Replacing dual batteries......charging issue?

Maxcustody

Explorer
Need some help here, not really in an area with any electrical specialists that I am aware of who may be able to help me diagnose my issue. So hopefully the fine folks here can offer some help..............Not really a mod I wanted to do.................had to order 2 new batteries they will be here next Friday. I went with North Star this time.

I have a dual battery setup and for some reason the starter battery has been dead a few times. Luckily I can link them together and it fires up, however not sure what the issue is..........Seems like it happens when it is the coldest. I am now living in West Virginia and no longer in California so maybe it was going bad and not as noticeable due to not being cold enough in California to bring it down. I think I may have let it go too low while camping, however not sure how that worked either due to my fridge being hooked up to the other battery. I have been off work due to an injury so the truck has not been going anywhere for days at a time.I have 2 Odyssey PC1400's, they are probably 2 years old. I have nothing drawing power I am aware of, I even disconnected my scan gauge which has been plugged in, thinking it may be that. I also turned off the breaker to all the rear outlets since nothing is back there right now anyway. I did take it in to Toyota, I was there getting my TPMS uploaded and had them test the batteries. Tech said he thinks it may be a charging issue. Starter battery was not registering same as other battery, other was full and starter was very low that tech said it told him to recharge to get a good reading.

When I get the new ones I will top them off and ensure everything is wired correctly before installing the new ones. I am no electrical guy, so a little puzzled...............any suggestions? I have the blue sea ACR as well as my isolator.

Here are some pics of current set up and new batteries I am replacing them with..................

20190304_134616 (1).jpg20190304_135350.jpg20190304_134604.jpgs-l300.jpg15af05c2-2d90-453b-b032-4e8b1c73e27f.png
 

john61ct

Adventurer
Cold weather is not a cause of failure, but certainly reveals weakness quickly.

You have a DMM and know how to use it? Essential. A clamp style ammeter even better.

Determine **for sure** there are zero parasitic loads while in storage mode.

Ideally fully isolate the battery with a BSS switch near the posts.

If there are necessary ongoing loads, then keep a battminder, solar panel or other low-amp source topping the batteries up if sitting more than a week. Or regularly give them a full overnight charge.

Proactively replace batteries long before EoL.

A good battery monitor is a good investment for the deep cycle bank, keep tabs on SoC as directly as possible.

Become an "electricity guy" wrt to the House side does not take much to know more than most "professionals"
 

WOODY2

Adventurer
The Blue Seas only links the 2 together when enough current exists. I would suspect that the starter battery is failing. You could swap them and see if the 'new' starter battery stays up and the second battery takes a dive? Another way is to disconnect everything from existing starter, measure voltage then measure again in a couple of days to see if it is dropping voltage, this method is by far the easiest if you're injured. BTW those are some serious battery connections. keep us updated. In any event good call on replacing both batteries at the same time.
 

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Maxcustody

Explorer
That the mechanic apparently lacked the sense & curiosity to look deeper isn't a good sign. Something to keep in mind if you use that shop again.
They did offer to check, however he said it was a lengthy process and I had another appointment I had to get to.....................
 

Maxcustody

Explorer
Hmmm. I can have friends, or I can correct peoples electrical descriptions..
Voltage is the correct thing.
Of course one must have enough current available to keep a desired voltage present, but thats different subject.
ok, anything else to add to help me diagnose my issue...................
 

shade

Well-known member
Its only two possibilities.
1, Battery is duff.
2, Something is drawing excessive current whilst the car is switched off.
I don't think it's been established that it isn't a charging issue. The start battery may be failing because it was chronically undercharged.
When I get the new ones I will top them off and ensure everything is wired correctly before installing the new ones.
Checking the wiring now may reveal the problem before the new batteries arrive. You can also get a better idea about what's going on by simplifying things, which will remove some variables.

Fully charge a known-good battery and install it as the start battery.
Leave all of the dual battery system disconnected, so that the system is returned to OEM-ish condition.
Record the battery's voltage without & with the engine running. Also, record it at 2500 rpm.
Monitor the battery's state of charge daily, and see what happens.

If there's a charging problem, it won't take long to reveal itself.
 
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chet6.7

Explorer
There are a number of videos on finding parasitic draw,I will link one below.I have the same brand of batteries,my truck did not get used for 3 weeks(flu followed by a cold),the batteries were lower then I would have liked when I hooked up the charger yesterday.This truck is never really off,some others on Cummins forum have noted the draining batteries,so they have added permanently mounted chargers,or made hooking the charger easier by extending a cable,or using a cigarette plug adapter.

