GM Volt Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
5,431 Posts
I believe that the 12 V lead-acid battery in the Volt is an overkill because there is no "starter" that will draw over 50 amps. A smaller 12 V battery can be used, and it can even be a Li-Ion type, or a bank of supercapacitors that weigh less. Has anyone measured the disharge loads of a Volt during startup?
 

·
Registered
Joined
·
2,634 Posts
Headlights, 55 watts each, maybe 150-200 total for all lights? seat heaters maybe 100 watts each (don't know, guessing), computers maybe 50 watts, just showing how quickly power can add up. If the car has say 600 watts of idle power (which I think is close to accurate), that is 600/12 = 50 amps.

So granted, it doesn't have a starter, but those need hundreds of amps to start (inrush of maybe 500 amps, not 50 amps, maybe 50 or 100 amps continuous). It might be sized such to account for standby current or something. It has way more inrush current capacity than it needs, but lead acid is still a cheap energy storage solution and AGM is good for not outgassing, so it was probably the most cost effective solution.
 

·
Registered
Joined
·
1,067 Posts
Once the Volt is "ON", is there really that much "load" on the 12v battery in the Volt? Or is it sort of just a link in the electrical system passing the current from the DC-DC converter which gets it supply from the main high voltage battery.

In a regular ICE vehicle, once the engine is running and the alternator is providing energy the car will run just fine with a "dead" battery (as long as it isn't damaged internally). So in a Volt the DC-DC converter sort of takes the role of the alternator. Seems to me that the highest "unassisted" load that the Volt 12v battery should see is initial startup of the computers. I guess I am assuming that the DC-DC converter has enough capacity to take over the supply without needing the 12v to act as a "buffer" to absorb high load levels. Just my thoughts.

VIN # B0985
 

·
Registered
Joined
·
3,396 Posts
Once the Volt is "ON", is there really that much "load" on the 12v battery in the Volt? Or is it sort of just a link in the electrical system passing the current from the DC-DC converter which gets it supply from the main high voltage battery.

In a regular ICE vehicle, once the engine is running and the alternator is providing energy the car will run just fine with a "dead" battery (as long as it isn't damaged internally). So in a Volt the DC-DC converter sort of takes the role of the alternator. Seems to me that the highest "unassisted" load that the Volt 12v battery should see is initial startup of the computers. I guess I am assuming that the DC-DC converter has enough capacity to take over the supply without needing the 12v to act as a "buffer" to absorb high load levels. Just my thoughts.

VIN # B0985
Correct, the battery is used more for a buffer than a significant power draw.
Only in accessory mode when APM is off are you really running on the battery alone
 

·
Registered
Joined
·
5,410 Posts
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top