Aftermarket alternator?

[Whaler27]

How challenging is it to bypass the Genesis system to determine if it's the root cause?

This is a smart question. I was also given a couple suggestions for replcing the Genesis system, which I’ll looking into.

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[Whaler27]

Forum Kool-Aid defined,
There is an aftermarket solution for every JL problem, and for every JL owner who thinks there is a problem.

Forum Kool-Aid comes in different flavors and of different intensities. Hard to tell exactly what you've been drinking.

My statement, "With your driving, equipment, and continuous charging, it is not clear that you should expect anything different than what you're reporting," was short handed from your posts. Those show you have replaced stock equipment with an aftermarket 2 battery system and you continually use, in an unknown way, a charging device of unknown capabilities and limitations. Your driving is infrequent enough to doubt that a functioning alternator alone would keep 2 batteries at full charge. And it is unknown what other loads/factors are involved, including ESS operation.

So it's not clear that the 2 battery/charging system/routine you created and use is expected to function well. Perhaps you will pursue meaningful diagnostics before replacing the alternator.

I‘m here requesting advice from the many smart folks on this forum who are very familiar with the…
1) JL electrical system functions and common challenges as they work with the...
2) Popular Genesis dual battery system, and the
3) Noco 10 amp smart charger (referenced above)

I gather you’re unfamiliar with all of these things, but there are many people here who are quite familiar with all three and have diagnosed and solved related problems. Some have already contributed to this thread.

I’ve owned Jeeps since the mid-70s, but there’s an awful lot I still don’t know. The newest computer-driven problems are most vexing for me so.

When I’m over my head and have nothing meaningful to contribute I try not to weigh in all. Just a thought.

 

[roaniecowpony]

How challenging is it to bypass the Genesis system to determine if it's the root cause?

Well, to just test, you can simply use one of the batteries by putting both cables on one. Might have to remove one battery to get it oriented where the cables reach. That's my plan next.

As for eliminating the Genesis, seems like just running them in parallel should work.

 

[THAW]

How challenging is it to bypass the Genesis system to determine if it's the root cause?

This is a smart question. I was also given a couple suggestions for replcing the Genesis system, which I’ll looking into.

[@roaniecowpony beat me to it.]

Not challenging.

Just remove the Genesis negative terminal connector from the negative post of the crank battery (the one that has the factory positive cable terminal connector attached to its positive post) and move the factory negative cable terminal connector (w/ IBS) from the auxiliary battery negative post to that crank battery negative post.

The above method completely disconnects the auxiliary battery. To run the batteries as a bank for the Jeep (in permanent parallel), a couple extra battery cables are required.

 

[THAW]

Well, to just test, you can simply use one of the batteries by putting both cables on one. Might have to remove one battery to get it oriented where the cables reach. That's my plan next.

As for eliminating the Genesis, seems like just running them in parallel should work.

You shouldn't have to remove a battery. It's a little tight, but the factory negative cable terminal connector should reach the crank battery negative post - especially with the Genesis-recommended IBS/clamp reorientation. I run my connections this way for my Genesis tray and REDARC BCDC setup.

 

[THAW]

You're not alone. My Gen2 Genesis system killed my Odyssey batteries (3 of them). They seemed to hold up for almost a couple years each. But it was overcharging them. I put a new engine with a brand new alternator in my JL, along with a brand new Mopar PCM (which has the regulator) and it killed the replacement Odyssey main and finished off the aux.

I installed the Gen3 in April and went on a road trip and it drained the brand new FullThrottle batteries down to 12.4v during the trip and the alternator would only charge at 12.6v. I've replaced the PCM with my spare, replaced the alternator with a spare, and replaced the IBS. None of those things corrected the decay to 12.6v charging rate. Everytime the battery is disconnected the charging resets to 14.3v and it's fine for a while but decays over a 100 mile long drive and few cycles. I verified these Gen3 Genesis battery charging issues over months of testing. Basically, the Gen2 overcharges the batteries and the Gen3 undercharges.

I called them in April, suspecting it was the newly installed Gen3. The told me nothing on their board would affect the charging voltage.

So, I installed the Gen2 again about a week and change ago, and it charged at 14.3v and never decayed.

Last night, I re-installed the Gen3 just to verify it decays to 12.6v again. A 30 mile loop around PV and it's starting to drop. Still up around 13.8v (which is fine) but if I'm right about this device, it will decay back down to 12.6v and stay there, with the battery voltages around 12.4v (60% charge). I want to be doubly sure it's their product causing this. My uneducated guess is that their battery charging management device is not playing well with the IBS and PCM.

Is there per-trip "decay"? That is, does alternator voltage start in the high 13s low 14s Volts every time you start the engine, then slowly drop during the long drive? Or is it the case that once it hits 12.6 Volts after a disconnection reset it stays there indefinitely?

