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Has Anyone Put a Battery Tender on their Auxiliary Battery?

ShadowsPapa

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so with this isnt there still damage being done? Even with parallel charging I always thought that unequal charge percentages of like batteries still reduced life expectancy.
Nope, no damage at all. How could there be damage? They act as one when charging - the charging system sees one big battery to charge. The batteries themselves decide how much they'll take of the available current.
You are better off charging both fully and resetting the IBS if you change just one of the batteries, and don't put a fully charged battery with a dead one or low charged battery but seeing all the stuff out there on the details and science, I'm seeing a lot of old-school thinking out there even on battery sites.
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chorky

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don't put a fully charged battery with a dead one or low charged battery
this right here is what i am questioning though. So by having an active ESS event you are essentially depleating the small aux battery while the main large one stays near 100%. or maybe I’m misunderstanding what your saying
 

JETNC

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Irritable Bowel Syn... oh wait. Wrong forum.

It stands for Intelligent Battery Sensor.
I figured it was something like that, I just couldn't figure it out....lol. Good comeback though!
 

Delhux

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Cascadia’s hood panel trickle charges while offering a 12v out. Covered storage would pose a problem but I had it backed into our car port at the previous home and it still gathered enough light to keep it topped off in winter.


8E83AC90-693E-480C-9A52-93BC5C6F319A.jpeg
I ended up doing the same thing after dealerships refused to fix the auto stop/start system never working due to defective batteries. With the Cascadia tensing it, the engine start/stop always works and I’ve got extra power for accessories.
 

ShadowsPapa

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I ended up doing the same thing after dealerships refused to fix the auto stop/start system never working due to defective batteries. With the Cascadia tensing it, the engine start/stop always works and I’ve got extra power for accessories.
Which system? 80 watt or higher/lower?
 

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chorky

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jebiruph

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Ok so heres a thought. The purpose of the IBS i for the PcM to basically track what is doing in and out of the battery. But the IBS is on top of the primary battery. So I see easily how it can track power going in and out of that battery but how on earth does it even understand what the status of the aux bttery is?
From my observations, during every cold start the batteries are briefly disconnected so the status of the aux battery can be determined. If the aux battery fails the test, the start is terminated and the ESS system is disabled with the ESS error light turned on. With the ESS system disabled, the next (and susequent) start attempt skips the aux battery test and continues with the start sequence. Once the engine starts, all the system knows about the aux battery is either it passed the cold start test or it didn't.
 

ShadowsPapa

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I have wondered about such a thing to run a "cooler" (can't recall the draw, the one I have can only lower the temp 40 degrees from ambient - good enough for me most of the time).
It would also help when using my truck to charge my phone, run a light or two or charge hearing aids while camping at shows and swap meets.
 

chorky

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From my observations, during every cold start the batteries are briefly disconnected so the status of the aux battery can be determined. If the aux battery fails the test, the start is terminated and the ESS system is disabled with the ESS error light turned on. With the ESS system disabled, the next (and susequent) start attempt skips the aux battery test and continues with the start sequence. Once the engine starts, all the system knows about the aux battery is either it passed the cold start test or it didn't.
Yeah but the IBS monitors the battery state more than just during start-up from what I understand. But if the IBS is only really connected directly to the main start battery, with no other ground underneath that IBS but before the battery post, how does it accurately assess the Aux battery state?


I have wondered about such a thing to run a "cooler" (can't recall the draw, the one I have can only lower the temp 40 degrees from ambient - good enough for me most of the time).
It would also help when using my truck to charge my phone, run a light or two or charge hearing aids while camping at shows and swap meets.
I would be curious also how much their rate of charge diminishes with, say, only 70% sunlight at a 65 degree angle.
 

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ShadowsPapa

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this right here is what i am questioning though. So by having an active ESS event you are essentially depleating the small aux battery while the main large one stays near 100%. or maybe I’m misunderstanding what your saying
The small battery runs the electronics - the main battery is connected to the EHPS and the fan (and likely some other things) so it does drop as well, but if it goes to a certain level the engine starts again.
I watched the voltage on my main battery drop to 12.2 while sitting during an ESS stop - the aux battery was only a bit lower.

I'm close to ordering two volt meters/trackers I can install on my truck to monitor things more closely - not because it has any trouble, in fact it works perfectly, but to learn more.

Anyway, when there's a drain on the system (not ESS stop) and it's say 15 amps draw, if the large battery was twice the size of the small battery then the large one would supply 10 amps and the small one would supply 5 amps. They'd each contribute according to capacity, the voltage drop in each would be the same. If the main dropped to 12.2 then the aux would also drop to 12.2
When charging it would be as if charging one battery - the larger battery would have lower resistance due to size so would take more power in than the small one.
You can't overcharge the small battery when charging both together.
I had different feelings on it 2 years ago but I was thinking of different configurations. Parallel setups of like-chemistry batteries aren't a problem.
As long as the resistance of the cables connecting the batteries remains so that each actually "sees" the same voltage, they receive the same voltage and take in according to their size and ability.
Some may say - well the aux battery has smaller wires, etc. - well, the main battery has an IBS that has over 1 ohm resistance dropping the voltage to it accordingly. It ends up about even.

