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20 Ruby Platinum HL, 19 Lexus UX200, 17 Yaris iA
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Discussion Starter · #1 ·
This is NOT for Hybrids (who likely have an AGM start battery) Let's keep this to Gen 4 gas Highlanders specifically please.

What is your resting (after a few hours) start battery voltage?

What is the voltage on the battery terminals at idle?

NOTE You can get a good enough volt meter at Harbor Freight sometimes for free with a purchase.

I am asking because my car did not start recently at a bad time, of course.

The battery is OK, the dealer verified on a machine and so did I with a SnapOn battery load tester / cycler.

This thread is a follow on to: Is it normal to have 12.1v battery?

Let's keep this to Gen 4 gas Highlanders specifically please.
 

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Has been parked for 3 days. Reads 12.37V just sitting there. Didn't start it.
 

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All the on-board electronics draw quite a bit of power all the time. In contrast, my lawn tractor is sitting around 12.8V (checked that at the same time), but it shouldn't have any draw at rest. I know the battery in my Tacoma will be dead in just two or three weeks of sitting without being started. I imagine Highlander is the same way.

I also wonder what's normal for that stop/start battery in the Highlander. If it's not AGM, then it's an "enhanced" or "advanced" flooded battery that's designed for faster charging, deep cycling, and more cycles in its life.
 

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20 Ruby Platinum HL, 19 Lexus UX200, 17 Yaris iA
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Discussion Starter · #6 ·
Constantly being drained into the danger zone can not be good. Plus sitting at that state for days also not good. Violates the recharge in 24 hours rule for Lead Acid.

I have measured after a hundred mile drive and do not find the battery near full.

When it would not start, it knew the battery was having issues. The dash lit up with all manner of warnings about this electrical system failure and that system not available due to low voltage.

I predict we will see more battery related issues in the future due to this poor battery management.

It would be great to be able to put the car to sleep like fob, for example.

Thinking about it, it seems like it is not just parasitic drains while parked but the charging system also not doing a great job.

This may need to be instrumented to see what is really going on.

BTW: My battery is good. It charges good on the smart charger. It holds a charge. It has plenty of capacity when load tested. It just gets drained sitting. Not good.....
 

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20 Ruby Platinum HL, 19 Lexus UX200, 17 Yaris iA
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Discussion Starter · #7 ·
Thinking I may need to add a battery maintainer or solar charger. This is not a situation I expected after a year of ownership.......
 

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What numbers are you seeing and after how much time passes?

A bunch of warnings about the electrical system are normal whenever the car is in the "ignition on" state but the engine isn't running. That's not necessarily telling you there's an electrical problem that's preventing it from starting.

How long was it sitting before the no-start situation"?

And always need to ask this when someone posts about electrical problems. Are there any non-factory electrical items installed, either by you or the dealer before you bought it? Anything as simple as changing from filament to LED bulbs counts.
 

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12.6 and above is golden. If your discharging you have a parasitic draw that is too high(50 to 70 miliamps is ok).

By the way, clear surface charge off battery by turning headlamps on for one minute before taking basic battery voltage.

P.S. Harbour freight meters suck, and they're made in China.

Cheers from Canada!
 

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2021 Highlander XSE V6
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Our cars have the fairly new Toyota battery management system which uses a variable voltage alternator. It doesn't always charge the battery as you drive, this is supposed to help with fuel economy and emissions. If you look at your battery you'll see a connector on the negative battery terminal, this is for the battery current sensor for the management system. Not sure if this system is even designed to charge to 100%. I know some other manufacturer's "Smart" systems charge only to 80% capacity to extend battery life.

I have a Scanguage II with Alternator Output Duty Cycle setup and I can see it regularly at 0% or 9% with battery at 12.1-12.3V while driving. When the alternator kicks on I've seen it anywhere from 20-50% duty cycle and as high as 14.8v for a second or so then starts dropping down again. It never really settles at one voltage for long.

Combine that with all the modern electronics pulling juice with the car just sitting there and infrequent/short tripping and no starts are going to happen. I do a 130km drive twice a week so I dont need to worry too much, but I do keep a lithium jump starter in the cargo tray for these special occasions. Haven't had to use it yet.
 

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20 Ruby Platinum HL, 19 Lexus UX200, 17 Yaris iA
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Discussion Starter · #11 ·
You can monitor the voltage at the battery via the service screen.

This morning first thing, I checked and my battery was at 12.0 volts via a the service dispaly. It was raining so I did not feel like verifying with my Fluke.

I did observe the charge voltage while driving via the service display and it jumped to 14 something.

Charging a lead acid to 100% does not decrease life span like it does for certain Lithium chemistries.

What good is a battery management system that favors fuel economy at the expense (a BIG expense) battery and not starting the car?????

BTW My service advisor stated there are lots of no starts they have to deal with these days. I do NOT wonder why........

