One clue might be to try sitting in your garage, turn on the headlights (Hi Beam) without the engine running and watch your volt meter for a bit. Voltage might go below 11 VDC fairly quickly. Start the engine and see what it pops up to, ideally, if the alternator is 'smart' it would attempt to recover by putting out 13.5 or more until the battery has been brought back to 'FULL' The headlights should brighten considerably, if not, I'd be suspecting your alternator is nearly toast.



In the olden days, if an alternator didn't make at least 13.5V -with a fully charged battery, I considered it was on its way out. Battery that was partially discharged the alternator / regulator combo should ramp up to 15 volts or more.

 

One clue might be to try sitting in your garage, turn on the headlights (Hi Beam) without the engine running and watch your volt meter for a bit. Voltage might go below 11 VDC fairly quickly. Start the engine and see what it pops up to, ideally, if the alternator is 'smart' it would attempt to recover by putting out 13.5 or more until the battery has been brought back to 'FULL' The headlights should brighten considerably, if not, I'd be suspecting your alternator is nearly toast.



In the olden days, if an alternator didn't make at least 13.5V -with a fully charged battery, I considered it was on its way out. Battery that was partially discharged the alternator / regulator combo should ramp up to 15 volts or more.

My understanding of a smart alternator strategy is that it keeps the battery at only about 80% charge and charges aggressively when you coast or brake to harvest some of the otherwise wasted energy. During steady driving / acceleration it stops charging at all unless the battery is below that 80% level.


But I was hoping someone had some specific insight into the strategy employed by the Gen 3.

 

I’m another voltmeter in the lighter socket guy. I have several of them and they can be out half a volt. Best to use a known good quality meter to find out how much it is out.

I’m seeing 14.2 volts (corrected) most of the time while driving short trips. It diminishes to high 13.x on an hour long trip. This seems a bit low to me as we have too many short trips causing the battery to go down to 12.3 volts an hour or two after turning the engine off, about 75% I think. The RV folk say battery damage begins at 12.0 (50%). http://www.marxrv.com/12volt/12volt.htm

We live in northern Alberta where it can be pretty cold. We are taking a 2 week holiday in Hawaii in January. Our 2004 vehicle will be left with the battery disconnected and I know it will stay above 12.9 . Do I dare disconnect the battery for 2 weeks on a 2018 vehicle? Some say it’s asking for trouble to deny power to the computer. Have any of you tried it? Any trouble disconnecting the battery for a few minutes?
https://www.aa1car.com/library/battery_disconnect_problems.htm
I’ll be measuring the parasitic drain due to computer, radio, clock, remote radio, etc before deciding what to do. Anyone know what the parasitic current is for a late model Highlander?

 

I’m another voltmeter in the lighter socket guy. I have several of them and they can be out half a volt. Best to use a known good quality meter to find out how much it is out.

I’m seeing 14.2 volts (corrected) most of the time while driving short trips. It diminishes to high 13.x on an hour long trip. This seems a bit low to me as we have too many short trips causing the battery to go down to 12.3 volts an hour or two after turning the engine off, about 75% I think. The RV folk say battery damage begins at 12.0 (50%). http://www.marxrv.com/12volt/12volt.htm

We live in northern Alberta where it can be pretty cold. We are taking a 2 week holiday in Hawaii in January. Our 2004 vehicle will be left with the battery disconnected and I know it will stay above 12.9 . Do I dare disconnect the battery for 2 weeks on a 2018 vehicle? Some say it’s asking for trouble to deny power to the computer. Have any of you tried it? Any trouble disconnecting the battery for a few minutes?
https://www.aa1car.com/library/battery_disconnect_problems.htm
I’ll be measuring the parasitic drain due to computer, radio, clock, remote radio, etc before deciding what to do. Anyone know what the parasitic current is for a late model Highlander?

Go to this post where I measured posted a long video of the measurement of parasitic draw with an accurate 6.5 digit Keysight benchmeter in calibration for over 30 minutes after the system was shut off. Instead of disconnecting the battery for 2 weeks, why not just get a good battery tender - one that actually shuts off and comes back on only when needed. Not a constant trickle tender like so many are.

https://www.toyotanation.com/forum/...-current-draw-2015-highlander-limited-advanced-tech-package-2.html#post13559770

 

Thank you very much BVH! That is good news. At 24 mA locked the battery should easily handle a month. I’m wondering why you would bother with a maintainer. One reason why I’m worrying is that I recently lost a battery on another car, a 2006 Chevrolet wheelchair van with a built in maintainer. The maintainer failed (burnt chip on its circuit board) and the battery died.

