Normal Voltage Reading?

LJDC · Oct 24, 2023

Jerry Bransford said:
Both the PCM and the radio have a 7/24 draw on the battery. Any aftermarket things like an aux amplifier that is staying on all the time? Even miswired relays for things like driving lights can cause a permanent draw when they're miswired to energize what they're connected to by being shut off and turned on to shut the device off.

I have a bunch of aftermarket electronics, but they’re all connected to the battery by a single high-voltage circuit breaker (which works). I’ve had it flipped off for a while, so I know it isn’t that. This also disconnects the power to the relays for the two air compressors, though both remain connected to the battery, as does the winch. I haven’t disconnected those yet, as I slowly search for the “leak.”

The aftermarket radio usually draws power, and I wonder whether there could be an issue there. The old aftermarket radio that it replaced did the same thing. For that reason I’ve disconnected it, for now. No amp, other than the factory amp. I’ll probably pull the fuse for that next.

I know that the multifunction switch is broken—the fog lights will stay on all the time. I have a replacement but I’ve been waiting to do the work. In the mean time I pulled the relay for the fog lights.

I know that’s kind of rambling. I’ve disconnected what I can think of that might draw power, including all aftermarket relays, other than the PCM. I’m pulling them one-by-one, as I also try to reason my way to an answer.

LJDC · Oct 25, 2023

Jerry Bransford said:
Both the PCM and the radio have a 7/24 draw on the battery.

I apologize for my ignorance, but what is a 7/24 draw?

macleanflood · Oct 25, 2023

LJDC said:
I apologize for my ignorance, but what is a 7/24 draw?

24/7

24 hours a day, seven days a week.

-Mac

LJDC · Oct 25, 2023

LJDC said:
I apologize for my ignorance, but what is a 7/24 draw?

As we said when we were kids, duh

I’ve never had to track down a draw like this. I think it’s coming from the radio. Overnight the voltage will tick down to 12.3v, then lower. Is there a good way to measure what’s being drawn? Or thinking about it another way, how long should the Jeep be able to sit before the small draw becomes too much for it to start?

Jerry Bransford · Oct 26, 2023

LJDC said:
I apologize for my ignorance, but what is a 7/24 draw?

7 days a week, 24 hours a day.

dodj · Oct 26, 2023

LJDC said:
Is there a good way to measure what’s being drawn?

Clip on dc ammeter works well if you have one.

My jeep has sat for 10-14 days without a battery power issue. Probably go a lot longer but I haven't let it sit longer.

Mac57 · Oct 26, 2023

LJDC said:
As we said when we were kids, duh

I’ve never had to track down a draw like this. I think it’s coming from the radio. Overnight the voltage will tick down to 12.3v, then lower. Is there a good way to measure what’s being drawn? Or thinking about it another way, how long should the Jeep be able to sit before the small draw becomes too much for it to start?

First thing is to verify your battery is good. Have it load tested as others have said. It's pointless doing any other testing until you know for certain the battery has no issues.

Next perform a parasitic draw test using a multimeter and pulling fuses one at a time to isolate and identify the circuit drawing excess power. Plenty of u tube videos available to guide you. Once you have the circuit identified you can investigate further.

Jeep should be able to sit for at least a week minimum, even more, and still start up just fine

LJDC · Dec 7, 2023

Jerry Bransford said:
The voltage output of the alternator varies with the state of the charge on the battery, your 13.3 to 13.4 is fine for a battery that is charged and doesn't need more charge. Over 14 is only going to be seen when the battery is low and needs charging. With the engine off a fully charged conventional battery measures 12.6 volts, a fully charged AGM battery measures 12.8 volts.

I'd charge the battery overnight (not just a couple hours) with a benchtop charger, not a trickle charger. Then take it to a battery retailer and ask them to do a "Load Test" on the battery which is the only way to know if the battery itself is good. They will place an amperage load that is 50% of its max rating for 15 seconds and measure its voltage at the end of 15 seconds. How much it dropped at the end of 15 seconds indicates if it is good or bad.

Life finally allowed me to do this. The battery tested bad: The test read 12.86v at 553 CCA, or 79% CCA. How bad is that?

I've read threads from a few years ago until about last year, and I see there are short-term trends (edit: meaning, the latest news on reliability) in what batteries people prefer. I plan to switch to an AGM battery. Are there preferred brands today? Because of where I park my Jeep, I won't be able to keep it plugged in. But I could potentially drop a solar panel on the roof to keep the battery in better shape (when I figure out how to mount the panel so I don't have to screw around with it when I take the Jeep out).

C.J. Roberts · Dec 7, 2023

LJDC said:
Life finally allowed me to do this. The battery tested bad: The test read 12.86v at 553 CCA, or 79% CCA. How bad is that?

I've read threads from a few years ago until about last year, and I see there are short-term trends in what batteries people prefer. I plan to switch to an AGM battery. Are there preferred brands today? Because of where I park my Jeep, I won't be able to keep it plugged in. But I could potentially drop a solar panel on the roof to keep the battery in better shape (when I figure out how to mount the panel so I don't have to screw around with it when I take the Jeep out).

