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New here to the Tesla community. I don't own one unfortunately, but I've become pretty interested in them, finding out how they work etc...
I was curious if anybody would be able to tell me if these cars have some sort of 12 volt auxiliary battery system that runs the accessories (wipers, headlights, etc...) like on hybrids or if they are just ran off the high voltage battery pack?
Welcome!Originally Posted by billytuffnuts
The newer models of the Roadster use a DC-DC converter which provides 12V power to all the accessories. There is a small 12V battery which is used to power the VMS (Vehicle Management System) and for unlocking the doors.
SOLD | Roadster 2.5 #1077 | Very Orange | Forged Wheels | Electronics Package
Model S #SSL146 / VIN #246 | Signature Red | Black Interior with CF Accents | 21" Silver Wheels | Panoramic Sunroof | Performance
http://fearlessbit.com/
So then is the DC to DC converter constantly trying to keep the 12v battery fully charged as the vehicle is running (using these 12v accessories), similar to how an alternator maintains a batterys charge on an ICE equipped vehicle?
All of them have a 12V system for some standard things like radio, wiper motors, etc.
The ~375V main "traction pack" can power the A/C drive motor, and (I think) also the heater and possibly air-conditioning compressor.
Toyota Hybrids like the Prius have an Aux 42V system for things like power steering, but I don't think the Roadster has that.
I believe there are two 12V power systems in all Roadsters, Vaps and Vsb. Vaps appears to be used by the major EV systems in the car (PEM, HVAC, etc). The Vsb (secondary battery?) seems to be used for all car critical systems (VMS,ABS, SRS, doors, alarm, etc). Some systems (like the VDS and possibly the VMS) appear to have the ability to draw power from either, if one should fail.
I'm not sure which one the radio runs on, but I'll check (when I get back on 1/7/11).
Regarding the 12V outlet in the passenger area. The (2.0) Owner's Manual says:
When I went looking for an accessory that I wanted to buy to use in the outlet I saw that some devices, designed to connect to car 12V (cigarette type) outlets, are rated to draw more than 10A. I think I saw something like 12A or 15A and the box for the device noted that some older outlets only supported 10A (and apparently some newer ones support the higher current I saw).Note: The power socket is suitable for
accessories requiring up to 10A or a
maximum of 125 watts.
It is so choice. If you have the means, I highly recommend picking one up.
- Ferris Bueller about the 1961 Ferrari 250GT Spyder California
- Me about the Tesla Roadster
I live my life 240 [ideal] miles at a time.
- Paraphrasing Dom in The Fast and the Furious
I don't think the Roadster is designed to have a lot of extra 12V amperage capacity. Probably not a good car to plug in an inverter and try to run appliances off of the lighter socket.
Apparently some custom stereo shops ran into the output limits when trying to add external amplifiers for high end audio systems.
There are 15amp+ 12V devices sold out there like heaters and such:
http://www.amazon.com/RoadPro-RPSL-6...ref=pd_sbs_k_3
http://www.12volt-travel.com/cuisina...er-p-7782.html
http://www.12volt-travel.com/12-volt...le-p-5902.html
http://www.12volt-travel.com/12-volt...er-p-5906.html
http://www.12volt-travel.com/12-volt...ts-p-5929.html
(To be clear, I think it would NOT be good to use any of those above high current draw devices in a Roadster)
Last edited by TEG; 12-30-2010 at 12:09 PM.
The A/C compressor is labeled 400 volts (AND 12 volts). The cabin heat draws several KW, so that's also not off any 12V system. One of the NY techs told me the small 12V lead-acid battery (See this thread) only runs the critical systems like the locks and VMS (could have been VDS, but I'm not sure that makes sense). There are the contactors for electrically connecting the 375V traction system to either the charger or the motor -- those used to be powered by said lead-acid battery but it proved to be too weak in the cold and was moved to some other system (according to the tech) -- perhaps that's the "Vaps" system?
BTW, there's a DC-DC (375V - 12V) converter next to the compressor in the front.
I just noticed the radiator fans are 12V. I also noticed that the DC-DC converter is on (there's a power light) even though the car isn't charging or driving.
SOLD | Roadster 2.5 #1077 | Very Orange | Forged Wheels | Electronics Package
Model S #SSL146 / VIN #246 | Signature Red | Black Interior with CF Accents | 21" Silver Wheels | Panoramic Sunroof | Performance
http://fearlessbit.com/
The HVAC runs off the APS 12V supply to control the 400V for both the A/C compressor and the resistive heater. The box next to the compressor in front, is not the DC-DC converter for the 12V system in the car. It is a DC controller that converts the 275V-410V from the ESS to a variable voltage for the resistive heater and a variable voltage for the muiltspeed compressor. (It possible that the 2010 compressor is an AC motor, so the box would also be a variable frequency inverter)
The battery for the 2010 is located behind the right headlamp. I believe this battery is there because of DOT requirements. The door locks do not appear to run off this battery (b/c when the Vaps is off, the locks do not work). ABS, SRS, VDS and VMS do appear to run off this battery. The VDS can run off either Vaps or Vsb because it can be use to turn off the primary +12V supply (Vaps) while running off of (Vsb). The techs always turn off Vaps via the VDS whenever they are working on anything electrical in the car. (that would imply that all the 400V contactors are controlled by Vaps not Vsb/small battery)One of the NY techs told me the small 12V lead-acid battery (See this thread)
only runs the critical systems like the locks and VMS (could have been VDS, but I'm not sure that makes sense).
Yes. Probably moved to Vaps because when it is off, there would be no 400V or high current 12V present. There are multiple contactors in the car. I don't believe there is a contactor between the PEM and the motor because of the huge (~700A) current it would have to handle. In the 2008 there is a AC propulsion patent that describes how the motor is actually used as an inductor for the charging system.There are the contactors for electrically connecting the 375V traction system to either the charger or the motor -- those used to be powered by said lead-acid battery but it proved to be too weak in the cold and was moved to some other system (according to the tech) -- perhaps that's the "Vaps" system?
No. The box you refer to is the power controller for the HVAC system described above. The DC-DC 400V to 12V converter is in the ESS battery pack. This dual DC-DC converter supplies the 12V@100A to run the 12V systems in the car and a secondary 12V@25A supply for more critical and always on devices (e.g. radio +Battery line).BTW, there's a DC-DC (375V - 12V) converter next to the compressor in the front.
I just noticed the radiator fans are 12V. I also noticed that the DC-DC converter is on (there's a power light) even though the car isn't charging or driving.
Last edited by scott451; 01-10-2011 at 10:04 PM.
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?
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