AndyH
Well-known member
It might take 200A to start a gasoline engine if the engine has been off for a while. My 2L turbodiesel can pull more than 600A first start of the day. After that, either engine will only need 50-100A to start.evnow said:Here is the rewrite ...
If you use LEAF as a booster vehicle, the electricity for jump starting ICE vehicle is not enough due to the amount of electric power needed at jump starting is larger than the power available in the Leaf 12-volt battery. However it is no problem using gasoline engine vehicle to supply power to the LEAF battery.
Last summer I tossed-together a 12V 20Ah LiFePO4 pack and used it to start my VW turbodiesel. Here's a voltage plot from the start. It didn't catch the first time I turned the key so it took two starter-events to get the engine running (I'm used to it starting very quickly so released the key too soon).
The numbers on the bottom are time hacks in seconds. The total two-key-turn start event -- from first key turn to engine running -- took 7.25 seconds.
The ragged up curve is the voltage rising when the alternator came on-line. (Notice how ragged the alternator output is? We're not talking computer-grade power in cars here!)
Now - jump up to the youtube videos posted above. The LiPo pack that's cranking and cranking the Integra? That's THREE lithium cobalt polymer cells in series and a total capacity of 4Ah.
It doesn't take a lot of total energy to start an ICE - but we have to be able to move enough current quickly enough to run the starter motor. And that's more about the quality of the jumper cables than the capability of the battery.
The DC-DC in the Leaf is not designed to jump start a car on its own - it's only sized to keep the 12V lead-acid battery charged. And that's just fine! Saying that we can't use the Leaf to jump start another car because the DC-DC is small is just like saying that we can't start a car with a dead battery because our trickle charger is only 2A. DUH!