Charging Issue with New Battery and Alternator

[19963.4lsr5]

With a Alt that’s up to temp.....

In gear with the brake on and headlights I was at 13.1v at the cig lighter.

Turning everything else on under the same condition had me down to 12.3v


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[gamefreakgc]

With a Alt that’s up to temp.....

In gear with the brake on and headlights I was at 13.1v at the cig lighter.

Turning everything else on under the same condition had me down to 12.3v


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Thanks, that info is helpful. I shouldn't be anywhere near that with a 140A vs a stock 80A, let alone dropping as low as I am. I bought a simple cig lighter volt reader so I'm not having to do it through the OBD-II port which seems to be lower than everything else.

 

[nevada]

With a Alt that’s up to temp.....

In gear with the brake on and headlights I was at 13.1v at the cig lighter.

Turning everything else on under the same condition had me down to 12.3v


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12.3 with the engine running? you need a bigger alt man. you're going to kill your battery.

 

[19963.4lsr5]

12.3 with the engine running? you need a bigger alt man. you're going to kill your battery.

I replaced the voltage regulator in it and I’m not happy with its performance. It’s the 70a. I have a good 80a I should just put on.


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[gamefreakgc]

I replaced the voltage regulator in it and I’m not happy with its performance. It’s the 70a. I have a good 80a I should just put on.


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After doing the CS144 swap several times now, the stock alternator is stupid easy to get in and out! Don't even have to remove the battery tray.

I will get back home to my 4Runner soon and I'll post up on my findings. Thanks to everyone who helped with data & suggestions, here's to hoping I find the culprit once and for all.

 

[Toy2play]

Thanks, that info is helpful. I shouldn't be anywhere near that with a 140A vs a stock 80A, let alone dropping as low as I am. I bought a simple cig lighter volt reader so I'm not having to do it through the OBD-II port which seems to be lower than everything else.

I'm curious why the reading off the OBD-II port is so off. Mine is only off by about .1 volts from reading directly off the battery and my scan gauge. I'm also running the same cs144 and big 3.

When you converted the alternator connection from GM to Toyota, did you spice into the wires or did you buy a pigtail?

 

[LittleCaesar]

Sounds like you just need to keep plugging away.

Had a friend whose modded 300zx kept blowing alternators (read six at least) and they got hot, every one. Turns out that one of his lugs on a custom cable to the ALT had become loose and was causing some sort of high amperage draw. A new cable solved his problems.

I would throw the 80amp alternator back in and see if the same problems manifest themselves.

 

[19963.4lsr5]

I'm curious why the reading off the OBD-II port is so off. Mine is only off by about .1 volts from reading directly off the battery and my scan gauge. I'm also running the same cs144 and big 3.

When you converted the alternator connection from GM to Toyota, did you spice into the wires or did you buy a pigtail?

Good question. I’ve mentioned before that that adapter could be suspect. Those CS alt’s are pretty hardy and as simple as the Denso. Now if he spliced......I hope it was solder with a western-union splice and shrink tube.


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[gamefreakgc]

I'm curious why the reading off the OBD-II port is so off. Mine is only off by about .1 volts from reading directly off the battery and my scan gauge. I'm also running the same cs144 and big 3.

When you converted the alternator connection from GM to Toyota, did you spice into the wires or did you buy a pigtail?

I bought a pigtail that worked fine. That's the next test I'm going to try and do. EDIT: Pigtail tested fine, all wires has 7 or less ohms.

Ok a few updates. Took some readings:

Battery to chassis ground - 1 ohm.
Alternator case to chassis ground - 1 ohm.
Alternator post to battery positive - 25 ohms. Is this too high? EDIT: I removed the cables from the positive battery post, cleaned them up and got this down to 2 ohms. Pretty happy about that. Should help with the voltage drop too.

When the vehicle is off, I have a draw of 80 miliamps. Pretty sure that's my amps, not too worried about that.

Voltage drop from Alternator positive to battery positive is 0.07V-0.11V (a bit high???)
Voltage drop from Alternator case to battery negative is 0.05V

And some battery voltage tests while running after I cleaned off all connections and grounds:

Startup: 14.2V
Idling with all accessories on: 13.2V-13.9V. Drops to 13.2V only when fan kicks on with ALL accessories on. That includes light bars and all that so a lot of current being drawn.
1500 RPM with all accessories on: 14.0V

I think that points to my alternator working fine, and my battery being fine. I also found a short on my e-fan wiring that I think is causing some resistance, the connector looks burnt so I need to re-do that part of the wiring. That might be part of the issue of why the voltage drops so much when the fan kicks on.

Any thoughts? At this point I think I'm good to go for driving since it's putting a solid 14.0V at the battery while the engine is running. Looks like it was a wiring issue after all!

 

[gamefreakgc]

I re-wired my e-fan and it doesn't draw as many volts down now!

THANK YOU for everyone's help and input. Thanks [MENTION=99144]19963.4lsr5[/MENTION] for giving me some voltage readings to compare to as well, that made it much easier to see if I was off base or not. The Turd lives on!

