(really) Slow charge

turf · 09-07-2022, 08:41 AM

hey folks,
i pressed delete on my first try posting, so this one is probably more abbreviated.

im having a slow charge problem. the charger thinks my battery is charged, my independent battery meter disagrees. the charger is stuck on slow (because it detects a full charge) and at this rate it will take 2 weeks or so to get it fully charged.

i started a week ago to charge my start battery (a pair of grp 31). the battery meter showed a state of charge ~ 5%. but it reads 14.3v.

because of the high voltage, the charger shuts down. maybe it trickles .1a, maybe.

each day of charging at this slow rate gets me 4-5%, after a week, i broke 30% state of charge this morning.

my battery meter may be wrong, the batteries are old - purchased in 2017, on my way to that palooza.

i abuse the battery, likely just needs to replace the battery but hoping to find a way to wake up these ones.

thanks

TheHubbardBus · 09-07-2022, 11:29 AM

What battery meter do you have, and/or what logic does it use to determine state of charge? Most would just use voltage, which if this is the case, means either your charger is incorrectly determining voltage, or your meter is. But... a bad battery can show 'good' voltage, and a bad battery can also prevent chargers from functioning as you'd expect. When you're reading voltage is it on the charger? What does your meter read after sitting off the charger for a few hours?

Considering the age of the batteries, if I were you, I'd pull them both and have them load tested. Then after you either confirm one or both are bad and get replacements, or confirm they're good and get them charged on another charger, put them back into service and see if your meter and charger agree and start behaving as they should. If not, troubleshoot from there to ID the bad device if there is one.

I know you've got exceptional life out of batteries you admittedly abuse, but I really think you should consider adding a battery maintainer you leave on all the time you're not running the bus.

turf · 09-07-2022, 12:20 PM

about a month ago, i took my bus to the front range... 200 mile roundtrip.just after i left, the alternator wire fell off my alternator and stopped charging my battery.
my old mechanical doesnt seem to mind running without the battery, so i ran it down to 9 or 10v and put it on the charger when i got home.

the battery meter i have is one i built in..let find a link.

https://www.nasamarine.com/product/b...ttery-monitor/

i have pair of them, one monitors the house, one monitors the truck.

they have some sort of magic inside that measures the depth of charge. irrc, i set the total amp hours for the battery pack, i'd guess i set it 200ah (2x100ah grp 31)

it has been pretty accurate, but the starter load on the shunt has melted thru its first mounting location. the wires probably have some heat damage now.

TheHubbardBus · 09-07-2022, 12:30 PM

Yeah, I'd be inclined to think that was the final nail for those batteries, and your charger & meter are both telling you that in different ways. But if you either load test the batteries or just replace them outright, you'll know for sure. Even if they were good, at this age &what they've been through they'd fail before long. Seems like a good time to take care of that now.

turf · 09-07-2022, 12:35 PM

the photo here shows my battery panel.

the house battery on the left, the truck (starter) battery on the right.

i went out and started up the bus this morning, the alternator goes up to 25a charging and then settles back down to less than 1a.

after i shut the bus down, i left the lights on for a half hour. when i just went out and snapped the picture, the meter had gone up ~ 10%. 35 or so this morning..... 44% right now after i ran the motor and the lights.

i just put the charger back on and ... nothing.... .1a charge, it detects 100% charge.

TheHubbardBus · 09-07-2022, 01:04 PM

I looked at that charger. It does indeed use 'magic' in terms of the algorithms it uses, which they only briefly describe in vague detail.

I think you're past the thinking about things part. Its all conjecture until you either load test the batteries and / or replace the components which may be giving erroneous readings with known good units.

It may be possible you're slowly desulfating the plates with the smart charger in trickle mode. That could explain the slowly rising capacity. But IF that is whats happening, you'll never make them 'new' again.

Again, I'd consider your batteries likely past their useful life either right now or in the near future. So if it were me, in the interest of both having a bus that won't leave you stranded in BFE as well as a reliable foundation upon which to troubleshoot your system, I'd test or replace.

