Cranking battery not able to start jeep at 12.2V

SDG said:
Since you get a voltage drop on startup sounds like the cranking battery is toast. A battery that has no juice left can still be at iver 12 v but as soon as load is applied it drops like a rock.

A problem I have heard with the genesis setup is the smart isolater it's self consumes juice, when it's left for long periods it can actually kill the battery. A friend has this setup and rarely drives the jeep except to wheel, he has killed 2 sets of batteries. The last time it was even hooked to a trickle charger. May not be your case but something to ponder.

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This, sounds like dead cells in the battery, which will still show decent voltage, but put it to use and it drops instantly. Sounds like the genesis equipment is functioning exactly as it should, linking the batteries when the cranking one doesn't get the job done.
 
I have a Genesis setup with dual Odysseys. In my blissful ignorance, I thought that because they were deep cycle batteries that I could leave them connected and unattended for 2 months this past winter... parasitic draw be damned. After failing to start my JK I was able to bring them back to 12.8V, however they would both drop back to 12.2V overnight. Thankfully my point of purchase replaced both batteries under warranty NQA. I have since learned that "Whenever any lead-acid batteries (including AGM batteries) are discharged below 12.4 volts, sulfation will begin to form, which diminishes both capacity and lifespan," (optimabatteries.com, Basic Information on Battery Voltage). Now if my JK stays parked for more than a few days, I connect the batteries to a multi-step charger and/or disconnect them from the vehicle.
 
doubletapdaddy said:
I have a Genesis setup with dual Odysseys. In my blissful ignorance, I thought that because they were deep cycle batteries that I could leave them connected and unattended for 2 months this past winter... parasitic draw be damned. After failing to start my JK I was able to bring them back to 12.8V, however they would both drop back to 12.2V overnight. Thankfully my point of purchase replaced both batteries under warranty NQA. I have since learned that "Whenever any lead-acid batteries (including AGM batteries) are discharged below 12.4 volts, sulfation will begin to form, which diminishes both capacity and lifespan," (optimabatteries.com, Basic Information on Battery Voltage). Now if my JK stays parked for more than a few days, I connect the batteries to a multi-step charger and/or disconnect them from the vehicle.
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I looked up the smart isolater and looks like it draws ~8mA. So I'm not sure what the capacity is of one of these batteries but if someone knows we could figure out the math on how fast the isolater would drain the battery.

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SDG said:
I looked up the smart isolater and looks like it draws ~8mA. So I'm not sure what the capacity is of one of these batteries but if someone knows we could figure out the math on how fast the isolater would drain the battery.

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this would be times 2 until the isolator disconnects them at 12.6V

Item Number: SLI34AGMDP
Brand: X2Power
Voltage: 12
Format: BCI Group 34
Lead Acid Type: Deep Cycle, Dual Purpose (Starting/Cycling), Starting
Cold Cranking Amps: 880
Battery Type: Ultimate
Capacity 20hr: 68AH
Chemistry: Lead Acid
Color: Blue Top
Lead Acid Design: AGM
Made in the USA: True
Product Category: Auto/Light Truck
Product Sub Category: Starting Lighting And Ignition
Terminal Type: SAE, Automotive Post
Usage: RV
Warranty: 60 Month Free Replacement
Weight: 49 lbs
Length: 10.87 in
Width: 6.99 in
Height: 7.76 in
 
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