 

[alphawolff]

The vehicle has no idea you have a dual battery system. It will always slowly undercharge your genesis system unless you top it off with a trickle charger from time to time. You're putting way more battery capacity onto it and it's just using floating voltage/drain rate to determine how much to charge based on its factory specifications. It usually has to deal with a 600-1000 CCA capacity depending on if you have the towing package/stop start. You're probably sitting at 2000 or so. That's a lot of extra battery that the system isn't accounting for.

If it was a old school alternator this would be fine, but it's never going to properly function with a smart alternator like ours

 

[Terrymo]

I‘m here requesting advice from the many smart folks on this forum who are very familiar with the…
1) JL electrical system functions and common challenges as they work with the...
2) Popular Genesis dual battery system, and the
3) Noco 10 amp smart charger (referenced above)

I gather you’re unfamiliar with all of these things, but there are many people here who are quite familiar with all three and have diagnosed and solved related problems. Some have already contributed to this thread.

I’ve owned Jeeps since the mid-70s, but there’s an awful lot I still don’t know. The newest computer-driven problems are most vexing for me so.

When I’m over my head and have nothing meaningful to contribute I try not to weigh in all. Just a thought.

The battery exspurts can be a cantankerous bunch…except for @THAW who seems ok most days. Every once in a while @Mguy is pretty ok as welL and even lets his sense of humor show from time to time.

 

[THAW]

@THAW who seems ok most days.

My spirits rise and fall with my daily trip to the mailbox to check for beer.

 

[Terrymo]

My spirits rise and fall with my daily trip to the mailbox to check for beer.

Having your hopes dashed each day can be tough.

 

[THAW]

Having your hopes dashed each day can be tough.

 

[THAW]

The vehicle has no idea you have a dual battery system. It will always slowly undercharge your genesis system unless you top it off with a trickle charger from time to time. You're putting way more battery capacity onto it and it's just using floating voltage/drain rate to determine how much to charge based on its factory specifications. It usually has to deal with a 600-1000 CCA capacity depending on if you have the towing package/stop start. You're probably sitting at 2000 or so. That's a lot of extra battery that the system isn't accounting for.

If it was a old school alternator this would be fine, but it's never going to properly function with a smart alternator like ours

Interestingly, it's the other way around; the IBS/PCM track Current/SoC/Residual for only one of the dual batteries, so the Jeep sees a ~60ish Ah battery instead of a stock-spec ~70-80ish Ah battery. The extra battery silently absorbing current likely just forces the alternator duty-cycle slightly higher to maintain the target voltage - much like the lower-capacity AUX (ESS) battery would, typically on a smaller scale.

I'm not sure how much battery capacity matters though, because in my experience with my '23 2.0, voltage is adjusted based primarily (entirely?) on IBS battery temperature compensation at a very standard ~3 mV per cell per °C (or about 0.1 Volts per 10 degrees Fahrenheit for the 6-cell 12V).

So, ya, the Jeep doesn't know there's a dual-battery system.

 

[Mguy]

The battery exspurts can be a cantankerous bunch…except for @THAW who seems ok most days. Every once in a while @Mguy is pretty ok as welL and even lets his sense of humor show from time to time.

Who you sayin’ is cr[an]ktankerous?

 

[Terrymo]

Who you sayin’ is cr[an]ktankerous?

See I wasn’t wrong about you.

 

[Mguy]

See I wasn’t wrong about you.

Yes, but you've mixed things up, again. "Cr[an]ktankerous," like over-the-top reference to Jonestown Kool-Aid induced herd behavior, is my feeble attempt at humor. A cantankerous post from me would go something like this,

Who knew, that with a thread title like "Aftermarket Alternator," the OP wanted to hear from JL owners who use NOCO Genius 10 chargers with the Genesis 2 battery system? Does a JL owner like me, who has that very charger, and has been personally familiar with, and use, ACRs like these, which are essential to Genesis systems, qualify for posting? Should I tell the OP that NOCO literature and other available information does not indicate a continuous well-regulated float stage suitable for charging in circuits with funky loads? Should I disclose why I think ACRs are not appropriate for JLs unless the owner regularly uses a winch or other high loads (like after converting a Jeep to RV status)? Should I mention and discuss critical facts, like triggering parameters need to be compatible for power sources and ACRs to work properly? Would the OP like to know what configuration changes might improve his battery performance?

The answer is no, I'm not going to get into a discussion about OP specified qualifications for posting, or what my further posts might look like. Instead, I'm going to wait. The schadenfreude will be overwhelming if it turns out the OP made the Genesis mod to "better" ESS operation during his 50 miles per week driving.

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