Battery worries
 

Hi guys very new to this so bare with me lol this looks like the place to be for boxster worries which I have at the min right here goes just changed my battery for a new one which is slightly bigger than the last the cca output is 800 I think this is not what concerns me it's the fact that when I took it for a drive after it felt Wierd as tho there were Power fluctuations as tho it was struggling then the power would come in surely a bigger battery can't affect it in this way can it ? Just after some advice or if anyone else has had same problems last thing I wanna do is run car if it's gunna damage it sorry if I sound dumb but it's my first boxster it's a 98 model if that helps look forward to ya replies cheers bob x

If you have a basic Boxster with 5 speed, the 700Amp would have been fine. A Boxster with a Tip in cold climate would do better with the 800Amp. You need to see if your alternator/voltage regulator can handle that size of battery. :cheers:

Hi jcb cheers for reply again bare with me is amp same as cca lol just heard both mentioned would u advise changing to 700 also is it easy to check what u said or is it a garage job and if all can handle it would it affect performance like I seem to be getting gunna give it a run again tomos to see if still the same cheers pal

The new battery you put in is fine and more than adequate compared to OEM. That is of course assuming battery itself is good as occasionally some are bad off the shelf.

The loss of power issue you are feeling is likely just the car re-learning air flow, mixtures and your driving style. Memory of this is lost when the power source is disconnected but it should revert back to what you're used to after 30-50 miles of driving.

That being said, you may want to check the battery and alternator using a DMM (digital multi meter). Place the probes across the battery terminals with the car not running and ignition off. Battery should read 12.6V. Repeat test w/ the car running at idle and the DMM should read 13.4-14.4V

Good luck and to help us trying to read your future posts, please use sentences and punctuation . . .

:)

"I've giv'n her all she's got captain, an' I canna give her no more."
 

Here's my 2 cents worth......
In a typical car, a battery can only affect HP (horsepower) if it's less than 12 volts. And by this I mean ignition and a continuos spark.
For example....
If a battery doesn't have enough CA (cranking amps) or has a bad cell, then the ignition coil or coils of a Boxster will not receive the necessary voltage needed to put out onto the spark plugs. This would equate to less premium of a spark. Less spark, less HP and/or a code.
As the old saying goes, "you get out what you put in". Think of a coil as a transformer. The coil is looking for a 12-13.8volt source to produce 30k-50k volt spark. (I'm not sure what the Boxster actually needs but it would be in that range).
I did a little research for you and have found that a MAJOR leading battery manufactuer produces your battery with the following specs:
Product ID: MTP-91
Amps: 875
Cranking Amps: 875
Cold Cranking Amps: 700
Voltage: 12

When you compare your battery to this one, as far as cranking amps (CA), your battery is good. However, nothing is perfect in life, so I would take it to an Auto Part store and have them check it out for free. Just make sure they check your battery WITH IT BEING HOOKED UP (this will check your alternater for charging output) and WITH IT NOT BEING HOOKED UP (this will check the battery independently).
After all this is said and done and everything check out fine, then you might have a bigger issue (voltage regulator, cloged fuel filter, only get 1 jiga watts of power instead of 1.2)

Hope this info helps, keep us posted.

In regards to AMPS:
It's best to have more than THE NEEDED amps. In any circuit, if you reduce the amps available at the power source you will put a strain on the battery/power source. So if anything......go higher on CA.

When you replaced your battery, the "learned" or "adapted" engine settings in the DME were erased. This resulted in the engine defaulting to the original performacne maps and thus, it operated a little differently than it did before you changed the battery.

No fix required, just drive the car as you always do and the DME will re-learn the engine settings and things should be back to normal in about 25-50 miles.

Thanks alot guys you have put me mind and rest I shall drive the car and see what happens thanks for all ya help will keep u informed and I will be back 986 forum rules lol bob

It is true the DME has been reset to default and will need to re-adapt itself. My concern would be the dramatic change, which would indicate the DME is compensating and adjusting for underlying undetermined issues.

Um don't really know what to say now got me worried again what underlying problems do u think could be wrong ?. Drove it today a bit ropey on start up but a coue of miles down the road back to the same joyest ride it's always been .

Very good...Same to me..