Dead Battery

T - yes hatch was open, but the trunk light was also switched off. Is there another light back there which can't be deactivated? Such details of the current model Prius elude me.

 

<div class='quotetop'>QUOTE(Pinto Girl @ Nov 10 2006, 09:02 PM) [snapback]347270[/snapback]</div>

Certainly, overnight would not be a problem with 0.4A drain. That's only 3 to 4 amperehours. The Prius battery spec I found on PC is 28AH. The problem with my wife's habit is that she left the hatch open every evening and on the weekends. With a commute of only 8 miles one way to recharge it, she probably eventually drained the battery. She continued to leave the hatch open yesterday as well. It's an old habit and it may take awhile for her to get over it!.

<div class='quotetop'>QUOTE(theorist @ Nov 11 2006, 02:37 PM) [snapback]347509[/snapback]</div>

Yes the current drain drops below ~50ma (the resolution of my current clamp) with the hatch closed. There is very interesting behavior of the current drain. I had the meter and clamp in the trunk and viewing it through the hatch window. Open the hatch, the current jumps up over 0.5A and then settles to 0.4-0.5A. Close the hatch, the current drops to an intermediate level as if the ECU was initiating a shutdown program and then drops to its final low current draw. This takes about 10-15 seconds.

 

Depending on how old your battery is, it may no longer be 28 Ah and is likely in the low 20s or high tens, and that would be its new *maximum* capacity.. In general, because of the parasitic drains from the car electronics and the very slow charging rate when the vehicle is on, it's unlikely that a Prius battery is ever "full", so it's definitely within the realm of possibility that a 3-4 Ah load might drain the battery if it was low to begin with. This is why it is very important to actually recharge the battery with an external charger if it ever dies rather than relying on the vehicle systems to charge (again, the effective charge rate from the converter is *very* slow, so a dead battery, after an hour drive would still be mostly dead and would likely not last the night if you left a door open, etc)..

 

*Always* lock the car no matter where you park it. If anything is amiss (such as the trunk ajar, which can drain the battery) it will give a long beep of complaint when you try to lock it. This saves a lot of bother.

 

<div class='quotetop'>QUOTE(Rick Grahn @ Nov 18 2006, 07:23 PM) [snapback]351521[/snapback]</div>

I've never shopped for a battery at a car dealer before. Does the Prius (2004+) use a group 51R battery? It seems that Autozone sells these for between $50 and $80, depending on the qualities. I imagine that in the Prius we wouldn't need to worry about CCA or even CA too much, just reserve capacity and lifetime. Perhaps we need to worry about longevity in the heat in some places as the battery might get hotter under the hatch than under the hood in some very sunny climates?

I hope Toyota would replace the battery under warranty if a dealer identified a parasitic drain on the battery caused by a manufacturer defect.

 

<div class='quotetop'>QUOTE(theorist @ Nov 18 2006, 08:48 PM) [snapback]351583[/snapback]</div>

Autozone.com says it's a 51R with batteries available from $60 to $80.

 

The dimensions of 51R batteries are 9.4 x 5.1 x 8.8 (LWH) inches, which might require some revision at least in the securing bracket. Someone will post the Prius battery dimensions very soon here I am sure.

The OEM battery includes a vent tube, which has led people to specific aftermarket choices. Also the connecting posts are of a slightly unusual size.