 

I don't use a maintainer and I frequently go 2 weeks without a startup. I more or less suggested it for peace of mind.

 

I got the same advice from the man at the Toyota dealership I spoke to, today. He volunteered that quite a few people have battery problems due to driving mostly short trips. He said our Highlander would be fine for two weeks but not a month. I did a quick, rough measurement of the parasytic current using a clampmeter this morning and it said 0.5 amps. I’ll have to do a more accurate measurement with a better meter. After hearing the list of minor problems from disconnecting the battery I will connect a power supply to the battery cables to maintain continuous power while I disconnect the battery.

 

If you are concerned, I too would recomment a battery charger that plugs into a wall. As long as the clips are on secure, it should be a good way to keep it topped off while gone. If you disconnect it, there are some thing the ECU resets, but I don't think it looses anything critical? I remember some past threads discussing this... Likely a good idea to do a Advanced Search and dig those up.

 

Update. The maintainer worked well; after two weeks we arrived home to -40 temps (not wind chill) and daughter had no trouble starting Highlander to pick us up at the airport (2 hours of driving, 2 starts). However, the next morning without the maintainer the battery was down to 12.0 volts (50%).

I took it to the dealer yesterday for its 1 year checkup and asked for an investigation of parasitic current draw. Manager said she was short handed and didn’t have anyone who could do it. I handed her my clampmeter and said it could be measured in 30 seconds. The young guy used it and agreed the draw was half an amp. This kid was interested and believed there was a problem. I said we would give up use of the remote door locking feature to save the trouble of charging. He knew without looking it up which fuse powered the remote system. He said that fuse is left out at the factory to prevent killing the battery while transporting to Alberta. DW will not be happy if our $48000 new car loses its remote feature.

Good news! I happened to turn the headlight setting from auto to off while the clampmeter was in place and noticed that the drain dropped to a quarter of an amp. Next morning battery voltage was 12.6 volts! My guess is the auto headlight feature requires the computer to be actively checking for daylight and it’s the computer that wastes the quarter amp, maybe more at times.

I don’t want to blame just Toyota for this - people here in the north are complaining about these problems with other brands, too. There needs to be more consideration for battery power conservation or something. Whatever happened to the imminent switch to 48 volt car battery systems?

 

Good news! I happened to turn the headlight setting from auto to off while the clampmeter was in place and noticed that the drain dropped to a quarter of an amp. Next morning battery voltage was 12.6 volts! My guess is the auto headlight feature requires the computer to be actively checking for daylight and it’s the computer that wastes the quarter amp, maybe more at times.

Thanks for sharing...... don't know if I have an issue in my '19 SE but since it is my 2nd car it could easily sit in the garage a few weeks....and I leave that headlight auto switch on as well. I do have a meter I could plug into the cigarette lighter socket so I will use it to start monitoring. I had a parasitic draw on my old saturn outlook that would drain the battery if I did not start her up at least once every 10 days....until I pulled the fuse for the malfunctioning CD player which solved the problem. Sounds like this may not be nearly as severe.

Key1

 

I have a 2019 Highlander and also live in a cold climate and drive mostly short around town trips. After reading this thread and since I haven't driven the car for about week, I connected my 20 amp battery charger and was surprised to see it was drawing about 8 to10 amps for the first 5 minutes before tapering to less then 2 amps.

Looks like I'll be using my motorcycle 750mA trickle charger on this car, at least during the winter months. Also, moved the headlight switch from auto to off.

 

Anyone know if you can turn off the vehicles smart charging mode? Living in cold climate and driving mostly short trips, if I can turn it off this would insure my battery it always fully charged.

 

I have a voltmeter plugged into the cigarette lighter socket and I've been watching the voltage as I drive. This lower voltage while driving would have an impact on trailer battery charging while driving, as well. Anyone know more about the Highlander charging strategy?

