2019 Rav4 parasitic draw test observations and thoughts.

[SC Maintenance]

I have a <1 year old Walmart battery in our Rav4 that seems to be failing already - according to my tester its 70% state of health even after recharged with Noco charger. Not unusual but I figured I would run a parasitic draw test just to ensure this thing isn't pulling hard on it constantly.

Hooked up my ohm meter properly.

Initially surge on connection was well over an Amp. Good thing I used the 10A setting!

A few seconds and it dropped to 400mA.

In about 60 seconds it dropped to 200mA. It stayed there for quite a while. There is a "hood open" picture in the dash, which is why I presume what was pulling much of that.

By about 45 minutes it was down to 10mA. However it did this weird cycle. Would sit at 10mA for about 15 seconds, then would cycle almost instantly up to 40mA, back to 10mA, then 20mA, then back to 10mA. So in about 2 seconds - 10mA-40mA-10mA-20mA-10mA. Then would sit there for 15 seconds approx. and start again. I presume possibly that is the DCM pinging something every 15 seconds or so? I might try to disconnect the DCM and test that way sometime?

So my observations are that it gets to a pretty low rest current - 10mA. Even with the constant momentary cycling to 40mA seems to be much less current than it seems most people on the www claim these new cars pull at rest. I doubt any of this is the problem with my battery, likely just another lousy JCI battery failing in warranty.

Thoughts?

 

[fantastic]

I have a <1 year old Walmart battery in our Rav4 that seems to be failing already - according to my tester its 70% state of health even after recharged with Noco charger. Not unusual but I figured I would run a parasitic draw test just to ensure this thing isn't pulling hard on it constantly.

Hooked up my ohm meter properly.

Initially surge on connection was well over an Amp. Good thing I used the 10A setting!

A few seconds and it dropped to 400mA.

In about 60 seconds it dropped to 200mA. It stayed there for quite a while. There is a "hood open" picture in the dash, which is why I presume what was pulling much of that.

By about 45 minutes it was down to 10mA. However it did this weird cycle. Would sit at 10mA for about 15 seconds, then would cycle almost instantly up to 40mA, back to 10mA, then 20mA, then back to 10mA. So in about 2 seconds - 10mA-40mA-10mA-20mA-10mA. Then would sit there for 15 seconds approx. and start again. I presume possibly that is the DCM pinging something every 15 seconds or so? I might try to disconnect the DCM and test that way sometime?

So my observations are that it gets to a pretty low rest current - 10mA. Even with the constant momentary cycling to 40mA seems to be much less current than it seems most people on the www claim these new cars pull at rest. I doubt any of this is the problem with my battery, likely just another lousy JCI battery failing in warranty.

Thoughts?

Anti-theft or safety alarm using some small current? Maybe that's only active when you lock the doors? I'd say that's pretty small but lead acid batteries are not great at taking in the last 10% especially if you're using it for shorter runs & battery doesn't get charged. Not saying you are or aren't but curious to know what the avg charge time is for your commutes. Either way 10-40ma seems like lower current. Can you try locking the doors to set the anti-theft system to see what draw it shows or do you not lock the doors? Just throwing out ideas.

 

[SC Maintenance]

Anti-theft or safety alarm using some small current? Maybe that's only active when you lock the doors? I'd say that's pretty small but lead acid batteries are not great at taking in the last 10% especially if you're using it for shorter runs & battery doesn't get charged. Not saying you are or aren't but curious to know what the avg charge time is for your commutes. Either way 10-40ma seems like lower current. Can you try locking the doors to set the anti-theft system to see what draw it shows or do you not lock the doors? Just throwing out ideas.

Good Idea. I tested it in my garage with the doors unlocked. I will try the next time locking the doors and see what different it makes. I will also look into killing the Data Communication module. I am pretty sure that surge is something like that pinging something.

Pretty sure its getting charged. Shortest trip this car ever sees is 11 miles one way commute. It occasionally does a much longer drive on the weekend, but its never short tripped. Also, I fully charged it with my Noco and tested it 24 hours later, and it was already back down to 75% or so. Pretty sure its just another JCI dud battery.

 

[wtd]

Does your vehicle have a light that blinks for a security system? If so, that is probably what is spiking the current. Anything under 50ma is considered good so if you are only going up to 40, that won't be your problem.

 

[JRay’07]

You need to find out if these fluctuations in current draw are considered normal for this model. Latch the hood (so the car thinks it is closed) and retest. Canbus activity could also be the culprit. I don't consider a 10-40 mA draw to be excessive either.

 

[Fair enough]

I put battery monitors on my cars. Can read on a phone when desired. So many for sale, I am thinking about getting one with a shunt to read the amps. Not really necessary as now I can see if the battery needs charging without touching the car. The cheap ones I have keep a 7 day record of the voltages. It also shows how chargers charge, and they seem to be all different.