Question about cold start knock, battery
 

My car struggled somewhat to start this morning in 31*F weather with a low battery. A couple seconds after cold start the engine did a quick stumble which I could hear and feel and guess it was knock. Note I could hear it knock clearly. Everything else after was ok, car drove really strong all day in the cold temps.

Question is, could the low battery induce a knock situation on a cold start?

That's quite possible.

Sounds like you should invest in a new battery.

Back-in-the-day, on cold mornings, back on the farm, it was always best to hand crank the engine over a few times (with the magneto wire unplugged) before trying to start it.

If you didn't and lost your grip on the crank (or fell off the bucket you used to reach the crank) or the engine rocked back about the same time one plug fired ...... you would get a big knock (backfire).

Yes, and it was snowing out and tractor was parked on the uphill side of the shed ..... :thumbup:


humfrz

So the engine started and ran for a couple seconds at the normal 1500 RPM? My gut says no.

@humfrz well I'd rather preserve the battery rather than just throw it away, maybe I could use a battery tender, or booster if necessary?

@Ultramaroon there was a noticeable knock sound and the car hesitated. Perhaps it was the alternator clutch kicking in while the car was still starting? Either way it kicked which is abnormal for a start.

If it kicked back cranking slowly/weakly when it first lit the fire then yes, that shit happens with a weak battery. If it was already running then no, knock not caused by battery.

Once a battery starts to go there is no "preserving" it. All the chargers and tenders in the world will just slightly delay the inevitable. In fact they could even speed up the demise. Bite the bullet and buy a new one. NOT from the dealer.

@Tcoat well it's always started slow when temps dropped below 31F. A little boost and voila, good start.

It's the stock Panasonic battery, and it works well enough when its not freezing. Starts quick on other days.

I accidentally left my overhead console light on twice and had to boost the battery with a portable jump starter. I notice that as it's gotten colder the starter seems to crank kind of slow as if the battery is weak - it always starts, but seem to struggle, and on a couple of occasions, the engine ran really rough until it 'caught'.

Any chance our batteries and motors are biplane leftovers?

And should the overhead light even drain a battery? In a current year vehicle, don't all lights automatically turn off after a programmed amount of time? Confession, have not researched the owner manual on this.

Sorry for the unintentional thread quasi hijack.

Classic signs of a battery on the decline. You should never have to boost a battery. Eventually it just won't work at all and then you will be stuck.

I left my trunk open for 16 hours once and had no battery issues. Mine cranks the same at -20 as it does in the middle of summer.
I have followed these starting and battery issues closely (just ask @Ultramaroon ) and it is interesting that about 8 out of 10 people with premature battery failure or problems starting have BRZs. We see the occasional FRS with issues but they are very rare. Considering there are about 10 times the number of FRSs to BRZs out there that is a very telling number. Now the question that raises is, why? There is something different between the two that is causing either a parasitic draw when shut off or preventing the battery from charging properly when running. I have no theory as to what that is though. It will be interesting to see as the 86 gets closer to the same equipment as the BRZs if the frequency of battery issues increases.

It is uncanny. I'm still on the factory battery but I'm also a Panasonic fanboi.




It knows.

Well, it's your call ....... but if it were me and I was living in a cold climate, I wouldn't want to depend upon a weak battery.

As you know, in an emergency ....... the last thing you want is a car that won't start.

Besides, by trading in the old battery, you are "preserving" it ....... it will "live" as parts of a new battery ..... ;)


humfrz

The short answer is NO. However, the lights will eventually go off ...... when the battery runs out of electrons.....:D


humfrz

No if the light is set to manual on. If on auto then it goes off after a few seconds. Unless of course you leave the door open.