Using Aux battery setup for useful purposes

[flick2614]

Has anyone figured out how to rewire the factory aux battery setup to actually be useful by powering all the extras? It seems stupid to me that we take out and bypass a perfectly good aux battery setup only to spend more money/time/space to put an aftermarket dual battery setup back into the mix.

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[AndySpill]

Has anyone figured out how to rewire the factory aux battery setup to actually be useful by powering all the extras? It seems stupid to me that we take out and bypass a perfectly good aux battery setup only to spend more money/time/space to put an aftermarket dual battery setup back into the mix.

I too have thought about this. (Disclaimer: I run my dual AGM battery JL with both batteries as per factory, trickle charge, and run ESS events. But I certainly appreciate why others would not.)

Here's the rub: I imagine that charging of the aux battery back up from the loads you envision might best be done in a way that connects the aux battery to the main battery or alternator, but not directly in parallel as per factory, even with the engine on--perhaps with the use of some DC to DC charger.

I say this because I am concerned with the Aux battery, even if only connected with the engine and alternator running, cannibalizing the main battery if the former battery is "on its way out," and I would desire some method to break this connection under such circumstances.

Another approach might be to independently charge this Aux battery from shore power when parked, if available, or a dedicated solar panel, be it roof rack mounted, sitting alongside the vehicle, or maybe Cascadia 4X4 based: all options in which cost has to be weighed against utility.

Then of course there's Genesis Offroad's Stock Battery Replacement Kit which might allow you to run appliances off a beefer Aux battery, that if you periodically swap with its equal sized main, might allow you to wear down those two Group 25 batteries more evenly-but it's out of your desired scope, as no doubt is Genesis Offroad's Gen 3 kit.

 

[GATORB8]

I wouldn't do either now that Portable Power Stations and jump packs are available and affordable.

 

[azjl#3]

I thought I could wire up a plug by the wheel well so I could help any motorcycle jump his bike. Thats all I got.

Honestly soon as the factory mini me battery starts to dump, it's gone, and a bigger main goes in.

 

[flick2614]

I wouldn't do either now that Portable Power Stations and jump packs are available and affordable.

I have a small power station for powering things around camp. Still would be nice to have a 2nd battery to power things like scene lights, fridge sometimes and small items.

 

[GATORB8]

I have a small power station for powering things around camp. Still would be nice to have a 2nd battery to power things like scene lights, fridge sometimes and small items.

IIRC the factory Aux is like 40 Ah, so like 20 Ah usable since it’s lead acid. A mini lifepo would make more sense, but then you’d need a DC-DC charger.

 

[flick2614]

I too have thought about this. (Disclaimer: I run my dual AGM battery JL with both batteries as per factory, trickle charge, and run ESS events. But I certainly appreciate why others would not.)

Here's the rub: I imagine that charging of the aux battery back up from the loads you envision might best be done in a way that connects the aux battery to the main battery or alternator, but not directly in parallel as per factory, even with the engine on--perhaps with the use of some DC to DC charger.

I say this because I am concerned with the Aux battery, even if only connected with the engine and alternator running, cannibalizing the main battery if the former battery is "on its way out," and I would desire some method to break this connection under such circumstances.

Another approach might be to independently charge this Aux battery from shore power when parked, if available, or a dedicated solar panel, be it roof rack mounted, sitting alongside the vehicle, or maybe Cascadia 4X4 based: all options in which cost has to be weighed against utility.

Then of course there's Genesis Offroad's Stock Battery Replacement Kit which might allow you to run appliances off a beefer Aux battery, that if you periodically swap with its equal sized main, might allow you to wear down those two Group 25 batteries more evenly-but it's out of your desired scope, as no doubt is Genesis Offroad's Gen 3 kit.

I'm wondering if the PCR disconnects the batteries during an ESS event can I possibly use that as a switch? Disconnect the PCR from wherever and put a manual switch in front of it. That would then isolate the batteries when I'm stationary and just want to use the Aux. Throw the switch when I'm ready to start the Jeep back up to reconnect both batteries.

 

[GATORB8]

I'm wondering if the PCR disconnects the batteries during an ESS event can I possibly use that as a switch? Disconnect the PCR from wherever and put a manual switch in front of it. That would then isolate the batteries when I'm stationary and just want to use the Aux. Throw the switch when I'm ready to start the Jeep back up to reconnect both batteries.

Operation description from AllData:
In a normally functioning system, the two batteries and sides of the system are always connected through the power control relay except for the brief periods during cranking events. Both batteries are connected to the entire electrical system during this mode. This allows charging of the auxiliary battery through it’s connection to the main battery side, and the main battery to be connected to the Power Distribution Center (PDC) and assist the auxiliary battery in operating the modules and accessories. Since the batteries are nearly always connected, the IBS info provided will be the average SOC of the two batteries. The PCM can determine the SOC of each battery during a cranking event when the batteries are isolated for a brief period during initial starter engagement. During this period, the battery voltage provided to the PCM is coming from only the auxiliary battery, and the battery voltage reported from the IBS will only be reporting the main battery voltage. This helps the PCM to make a determination on allowing ESS operation.

 

[THAW]

IIRC the factory Aux is like 40 Ah, so like 20 Ah usable since it’s lead acid. A mini lifepo would make more sense, but then you’d need a DC-DC charger.

It's 12 Ah and AGM.

 

[THAW]

...the IBS info provided will be the average SOC of the two batteries.

This portion of that document is false (not your fault).

The IBS monitors only the CR[an]K (aka main) battery SOC.

 

[THAW]

I'm wondering if the PCR disconnects the batteries during an ESS event can I possibly use that as a switch? Disconnect the PCR from wherever and put a manual switch in front of it. That would then isolate the batteries when I'm stationary and just want to use the Aux. Throw the switch when I'm ready to start the Jeep back up to reconnect both batteries.

In theory, your proposal could work. But keep in mind the AUX (ESS) battery might have to power post ignition-off Jeep electronics processes (e g. evap system) without the help of the CR[an]K (aka main) battery. That probably wouldn't leave much power for you (if there's even enough power for those processes).

In general, the AUX (ESS) battery capacity is too small to be of much value as an external accessory power supply.

 

[GATORB8]

It's 12 Ah and AGM.

Yeah I remember it being low and not really worth it. AGM is still lead acid and subject to severe limitations on discharge, so what maybe 8 Ah usable.

 

[Kyanche]

If you get the genesis battery tray alone, you get a whole lot of space you can use.. for batteries, of course!

 

[Mguy]

In general, the AUX (ESS) battery capacity is too small to be of much value as an external accessory power supply.

But the aux battery alone can start a JL 3.6L engine, and the "mod" for making the little thing an always available emergency start battery is cheap. See this thread.

Thaw, have the last word in this thread.

 

[Mguy]

I wouldn't do either now that Portable Power Stations and jump packs are available and affordable.

Which battery chemistry and manufacturer do you use? I've had bad luck with small forgettably named "lithium" packs.

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