AGM battery voltage booster issues - Toyota FJ Cruiser Forum
Stereo / Electronics / Electrical If you have a topic that deals with the electronic components, stereo, etc. then post it in here.

 4Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 13 (permalink) Old 04-16-2019, 06:49 PM Thread Starter
Forum Regular
 
Jason Bourne's Avatar
 
Join Date: Aug 2016
Location: Staten Island, New York
Posts: 125
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Lifetime Supporting Member
(Thread Starter)
AGM battery voltage booster issues

Brothers without banners! So, I had my Optima yellowtop get drained completely while the FJ was sitting at the airport for a week. From all the aftermarket stuff, I'm sure there is a parasitic draw. Anyhow, after jumping the car, it was running fine other than showing low voltage on the voltmeter.

Then, partly due to the continued draw and partly for the awful protected cold, the battery started needing frequent jumps. It would run fine after starting, but the voltage held around 13.4-13.5V with did every time I braked or turned on the heat. Even the wiper suited would allow down as I approached stop signs/red lights.

So I took out the battery and used a battery charger (with another lead actor d connected in parallel, as per Optima website instructions) to charge the battery fully.

Even then, the voltage was holding up around 13.7 and usually coming up to 13.9 on the highway/higher revs.
Looked through the forums and ordered the voltage booster from Dirty Parts.

While it still showed the same voltage, my understanding is it was tricking the alternator to put out a higher output to help charge the AGM properly.

Now, the dash light for the check battery started showing up occasionally, so I figured, it must be because of the low voltage being sensed.

Then the check brake and slip/VSC light started showing up, esp after sitting down/idling - generally coinciding with lower revs.

I now have removed the voltage booster and put the 7.5 fuse back. The check battery light is gone. But the brake and VSC lights still are on.

Spoke with Larry, at Dirty Parts, he doesn't seem to have any other suggestions than disconnecting the battery for an hour, which didn't work.
Ran an OBD check, no fault codes.

Brakes are brand new, only a month old.

Any suggestions appreciated.

Thank you for your time

Valar morghulis
Jason Bourne is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old 04-16-2019, 07:29 PM
Forum Superstar
 
mikey's Avatar
 
Join Date: Jun 2006
Location: Edmonton, Canada
Posts: 11,103
Blog Entries: 1
Mentioned: 48 Post(s)
Tagged: 1 Thread(s)
Quoted: 1352 Post(s)
Send a message via MSN to mikey
Lifetime Supporting Member
Re: AGM battery voltage booster issues

How much stuff do you that is drawing power?

Which booster were you running?

After Monday and Tuesday even the calender says WTF


"It's not easy being Green"
Kermit the Frog
mikey is offline  
post #3 of 13 (permalink) Old 04-16-2019, 09:41 PM
Forum Superstar
 
Join Date: May 2014
Location: San Andreas Fault Zone
Posts: 2,786
Mentioned: 123 Post(s)
Tagged: 0 Thread(s)
Quoted: 1268 Post(s)
Re: AGM battery voltage booster issues

The battery is used only for starting the engine, and for supplying electrical loads when the engine is not running.

When the engine is running, the alternator supplies all the electrical power to the vehicle. If the lights dim or the wiper motor slows down at low engine speeds, there is a defect in the alternator, some defect in the wiring (typically high resistance at the battery clamps or ground connections), or the total electrical load exceeds the alternator's output at low speed.

How many miles on the vehicle, and how long has the battery been in service? If there are more than 85K miles on the vehicle, and especially if it has been frequently driven on dusty dirt roads or submerged in muddy water, the alternator brushes may be worn out, or the brushes may be sticking in their holder.

A voltage booster will not compensate for a dying battery or a defective alternator. Also, most plug-in voltage boosters are "polarized"and must be correctly oriented in the fuse holder, or the alternator will not charge the battery.

You mentioned several voltage measurements; how were these made (what kind of voltmeter), and under what condition?

If you have a good-quality (accurate) digital multimeter, here are the basics voltages you should see with a standard Toyota charging system:
1. At least 1/2 hour after engine shut-off, at a temperature of 66-72F, battery voltage should be ~12.6-12.9 volts (no voltage booster).
2. With all accessory loads turned off and the engine running at 2,000 RPM, the voltage at the battery terminals should be 13.2 - 14.8 volts.

Where did you measure the 13.7-13.9 volts, and under what conditions?

Finally, with engine off and all accessories off, maximum parasitic current draw should not be more than a few tens of milliamps. More than this, and you will have problems starting the vehicle after remaining parked for a week, even with a good alternator and a good battery.

Clean both battery terminals and clamps down to bright bare metal, and unbolt the battery ground connection at the fender liner, clean to bright bare metal, and re-tighten.