If you're planning on replacing it sooner rather than later anyway, just get the cheapest battery you can find. See if there is a used battery place near you. If not, a Walmart 2 year battery is just over $100.
Harbor Freight has a small solar panel that you could probably mount in front of your grill, on the sway bar cover. $15.

LJDC · Dec 7, 2023

C.J. Roberts said:
If you're planning on replacing it sooner rather than later anyway, just get the cheapest battery you can find. See if there is a used battery place near you. If not, a Walmart 2 year battery is just over $100.
Harbor Freight has a small solar panel that you could probably mount in front of your grill, on the sway bar cover. $15.

Why the cheapest option?

Cool solar panel... maybe it'll fit on the cowl or on top of the spare tire? I trimmed the sway-bar cover, and there isn't much room between the grille and the winch.

C.J. Roberts · Dec 7, 2023

LJDC said:
Why the cheapest option?

Cool solar panel... maybe it'll fit on the cowl or on top of the spare tire? I trimmed the sway-bar cover, and there isn't much room between the grille and the winch.

If you're replacing it soon anyway, you don't want to spend $300 on a battery you're not going to keep.

LJDC · Dec 7, 2023

C.J. Roberts said:
If you're replacing it soon anyway, you don't want to spend $300 on a battery you're not going to keep.

Sorry, I'm confused. I have a battery that needs to be replaced. I want to replace it with a reliable AGM battery. I'll stick with that replacement for however long it lasts.

Was it my reference to "short-term trends"? By that I meant that the reputations of certain batteries seem to change quickly, so I'm wondering what the best options are now. I'll edit the post to avoid that confusion.

C.J. Roberts · Dec 7, 2023

LJDC said:
Was it my reference to "short-term trends"?

Yeah, that was it. So yeah, if the AGM is the plan, get one.

LJDC · Dec 7, 2023

C.J. Roberts said:
Yeah, that was it. So yeah, if the AGM is the plan, get one.

Oops. Sorry

Any thoughts on brands?

C.J. Roberts · Dec 7, 2023

LJDC said:
Oops. Sorry Any thoughts on brands?

Several posters here have spoken favorably about NAPA AGMs.

Jerry Bransford · Dec 7, 2023

The brand to AVOID is Optima, their quality took a giant dive several years ago after they were purchased by Johnson Controls. I would normally recommend an Odyssey AGM but there have been a few negative reports on them lately.

So my recommendation is the AGM battery with the best warranty you can find locally. Or a Dekka which gets lots of strong recommendations here. Personally I'd go for them or any locally sourced AGM with a strong warranty. My current Northstar AGM battery has been outstanding but they were purchased by Odyssey. I'm a little shocked/dismayed by the several bad reviews of Odyssey seen recently but I'd certainly buy them or any other AGM with a good warranty before I'd buy any Optima battery. I personally had THREE premature Optima battery failures that weren't covered under warranty.

I'd keep any battery you want to have a long time on a battery maintainer when you're going going to be driving it a lot. I bought the below maintainer on Amazon 10-12 years ago, it works great. I keep it permanently attached, I mounted onto the top of the air intake filter box. I extended its AC cord so it hangs in front of the radiator so I can plug it in or unplug it easily.

B1Toad · Dec 7, 2023

Some of Oreilly's Super Start AGMs are made by Deka. I have a big H-8 in my Sprinter and it's been very good but I do keep it on a smart maintainer. It is quite a bit more expensive than the Costco Interstate AGMs though.

macleanflood · Dec 7, 2023

Not to hijack the thread...but what do folks think about Costco Interstate AGM batteries?

I'd think the turn over would be enough to guarantee fresh enough stock.

I just DJ'd a holiday party for the local distributor and they seem like a nice family oriented business with a lot of long term employees. Should have asked questions but didn't since I was working.

-Mac

B1Toad · Dec 7, 2023

macleanflood said:
Not to hijack the thread...but what do folks think about Costco Interstate AGM batteries?

I'd think the turn over would be enough to guarantee fresh enough stock.

I just DJ'd a holiday party for the local distributor and they seem like a nice family oriented business with a lot of long term employees. Should have asked questions but didn't since I was working.

-Mac

I just bought one for my TDI, so can't really say how long it will last but the price was very low. Costco did modify their warranty though, no more free replacements, it now 3 year warranty pro rated. Checking around it looks like everyone has eliminated the free replacement program.

LJDC · Dec 7, 2023

Jerry Bransford said:
I'd keep any battery you want to have a long time on a battery maintainer when you're going going to be driving it a lot. I bought the below maintainer on Amazon 10-12 years ago, it works great. I keep it permanently attached, I mounted onto the top of the air intake filter box. I extended its AC cord so it hangs in front of the radiator so I can plug it in or unplug it easily.

I would like to be able to do that, but most of the time I can’t park my Jeep close-enough to the house for a cable to reach. The best I can do is to mount a solar panel, which I’m looking into.

Normal Voltage Reading?

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