They must have had a good reason to include it with the 2.0 I assume an instant power draw like heaters and lights was pushing the ability of the DC/DC converter too much. 120 amps goes fast on startup of AC/heat and lights.
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Replacing the 12V aux Battery
- Thread starter scotty2541
- Start date
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- Tags
- Roadster
n2mb_racing
Active Member
I can't really understand how the car would work without the 12V battery. It powers all the electronics, opens the door locks, etc, while the HV battery is turned off.
smorgasbord
Active Member
The battery runs the 12Volt items in the vehicle if the vehicle is completely off.
What happened with me one time, several years ago, is that Tesla forgot to reconnect the 12 volt battery after doing some work on my vehicle. I drove away, parked and had an early dinner. Afterwards the door wouldn't open. Opening the charge port energized the 12 volt circuit and I was then able to open the door, drive back to Tesla. This is a V2.5.
If the vehicle is plugged in the charge port door is open and so the 12volt stuff works even without a battery. Note that there might be some components whose temporary power draw exceeds the 12 volt charge current, and those may not work without the battery as a booster/buffer.
Apart from the delay for APS that MLAUTO mentions, the 12V battery is designed to be used to power emergency safety systems. In the event of an accident, and main pack cut-off, the 12V battery powers things like brake lights, hazard warning lights, etc.
I had to replace the aux battery recently so thanks to scotty2541 for the instructions!
Just to add his instructions -
1. Taking off the wheel - even if you know how to do this in general, remember that the roadster has a wheel lock and special lug nuts. I had to go and get some tools to do this - mainly you'll need the 17mm socket to fit the wheel lock key/special lug nut tool to get them off.
When putting the wheel back on, make sure you have a torque wrench - for the roadster the lugs should be tightened to 77 ft-lbs.
I used the Gruber battery - Gruber Power | UPS Equipment, Batteries, & Service and it comes with extensions to make the battery
install/remove easier -
You might want to get some extra M6 bolts/washers/nuts in case some of the old ones are corroded. Additionally the replacement battery had some extra depth so the bracket screws needed to be longer. We'll see how much longer this battery lasts vs the OEM one.
Just to add his instructions -
1. Taking off the wheel - even if you know how to do this in general, remember that the roadster has a wheel lock and special lug nuts. I had to go and get some tools to do this - mainly you'll need the 17mm socket to fit the wheel lock key/special lug nut tool to get them off.
When putting the wheel back on, make sure you have a torque wrench - for the roadster the lugs should be tightened to 77 ft-lbs.
I used the Gruber battery - Gruber Power | UPS Equipment, Batteries, & Service and it comes with extensions to make the battery
install/remove easier -
You might want to get some extra M6 bolts/washers/nuts in case some of the old ones are corroded. Additionally the replacement battery had some extra depth so the bracket screws needed to be longer. We'll see how much longer this battery lasts vs the OEM one.
ElectricLove
Member
Ohmmu will soon be carrying a Lithium 12V for the Roadster! www.ohmmu.com
Not there yet but should be next month sometime.
Not there yet but should be next month sometime.
This is a fantastic write up. I just installed my brand new Gruber 12v battery and made sure the polarity was correct, put everything back. However, my fob still won't unlock either doors, also my infotainment touch screen is unresponsive. However, the fob activates the security system and when i open the charging door, the white ring lights up. Anyone encountered the same issues?
ElectricLove
Member
Now available from Ohmmu!!!
Drop-in replacement, exact fit and connection as stock battery but 25% of the weight and will last twice as long! It took a while to get there but we finally were able to add the original Tesla Roadster to our offerings, happy to do so for the community/vehicle I started with on my Tesla adventure.
https://www.ohmmu.com/product-page/12v-lithium-battery-for-tesla-roadster
Drop-in replacement, exact fit and connection as stock battery but 25% of the weight and will last twice as long! It took a while to get there but we finally were able to add the original Tesla Roadster to our offerings, happy to do so for the community/vehicle I started with on my Tesla adventure.
https://www.ohmmu.com/product-page/12v-lithium-battery-for-tesla-roadster
n2mb_racing
Active Member
Great! You mentioned it includes a BMS for cell balancing. Does it also protect against overcharge / overdischarge?
spaceballs
Member
Got to have that in any commercial battery product with normal lithium chemistries. My question would be how does it work in negatives temps, built in heater? limit current? or does it just shut off?
Good question. Here's my answer (yours may be different):
- If it has a heater you don't want it because it will waste a lot of energy keeping it warm.
- If it limits current you don't want it because functionality will be limited and it's still bad for the cells to charge them below freezing even if limited.
- If it shuts off, well, what's the point of having a battery that shuts off? 'nuff said.
I was getting the "low battery" errors so tackled this replacement with the Gruber 12Ah unit.
The "hidden" bolt through the mud flap comes up from the bottom in the area of the red circle
I didn't remove the mud-flap. Just bent it back to remove the battery panel
Wait, what's that?
It's a 2Ah LiFePo battery stuck down there!
Looks like this was behind the "Low Battery" errors I was getting? Specs say it has the CCA of a normal 7Ah battery, but this isn't a starter battery application
Gruber battery in
You might want to replace the rusting bolts and nuts while you're in there
The "hidden" bolt through the mud flap comes up from the bottom in the area of the red circle
I didn't remove the mud-flap. Just bent it back to remove the battery panel
Wait, what's that?
It's a 2Ah LiFePo battery stuck down there!
Looks like this was behind the "Low Battery" errors I was getting? Specs say it has the CCA of a normal 7Ah battery, but this isn't a starter battery application
Gruber battery in
You might want to replace the rusting bolts and nuts while you're in there
shrink
Member
Gruber has a modification to relocate the 12V battery to the trunk. It’s much, much easier to replace the battery with their modification. I thought about it when I had my Roadster, but didn’t want to lose precious trunk space. It’s definitely not for everyone, but some may find it useful. Info is below.
da2ny
2010 Roadster Sport Twilight Blue #913
I went this route back in June. No rproblems. I like the terminal connectors. Much lighter than the OEM.Is anyone running an Ohmmu lithium battery... @ElectricLove? If so, how's it holding up? I'd love to kick the PbAc to the curb; esp. if this one lasts longer and weighs less.
I called to order their 12v Battery and this option wasn't mentioned to me . . . though the trunk space is at a premium
ElectricLove
Member
Is anyone running an Ohmmu lithium battery... @ElectricLove? If so, how's it holding up? I'd love to kick the PbAc to the curb; esp. if this one lasts longer and weighs less.
We have a few out there running around now and all are happy campers thus far!
Saves weight and fits same place without any needed adapters to worry about. Or corrosion concerns. And, most importantly it will last way longer!!!
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