12 Volt Starter Battery, what it's for

[Tuningin]

Anyone heard of why there is a standard automotive 12v battery under the hood?

It seems to go to the common relay/fuse box so I'm thinking that it provides power to the accessories and the car's computers. I'm assuming that while the car is on, the system pulls power from the EV battery to charge it.

What the maximum amps the car will provide the batter?. I'm thinking that in an emergency, it would be handy to hook up and inverter to this circuit (clamp to the battery terminal). I wouldn't want to exceed the charging rate though.

 

[GetOffYourGas]

I'm guessing it's all the 12V accessories that are the same as the gas Golf. On my Leaf, there is a DC-DC converter to charge the battery whenever the car is on or charging.

 

[GadgetGav]

The eGolf is built on the same assembly lines as the ICE Golfs, and it shares a lot of components with them. The 12V circuits are still the same so the 12V battery is needed to operate everything from the interior lights and door locks to the starter button software. As I understand it, the traction battery is just for just that, powering the electric motor. All the accessories are running in the same way they would be in an ICE car. The only thing I'm not clear on is whether the eGolf uses a DC-DC converter or whether is still uses an alternator to generate 12V when moving & recharge the 12V battery. I might look at the 'making of' video again and see if it's visible as the motor unit is put into the bodyshell.

 

[rjnerd]

The single most important job the 12 volt battery has, is to engage the contactor built into the traction battery. Until that happens, there isn't any voltage on the wires leading out of the traction batteries case. Its standard safety protocol in any car with high voltage batteries.

The 12 volt battery also gets to run accessories before the traction battery is enabled. Things like the receiver for the key fob, etc.

Once the traction battery is enabled, a DC-DC converter recharges the 12 volt battery, and supplies 12 volts to run everything but the traction motor.

 

[Tuningin]

Thanks for the information. I didn't realize that most EV's still rely on a 12v battery for systems.

Based on what I've read on the Leaf forum, it seems that people are already using their 12v battery circuit to power inverters. Looks like I've found an additional source of emergency power for my home.

 

[GetOffYourGas]

Thanks for the information. I didn't realize that most EV's still rely on a 12v battery for systems.

Based on what I've read on the Leaf forum, it seems that people are already using their 12v battery circuit to power inverters. Looks like I've found an additional source of emergency power for my home.

The Leaf's inverter provides something like 100A to the 12V circuit. So a power inverter should really be about 1kW or less. Does anyone know what the eGolf's DC-DC is capable of? Can it push that kind of power, or is it really just a few hundred Watts to keep the 12V battery topped off?

 

[kirby]

The Leaf's inverter provides something like 100A to the 12V circuit. So a power inverter should really be about 1kW or less. Does anyone know what the eGolf's DC-DC is capable of? Can it push that kind of power, or is it really just a few hundred Watts to keep the 12V battery topped off?

Is there a definitive answer on this? I'm looking to either power an inverter or other 12VDC devices.

 

[JoulesThief]

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