Verify voltage levels as specified above, and have the battery load-tested. It is possible to simultaneously have a dying alternator and a dying battery.
sonof40 and Uncharted like this.

Last edited by FJtest; 04-17-2019 at 11:58 PM.
FJtest is offline  
Sponsored Links
Advertisement
 
post #4 of 13 (permalink) Old 04-17-2019, 06:53 AM
Forum Master
 
Serenity Now's Avatar
 
Join Date: Jan 2015
Location: Minnesota, USA
Posts: 1,244
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 375 Post(s)
Garage
Re: AGM battery voltage booster issues

I definitely saw a change in charging voltage after installing the Dirty Parts booster on my 2010, went up roughly 0.5 volts to 14.77V.

Steve in MN
Sponsored by Blue Sun Corporation
2010 FJ, now with exciting grill and shifter knob mods

"Speed has never killed anyone. Suddenly becoming stationary, that's what gets you." - Jeremy Clarkson
Serenity Now is offline  
post #5 of 13 (permalink) Old 04-17-2019, 10:07 AM
Forum Master
 
norm356's Avatar
 
Join Date: Oct 2015
Posts: 1,232
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 403 Post(s)
Re: AGM battery voltage booster issues

I read previously on this forum that an AGM needs the voltage increased, but I've used AGM batteries for years, in a Camry for 10 years and in my FJ for around 4 years, all with the stock voltage and have not had any issues when using as a daily driver.

Once when I left it sit for a month the battery discharged, so I keep it on a battery tender when not in use. For daily driving, have found no need to change the charging voltage.

Not sure if this helps you with your issue, but that's been my experience with AGM batteries (purchased from Batteries Plus).

Norm

norm356 is online now  
post #6 of 13 (permalink) Old 04-17-2019, 11:43 AM
Forum Superstar
 
Join Date: May 2014
Location: San Andreas Fault Zone
Posts: 2,786
Mentioned: 123 Post(s)
Tagged: 0 Thread(s)
Quoted: 1268 Post(s)
Re: AGM battery voltage booster issues

Quote:
Serenity Now previously said: View Post
I definitely saw a change in charging voltage after installing the Dirty Parts booster on my 2010, went up roughly 0.5 volts to 14.77V.
Correctly installed, a diode-type voltage booster will definitely increase the alternator's output voltage by 0.5 - 0.8 volt, depending on the forward voltage drop of the particular diode used in the booster.

However, since the majority of "voltage boosters" are just a diode and a fuse connected in series, they are "polarized" and must be properly oriented in the fuse holder for the alternator to properly sense battery voltage. If they are installed "backwards", the alternator will not see the battery, and will not provide an output.

There are a few voltage boosters that contain TWO diodes in opposing polarity so the booster will work regardless of which direction they are installed in the fuse holder.
BrodieTheDog likes this.

Last edited by FJtest; 04-17-2019 at 08:33 PM.
FJtest is offline  
post #7 of 13 (permalink) Old 04-17-2019, 04:35 PM
Forum Master
 
Blown383's Avatar
 
Join Date: Nov 2008
Location: Los Angeles, CA
Posts: 913
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 117 Post(s)
Re: AGM battery voltage booster issues

Have you had your alternator tested?

-B

2015 Camry SE
2012 Porsche Cayenne
2008 FJ Cruiser
2003 Camry LE (RIP)
2000 Mazda Miata
1997 Camao Z28 383ci supercharged
Blown383 is offline  
post #8 of 13 (permalink) Old 04-17-2019, 08:22 PM Thread Starter
Forum Regular
 
Jason Bourne's Avatar
 
Join Date: Aug 2016
Location: Staten Island, New York
Posts: 125
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Lifetime Supporting Member
(Thread Starter)
Agreed, while running alternator is supplying current while the car is running. My understand is that when the battery is deeply discharged, the alternator favourably tries to recharge the battery first and supply accessories later. Since it's already having a hard time charging the AGMs (which need higher voltage) when deeply discharged, alternator struggles to provide enough voltage and you see the lights dim etc.

I will try to clean the battery terminals as suggested.

I have 90k miles. The battery is about 2 years old. It has been very well cared for. Never been driven offroad, submerged etc. The author should not have more than normal wear tear. It has been my daily for 10 years.

Actually after riding the voltage booster with the plain fuse, the voltage has been closer to 14.1, which it had been prior to the deep discharge.

I have an aftermarket voltmeter that I installed. While it's not a high grade by any stretch, the readings have been reliably consistent ie after full discharges ( has happened on three occasions in the last year) the voltage is read low (13.4-13.6 running even at higher revs) and when fully recharged back at 14.1 running, unrelated if idling or high revs

I'm certain I have a high parasitic draw - likely culprits are dash cam (has an auto cut off below battery voltage of 11.5) and remote starter. I need to isolate that


Quote:
FJtest previously said: View Post
The battery is used only for starting the engine, and for supplying electrical loads when the engine is not running.