Good point on secondary (trailer) batt. charging. No, don't know enuf, but got curious. Did a quick read on "smart alternator". If I understood correctly, its not designed to charge a second batt. For those who tow, might wanna look further into "how to charge a secondary (i.e. trailer) battery if this HL does have a smart alt or has that already been established it does? Tks. :wink:

 

I still don't know if the Highlander has a smart charge feature, but in Europe where smart alternators are very common, they have solved the problem with a DC-DC charger. It basically takes power off the tow vehicle battery and bumps up the voltage to charge the trailer battery. The smart alternator senses that the tow battery needs juice and recharges it. https://www.12voltplanet.co.uk/auxiliary-battery-charging-in-vehicles-with-smart-alternators.html

 

The voltage method of measuring state of charge is tricky due to “surface charge”. For quite a while after charging the voltage on the battery is actually the charging voltage, and overly optimistic. The real deal is a battery monitor that counts amp hours (energy) going in and out of the battery. I have one on our camper that shows the per cent of full charge accurately all the time. It cost $25. It would be tricky and scary to install on a new car, though.

 

I forgot to mention that I measured the parasytic current this morning after leaving the auto headlight fearture off overnight. It was much less than 250 mA, still with the clampmeter. And getting too low to be accurate on its 40 amp range. I am now thinking that the auto headlight feature is the only problem and thank goodness can be turned off.

 

If you need a smart charger the Ctek is one of the best. I’ve had one hooked up full time on my Corvette for the last nine years without a problem.

 

Hi see there is a good looking battery monitor on eBay for $28 US. It counts amp hours and always shows % of full charge on wireless remote display. Uses a Hall effect current sensor so no need to install a shunt. Looks easy to install. BUT it doesn’t say how large the sensor is; maybe the battery cable won’t fit through it. Too bad this gadget doesn’t come built in to cars.
https://www.ebay.ca/itm/Battery-Mon...AH-SOC-Remaining-Capacity-Z/264202160667?hash=item3d83ad0a1b:g:GGwAAOSwOAJcai3w


I found a review of it on a quality RV forum. The diameter of the current sensor is mentioned.
https://forums.goodsamclub.com/index.cfm/fuseaction/thread/tid/29798122.cfm

 

It’s above freezing here in northern Alberta at last. I measured the voltage across each fuse in the two fuse boxes in the engine compartment, found some with one or two millivolts across the fuse indicating some current is being drawn. I haven’t identified the purpose of those yet but more good news - the total parasytic current is now down to less than 100 mA. Maybe something to do with warming, car or meter.

I tried to find and open the interior fuse box below and behind the steering wheel. I couldn’t see it so went by feel and suddenly a flashing red icon just left of the clock activated.

Any idea what this icon is for? The back gate worked normally.

 

I couldn’t see it so went by feel and suddenly a flashing red icon just left of the clock activated.

Any idea what this icon is for? The back gate worked normally.

That tells you the alarm is active

 

Thank you, snuf! I didn’t know there was a burglar alarm system. There was no sound.
I read pages 82 and 83 in the manual on the alarm but am not clear on this feature. When you say “active” do you mean it is ready to catch a break in but not triggered? If so, it’s odd that we have never seen that flashing symbol before. I contacted the Toyota sales lady who sold it to us and she was worried that I had touched something that disabled the car so it wouldn’t start. By the time I got around to checking that the red padlock had turned itself off and the car started normally. I guess it’s an alarm that just flashes an icon for some unknown length of time and perhaps prevents it from starting.

I wonder if there is something wrong with the alarm feature causing extra current to be drawn from the battery?

 

Just had 18 month checkup. Since spring the parasytic current draw has been only a tenth of an amp, measurement same with clampmeter and good quality multimeter. I don’t know if the problem has disappeared or if it is a cold weather problem. The service manager has stated in writing that it won’t harm anything to disconnect the battery so I’m much happier. I bought one of those battery post disconnects and will use it when not driving for a week or more.

Sorry if the photo is rotated.

 

Delphi, why not just buy a battery tender and run a pigtail connector to the outside grill area? That's what I do when the vehicle sits for more then a few days.