 

[gamefreakgc]

Drove it this morning for a good 30 minutes. Voltage reported between 12.4 - 13.0V via OBD-II, which from my testing yesterday means about 13.9 - 14.5V at the battery. It dropped momentarily to 12.0V when my fan kicked on at idle but came back up quickly. Looks like my positive battery cable connections was the culprit after all! I learned a lot from all this and even though the cable "looked fine" with no corrosion, there was enough dirt and grime that found its way in to make the connection deteriorate.

 

[19963.4lsr5]

I’m going to do the voltage drop test on my rig between the Alt charge post, Underwood junction box, and battery myself before I call my aftermarket voltage regulator junk.


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[Kanoe]

Voltage reported between 12.4 - 13.0V via OBD-II, which from my testing yesterday means about 13.9 - 14.5V at the battery.

I wonder what is up with that. My Ultraguage measures within .1 or .2 of battery voltage.

You could put your DVM on the 12V pin of the OBD2 port to see if it is a voltage drop in your wiring or if it is a misreporting by the device you are using. What are you using on the OBD2 anyhow?

 

[gamefreakgc]

I wonder what is up with that. My Ultraguage measures within .1 or .2 of battery voltage.

You could put your DVM on the 12V pin of the OBD2 port to see if it is a voltage drop in your wiring or if it is a misreporting by the device you are using. What are you using on the OBD2 anyhow?

It could very well be the bluetooth reader. It's never been that high (13.1V is the highest I've ever seen in 5 years of having it), it's the BAFX cheapo reader off Amazon so I'm not expecting the world from it. However, it does seem to rise and drop in proportion to the battery voltage accurately.

I have no low voltage issues anywhere in the cabin so I haven't really worried about it much. Headlights don't dim or anything like that so I think it's probably just the reader. I did order a cigarette lighter voltage reader though which I'm interested to see if that's more accurate: https://smile.amazon.com/gp/product/B07C5H7VPT/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[19963.4lsr5]

Redo your pcm grounds on the intake manifold. Or check the crimp voltage drop to the negative battery terminal. The ground crimps could be corroding. If so redo the crimps and solder the crimps after crimping to remove any chance or corrosion later.

For grounds I use non insulated crimps.


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[phattyduck]

Startup: 14.2V
Idling with all accessories on: 13.2V-13.9V. Drops to 13.2V only when fan kicks on with ALL accessories on. That includes light bars and all that so a lot of current being drawn.
1500 RPM with all accessories on: 14.0V

These are all perfect numbers. The voltage reported via OBD-II should be what the ECU is receiving - you likely have bad grounds or power to the ECU, which is probably worth checking out! Check grounds, re-seat connectors, relays and fuses, etc.

-Charlie

 

[RAD4Runner]

I see a lot of guess work here. START WITH SIMPLE AND FREE THINGS FIRST.
The one thing in common with those alts is the wiring. If the third alt fixed the problem, it was because disconnecting and re-connecting connector rubs off oxidation on the pins.
Toyota components are bullet-proof. Bad wiring usually causes problems. had what looked like a serious problem last week, only to find out it was a bad "S" pin connection. Fixed by cleaning and tightening connector pins.

Isn't there supposed to be battery voltage fed TO the alternator on one or them to make the alternator work?

... I have read about broken wires right on the connector, maybe a good visual will turn up something.

Yes this^^^
S- wire senses battery voltage. If this is broken, you would get over-voltage
IG - wire "excites" the alternator. If this is broken you will not get charging, low charge if high IG is almost broken (high resistance).
L - is merely fault light signal it will not prevent alternator from doing its job. It should be close to 12V when system is working well. Close to ero when there is a system fault.

 

[gamefreakgc]

Looks like I got me some grounds to clean!

Redo your pcm grounds on the intake manifold. Or check the crimp voltage drop to the negative battery terminal. The ground crimps could be corroding. If so redo the crimps and solder the crimps after crimping to remove any chance or corrosion later.

For grounds I use non insulated crimps.


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I will take a look at it and clean. I don't remember ever cleaning it and my engine bay gets grimey with oil + dust.

These are all perfect numbers. The voltage reported via OBD-II should be what the ECU is receiving - you likely have bad grounds or power to the ECU, which is probably worth checking out! Check grounds, re-seat connectors, relays and fuses, etc.

-Charlie

By chance do you recall where the ECU ground point is? I think I remember it being behind the passenger's side kick panel but I might be mixing it up in my head with something else.

 

[19963.4lsr5]

I coat my terminals both battery and all my grounds in a conductive grease.

I use this stuff. If it can keep aluminum ground lugs in the bottom of our manholes at work clean between our yearly inspections of the high voltage distribution it will work under the hood of a car a long time.

One 15-29 dollar tube of this stuff will last two generations.


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[gamefreakgc]

I wonder what is up with that. My Ultraguage measures within .1 or .2 of battery voltage.

You could put your DVM on the 12V pin of the OBD2 port to see if it is a voltage drop in your wiring or if it is a misreporting by the device you are using. What are you using on the OBD2 anyhow?

You called it, it's my OBD-II reader. I get a solid 12.5V at the port itself with key ON. Time to try and explain to the wife why I need another car gadget...

On the plus side, the cheapo cig lighter voltage reader read at 12.4V. I'll use that from now on I think.