Engineer, and I understand that you believe that's how things work, but it's simply not the case. The battery is in parallel with the alternator, and the car loads see them as a unified source of power. There is no mechanism that prevents the flow of current from the alternator to the car, limiting it to supplying only the battery. Current does not flow into the battery, and then out to the car.

As you point out yourself, the battery is ~12V, while the alternator produces ~13.6V. An accurate analogy of voltage is water pressure in a pipe. If you have two pipes connected together in a "Y" that then go to a sprinkler, and one pipe has a higher pressure than the other, which pipe will be feeding the sprinkler? The one with the highest pressure, of course! The lower pressure pipe will in fact reverse it's flow until the pressure equalizes, which is how the battery charges!

Since the battery's built-in voltage (pressure) is 12v, even when it fully charges it will not take over the sourcing of current. If the alternator were turned off, the battery would return very quickly to it's 12v potential, which would signal the alternator to immediately turn back on.

The "Alt" idiot light actually lights up when the battery is sourcing the current instead of the alternator. Remember the real current gauges in cars? The current gauge had a "0" in the middle, and it swung both positive and negative. It measured current flow in/out of the battery. Positive showed when the battery was charging, and negative showed when the battery was sourcing power. At idle, the gauge would go to 0 or just slightly negative, as the alternator was not spinning fast enough to provide 13.6V. When you revved the engine or were travelling at a steady speed, it swung positive. A big negative swing of the meter was your signal that your alternator had quit. The idiot light shows the same thing, that something is wrong, and your battery is providing the car's power.

One last thing, the voltage regulator does exactly what it says... it regulates voltage. The alternator will produce voltages far in excess of ~13.6v, so it has to be regulated. The battery is self regulated, in that as it comes to a full charge, it will accept less and less current. The voltage regulator keeps the voltage at safe levels that will not overcharge the battery or damage any electronic equipment in the car. There is no current regulation going to the battery, except for the max voltage potential applied to it by the alternator as it runs the car.

"As you point out yourself, the battery is ~12V, while the alternator produces ~13.6V. An accurate analogy of voltage is water pressure in a pipe. If you have two pipes connected together in a "Y" that then go to a sprinkler, and one pipe has a higher pressure than the other, which pipe will be feeding the sprinkler? The one with the highest pressure, of course! The lower pressure pipe will in fact reverse it's flow until the pressure equalizes, which is how the battery charges!"


So, based on your discussion, if I wanted to provide more current to my outboard audio amps which are wired directly to the to the battery) the best strategy would be:


1. Get a higher output alternator

2. Get a larger battery

3. Stick a large cap in the circuit from the battery to the amps


I am especially curious about the third case. My current setup seems to be working fine, but when I had a smaller battery (11 lb Braille) in the car, when I was driving with the headlights on and the music playing loud, you could see the dash lights dim in rhythm to the music at high (very) high volume levels. With my current 15lb Braille battery everything seems to be working fine, but I am still curious about a large cap in the circuit.

Ed

:dance:

What you were seeing is voltage drop across the resistance in the car's wiring, and also internal resistance inside the battery. The more current you pull, the larger the voltage drop.

Since you are wired directly to the battery, you're seeing the drop in the wiring from the alternator to the battery. You old, smaller battery also likely had a higher internal resistance, so it was less able to keep up with the dynamic current demands of your audio setup. You new larger battery probably has less resistance, and while replacing it you may have created better connections at the battery as well, which would help.

The big capacitors are placed as close to the amp as possible, and are there to provide a low resistance path for providing those short peaks of high current that the amps need for musical peaks. Capacitors are basically energy batteries that can release and recharge their energy very quickly and easily. The end results is you will have less distortion during peak power demands. Whether you'll hear the difference depends on your equipment, musical taste, and ears. :D

Unbelievable...have you ever owned a recreational vehicle that didn't have a battery? At idle the headlight is dim, rev the motor and the light brightens up. That's what happens in a system with no battery (remember constant voltage?).

So in your scenario the same thing would happen, quote "the alternator supplies *all* the current to run the car". The alternator is not run on a constant speed. Explain that one.

Your first one... apples and oranges. And a system with no battery is NOT "constant voltage". That's why the headlights dim.

Your second one... That's what the voltage regulator is for. I already explained it as well.

Take a look here: http://www.bcae1.com/charging.htm

Look at the second paragraph: "As long as the engine is running, all of the power for the accessories is delivered by the alternator. The battery is actually a load on the charging system. The only time that the battery would supply power with the engine running is when the current capacity of the alternator is exceeded or when engine is at a very low idle. "

I really don't have time to educate you on this. Please do some searches, and some reading.

JackG doesn't really need my help, but he's 100% right.

Then why does the OEM use the battery it does? Being the sports cars these are they should have a lawnmower battery under the hood.

Because Porsche designs the cars to suit 90% of the buyers. Most people buying Boxsters don't want to eek out the last 1% of performance that a lightweight battery would provide. They'd rather have a battery that will last through a week or two of non-use and still start the car; a battery that will start the car when it is negative 18 degrees out; a battery that will last more than 15 minutes of leaving the lights on before it's dead.

If you replace the OEM battery with a lawnmower battery, those are the kind of issues you'll have to look forward to. And Porsche, along with the vast majority of the buyers, just don't want that.

Well, it seems that in terms of losing weight for ax, it's not all or nothing.

Dedicated ax'ers regularly spend time prepping their cars for an ax or track event, swapping wheels/tires, brake pads, some even pulling the passenger seat. Why not add a battery swap to this regimen if the results warrant it?

Instead of removing the battery terminals, you could just as easily remove the cables at their other ends (still a single nut) and install a pair with terminals dedicated to the smaller battery. Even a lawn mower battery would be sufficient for the day and could then be removed and kept on a tender until needed again. It's not a lot of $ or effort, if you're dedicated enough.

Just as a point of information, my 1.5 year old Braille 15 lb battery popped the engine right over this morning no problem. It was 18 degrees when I started the car. Battery did great, but boy the suspension felt hard, dont know if it is the tires or coilovers, but I could really feel the road. Hey the other thing I noticed for the first time this year is the "innercooler" effect of cold weather. Feels like I have picked up 10 hp or so when its cold outside. This thing really scoots when its cold out.

Ed

:cheers: