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Discussion Starter #1
I have a voltmeter plugged into the cigarette lighter socket and I've been watching the voltage as I drive. Generally in a "regular" vehicle, the voltage with the engine running is at least 13.5 volts, occasionally jumping to 14.5 volts if the battery needs it. My 2017 Highlander sits at 12 volts for long periods while driving, which would indicate it is just reading the battery voltage with no alternator input. Braking does not seem to make the voltage surge, a strategy common on smart alternators on other vehicles. 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?
 

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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.
 

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Discussion Starter #3
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.
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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?
 

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Short Arc Searchlight Fanatic
2017 Limited
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199 Posts
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/333-highlander-3rd-generation-2014/1595186-standard-current-draw-2015-highlander-limited-advanced-tech-package-2.html#post13559770
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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.
 

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Short Arc Searchlight Fanatic
2017 Limited
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199 Posts
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.
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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.
 

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Moderator
2014 Highlander LE
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7,803 Posts
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.
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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?
 

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2019 Le Plus
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103 Posts
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.
 

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Princeton
'19 SE Highlander
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18 Posts
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
 

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2019 Le Plus
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103 Posts
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.
 

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2014 HL XLE AWD
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2,157 Posts
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:
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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.
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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.
 

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Discussion Starter #17 (Edited)
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
 

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2019 Highlander
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35 Posts
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.
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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-Monitor-Meter-Wireless-DC-120V-100A-VOLT-AMP-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
 

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2018 Highlander in Alberta, Canada
2018 Highlander
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21 Posts
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.
 
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