Gen2 jumpstarter - how many amps?

Since there is no starter and all you need is some healthy voltage the smaller would be fine. Make sure you have good contact. If you want numbers, with “ready on” you need just under 10A. Comparing this with a conventional car that uses the 12v battery to turn the starter would need between 100A and 300A. So really there is negligible amperage needed for a Prius jump starting.

The battery is also small and even though is AGM, it would be damaged after a few of these dip discharges. You might need a charger to keep it connected when not driving for several days.

 

too many amps is worse than too few

 

Try either a small glove box sized Lithium battery pack starter or a newer technology super capacitor charger. Either available on Amazon or at Wal-Mart, etc. Search Prius Chat for recent thread on subject.

 

Keep in mind that sometimes more capacity is needed than what is often thought, even for a Prius. The brake accumulator pump will often try to run when attempting to power up a Gen 2 while 'jumping'. This can significantly load down the 'jump' supply. Connect the jump pack and let it charge the battery for at least a few minutes before trying to power up the car.

 

If you are not driving it much, use a battery maintainer and keep the battery maintained. Battery maintainer maybe $30.

If you keep having to jump it you are degrading the battery.

12 volt Battery maintainer

 

Yeah I'd focus on chargers/maintainers, not jump starters.

 

There have been times when I was in doubt about the jump starter capacity, and just pulled the fuses for the brake pressure pump before doing the jump, and put them back in after the car was READY. That pump can be a substantial load in the first seconds of a jump (well, on the order of tens of amps, still nothing like a conventional engine's starter), but with it disconnected, there aren't a lot of other significant loads. Naturally you make sure you're not trying to jump the headlights, wipers, seat heaters, and window defoggers all at once....

 

Get a battery tender type of device and plug in your 12V battery into it between long periods of disuse. In general disuse is no good for these cars for many reasons other than the 12V battery. But life is what it is and you got to do the best you can. As was said above, the amperage to jump the Gen 2 is very small, you can probably do it with a power tool battery. But the 12V battery wil not tolerate being drained many times, so keep it maintained with a battery tender. Good luck and welcome to the Prius experience!

 

Our 2010 is frequently sitting as long as a week. It's plugged into a CTEK 4.3 charger virtually all the time, happy as a clam. Battery was last replace in September of 2015.

 

It would be interesting if someone with a DC clamp amp meter measures the max Amp draw around the battery ground cable when the car turns on.

 

Been done, and traced on a scope. You end up looking at about a second of total power draw, with peaks somewhere up in the mid tens of amps, 30 to 50 or so*. Ought to be able to find the posts with those graphs with a little searching.

* that's if I remember it right. If I have time later, I may try to search that up again myself.

 

Not really the right tool for this. It takes a while for meters to decide on a value even for a steady current. Here the current is probably going to jump all over the place as various loads come in and out, and then the inverter is going to kick in very early in the process. So I don't think it likely one would obtain a meaningful "this many amps from the battery to start" measurement.

 

That's why when it was done, it was done with a 'scope.

 

BTDT with a DC amp clamp and a scope. This doesn't show the brake actuator (I would expect that to be 10-20 amps for 5-10 seconds maybe?) but was a "typical" ready up - drawing about 5 amps for 7 seconds , then 20-30amps for a couple seconds more as systems boot up. Then the DC converter turns on and provides power for the low voltage system and charges the 12V. This particular capture was from a 2005 that had deeply discharged the 12V and needed a boost to get it inside- the AGM 12V battery was accepting 60 amps before I shut it down and "slow charged" it.




In comparison a normal car starter initially pulls around 700A very briefly (known as inrush current) then goes down to 150A for maybe a second total cranking until the engine runs.

 

Nice trace! Hard for me to measure on the image, but it looks like the 7s period starting at around 3s is only ~1A, perhaps less, not 5A. At what time point was the power button pressed, and if it wasn't at 3s, what happened there? I know that opening a door (or the rear hatch) uses about 500mA as measured with a clamp ammeter, and the current step that starts around 3s is within a factor of two of that, but all the rapid activity right at 3s would never be seen with the meter.

 

Welcome. First, be aware that your posts are moderated until you have at least five of them, so don't be surprised if they don't appear right away.

To answer your question, those Nocos are fine. I have a G40 and it easily started the neighbor's Ram 2500. Contrary to one comment above, there's no such thing as having too many amps available. Amps aren't pushed; they are pulled. You need a booster with enough ampacity to feed the load. The Prius needs vary few amps, as already shown, but once you have one of these, you'll discover that you use it on other vehicles more than your own.

To answer your problem, the immediate need is a charger that will maintain your battery while you're trapped in a prison state. That will reduce the need for a booster but not eliminate it. You never know when you'll kill your 12V or it'll just die on you.

 

Don't remember the details of what-when-where. Might do it a few times on my Gen2 and see. I might think that the low amp draw at 3 to 11 second marks was the CHS pump running.

Posted via the PriusChat mobile app.

 

Agree. More is better but rarely needed for a Prius.... until your 12v battery is severely discharged. At that point the boost pack must equalize with your battery to achieve an adequate starting voltage, sometimes requiring five minutes at high amps. In fact Toyota suggests jumping for five minutes before trying to Ready the car.

Another advantage of a better boost pack is when you are asked to be a good samaritan for the distraught young lady with two babies. She has a set of jumper cables and "it will take just a minute".

Instead of telling her your Prius can not jump start a car (which is not necessarily true) or chancing a reverse jump that will strand you without hope, the hero pulls out his Noco, jumps her vehicle and all is well in the world.

 

Exactly!!