I have owned a Ram for 6 years and not one dealer in my area, which is 4, has ever offered or given me a loaner when I have asked. I couldn’t even get one for warranty work. Obviously some are way better than others. Perhaps we should just start calling them out by name.
Aux Battery Swap for H8 Main Battery
- Thread starter frogjbm
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Dealership is basically a bank with an auto service department.
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At about 6,000 miles, I arrived home from work at 6:30 p.m., and when I wanted to leave at 5:00 a.m., it no longer worked. The battery was dead. I only pumped power to the main battery. When it did, there were twenty signs on the dash telling me about the truck's many problems. I couldn't even shift the transmission. I left it running, and at about 11:00 a.m., six hours after running it at idle and in park, the truck only left the check engine light on and was able to drive to the dealership.
They told me it was my fault for having connected an electrical cover to the pickup bed. Of course, it wasn't right, but nothing could be done.
I'd like to think about it personally: that afternoon when I got home from work, I didn't set the alarm; I just closed the door, and that's what caused the battery to die. I don't know the exact truth.
I've already seen how to eliminate the auxiliary battery. I don't know if I'll do it. I think the engineers who develop the RHOs are very smart and should have anticipated these problems.
What I'm planning to do is install an Antigravity Batteries lithium battery, perhaps an H8, under the rear seat. From there, I'll directly connect the electrical cover for the bed, the six KC headlights, the roll bar actuator, the winch, and all the other accessories I'll buy.
They told me it was my fault for having connected an electrical cover to the pickup bed. Of course, it wasn't right, but nothing could be done.
I'd like to think about it personally: that afternoon when I got home from work, I didn't set the alarm; I just closed the door, and that's what caused the battery to die. I don't know the exact truth.
I've already seen how to eliminate the auxiliary battery. I don't know if I'll do it. I think the engineers who develop the RHOs are very smart and should have anticipated these problems.
What I'm planning to do is install an Antigravity Batteries lithium battery, perhaps an H8, under the rear seat. From there, I'll directly connect the electrical cover for the bed, the six KC headlights, the roll bar actuator, the winch, and all the other accessories I'll buy.
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I just picked up my MY26 RHO last Friday; looks like they may have added a sticker to the battery cover that clarifies how you can jump it.
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Left my truck hooked up to a NOCO 5 amp charger for 2 days and the factory batteries would not fully charge. Haven’t had any major battery problems yet but decided to swap them out before winter sets in. Picked up this Duralast Platinum Elite H7 and the Platinum Group 400 (Platinum Elite aux battery wasn’t available).
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I'm trying to do this on my 2026 Limited, it has the dual IBS but no F52 fuse. I tied the positives and the negatives from the aux to a bigger H8 battery, but i think something wasn't right with the sensing because the charging voltage was constantly pegged at 14.8V and when the auto-start kicked in, a check engine light came on which read as Starter 3 Relay Stuck Off.
So then I disconnected the aux connectors from the h8 battery and just left them floating (taped), and everything works fine and the charging voltage seems to be more inline with what it should (14.4) as long as i have auto-start stop off, otherwise if it kicks in my truck won't start up again (even trying to turn off and crank it) and requires me to disconnect the battery to reset and be able to crank again.
Anyone know what to do to completely remove the Aux battery?
So then I disconnected the aux connectors from the h8 battery and just left them floating (taped), and everything works fine and the charging voltage seems to be more inline with what it should (14.4) as long as i have auto-start stop off, otherwise if it kicks in my truck won't start up again (even trying to turn off and crank it) and requires me to disconnect the battery to reset and be able to crank again.
Anyone know what to do to completely remove the Aux battery?
how did you connect the negative terminals? were you able to connect both current sensors? any pictures?
Tied both sensors together on the negative terminal.
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i was looking into this a while back, i have this sitting in my garage:
I was thinking of individually connecting each sensor to the battery separately with its own post. In your picture, you're going through the sensors in series. I wonder if that makes any difference.
True, but i think the bolt that goes through the sensor is just a passthrough, so it shouldn't matter. I think something else is going on with the truck seeing the same voltage for "both" batteries and then detecting a voltage drop on the auto-start stop event (on "both" batteries) and triggering that OBD code.
Also the lack of an F52 fuse leads me to think it's doing something different with the PCR than trucks that do have the F52 fuse.
I may just leave the posts paralleled like i have it and use auto start-stop eliminator.. at least this way if i lend my truck to someone or if i accidentally turn on auto-start stop it won't be stranded at the first red light.
