Are My Batteries Toast?

[o1marc]

Originally Posted by TeacherJoe

The bus sat for only a couple weeks. I recently replaced one of the three batteries and the bus started right up. Just yesterday they read 8 volts with a multimeter. I have good advice here and will pull the batteries and determine if they can recover. Unfortunately I can’t run a trickle charger where I store it. No electricity. I need to actually figure out what’s going on. It’s all good. This is exactly what I need to learn so I can be competent down the road.

Joe

Figure out your issue first and then get a battery disconnect switch, shut your batteries off when stored for any period.
https://www.amazon.com/Zoostliss-Bat...omotive&sr=1-5

[TeacherJoe]

Originally Posted by o1marc

Figure out your issue first and then get a battery disconnect switch, shut your batteries off when stored for any period.
https://www.amazon.com/Zoostliss-Bat...omotive&sr=1-5

Yup. I’ll do that.

Joe

[roach711]

Our E-450 with a 7.3L Powerstroke sits all winter so I put a charger on the starting (2 31D batteries) and house banks about once a month. Voltage on both banks will start off at 12.7 volts after a good charge and after 4 weeks will drain down to 12.3 volts or so which is 60% charge.

Even new, uninstalled batteries will slowly self discharge over time, but shouldn't drain any where near as fast as yours are. Most auto parts stores will load test your bats for free (in hopes that you'll buy your new ones from them). As others have said, replace them at the same time and look for recent and similar build dates.

To test for parasitic draw, disconnect the negative cable and wire a 12 volt light bulb between the cable and the post. If there's a draw the light will glow. Then you can pull fuses one at a time until the light goes out. That, at least, will show you where to look for the problem.

[ol trunt]

I love to muddy the waters! When the battery is disconnected in many late model vehicles with computerized engines, transmissions and ABS braking systems they loose their "learned" settings and operate very badly until all the units communicate with each other and "re-learn" what the driver expects of them. According to the operators manual for each of my computer controlled vehicles (last year of production Crown Vic, my newer Tahoe and my '05 Isuzu drive line in my skoolie) there are specific procedures to follow after each battery connection interrupt to get the re-training accomplished. My bus is particularly upset with a battery disconnect and hardly runs until things are reset.

I've had good luck with various solar powered chargers on a fleet of CV training vehicles which were used for a week or so every 6 months with out having to do anything else. Fortunately, My vehicles are all parked where shore power is available so when I park I just plug in.
Jack

[roach711]

Originally Posted by ol trunt

I love to muddy the waters! When the battery is disconnected in many late model vehicles with computerized engines, transmissions and ABS braking systems they loose their "learned" settings and operate very badly until all the units communicate with each other and "re-learn" what the driver expects of them.

I was afraid of that happening on our bus but several long term battery disconnects later we've had no re-learn issues. Maybe the technology is just old enough to avoid that hassle. After swapping out the battery, my 2001 GMC van would idle really slow or stall for a while when I let it idle. After I drove it for an afternoon it would be fine but what a pain, especially sine I didn't know what was going on at the time.

[o1marc]

When I worked at O'Reilly's we had a battery box that plugged into the diagnostic port when changing batteries. It mostly only saved your preset radio stations and nothing more.

[TeacherJoe]

Is this type ok?

Joe

https://www.amazon.com/Post-Battery-...gateway&sr=8-3

[BlackJohn]

Originally Posted by TeacherJoe

Is this type ok?

Joe

https://www.amazon.com/Post-Battery-...gateway&sr=8-3

That won't handle the size cables that buses have, better suited for autos or smaller boats etc. I use that on my Suburban battery but you need a heavier duty disconnect for your bus.



I was thinking of mentioning the issue that Mt Trunt brought up about disconnecting batteries and loosing memory of certain functions.

On second thought I decided not too because this would be a good opportunity to see what happens with your individual bus. Hopefully it won`t bother it but it may for a few miles and starts until it learns again how you drive it.
There are maintainers for this that eliminate any disconnect issues but I didn`t want to complicate your battery problem and correction so neglected to mention that point. keep it in mind for future though.


