2007 Prius with about 75K miles. A couple of months ago I put in an Optima Yellow Top after the original 12V died (the local garage got nothing when I brought it in and they hooked it up to the tester / charger). Got good numbers when I ran the voltage diagnostic that's been described using the MFD. Now, I've had to get a jump twice over the past week, usually after leaving it sitting for a little while after some stop/start driving. I want to look for a source of parasitic drain. So my questions are: 1) I've watched videos on checking for this on non-hybrid vehicles by connecting a multimeter in the DC Amps mode in series with the negative / ground battery cable, looking for >50mA of current, and sequentially pulling fuses until the current goes away. Any problems doing this on the Prius 12V? 2) Since it's best to do this with the doors closed on most cars, is there a way to make the Prius think that the back hatch is closed? I can't find a button around the perimeter of the hatch like on most doors. Thanks
If it has a smart key, that system will reliably be drawing some current. I think your car has a button or switch to disable it, so you ought to do that before getting out the ammeter. Does your car have an aftermarket alarm or remote start installed? That would be where I'd start.
No aftermarket equipment installed. It does have a smart key, but that didn't seem to cause any problems in the few years that we've owned the car. And everything has worked fine over the 2 months or so since I replaced the battery. Certainly worth disabling that to rule it out, though.
I'm not suggesting that it's at fault. It represents a current draw so you need to eliminate it to see what else is there.
It's the Optima battery... Super low quality control and shoddy design... Hopefully when they ripped you off they gave you some kind of warranty? I've read on Prius Chat about Optima batteries being dead on arrival and having to be returned. Sounds like your problem is similar... Next time buy a real battery and not a pretty shapely Yellow one.
1. No problem in concept. You should see around 20 mA of quiescent current, after the doors are shut and locked, and the Prius ECUs settle down. Keep the Smart fob well away from the car during the testing. If it is around, the two-way communication between fob and vehicle will use some current. 2. I don't think it would be easy to fool the body ECU into thinking the rear hatch is closed. If you want to connect the DMM at the battery, you may need to place it where it can be seen when the hatch is closed. Alternatively you might try connecting the DMM up at the dedicated positive jumpstart terminal located within the main relay/fuse box. Remove the nut there with a 10 mm socket, then pull up on the cable attached to the stud. If you insert your ammeter between the stud and cable that would be the equivalent of inserting the meter at the positive battery terminal. I'm not sure whether the body ECU will care that the hood is open, in terms of drawing more current than when at rest. And of course, you will need access to the hood area anyway, to remove some of the fuses. You will find that when you open the driver's door, the current draw will go way up even if you have turned off the cabin ceiling lighting. This is because the skid control ECU will start to pressurize the brake hydraulic system via running the brake actuator pump, in preparation for the car being driven.
I'm just passing along info here. A few weeks back I visited Boulder Hybrids (Boulder CO) on an unrelated issue, but noticed many (10+) Yellow Top batteries laying around. I ask about this as I had recently done some research on this battery and the Prius. Paul, the owner, told me he's seeing many failures with this battery. Perhaps the battery was not charged well before installation? I don't know but he recommended the OEM battery, but expensive! You might give Paul a call and discuss with him. He's a nice guy and a good resource. (303) 325-7411 Good luck. Scott
It appears that the quality and reliability of Optima batteries went in the toilet when production operations were moved to Mexico several years ago. Recently, had to replace the original battery and choosing an OEM replacement was an easy decision. Expensive ($182 + tax), but worth it for the peace of mind.
There are plenty of options for Batteries for Prius that are twice the amp hours and twice the quality for only half the price of an Optima... I'm so glad we're finally starting to wake people up to how they're getting swindled by Optima. BrittPrius on here has done great work at educating people on the safety, reliability and durability of mobility (wheelchair) batteries. They're twice the amp/hour of OEM batteries and thus will last much longer than OEM. And of course in a regular car with a starter motor powered by a 12v battery a mobility battery wouldn't be appropriate, but for a Prius that doesn't have a 12v starter they are perfect! Of course BrittPrius is not in the USA and a lot of clueless posters on here have persecuted him with fear, fire and brimstone for not being blindly loyal to Optima, even though these people have very little facts on which to base their arguments. Expect more really smart battery posts from BrittPrius soon! Here are just a couple of many, many available options: WKA12-55C/FR 12V 55Ah Werker AGM Flame Retardant Battery - STEEPCLIMBER - Solo Wheelchairs - Wheelchair or Mobility - Batteries Plus Zeus PC55 12 12V 55Ah 22nF Medical Mobility Scooters Wheelchairs SLA Battery | eBay
Less expensive, but non automotive electrical posts on those wheelchair batteries. Has anyone gotten one to work on their Prius yet? Install pictures?
I think you will find lots of info on this topic here. Fitting mobility 12volt AGM battery. | PriusChat