NOTE that many charging systems use a variable voltage that creeps up as the level of charge changes.. NORMAL!
 

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Just curious... Do you let it use the stop/start function as designed, or do you keep shutting that off each time you drive? If it is stopping and starting all the time, about how many times per trip (roughly) is it doing that?

Which service display are you talking about - the one in the Entune head unit?

That's my big fear with this stop/start stuff - that it won't start sitting in the middle of traffic. I know hybrids have done this for years, but they're full of other batteries that could at least get you over to the side of the road and out of the way.
 

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20 Ruby Platinum HL, 19 Lexus UX200, 17 Yaris iA
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Discussion Starter · #15 ·
Just curious... Do you let it use the stop/start function as designed, or do you keep shutting that off each time you drive? If it is stopping and starting all the time, about how many times per trip (roughly) is it doing that?

Which service display are you talking about - the one in the Entune head unit?

That's my big fear with this stop/start stuff - that it won't start sitting in the middle of traffic. I know hybrids have done this for years, but they're full of other batteries that could at least get you over to the side of the road and out of the way.
I frequently turn the auto stop off. I HATE the function! I have a circuit board to install that turns it off every time you start the car, but do not care to dig in yet.

You can see your battery voltage in one of the menu options for the service display as above.
 

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+1. If I forget to press the off button when I start the car, I'm reminded as soon as I get to the first intersection and I get some sort of message about stop/start on the MID. Usually it's either "press brake harder to engage it" or "not engaging for climate control".

How long did the car sit before the no-start, and was the battery replaced after that? Like I mentioned, I know Tacoma will kill a battery in three weeks because I did it. Even though I got the truck going initially, the battery was never right again and had to be replaced two weeks later. That was a 2015 Tacoma with less electronics than today's models. Since the Tacoma may have situations where it sits for a couple of weeks, I have rigged up a permanent extension lead for a battery charger that goes from the battery to the cowl on the drivers side. The way it sits in the garage, popping the hood is not an option. I hook up a small charger at least once every two weeks if it doesn't drive before that.

Maybe the dealers are seeing a lot of no-starts because people are staying home more and driving less. It may not be a symptom of a design problem.
 

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20 Ruby Platinum HL, 19 Lexus UX200, 17 Yaris iA
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Discussion Starter · #17 ·
Ruby sits for a few days at a time. The no start happened in a parking structure I had parked in an hour earlier. I drove about 20 minutes from home and parked for an appointment.

The battery tests OK for load. Both at the dealer and independently with a SnapOn battery analyzer. It charges up fine on the smart charger. It will get to 100% or 12.8 to 13.0 no problem and hold that for several hours. Over night it drops maybe 0.2 volts.

I am logging by hand now (tedious) but my initial suspicion is the charging system never actually charges the battery fully. I am not sure why yet, but I do see a difference in the displayed voltage verses the actual voltage. Like there is a sensing issue.

This is nerdy stuff and I am an EE, with battery tech experience. I will figure it out. I am close to adding a data collection system. This is nuts!
 

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2021 Highlander XSE V6
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I would do a parasitic drain test, just to rule it out. Takes 2 minutes if there's no excessive drain. If there is , then you're much closer to your solution.
Good luck and please update!
 

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Ruby sits for a few days at a time. The no start happened in a parking structure I had parked in an hour earlier. I drove about 20 minutes from home and parked for an appointment.

The battery tests OK for load. Both at the dealer and independently with a SnapOn battery analyzer. It charges up fine on the smart charger. It will get to 100% or 12.8 to 13.0 no problem and hold that for several hours. Over night it drops maybe 0.2 volts.

I am logging by hand now (tedious) but my initial suspicion is the charging system never actually charges the battery fully. I am not sure why yet, but I do see a difference in the displayed voltage verses the actual voltage. Like there is a sensing issue.

This is nerdy stuff and I am an EE, with battery tech experience. I will figure it out. I am close to adding a data collection system. This is nuts!
Smart charging needs to hold the battery at less than full charge. The battery is charged opportunistically to minimize fuel economy impact, with priority during braking and at certain engine loads. So the battery needs to have some room for charge acceptance. Even 80% does not afford much charge acceptance -- it's a tough compromise although stop start requirements usually upsize the battery capacity greater than that determined for cold cranking.
 

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20 Ruby Platinum HL, 19 Lexus UX200, 17 Yaris iA
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Discussion Starter · #20 ·
I have been greeted to a battery at right at 12 volts every morning for the last days. It tests fine.. How long that will still be the case, I do not know.

It is a pain to keep bring the diagnostic screen up, so I think I will put in a little remote volt meter. I never see charge voltages above 14.1 which means, as far as I can tell, it would never fully charge. Than can not be good.....

Still thinking about it, but I certainly am not happy about the resting voltage in the morning. I am one or two starts away from dead.

Does the factory have a charging system test?????
 
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