Question about optima yellow top charging

D

Dirtrider216

New member
I recently had toyota replace my alternator, however shortly before I got to the toyota dealership for the alternator I figured Id drop a new battery in hopes that I might not have to shell out for an alternator since my old battery was pushing 7 years in florida weather. I went to autozone and picked up a optima yellow top Group 35D
Lately I have noticed that when I start my car in the morning voltage is about 13.8 but after about 10 minutes of driving it drops to and stays at 13.0-13.3 volts and only getting to 13.6 if im on the interstate driving at about 2k rpms.
Do i need to worry about the lower voltage and should I look into a onboard charging setup? My apartment parking garage doesnt have any poweroutlets near my assigned space so a once a month charge from an external charger isnt really an option...
Thanks in advance
 
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i would return the yellow top and go with northstar 31, you can fit 27f in stock location.

if you want to save a little, get the x2 from batteries plus, its a northstar brand, just rebadge for batteries plus store.
do online order and use coupon code, then do store pick up.

as far as voltage, its normal for 13.8 , a good digital volt meter should read at 13.4-13.8 at idle during cold start.
 
I second the X2 power from batteries plus (rebranded northstar). I got the 24F.

I paid $260 after tax and 20% off coupon from their website.

they installed it right there.

5 year non pro rated warranty sold me.
 
You can trick your alt-s diode to output slightly higher voltage, better for charging AGM batteries but they will still require a top off every once in a while if you don't go for long highway drives often.

There's an ebay option I've tried that works and I recently switched to the GM part number in the link below. It must be shaved down but works the same with a cleaner look installed.

Tech Center - Chi Town 4x4
 
Thanks for all the input, Ill have to look into that.
A concern I have with putting a larger battery in is that I also changed out my terminal connectors and when I did that, I shortened the battery positive wire a small amount to the point that it is stretching slightly to fit onto my current battery and I don't know that it would fit on a larger battery anymore... yeah kind of a big oops.
Would I be able to use something like NSi Industries | Easy-Splice™ 4/0 Kit
to extend the wire about 6 inches? I don't really have the time or the money to rewire from the starter to make the cable longer..
 
Keep in mind that AGM batteries such as Optima, require a higher voltage to fully charge than the standard batteries. Your alternator, while operating within it's normal range of output voltage, will not charge it completely.
 
blackoutt said:
You can trick your alt-s diode to output slightly higher voltage, better for charging AGM batteries but they will still require a top off every once in a while if you don't go for long highway drives often.

There's an ebay option I've tried that works and I recently switched to the GM part number in the link below. It must be shaved down but works the same with a cleaner look installed.

Tech Center - Chi Town 4x4
Click to expand...

Would I be able to install this GM part along with https://www.autozone.com/electrical...sories/cooper-bussmann-atm-fuse-tap/32416_0_0 so that I could maintain the factory 7.5 amp fuse, essentially creating the dirty parts setup for ~ $12 plus shipping for the diode? Also will that diode affect any other systems? I have bad luck with headlights and would hate to have my new xenon depot system blow due to the change in volts, amps or current...
 
Dirtrider216 said:
Would I be able to install this GM part along with https://www.autozone.com/electrical...sories/cooper-bussmann-atm-fuse-tap/32416_0_0 so that I could maintain the factory 7.5 amp fuse, essentially creating the dirty parts setup for ~ $12 plus shipping for the diode? Also will that diode affect any other systems? I have bad luck with headlights and would hate to have my new xenon depot system blow due to the change in volts, amps or current...
Click to expand...

No need, the GM part IS the 7.5a fuse and diode all in one.
 
Rodtheviking said:
On a whim I tired this and it works, 14.7v at idle. 8.00 at the dealer for the diode.
Click to expand...

Yep, I even quoted Chi town 4x4 as a more reputable source for info than me! It works exactly the same as my ebay add a fuse diode thing which was more expensive. I kept it as a spare but if anyone wants the add a fuse/diode hodge podge $20 shipped. Or just go get a GM diode.
 
This must be what's happening with my DieHard Platinum AGM. It looks like there are several of you running the higher voltage without issue... has anyone had any problems with this?
 
shmabs said:
To those using the GM diode and an AGM.

What are you seeing for running voltage, and how are you measuring it?
Click to expand...

If I'm remembering correctly - High 14.x's cold start, low 14.x's on both batteries when connected warm and cruising highway speed. I have a dual voltmeter installed in my center console to monitor but you could also use things like scanguage or a cheap cig lighter plug in, or OBD scan tool - bluetooth/wifi dongle with torque lite app.
 
blackoutt said:
If I'm remembering correctly - High 14.x's cold start, low 14.x's on both batteries when connected warm and cruising highway speed. I have a dual voltmeter installed in my center console to monitor but you could also use things like scanguage or a cheap cig lighter plug in, or OBD scan tool - bluetooth/wifi dongle with torque lite app.
Click to expand...

Thanks for the reply!

I installed an AGM battery and the GM diode and was seeing 15 volts occasionally (via scan gauge), which seemed awful high. I went back to the regular 7.5 amp fuse, and I'm seeing 13.8-14.0. Does anyone have any documentation on the charge profile that AGM's require? I've heard they require more, especially optimas. My 4runner isn't a daily driver, so I'll have to double check my numbers again. Most of the online charts I'm seeing show that more than 14 is required at 77 degrees, maybe I will have to swap that diode back in. Is anyone seeing and negatives to a standing voltage of that high?
 
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