12 volt accessories?

[TEG]

How does the lead acid 12V battery on the 2010 Roadsters get charged? Would it be safe to run an aftermarket stereo off this 12V lead acid battery?

<speculative answer>I assume that the DC/DC converter from the traction pack recharges it. Also it is a rather small battery, so I wouldn't count on having it provide a lock of backup power for a large stereo upgrade. I recall hearing that it is a motorcycle battery.</speculative answer>

[vfx]

... I recall hearing that it is a motorcycle battery....

true

But since it's in an actual production car does that not mean by definition it is not?

And is it an EV battery?

[TEG]

Meh (I think this is the first time I ever used that expression), you know what I meant. A battery mostly sold for motorcycle use.
Also too small to work effectively as a primary battery for an ICE vehicle that would need to run a starter motor.

By the way, it probably meets this definition of a motorcycle battery:
http://www.whybike.com/motorcycle107.htm
(But so do most 'car batteries' if you could fit them in a motorcycle.)

[Doug_G]

Here's a photo of the battery in question:

[TEG]

Hmm... Looks like this:
http://www.sepbatteries.com/pt7b-4-p...c-battery.aspx


http://www.mbsbattery.com/Shop-By-Us...T7B-4-p25.html

Volts:12

Amp-Hours: 6Ah


Battery Application
Motorcycle

• Kawasaki KLX400SR 03-04
• Suzuki DR-Z400, e, s 00-06
• Yamaha TTR250 99-03
• Yamaha TTR225 01-06

ATV

• Yamaha YZF450 04

http://www.batteryprice.com/powerson...tvbattery.aspx

[Doug_G]

TEG, I think that's the right brand but it looks twice as tall as the one in the car. Power Sonic http://www.power-sonic.com/ has dozens of models, but judging by the size it's probably no more than 6AH.

I'd guess it's perhaps a PT7B-4. Complete table of specs at http://www.power-sonic.com/images/po...ifications.pdf

[cinergi]

Good stuff scott451 -- thanks! I'll have to correct MY sources now (don't quite remember who, but it was a Tesla employee)

BTW, I've noticed the 12V cig lighter powers on whenever the car "wakes up" e.g. to charge. I have a radar detector with bluetooth interface and I occasionally notice it's connected to my iPhone while it's parked outside I'd assume the entire 12V system is on at that time.

[scott451]

Good stuff scott451 -- thanks! I'll have to correct MY sources now (don't quite remember who, but it was a Tesla employee)

BTW, I've noticed the 12V cig lighter powers on whenever the car "wakes up" e.g. to charge. I have a radar detector with bluetooth interface and I occasionally notice it's connected to my iPhone while it's parked outside I'd assume the entire 12V system is on at that time.

Yes. The 12V cig lighter appears to run off Vaps. This causes a somewhat misleading user experience. To the user, it seems that the 12V cig lighter is always on, but it is not it. It only stays on for the first ~5min after the car is turned off. I found out the hard way while trying to charge my iPhone over night. I plugged in the phone to the 12V cig, locked the car and could see through the window that the phone was charging. At the time, I was unaware that the 12V cig would turn off 5mins later when the car went to sleep. The next morning I found my iPhone with 5min of charge. The week before I did the same thing, but left the car on the UMC charger overnight. While the car was charging its battery, the 12V cig was on, so I got a full charge on my iPhone.

[vfx]

Thank you for sharing Scott. I have a Magellan GPS plugged in the cig lighter socket. When I turn off the car it asks if i want to use the internal battery so i assumed the 12V shuts off. One night I let the GPS use it's own battery and figured it would be dead in the morning but it was on. I thought that was impressive but since the car was plugged in I guess the 12V plug was live.

So what about the "use internal battery?" screen on the GPS when the car is shut off? Well sometimes i see it come on when driving down the road. The "use battery?" screen stay on for about 3 to 5 seconds. I thought at first it was a loose 12V connection where it plugs in but am confident in that connection now and that the car is somehow-for some reason shutting the power off to the 12V momentarily. It still could be a loose connection somewhere in the car (1.5 cars do not have the 12V battery) but I wonder if it's a circuitry thing. That same sort of shut off may happen when the car is turned off.
?

Anyone else notice a similar while-driving loss of 12V power?

[stenkb]

Kind of on topic: I needed to find a constant power source on the car for an add-on that was installed and the only fuse I could find that had continous power when the car was off was the 7.5 A alarm fuse. All others that I tried - turn off (eg. power adapter plug in, etc.).

After about 3 minutes with the car turned off the power adapter plug loses power - I sat in the car and watched it happen. If you open a door or anything you get about 3 min of power again until it loses power again.