Hello Rennlisters,

Do you guys think that a higher capacity battery would be needed if one plans to run a lot of extra electronics in the car? I'm looking to run 4 Cell-B batteries hooked up to 2 sets of front/rear dash cams, a wifi hotspot, a remote front/rear radar detector, and a quint head laser jammer system on a 991.2 TTS.

Thank you,

John

 

When the car is running, your electronic accessories do not run off the battery. They run off your alternator which is part of your charging system. I haven't looked up the amperage of the 911 alternator but I will bet it is sufficient for whatever you are using. That is easy to check, however. So, the answer to your question is you do not need a higher-capacity battery. You might need a higher-capacity alternator but I doubt it very much. If you like to run your accessories when the car engine is not running, then you might need more battery capacity.

 

Thank you

 

Editing to correct number of batteries you are using:

I agree with the original response in that your car battery isn’t a concern, but I was a bit curious about the load on your alternator due to your use of two Celllink B batteries and looked into it some. Each of those batteries pulls 7 amps when hardwired so that totals 28 amps of additional load just from those. The other electronic devices are less of a concern. The alternator in you car is probably rated at about 70 amps, so just recharging those batteries when you start the car will increase the alternator load by 40%.

I’d be concerned that this may put too big a load on the alternator, especially when the car lights and audio system are on. I don’t know how much reserve capacity the alternator comes with. Also, and I’m not kidding, powering the alternator during their charge period will slow down your car, decrease gas mileage, and stress your finicky Porsche electrical system more. 28 amps is a substantial load.

I certainly wouldn’t charge two of them them through the lighter adapters since it would likely blow a fuse to prevent melting the wires to the lighters.

I’d suggest dialing back to just one of those and using just one camera for parking; thus bringing the additional load down to something more reasonable. We know the Celllink folks probably designed their unit to work safely in a car, but maybe not several of them at the same time.

 

Thanks StormRune. Makes sense. Will need to think about this some more. I may go ahead and try hardwiring 2 batteries instead of 4 and see how that goes.

 

You’re welcome. I don’t know if you saw my original post or the revised one just a couple of minutes ago when I corrected the numbers.

Yeah, I can see one working for sure, two getting worrisome but maybe working, and four being a big problem. You might find that the car will run for a while with that many, but if the alternator doesn’t keep up with it they might drain your car battery while you are driving, leaving you with an unpleasant surprise the next time you start the car. I’d pull up the voltage on the display and see if it holds up while you are driving if you decide to give multiple batteries a go. If you see it dropping below 12 I’d disconnect them.

Good luck and let us know how it works out!

 

Great tips. I'll keep everyone posted once I get the setup installed and running. Still haven't taken delivery yet. Should be released from port for transport any day now.

Thanks again,

John

 

Was big into car stereo's at one time...

The car is mainly running off of the alternator while running. Careful to mess with the recipe of battery and alternator too much.... It's a lot more complicated than just more/bigger batteries.

For dashcams, chargers, radar detectors, etc.... there is little to no risk of using too much juice while the car is running.

For people like Magic Rat and Audio junkies running capacitors and multiple class A amps and such then seek a professional. Rebuilt alternators are good but expensive. Not recommended on a performance car since you want anything moving to have a direct correlation with turning tires IMO.

 

Thanks R_Rated

 

So I looked it up and it looks like the alternator in a 2017 911 turbo is 2100W or 175 amps.

 

It looks like my googling needs some work. That’s a much better number! Sorry for the earlier disinformation.

So that is much less of a concern with two, and four might even be viable, but I’d still question the need. I’d recommend going with the least number you think you can get by with. Unless you are leaving the car parked outside for long periods - days- I think you’ll get along fine with less.

Out of curiosity, why four independent camera?

 

No problem. You made lots of good points that I didn't even consider so thanks! I was planning on covering all four sides of the car - front, back, sides. Kind of overkill but might as well. hahahah. Car will never be parked outside for long periods. Couple of hours max so I suppose one Cell B should suffice but I like to overdo things. lol

 

No batteries needed.

https://www.oreillyauto.com/flux-capacitor