John

[PeteinSF]

To keep this automatic (I am forgetful) I use this BlueSea "low voltage disconnect' device on all my vehicles that need to sit.


: https://www.amazon.com/dp/B00GZOP53M..._XiOHCbT4M77JR



Basically I leave the battery directly connected to the starter solenoid and starting heaters.


Everything else passes passes through the LVD.

[o1marc]

Originally Posted by BlackJohn

That won't handle the size cables that buses have, better suited for autos or smaller boats etc. I use that on my Suburban battery but you need a heavier duty disconnect for your bus.



I was thinking of mentioning the issue that Mt Trunt brought up about disconnecting batteries and loosing memory of certain functions.

On second thought I decided not too because this would be a good opportunity to see what happens with your individual bus. Hopefully it won`t bother it but it may for a few miles and starts until it learns again how you drive it.
There are maintainers for this that eliminate any disconnect issues but I didn`t want to complicate your battery problem and correction so neglected to mention that point. keep it in mind for future though.


John

Those units are rated at 400a and the bolt hole for the cable is the same as autos. Why wouldn't it handle use in a bus when specifically made for RV's? As many post as there have been fro members changing batteries, I've never heard a story of lost memory.

I do like that dash mounted switch on the one Pete posted. A bit more money, but the dash switch is a bonus.

[TeacherJoe]

Is this ok? What amp rating for the kill switch is needed?
https://www.amazon.com/Blue-Sea-Syst...824?th=1&psc=1

Joe

[david.dgeorge07]

Originally Posted by TeacherJoe

Is this ok? What amp rating for the kill switch is needed?

https://www.amazon.com/Blue-Sea-Syst...824?th=1&psc=1



Joe

I like that style. If it says ignition protected it should work.

[BlackJohn]

Originally Posted by TeacherJoe

Is this ok? What amp rating for the kill switch is needed?
https://www.amazon.com/Blue-Sea-Syst...824?th=1&psc=1

Joe

Joe, I wouldn't be too quick on getting a disconnect until you see what issues you have that are causing this drain. You are still going to need power to the computer so till you get things back to normal it is hard to recommend anything that might work.

You have a C7, not sure what power requirements are for starting that but with 3 group 31's installed it must take a lot of amps to start that. Mind you some of it is for heat and a/c too I would think.
Put a pic up of your battery cables so we know the size. That boat switch looks pretty small for the cables you must have, as well as being far underrated electrically speaking.
You may have to go the other route in keeping your computer powered at all times which that switch will not do.

Don't get ahead of yourself....just get the batteries ready for a load test. Then the parasitic draw can be located next. Eliminate that and then we can see what is out there for a maintainer if the batteries can be isolated when not in use.


What is the CCA rating of each battery? I'm thinking they should be in the 1100 CCA amp range if not more.
And the age of each battery?

John





John

[o1marc]

Originally Posted by BlackJohn

Joe, I wouldn't be too quick on getting a disconnect until you see what issues you have that are causing this drain. You are still going to need power to the computer so till you get things back to normal it is hard to recommend anything that might work.

You have a C7, not sure what power requirements are for starting that but with 3 group 31's installed it must take a lot of amps to start that. Mind you some of it is for heat and a/c too I would think.
Put a pic up of your battery cables so we know the size. That boat switch looks pretty small for the cables you must have, as well as being far underrated electrically speaking.
You may have to go the other route in keeping your computer powered at all times which that switch will not do.

Don't get ahead of yourself....just get the batteries ready for a load test. Then the parasitic draw can be located next. Eliminate that and then we can see what is out there for a maintainer if the batteries can be isolated when not in use.


What is the CCA rating of each battery? I'm thinking they should be in the 1100 CCA amp range if not more.
And the age of each battery?

