12V Battery Drain Causes?

Your measurement seems high. On our 2010 Prius I measured parasitic drain under 20 milliamperes, with sporadic spikes to around 40.

 

Yeah... The only thing - I have a weird amperemeter... Will try another one today, if that one actually screws up a number of digits...

PS. Yeah. These readings were correct. Got another multimeter with full display - drain gets between 95 and 130 mA. That's really high...

Update... Based on other readings, I decided to start removing fuses (under the hood) one-by-one. When I removed the fuse for "DOME", the drain dropped from 100 mA down to about 40mA. Removing two fuses called ECU dropped it even more (down to 7-8 mA), but I think it's not a good idea.

However, I found one "caveat" of this... Now I got "Slip indicator" on all the time. When I put a fuse back, the dome light turns on, "slip warning" turns off, but the drain gets back to 100-130 mA.

And yes, I checked all lights, they are off when the doors closed. However... thinking back... the light in my trunk is always off. I have to do some more testings if there is anything with either trunk door switch failed, or bulb went off (or shorted)...

 

has the new battery drained yet?

 

No. It is a "higher capacity" battery. And with 120-130 mA it will take a while to drain it completely. However, I'm trying to understand what's going on (and what happened)... As I said, removing the DOME fuse drops drain for about 80-90 mA...

 

is that with the new meter?

 

I just got a battery in my "more advanced multimeter". Another one gives only two digits after a period, the new one shows three. So, it's more accurate. However, in general, values are about the same (perhaps different "rounding").

I will check tomorrow, why I don't have a light in the trunk area - not sure if it's just a bulb or the "door switch". All "side doors" switches work fine, the light goes on and off with any door. And light bulb(s), if I remember correctly, take about 1A.

PS. And thank you for the support.

 

I have a similar thing going on now. What happened with yours?

 

Get yourself a small 0.8A CTek battery charger/tender that motorcycles use.[Good Swedish Quality]
These things are smarter than us!

The CTek comes with alligator clips, a cig lighter plug, and a plug to hardwire it direct to the battery.

Then you can leave it on for weeks at a time without worrying about it.


Here is a little marketing exercise





And for Porsche




And a CTek [They are all made in the same factory]

 

Those are all the same charger, and prices in US dollars?

 

Yes, USD $
Even worse in NZD.
When I purchased the Ferrari , the dealer left the Factory charger in the trunk [as a "Bait'n'buy" ] and 2 days later wanted NZD $1000 for it.
I said that if the car needed a recharge after 2 days I'm bringing the whole car back.

Anyway while the charger was in my possession, I load tested it and also load tested the CTek at our friendly parts store [they were the same]
And the Ferrari adaptor plugged into the CTek.

So I purchased the CTek and returned the Ferrari charger [then I mail ordered the Ferrari adaptor plug from the UK]
I'm into my charger by NZD $180 [USD $108] incl the Ferrari adaptor.

I had a friend scan the decal on the Ferrari Charger [if I ever want to relabel it]
But I also use the CTek on my other vehicles and trailer winch battery because of all the other adaptors.


On a Prius C I would hardwire the CTek adaptor to the jumper terminals



I also have a Detran Solar Battery Tender which I also hardwired with a CTek plug [to use the other CTek adaptors]
This is connected to a 40w solar panel , and I simply leave it on the dash of my Falcon Tow Hack [I only drive this a few times a year and it will slowly discharge the battery]


My Solar charger and CTek charger are all interchangeable between each other.