Hoping to get more feedback from people doing this and seeing if someone figures something out that's more foolproof and robust.
Also the lack of an F52 fuse leads me to think it's doing something different with the PCR than trucks that do have the F52 fuse.
I may just leave the posts paralleled like i have it and use auto start-stop eliminator.. at least this way if i lend my truck to someone or if i accidentally turn on auto-start stop it won't be stranded at the first red light.
Hoping to get more feedback from people doing this and seeing if someone figures something out that's more foolproof and robust.
I'm not an expert when it comes to electric, but just going off the of pictures of mine (attached), it appears your main battery sensor is picking up the current going through the aux wiring and the aux wiring sensor isn't picking up any current. You're not running the current through the sensor; the aux sensor is just bolted on essentially. nothing is going across/through the sensor.
Anyone, please feel free to chime in and correct me, I'm all for learning, as this is something I was hoping to do a long while back, but it became a dead issue.
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I see what you mean now.. the 1st sensor would actually be reading the current of both cables going through it.. and if the sensor is "polarized" somehow, meaning the input on bottom and output on top, i also have that inverted for the aux battery one.
I'm going to find a terminal that will allow me to attach both independently without going through in series and see if that fixes the issues.
I'm going to find a terminal that will allow me to attach both independently without going through in series and see if that fixes the issues.
i commend you for testing this!
Proceed at your own risk. My truck is L2+, which does not come with a PCR (therefore no F52 fuse).
I went back and re-did my AUX removal to fix my previous mistakes.
Seeing as how from everything I found the L2+ trucks don't have a PCR or fuse that can be easily bypassed, I went with my original approach.
I tied both IBS from main and aux - to the negative battery terminal, in my original removal I didn't realize i tied the aux battery - IBS to the main battery IBS output, so the main battery IBS was measuring the current draw of both which is what was probably causing my charging voltage to be 14.8 all the time. This was a mistake on my part. With this new method my charging voltage is 14.4 on startup and then drops to 13.8-13.9.
I then used a 50A fused wire link to jumper N3 (AUX Battery +) to N9 (Main Battery +), and disconnected the original N3 wire that runs to the AUX + and heat shrunk both ends just to keep it clean.
Everything is working as expected, with no OBD codes, and start-stop works also (although I will keep it disabled).
I used this to tie both IBS. https://www.amazon.com/dp/B09W24MCHD?tag=ramrho-20
Until a better, proven method comes out for the L2+ trucks I'll keep using this.
I went back and re-did my AUX removal to fix my previous mistakes.
Seeing as how from everything I found the L2+ trucks don't have a PCR or fuse that can be easily bypassed, I went with my original approach.
I tied both IBS from main and aux - to the negative battery terminal, in my original removal I didn't realize i tied the aux battery - IBS to the main battery IBS output, so the main battery IBS was measuring the current draw of both which is what was probably causing my charging voltage to be 14.8 all the time. This was a mistake on my part. With this new method my charging voltage is 14.4 on startup and then drops to 13.8-13.9.
I then used a 50A fused wire link to jumper N3 (AUX Battery +) to N9 (Main Battery +), and disconnected the original N3 wire that runs to the AUX + and heat shrunk both ends just to keep it clean.
Everything is working as expected, with no OBD codes, and start-stop works also (although I will keep it disabled).
I used this to tie both IBS. https://www.amazon.com/dp/B09W24MCHD?tag=ramrho-20
Until a better, proven method comes out for the L2+ trucks I'll keep using this.
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I must have a Level 2 ++ ...take that, peasants.
Intelligent Battery Sensor - Measures the current draw on the battery in order to tell the alternator how much to recharge.
Power Control Relay - Switches between the aux and main battery (or both) as the power source for the car depending on the state of the car.
Someone else can probably explain better, but that's the gist of it.
Hey guys, speaking of batteries, I’m on a lengthy road trip right now and my check engine light is on and I am hovering close to 16 V while driving. Yesterday before I left all my dash warning lights came on. I found the main battery at 63% and the aux battery at 45%. They both charged up fully and yesterday on the road. I was at a steady 13.8 to 13.9 V the whole trip. This morning I start the truck up check engine light is on and while traveling I’m just a tad under 16 V. That sounds to me like the batteries are failing and I think I’m just gonna take a gamble and pick up some batteries at a local auto store as opposed to burning a day of this trip at a dealership. For those of you who have had batteries fail, have you found that the running voltage increases close to 16 V.