 

Thanks, Tom. That is a good idea. DW will like it because she is used to plugging in a block heater when colder than -20.
I prefer turning the knob on the disconnect - works anywhere, no plug in needed and no danger no matter how long it is left.
I’ve had a few maintainers fail. The cords always get brittle in cold weather and break - difficult to replace the Chinese wires with real rubber ones. Last failure was a top brand. A chip burnt up and the battery was a writeoff.

 

Hi Redbelly,

I see you have an interesting post here that has not been completely answered in this thread. I am a 2019 Gen3 Highlander owner and am questioning similar observations. I started a new/current topic on this before seeing your post with my observations.

Highlander 3rd Generation (2014-2019)

Forum dedicated to the discussion of 3rd generation Toyota Highlanders.

www.toyotanation.com

Have you developed a better understanding of the intended charging profile and the longer-term impact on battery health/life?

Thanks,
Phil

 

The short answer is no. My interest was because I pull a camping trailer and I need the alternator to recharge the camper battery as I drive. I installed a DC-DC battery charger in the trailer which pulls power off the tow vehicle battery and delivers a charging voltage to the camper battery. I do know that the Highlander comes with a special battery designed to live under conditions of start stop and smart charging technology.

 

Great tip about the light sensor fuse for storage/shipping!

Voltage drop when the vehicle is off should be less than 50mv.

I've used a Deltran Battery Tender ( Deltran - Battery Tender )for 15 years or so and I'm happy with it. I install a fused "pigtail" onto the battery of all of my vehicles so that I can connect the charger easily.

This video is a big help for diagnosing parasitic draw:

 

Does anyone know how many different Toyota models have a smart charging system?

Information I found online seems to indicate that the RAV4 has a smart charging system. I have a 2016 Camry and it has a conventional alternator and charging system.

Here is a thread mentioning that the output voltage on Toyota alternators has typically been on the low side and that charging is not aggressive. That confirms my experience. My charging system does not keep up with a relatively low parasitic current drain unless the car is driven several times per week.

Alternator Question: 2017 4Runner

The thread mentions that many Toyota owners have increased the alternator voltage out of necessity by adding a diode in the battery sense line circuit.

 

Does anyone know how many different Toyota models have a smart charging system?

Information I found online seems to indicate that the RAV4 has a smart charging system. I have a 2016 Camry and it has a conventional alternator and charging system.

Here is a thread mentioning that the output voltage on Toyota alternators has typically been on the low side and that charging is not aggressive. That confirms my experience. My charging system does not keep up with a relatively low parasitic current drain unless the car is driven several times per week.

Alternator Question: 2017 4Runner

The thread mentions that many Toyota owners have increased the alternator voltage out of necessity by adding a diode in the battery sense line circuit.

If the vehicle has start stop technology then it has the smart alternator. I think it’s as simple as that.

 

My 2014 LE AWD has the "towing Package" which includes a heavy duty altenator, don't know any thing about a "smart charging system" either. My light switch is set to auto and I have never had a problem starting my engine (vehicle sits outside). Now that I am retired I use it 1-2 times per week and it starts right up no problem. I had the original battery replaced just before the 3 year warranty ended and that battery is now over 4 years old, starts imediately.

 

Thanks for the replies. It appears to me that both traditional alternators and smart alternators are too light on charging today.

The corporate average fuel economy (CAFE) standards are one reason and reducing alternator load helps in that regard. They may also be supporting different battery chemistries and maintenance free batteries. A few decades ago a modest overcharge was not a problem and water could easily be added to the cells.

However, once you add parasitic current drain you have a problem. I would like to see charging systems compensate in some way for the parasitic current drain.

The parasitic drain in my 2016 Camry appears to be about 22 milliamps which is 3.7 Amp hours per week. Discharge can accumulate depending on the length of each trip. You can then get into a situation where the car doesn't start if it is not driven for a week or two.

The Toyota dealers must be hearing a lot of complaints as they told me that newer vehicles need to be driven at least three times per week.

I think we need charging systems that do a better job along with lower parasitic drain.

 

Regarding which Toyota's have "smart charge feature " anything with Stop / start after 2017,

here is a page out of the 2017 tech update training stuff I have attached the full chapter on technologies that make the stop - start work, its allot more complex than one would assume.

I have read this a few times and still coming to term with the full extent of complications.