When the engine is running, the alternator supplies all the electrical power to the vehicle. If the lights dim or the wiper motor slows down at low engine speeds, there is a defect in the alternator, some defect in the wiring (typically high resistance at the battery clamps or ground connections), or the total electrical load exceeds the alternators output at low speed.

How many miles on the vehicle, and how long has the battery been in service? If there are more than 85K miles on the vehicle, and especially if it has been frequently driven on dusty dirt roads or submerged in muddy water, the alternator brushes may be worn out, or the brushes may be sticking in their holder.

A voltage booster will not compensate for a dying battery or a defective alternator. Also, most plug-in voltage boosters are "polarized"and must be correctly oriented in the fuse holder, or the alternator will not charge the battery.

You mentioned several voltage measurements; how were these made (what kind of voltmeter), and under what condition?

If you have a good-quality (accurate) digital multimeter, here are the basics voltages you should see with a standard Toyota charging system:
1. At least 1/2 hour after engine shut-off, at a temperature of 66-72F, battery voltage should be ~12.6-12.9 volts (no voltage booster).
2. With all accessory loads turned off and the engine running at 2,000 RPM, the voltage at the battery terminals should be 13.2 - 14.8 volts.

Where did you measure the 13.7-13.9 volts, and under what conditions?

Finally, with engine off and all accessories off, maximum parasitic current draw should not be more than a few tens of milliamps. More than this, and you will have problems starting the vehicle after remaining parked for a week, even with a good alternator and a good battery.

Clean both battery terminals and clamps down to bright bare metal, and unbolt the battery ground connection at the fender liner, clean to bright bare metal, and re-tighten.

Verify voltage levels as specified above, and have the battery load-tested. It is possible to simultaneously have a dying alternator and a dying battery.
Jason Bourne is offline  
post #9 of 13 (permalink) Old 04-17-2019, 08:24 PM Thread Starter
Forum Regular
 
Jason Bourne's Avatar
 
Join Date: Aug 2016
Location: Staten Island, New York
Posts: 125
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Lifetime Supporting Member
(Thread Starter)
I took out the voltage booster for now but will double check when reinstalling
Quote:
FJtest previously said: View Post
Quote:
Serenity Now previously said: View Post
I definitely saw a change in charging voltage after installing the Dirty Parts booster on my 2010, went up roughly 0.5 volts to 14.77V.
Correctly installed, a diode-type voltage booster will definitely increase the alternator's output voltage by 0.5 - .08 volt, depending on the forward voltage drop of the particular diode used in the booster.

However, since the majority of "voltage boosters" are just a diode and a fuse connected in series, they are "polarized" must be properly oriented in the fuse holder for the alternator to properly sense battery voltage. If they are installed "backwards", the alternator will not see the battery, and will not provide an output.

There are a few voltage boosters that contain TWO diodes in opposing polarity so the booster will work regardless of which direction they are installed in the fuse holder.
Jason Bourne is offline  
post #10 of 13 (permalink) Old 04-17-2019, 08:26 PM Thread Starter
Forum Regular
 
Jason Bourne's Avatar
 
Join Date: Aug 2016
Location: Staten Island, New York
Posts: 125
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Lifetime Supporting Member
(Thread Starter)
I don't have heavy duty stuff like a fridge, but I have a remote starter, dash cams and an echo dot. Also upgraded the speakers revently and have some aftermarket LEDs, but they shouldn't be drawing when car is off
Quote:
mikey previously said: View Post
How much stuff do you that is drawing power?

Which booster were you running?
Jason Bourne is offline  
Reply

  Toyota FJ Cruiser Forum > Toyota FJ Cruiser Discussion > Stereo / Electronics / Electrical

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Toyota FJ Cruiser Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List




  Similar Threads
Thread Thread Starter Forum Replies Last Post
Voltage Fluctuations F-YAY Stereo / Electronics / Electrical 46 04-10-2019 08:48 AM
Battery Voltage @ Idle????? GS-RON Misc. Technical Discussion 6 04-27-2016 04:21 PM
Dual Battery Installation Write-Up - Pics sbechtold 4x4 / Off-Road Tech 87 01-21-2013 01:14 PM
Installed dedicated battery for ARB fridge AZFJTOY Stereo / Electronics / Electrical 6 02-14-2012 09:28 AM
Minimum conservative starting voltage, aux load battery cutoff spincycle Stereo / Electronics / Electrical 5 08-05-2009 08:50 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome