Dead (really dead) 12V Battery

[Maverick Joe]

I had been routinely using my hybrid Maverick XL and then had it sit in the garage for 3 weeks while I used a different car for work, etc... I went to start it today to put some miles on it and it was totally bricked, no lights, no sounds, nothing.

I checked the battery voltage with a DMM using the posts inside the engine compartment. 2.0V was the reading. I figured I was getting a bad ground or something so I went to the battery(under the back seats) posts direct and still came up with 2.0V. How could the voltage have dropped that low in such a short time? Do you think something is wrong or do I just need to use it more often?

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[Stive]

I had been routinely using my hybrid Maverick XL and then had it sit in the garage for 3 weeks while I used a different car for work, etc... I went to start it today to put some miles on it and it was totally bricked, no lights, no sounds, nothing.

I checked the battery voltage with a DMM using the posts inside the engine compartment. 2.0V was the reading. I figured I was getting a bad ground or something so I went to the battery(under the back seats) posts direct and still came up with 2.0V. How could the voltage have dropped that low in such a short time? Do you think something is wrong or do I just need to use it more often?

This won’t help much at all, but I remember reading that the hybrid is not suppose to sit idle for more than a couple weeks. If that really is the case, does that mean one should put on a trickle charger?

 

[Gullzway]

I wouldn't think it should drop to 2.0 volts in a matter of weeks. I know hybrids do things (clicking) while the truck is off, but that seems way excessive. May need to have the battery tested.

 

[Captain]

I wouldn't think it should drop to 2.0 volts in a matter of weeks. I know hybrids do things (clicking) while the truck is off, but that seems way excessive. May need to have the battery tested.

Might be Ford Pass constant pulsing for signal. I remember a few years ago, Volvo had a issue with the navigation looking for signals constantly and killing off the battery.

 

[r100gs91]

Monday I charged my 12V battery under the rear seat. It is a 3 amp charger with a float mode. It charged for 8 hours at 2 amps after the initial ramp up of voltage, without going into float mode before going to bed. In the morning it was fully charged and the float mode was charging at 1-2 Amps for 5 seconds every 2 minutes after achieving a full charge. Didn't drive the car for 2 days. On Wednesday when I fired up the Maverick, both screens were brighter and sharper. FYI

 

[Maverick Joe]

This won’t help much at all, but I remember reading that the hybrid is not suppose to sit idle for more than a couple weeks. If that really is the case, does that mean one should put on a trickle charger?

Thanks for your reply. Yes you are right and I didn't know that. On page 325 of the owners manual, it states that the vehicle should be started every 15 days for 15 minuets, though it gives this guidance under the engine heading.

 

[uga]

Simple, just get a jumper box, I have a NOCO and its top rated.

 

[MostlySafeBear]

Pretty much any modern vehicle should be placed on a trickle charger if you're not going to use them for longer than maybe a week, two weeks at the most.

They're all full of stuff which drains batteries. "Keep Alive" (RAM) memory that stores parameters that the engine control unit has learned, the radio presets, the cellular connection that listens for remote commands from apps/similar, the systems that listen for keyfobs and unlock the doors, security systems, and maybe more.

 

[Rivers90]

I have a "battery minder" I got from amazon I use on any car that ends up sitting more then just a few days. During the pandemic lock-down I had 3 cars lined up on battery minders, because no one in my family was going anywhere.

 

[Greg_in_GA]

Do you have anything added to it like a dash cam or wireless adapter for your cell phone? If so that could have drained the battery.

Completely discharging a car battery can damage it so it really should not be that bad in three weeks. People leave them at an airport for that long all the time.

Heat can also damage a car battery and the battery may have sat in a warehouse or lot in a desert in Mexico when it was built and waiting to be shipped. That could also be a reason for there to be a problem with the battery.

I don't have my Maverick yet but every other car I have had would go into a power saving mode after a while.

I would have the dealer look at it since it sounds like there is a problem. It could also be that there is a software update that would fix this.

 

[Maverick Joe]

Do you have anything added to it like a dash cam or wireless adapter for your cell phone? If so that could have drained the battery.

Thanks for your reply. No, nothing obvious like that. Interior lights switched off and I switch off the headlights when I'm driving in the day. No devices or mods of any kind.

 

[Maverick Joe]

Thanks for all the replies!