I believe Rock&Ruth posted recently about how they got really, really long life out of their house bank. That might be info of interest to you. Can't remember the exact thread... I meant to bookmark but forgot. But me... I'd rather not ride the razors edge on starting batteries, even if you can milk them longer. Ymmv.

FreeEnergy4All · 09-07-2022, 01:16 PM

Quote:

Originally Posted by turf

the photo here shows my battery panel.

the house battery on the left, the truck (starter) battery on the right.

i went out and started up the bus this morning, the alternator goes up to 25a charging and then settles back down to less than 1a.

after i shut the bus down, i left the lights on for a half hour. when i just went out and snapped the picture, the meter had gone up ~ 10%. 35 or so this morning..... 44% right now after i ran the motor and the lights.

i just put the charger back on and ... nothing.... .1a charge, it detects 100% charge.

If you have a problem with your equipment, get better more reliable equipment. But with low voltage, you can expect weird and sometimes decidedly unhelpful circuit behavior.

I once had a Toyota Camry with air conditioning and a radio. I was just driving down a country road with the AC on and the radio going,,, the car suddenly just stopped working. It died, no lights, nothing.

But it's the fix that bent my world against low-voltage circuits. I could not make this car work. I tried wrenching on the battery cables with my hands, expecting one of them to give way, and was a bit loose. But they were tight, no budging in the connections at all.

~~~

I was stuck for a while, and then I just decided to undo the battery connection, reconnect it, and see if somehow that helps. I did that, and it started up immediately without hesitation.

Remember, I could not budge the connection, and I put some weight into it. They were solidly connected, but the car would not start, no dome light, nothing. The entire car was dead even though the connection remained physically connected AND was also rigidly connected.

I never knew cars can be so touchy and unreliable. So I am not a big fan of 12-volt systems. Connections are prone to mysterious disconnection even though it's physically connected.

~~~

Good luck getting a more matched charging system with your batteries. They need to agree about what is going on so something odd was going on there.

turf · 09-07-2022, 01:21 PM

i just winterized her.

blew out the water. refreshed the antifreeze until it floats balls.

now, i got 2 batteries on my xmas list. if you're shopping, im a size 31

when i went to the front range last month, i depended on the third battery to start a generator to charge up the first 2

. i kinda know im on borrowed time.

the 2017 purchase date is no complaints in the longevity dept. they were farm store specials.

FreeEnergy4All · 09-07-2022, 01:28 PM

Quote:

Originally Posted by turf

the photo here shows my battery panel.

the house battery on the left, the truck (starter) battery on the right.

i went out and started up the bus this morning, the alternator goes up to 25a charging and then settles back down to less than 1a.

after i shut the bus down, i left the lights on for a half hour. when i just went out and snapped the picture, the meter had gone up ~ 10%. 35 or so this morning..... 44% right now after i ran the motor and the lights.

i just put the charger back on and ... nothing.... .1a charge, it detects 100% charge.

Is there a place on the charger to select the kind of battery you are charging? Because most battery chargers can do more than one kind of battery, and so I suspect something is off in one of the charging settings.

Or maybe the charger is not functioning properly or the battery has been damaged.

Several problems could be happening by now, hard to say especially until you can determine reliable system perameters.

turf · 09-07-2022, 01:34 PM

i hate smart chargers.

if im using a charger, i want it bulk charging enuf to kill something.

my rv battery charger is the same way....
running it off the generator, you dont want it doing its float charge. you want it bulk charging.

TheHubbardBus · 09-07-2022, 01:40 PM

Quote:

Originally Posted by turf

i just winterized her.

blew out the water. refreshed the antifreeze until it floats balls.

now, i got 2 batteries on my xmas list. if you're shopping, im a size 31

when i went to the front range last month, i depended on the third battery to start a generator to charge up the first 2

. i kinda know im on borrowed time.

the 2017 purchase date is no complaints in the longevity dept. they were farm store specials.