 

Maxcustody

Explorer
There are a number of videos on finding parasitic draw,I will link one below.I have the same brand of batteries,my truck did not get used for 3 weeks(flu followed by a cold),the batteries were lower then I would have liked when I hooked up the charger yesterday.This truck is never really off,some others on Cummins forum have noted the draining batteries,so they have added permanently mounted chargers,or made hooking the charger easier by extending a cable,or using a cigarette plug adapter.

Thank you I am actually watching some now on Youtube, as well as looking at adding a battery disconnect switch.
 

Ducky's Dad

Explorer
Determine **for sure** there are zero parasitic loads while in storage mode.

To clarify, there will never be "zero" parasitic loads on a 2017 Toyota, unless the battery is disconnected from the system. Things like the vehicle electronics, alarm system, etc. will draw some minimal amount of power. I have no idea what the range is for parasitic loads on a 2017 Toy, but there is a spec somewhere, probably 35-ish ma. And, speaking of 2017 Toys, those vehicles are reputed to have a charging system that maxes at 13.9V, while Odyssey AGMs seem to like 14.7V. Having said that, I have a Northstar G31 AGM in my 2008 Tundra with a stock charging system. Truck is often parked for long periods with Toy factory alarm system armed, and I have had zero battery issues in that truck for the last three or so years.
 

mlrtime99

New member
Ducky and shade hit the nail on the head. You are not properly charging the battery. The 4Runner alternator provides about 13.6v peak meant to charge a flooded lead acid battery. This is not adequate for an AGM battery which requires 14.7v. Luckily it's also an intelligent alternator which has feedback control and you can "trick" the alternator into providing slightly more voltage. Googling "4runner AGM voltage" will show you the couple 100 threads which exist on this topic. I bought the HKB diode available here - https://www.hkbelect.com/

I'd still recommend a dedicated AC AGM charger to bring the AGM battery up to optimal charge through intelligent phases.
 

rayra

Expedition Leader
on parasitic drain, keep in mind that even the small USB adapters, inverters of any size are a parasitic drain if they aren't switched or on keyed circuits.
I was chasing a 1A+ drain for a while and (re-)learned that bit about all the USB adapters I had added. But I also found my obsolete analog OnStar was trying to phone home, with no antenna on the vehicle, no subscription service, and no analog tower system remaining to answer it. Had to re-set the vehicle to quench it. And next hard off-road jolt or bumper bump will trigger it again. And it's integrated with the vehicle in a way that makes it very difficult to disable.

eta
going forward, I'm re-wiring all the USB power adapters I've added to run from my aux battery, which is also fed by my rooftop solar. My batteries are combined by a 200A solenoid triggered by a keyed accessory circuit. My batteries as things sit now always show a disparity, as the aux is kept topped by solar panel and charge controller, and the starter battery gets nibbled on by factory parasitic drains and the power adapters. The batteries are the same grp72(?) SLA bought about a year apart and the starter is usually ~12.7-.8 and the Aux sits at 13.0. And the disparity stays with location when I swap the batteries. When I first noticed the difference with a test meter, I thought maybe it was a difference in the batteries.
About the only time they ever show same is shortly after a long freeway drive, even after the false 'surface charge' bleeds off. But by the next day they are different again anyway.

There are other more costly ways to arrange and combine things, could use a 'smart' Blue Sea' device or similar and tie the solar PWC to the same terminal as the alternator connect. And then my starter battery would benefit from my solar panel when the vehicle is parked curbside for a day or three. But as it is now I just switch the key on, hear the thunk of the solenoid mounted on the firewall, and the batteries are combined.
now if I'm ever truly camped / parked long enough to severely draw down the aux battery, that automatic combining isn't a good thing.
 
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Ducky's Dad

Explorer
that automatic combining isn't a good thing.

I have said a few times that I don't like anything that is automatic or computer controlled on my vehicles. My solenoid is a Painless Performance unit with a toggle on the dash that allows me to combine or disconnect at will. On my two-battery GMC, that solenoid is all I use. On my three-battery Power Wagon, I added a Blue Sea rotary switch that allows me to combine or disconnect any combination of the batteries for starting, winching, jumping, charging, or running accessories. I also have a Blue Sea rotary switch as a disconnect for the starting battery so that I can leave the truck parked for weeks with no worry about parasitic drain. That has helped a lot. An advantage of the Painless solenoid switch is that I can set it so that solar is charging either or both of the house batteries (or neither one), and I can also switch the starting battery in or out of solar charging when truck is parked, whether kill switch is activated or not. Unfortunately, I have not gotten around to finishing the solar install.
 

john61ct

Adventurer
Automatic combining is a godsend, if designed and implemented correctly.

Not needed for some simpler systems.

If forgetting to turn a switch means I run down my Starters, my forgetfulness will regularly leave me stranded.

You do you but don't over generalize
 
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