Update: I purchased a Viking 4A battery charger from Harbor Freight and tried to charge the battery in place. This did not work because, it seemed to me, as the charge became greater in the battery after a minute or so of charging, the vehicle electronics would turn on and kick the battery charger into a battery-fault state, thus stopping the charging.

I removed the battery and tried again and after 8 or so times of rejecting the battery after a minute or so of charging, but slowly building back the battery charge each time, it worked and brought the battery into float mode @ 13.3V within about 5 hours.

I let it charge overnight, hooked the battery back up and drove the vehicle to work and back (30 mi. round trip) today with no apparent issues. After turning the vehicle off I checked the battery voltage using the studs in the engine compartment. 12.57 V . which I believe is close enough to the 12.6V that an idle 12V battery should be at.

I plan on letting the vehicle sit for 24 hrs and checking again.

A thought: I always drive on eco mode and sometimes run the A/C. It's hard to tell but sometimes I felt like the engine would stop even with the A/C running. Obviously that would be a huge load on the system(I presume it is drawing from the 12V system and not the hybrid battery) and maybe if you're coasting quite a bit of the time you aren't building back the charge on the 12V battery.

I would love to hear any thoughts or ideas you have. Thanks again!

 

[MakinDoForNow]

Thanks for all the replies!

Update: I purchased a Viking 4A battery charger from Harbor Freight and tried to charge the battery in place. This did not work because, it seemed to me, as the charge became greater in the battery after a minute or so of charging, the vehicle electronics would turn on and kick the battery charger into a battery-fault state, thus stopping the charging.

I removed the battery and tried again and after 8 or so times of rejecting the battery after a minute or so of charging, but slowly building back the battery charge each time, it worked and brought the battery into float mode @ 13.3V within about 5 hours.

I let it charge overnight, hooked the battery back up and drove the vehicle to work and back (30 mi. round trip) today with no apparent issues. After turning the vehicle off I checked the battery voltage using the studs in the engine compartment. 12.57 V . which I believe is close enough to the 12.6V that an idle 12V battery should be at.

I plan on letting the vehicle sit for 24 hrs and checking again.

A thought: I always drive on eco mode and sometimes run the A/C. It's hard to tell but sometimes I felt like the engine would stop even with the A/C running. Obviously that would be a huge load on the system(I presume it is drawing from the 12V system and not the hybrid battery) and maybe if you're coasting quite a bit of the time you aren't building back the charge on the 12V battery.

I would love to hear any thoughts or ideas you have. Thanks again!

I have not had any problem with my 12v battery. Hybrid FE. I have put a voltage monitor in my dash power point and have observed the voltage available on the bus to closely follow the expected sos charge rates expected for a 12v deep cycle lead acid battery. I usually have lights on automatic and AC on heat or cool at around 73. Mostly the voltage will show at 14.7 couple times 14.8 but this will be maintained whether ice is running or not. Apparently as 12v becomes charged the bus voltage will slowly be reduced to below 14v. I cannot watch real close but have seen 13.4. when I turn lights ,AC, radio, all possible 12v items when I ready truck and draw is not present and dc/dc converter is not charging 12v I can see 12v battery voltage of 12.1-12.8 and since from what I have read 12.85 is fully charged deep cycle battery (so that's why I think I have one). Apparently 12.1v is the "it's time for the HVB battery to be used to charge the 12v". I do not expect it to totally charge the 12v to save the HVB charge, but to maintain it (maybe 12.1-12.5 or maybe whatever 14.7 will do in a relative short time). I normally will place regular or eco mode drive into Low mode for the last mile or two as I believe this helps charge the HVB before I park it for the night or week. I do not have to drive very far in LOW before the engine will be used for braking instead of Regen presumably because HVB must be charged. Note that in the manual there is a up to 8hour battery learning procedure that should be run when a new battery is installed and possibly sometimes when an external charger is used to charge the 12v. For this reason I will try to only use the jump terminals under the hood which will initiate the HVB recharge of 12v and probably start ice. Apparently 15 minutes of ice will recharge HVB and probably continue for quite some time.

 

[Automate]

A thought: I always drive on eco mode and sometimes run the A/C. It's hard to tell but sometimes I felt like the engine would stop even with the A/C running. Obviously that would be a huge load on the system(I presume it is drawing from the 12V system and not the hybrid battery) and maybe if you're coasting quite a bit of the time you aren't building back the charge on the 12V battery.

I would love to hear any thoughts or ideas you have. Thanks again!

The A/C compressor runs off of the high voltage battery.

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