You cheap bastard. I can spit from my 'back range' to my 'front range', and if I'm not careful it will hit the next 'range' over. I'm a size 31 too. No need for a chimney, we don't have one of those either. Just leave it in front of the security screen, Santa.

FreeEnergy4All · 09-07-2022, 01:43 PM

Quote:

Originally Posted by turf

i hate smart chargers.

if im using a charger, i want it bulk charging enuf to kill something.

my rv battery charger is the same way....
running it off the generator, you dont want it doing its float charge. you want it bulk charging.

I believe all chargers can do more than one kind of battery. It's just the nature of the beast. Even if it does not do lithium, they may have a sealed AGM selection. So it pays to have a full grasp of the settings on your charger.

State of charge is NOT a universal way to understand the true state of the battery. Sometimes you can get superficial voltage readings that are not very accurate.

When one or several things could be wrong, until these wrongs are remedied, it's hard to clarify what all is wrong with the system. I wish you the best.

turf · 09-08-2022, 10:57 AM

here is my daily charging update:

yesterday the state of charge was ~ 44%

today i went out and started it up, ran it 5 minutes to fill the tanks and see the state of charge.
after the bus was shut off, i turned on the headlights and marker lights and let them run for 15 minutes. the meter showed a 14.3a load from the lights.

from here, the state of charge went from 44% up to 78%, while the lights were on.

right now i have the battery resting, no load, no charge, and i'll check the state of charge in a while before i restart the charger on it.

i think, i havent been using the battery enough for the meter to get a good read. the meter's shunt is easy to bypass when charging, so the meter need to use its magic to figure out state of charge, over just counting electrons going in and out.

today, i tried my own load test and won. i need electrons moving both directions for that meter to read accurately.

cadillackid · 09-08-2022, 02:56 PM

Quote:

Originally Posted by turf

i hate smart chargers.

if im using a charger, i want it bulk charging enuf to kill something.

my rv battery charger is the same way....
running it off the generator, you dont want it doing its float charge. you want it bulk charging.

my Victron smart charger has never let me down... yep it did a similar thing to the batteries in my red bus... my amp meter also did a similar thing on the dash... where the battery voltage showed somewhat low at standing no load... start the bus and the amp meter would hit hard for a short while than back way off..

my victron did the same thing...

load tester at batteries plus "passed" the batteries...

yet leave the lights on for an hour and a half and the triple 4 E said "NOPE!" not quite enough...

put the charger on.. it charged heavy for a short time then backed off..

reality is the batteries could Hold a standing charge when at "100%" and show good voltage.. they could also take a SHORT TIME LOAD so they would pass the battery-store load test..

but they had no RESERVE capacity or not a lot.. so leave the lights on for 90 minutes.. and the T444E still cranked but not fast enough or long enough to start...

went back to battery store... they put the tester on and hit it with a load.. said "passed".. i said.. now do that short test again.. "FAIL".. (but the batteries are depleted) the employee said..

OK.. go charge up a New identical battery and lets do the test..

came back in a couple hours.. test passed 3 times on a new identical battery and wouldve kept going but we didnt want to push it...

they loaded 2 new batteries in my pickup and said "get outta here".. they were under full warranty still...

so YES! you can have batteries that seem to pass tests but dont have the reserve capacity to hold a solid charge even though the top voltage comes up and the loaded-voltage doesnt go way down..

FreeEnergy4All · 09-09-2022, 10:44 AM

Quote:

Originally Posted by cadillackid

my Victron smart charger has never let me down... yep it did a similar thing to the batteries in my red bus... my amp meter also did a similar thing on the dash... where the battery voltage showed somewhat low at standing no load... start the bus and the amp meter would hit hard for a short while than back way off..

my victron did the same thing...

load tester at batteries plus "passed" the batteries...

yet leave the lights on for an hour and a half and the triple 4 E said "NOPE!" not quite enough...

put the charger on.. it charged heavy for a short time then backed off..

reality is the batteries could Hold a standing charge when at "100%" and show good voltage.. they could also take a SHORT TIME LOAD so they would pass the battery-store load test..

but they had no RESERVE capacity or not a lot.. so leave the lights on for 90 minutes.. and the T444E still cranked but not fast enough or long enough to start...

went back to battery store... they put the tester on and hit it with a load.. said "passed".. i said.. now do that short test again.. "FAIL".. (but the batteries are depleted) the employee said..

