High voltages of battery. Should I be concered?

Joined
Oct 8, 2012
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923
Location
California
Hi all, I am heading to very cold areas during winter so I decided to check the battery. Here are my findings with terminal connected to car. 1) Straight reading 13.8V 2) Turned on headlight voltage was 12.85V. 3) With car running for 5 minutes, voltage was 15.8V Those are very high numbers in my opinion. Should I be worried about this? Battery is 2-3 old, its Interstate MegaTron II. On my 2000 accord SE with 120k. Nothing in the electrical system is altered. Thanks.
 
Joined
Nov 14, 2013
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Chicago, IL
With my 01 Civic, I would get voltages up to 16V as the alternator was dying. I noticed the headlights were failing very quickly and even the SRS light came on. All of that went away with a new alternator. Like tinman asked, is 13.8 with the engine on?
 
Joined
Oct 24, 2008
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New Zealand
You might want to check the battery under high load with the proper tools. Those voltages are more indicative of the behaviour of the charging system rather than the battery.
 
Joined
Aug 14, 2010
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Northern Kentucky
Seems high to me. Without the car running you should almost instantly drop below 13v maybe to about 12.8v if the battery has a full state of charge. With the car running and accessories on you should be able to maintain at least 13.8v and should typically never see above 15v unless it's negative outside. Of course every system is different but your readings seem high. When you said you got 13.8v straight reading what does that mean? Is that with car running and all accessories off? You didn't specify in each test if the vehicle was running or not which is the important part. I have one of these and it's right onto line with my Extech meter as well as my other two cheap meters. http://www.amazon.com/INNOVA-3721-Battery-Charging-Monitor/dp/B000EVWDU0
 
Joined
Jan 7, 2009
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San Diego, California
I have owned 10 Honda cars, and worked on countless more. I have never seen over 14.6V with engine running and properly functioning alternator. I suspect failing voltage regulator.
 
Joined
Jan 31, 2006
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Idaho
Originally Posted By: oldmaninsc
[quote=tinmanSC] ……..Do you have another meter to double check the accuracy of the first meter?
I agree with this advice.
 
Joined
Apr 9, 2008
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Central NY
Seems normal for some vehicles. Having played around with the bluetooth scanner (which reports readings from the computer ...) I have seen that before. Granted if it were one of mine, I might worry!
 
Joined
Jan 3, 2006
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1,589
Location
Ohio
Originally Posted By: Rand
bad meter?
I would try another meter. A resting voltage of 13.8 on a battery sounds very unlikely, and 15.8 with the engine running sounds mighty suspicious.
 
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Joined
Mar 18, 2008
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Location
South Florida
Something is wrong with the charging system. I had a car that charged at 16.5 volts due to a bad alternator. Batteries didn't last very long in that car.
 
Joined
Aug 2, 2005
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Location
dayton oh
harbor freight free with coupon meter with a weak battery?they will read high long before the low battery warning lights. btw temp compensated regulators can hit 16v when cold. mine does.it wont stay there long though unless it goes by a battery temp sensor.mine is in the regulator inside the delco cs130.
 
Joined
May 18, 2012
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Baltimore, Maryland, USA
Originally Posted By: Jim_Truett
I have owned 10 Honda cars, and worked on countless more. I have never seen over 14.6V with engine running and properly functioning alternator. I suspect failing voltage regulator.
I agree. And yes I have a voltmeter installed in my car.
 
Joined
Feb 20, 2007
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Southeast
it may be fine. was it cold out? batteries require less voltage to charge as they warm up. Many oem's account for this in the ECU, and command a higher charge voltage when it's winter-cold. I would never expect it over 16, but if it settles down to ~13 after 45 minutes it may just be that. also, where di you probe for ground? battery post? engine block? weak grounds between alt, ecu and battery can cause this as well.
 
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