John





John

John, you keep mentioning the size of the cable. Most of use threaded terminal batteries in our buses. They all have either 5/16" studs or 3/8" studs. The size of the cable is irrelevant, only the terminal end needs to be the correct 5/16" or 3/8". Almost all those battery disconnects are rated from 300-600 amps. If you have a post battery, just change the cable end to a lug ring terminal to use the cheaper one I posted. I have a Red Blue Seas one for mine.

[BlackJohn]

Cable size is relevant to get the proper lugs which also have an ampacity rating. And they need to be properly crimped. Mechanical connections are doomed to fail so why not due it properly? Cheap doesn't always apply especially when trying to build something dependable over the long run.
But that's ok marc, it's not your bus or mine, do yours your way if you ever get it started again.
Did you just take a crash course in electrical, you have all the answers it seems now? Frame your diploma yet?



John

[TeacherJoe]

I’ve been getting good advice and will proceed methodically. I’ve got good local mechanics if I get stuck. I’ll post pics maybe tomorrow. It’s kind of a tangle with three batteries. I have removed rear passenger heat and the two engine driven a/c units. I hope to get to a solid two battery setup with clean connections, and maybe a kill switch if I can’t resolve the parasitic draw.

Joe

[family wagon]

Originally Posted by david.dgeorge07

I like that style. If it says ignition protected it should work.

"Ignition protected" doesn't have anything to do with use in connection with a starter motor. It's an anti-explosion concern. Remember that switch is marketed for marine use. In a gasoline-fueled boat fumes are prone to collecting in the engine compartment. Like any gaseous/vapor fuel, these can be explosive when mixed with oxygen at the right ratio.

When an electrical switch is opened or closed there's usually a spark. "Ignition protected" this means the chamber where that spark happens is sealed so that, even if the switch operates in a combustible or explosive atmosphere, that internal spark won't make things go "boom!".

In case anybody is interested in real-world starter current measurements, I have one measurement I can share. Last summer I did an experiment to measure the current drawn by the so-called "3 kW" starter on my ISC8.3 engine. The experiment involved use of a 2 ohm 300 watt resistor to put a measurable load on the system of battery, cables, post terminals, etc. I measured the voltage drop on all those parts and computed back to find their equivalent resistance around 11.2 milliohm. Then I recorded the voltage drop waveform across the starter cable using a data acquisition box while cranking the starter. The calculation came up with 232 amps. The calculation checks out: 232 amps drawn from a nominal 12.5 volt source is 2.9 kW.

Even that little disconnect that's rated for 200 amps continuous would do fine for my bus and probably OP's too. Still, I'd pick the Blue Sea Systems device instead. There would be less mass hanging like a lever on the battery post, I could use lugs and bolts instead of the post-clamp style, and there's less unfused energized metal exposed.

[o1marc]

Originally Posted by BlackJohn

Cable size is relevant to get the proper lugs which also have an ampacity rating. And they need to be properly crimped. Mechanical connections are doomed to fail so why not due it properly? Cheap doesn't always apply especially when trying to build something dependable over the long run.
But that's ok marc, it's not your bus or mine, do yours your way if you ever get it started again.
Did you just take a crash course in electrical, you have all the answers it seems now? Frame your diploma yet?



John

I love how you backtrack when you're called out. You're quick to tell me I'm wrong, but never explain how I am wrong. you do this often. I never said cable size wasn't relevant to the lug, I said it wasn't relevant to the disconnect as they all have the same size studs. Explain to me in detail how any of the disconnects I posted won't work on a battery in a bus. I'm all ears Mr Electric diploma.

[BlackJohn]

Well mr apprentice, cable size and lugs are relevant to the electrical characteristics of the starter draw. That is undetermined in this case so the lugs must be rated at least for the cable's capacity. I don't know what he has and either do you so you can't just generalize connections as you seem to imply. Hole size in a proper lug is crucial so there is no movement at the battery post and so no conductors have to be trimmed from the cable to make it fit an undersized lug.
Happy now?


John

[PeteinSF]

You never need to run the starter current through a disconnect switch.

All starters are disconnected via the starter relay/solenoid. You want to use the switch to disconnect everything else.