OK.. go charge up a New identical battery and lets do the test..

came back in a couple hours.. test passed 3 times on a new identical battery and would've kept going but we didnt want to push it...

they loaded 2 new batteries in my pickup and said "get outta here".. they were under full warranty still...

so YES! you can have batteries that seem to pass tests but dont have the reserve capacity to hold a solid charge even though the top voltage comes up and the loaded voltage doesn't go way down..

Right on, and thanks for kinda backing up what I said earlier. But your advice is good for what kind of battery chemistry, all lead-acid kinds including sealed gel cells and lithium, or?

cadillackid · 09-09-2022, 10:50 AM

Quote:

Originally Posted by FreeEnergy4All

Right on, and thanks for kinda backing up what I said earlier. But your advice is good for what kind of battery chemistry, all lead-acid kinds including sealed gel cells and lithium, or?

these are AGM group 31 batteries.. they are designed for "dual purpose" with a good cold cranking amp rating as well as a deep discharge ability (can be dropped to 10.6 volts as a hard floor.. 10.75 as a suggested floor)..

if the amp-hour counter on my victron 702 is accurate, the same batteries used in a house configuration can output their rated 100ah and still be at 11.0 volts so they can give a little more.. I typically dont like to discharge then any more than necessary.. in the DEV bus I am now running a bank of 4 (room to add a 5th) battery so i can keep my state-of charge higher on a normal basis.. also AGM.

turf · 09-09-2022, 12:49 PM

todays charge

i went from 77% yesterday, to 77% today when i went out there and started the bus.

with the bus running, i saw the meter start to change its numbers so i waited. by the time the air alarm stopped, the meter was reading 102% charge.

im guessing my meter has reset and reading accurately now.

load test in progress. lights on now, going to wait an hour or 2 and go see what has transpired.

my batteries are flooded lead acid. the charger has been on that setting.

FreeEnergy4All · 09-09-2022, 12:51 PM

Quote:

Originally Posted by cadillackid

these are AGM group 31 batteries.. they are designed for "dual purpose" with a good cold cranking amp rating as well as a deep discharge ability (can be dropped to 10.6 volts as a hard floor.. 10.75 as a suggested floor)..

if the amp-hour counter on my victron 702 is accurate, the same batteries used in a house configuration can output their rated 100ah and still be at 11.0 volts so they can give a little more.. I typically dont like to discharge then any more than necessary.. in the DEV bus I am now running a bank of 4 (room to add a 5th) battery so i can keep my state-of charge higher on a normal basis.. also AGM.

You speak far more highly of outdated technology than I can. But hey, if you want to live in the past, who I am to say that's wrong?

TheHubbardBus · 09-09-2022, 12:52 PM

Glad things are working out for you, Turf.
Most standard load tests are much shorter in duration, but if you've got the time, I've got the beer...

FreeEnergy4All · 09-09-2022, 12:53 PM

Quote:

Originally Posted by turf

todays charge

i went from 77% yesterday, to 77% today when i went out there and started the bus.

with the bus running, i saw the meter start to change its numbers so i waited. by the time the air alarm stopped, the meter was reading 102% charge.

im guessing my meter has reset and reading accurately now.

load test in progress. lights on now, going to wait an hour or 2 and go see what has transpired.

my batteries are flooded lead acid. the charger has been on that setting.

There are more than one level of speaking/thinking. So far you don't seem to understand how interconnected everything is. Until you get solid stats on anything, you can't say much about anything, yet you keep talking like you already know it. I will say it again. When you get reliable stats is when you can start making solid comments about your rig.

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