I need to dig up the links I found earlier where engineers explained it in better detail.
With my affliction, I get the results but struggle with "show your work". I excel at math but fail tests because I couldn't show the work - only the results.
 

chorky

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I see the charging side of things how it sorta doesn't matter if they are in different states of charge (even though that goes agains what I used to understand years ago) and it makes sense how they contribute according to their capacities. But I'm struggling understanding how the IBS keeps tabs on the aux battery when it only sees voltage passing through the main battery neg post. Maybe it does't? maybe the engineers designed the aux battery to be a specific 'percent' of the main battery and it is assumed that at XX power draw, based on math, that the aux battery would be X percent of what the IBS sees through the main battery?
 

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Opinion: The entire notion of having a small battery that notoriously falters and fails as the "protector" of sensitive electronics is laughable.
There's more risk in the switching and problems than there is in simply using one battery for all functions.

The ESS system exists for EPA ratings.

  • Start-Stop Systems:Start-stop systems (sometimes called idle-stop, smart start, or other manufacturer-specific names) save fuel by turning off the engine when the vehicle comes to a stop and automatically starting it back up when you step on the accelerator. Start-stop can improve fuel economy by 4%–5% and provides the biggest benefit in conditions where the engine would otherwise be idling, such as stop-and-go city driving.

https://www.epa.gov/greenvehicles/gasoline-and-diesel-advanced-technology-vehicles
 

staying_tuned

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I have wondered about such a thing to run a "cooler" (can't recall the draw, the one I have can only lower the temp 40 degrees from ambient - good enough for me most of the time).
It would also help when using my truck to charge my phone, run a light or two or charge hearing aids while camping at shows and swap meets.
I've had it setup with a few different configurations. Powering the cooler was the primary use case originally. At first, the fact that it would also trickle charge the truck was just a side benefit. Below is the current setup:

Cascadia Panel w/ Cascadia Controller:
- Trickle charge at all times (the controller stops flow when topped off)
- 12v out from controller -> EcoFlow Delta -> All else (Dometic CFX3 75DZ, lights, camping gear, etc.)

The above has been bullet-proof for us and carried us nearly a week while pinned down in the RTT north of Yellowstone due to the washout last year. Glad we had the delta for that scenario but once I realized how little the dometic draws (65w max cooling both fridge & freezer in San Antonio summer) I realized that the Delta itself was overkill. It's bulky with a large footprint. We travel with our boys so interior cab space is limited. I could have gotten away with a small Jackery that stays in the truck and even that would be underutilized given how darn efficient these fridge/freezers are. With the panel charging the primary battery, the bed outlet is more than enough for fridge plus other items. The panel itself installs cleanly, I opted to file the lip on the plastic wire channel/rail and run it long with the other wires in the OEM location down the side through the firewall.

Screenshot 2023-01-26 at 9.03.38 AM.png
 

ShadowsPapa

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Opinion: The entire notion of having a small battery that notoriously falters and fails as the "protector" of sensitive electronics is laughable.
There's more risk in the switching and problems than there is in simply using one battery for all functions.

The ESS system exists for EPA ratings.

  • Start-Stop Systems:Start-stop systems (sometimes called idle-stop, smart start, or other manufacturer-specific names) save fuel by turning off the engine when the vehicle comes to a stop and automatically starting it back up when you step on the accelerator. Start-stop can improve fuel economy by 4%–5% and provides the biggest benefit in conditions where the engine would otherwise be idling, such as stop-and-go city driving.

https://www.epa.gov/greenvehicles/gasoline-and-diesel-advanced-technology-vehicles
The blame on the smaller aux battery is more internet lore than fact. They seem to be failing at about the same rate, and that makes sense.

We've been down this road before, but the fact is, independent tests have been performed by Edmunds and others and show it's more like a 7 to 10% gain. The EPA tests are old, and not really consistent with the real world. So, these outfits tested on real vehicles driving real commute and other "paths' and found a larger savings than even the EPA suggested.
The "switching" itself has been pretty bullet-proof. I've not run across any cases of where the 'switching" failed, and if it did, worse case is the aux battery remains isolated and as long as it's ok, the vehicle will function. The aux battery gets charged from the same bus bar as the main battery - it just goes through a fuse. That's the one and only difference. Alternator to the high current fuse, alternator is fused to the fuse bus, then the alternator charging current goes to the main battery or through another fuse to the aux battery. So there's no difference in the path to either battery from the alternator - but for that one fuse. Even the distance is nearly the same. So there should be no difference in voltage seen by either battery from the charging system.

Don't believe what you read "on the internet" from those who simply type their anger, frustration or "annoyance" as most of them don't know squat and love to blame what they hate or don't understand (and it's mostly both because people tend to hate what they don't understand. Don't understand something? Then you find it annoying or worse.

It's received a bad reputation from those who sit back as arm-chair engineers in frustration claiming they know better.

This same system has been used for years - and in other vehicles - BMW, Volvo, Chevy and others. It's mostly Jeep people who complain because they feel they know their jeeps better - but they really don't as is evidenced in forums all over the web.
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