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+--- Thread: dead battery? (/thread-1800.html)
dead battery? - Blacktank - 09-02-2018
so i think pre damaged rv battery bit the dust
i got it 6 months old,dead flat and half empty on water so it's damaged
the first time it got some work is when i did the alternator test,looked good,looked like it would run a small fan all night.
after the tests i charged it up,everything turned off but still had the amp/volt meter hooked up,came back a week and a half later
10.4 and 0.4 amps???
charged it up,a week later,10.4v 0.4amps???
charged it over night,two hours later 12.7v,early evening 12.7v,24 hours later 10.4v 0.4 amps,that little meter isnt drawing that much
put the charger on and the amps go up to 2 and immediately down to zero,a well depleted battery should go to 5-6 amps and take hours to slowly go down
so what in the heck is that 0.4 amps,the meter,wire being charged,both? do i need to investigate?
looks like i need to buy a brand new sacrificial battery,cheapy walmart 12v
RE: dead battery? - GotSmart - 09-02-2018
Check for a drain somewhere. The battery is definitely bad, but the .4 amps?
RE: dead battery? - Blacktank - 09-02-2018
brand new craftsman multimeter,disconnected the negative at battery going to fuse box
10a setting no measurement so went to the 200m setting
everything off=0
master switch on=0
led light on =150
so the hardwired meter is 0.3-0.4 amps out of calibration?
RE: dead battery? - Blacktank - 09-02-2018
the hardwired meter on the 200m setting was reading 10.7
RE: dead battery? - sternwake - 09-03-2018
I never measured the draw of the hall effect ammeter voltmeter itself, but that Hall effect sensor's circuitry would have to be drawing something, even if it were not measuring any current.
The 0.4 amp reading is way more than I would expect the meter to draw. The directions, If I recall correctly, mentioned something about zeroing the meter when it is known there are no loads running through the hall effect sensor. Remember it only has a 0.2 amp resolution so 0.31 amps likely reads 0.4. I did not recommend ths product as a highly accurate and precise ammeter, but as a way to see how much amperage the alternator was feeding the depleted house battery, and parasitic draw is not a concern in this use
I do not have the instruction manual handy, or perhaps at all anymore.
Mine is only on when my key is on so I never considered the parasitic draw and did not think a warning about it was necessary.
Rememeber it is an 18 $ ammmeter, and I recommended it because it required no shunt and that it did not need to be on a ground wire like a shunt usually required to be, which can vastly complicate the wiring. It is as simple as an ammeter can be.
A battery that was low on water was lucky to survive, especially if half the plates exposed. Usually they are a goner then and there or within the next discharge cycle.
If you want a simple voltmeter to be left on 24/7/365 I would not recommend the hall effect ammeter/voltmeter combo I recommeded it so you could see charge current, specifically from the alternator into the battery when driving though of course it will read any current flowing through the wire/cable on which the ring terminal sensor is over.
My ammeter/voltmeter combo is so dang bright I had to put it behind a 1/4 inch piece of smoked acrylic and might have added another piece of window tint to tame it down, as at night My face would be glowing green from it and it would kill my night vision.
Even a healthy marine battery would have been drained slowly likely well below 80% state of charge, assuming it was fully chrged to begin with with the brightness of that display alone in a week and a half with no charging source present.
Remember the batery ideally wants to be 100% always, it is not OK to take a month to discharge it, and all is well as long as you do not go below 50%. Doing this pretty much batterycide.
Full charge always, whenever possible, on any lead acid battery that one cares about, unless you live in a world devoid of the laws of physics, as some no doubt think they do.
Even if a parasitic draw is 0.05 amps, that is 1Ah every 20 hours. A healthy group 27 marine battery has ~100 AH. I'd expect the brightness of the display alone to be twice that much draw, not including the circuitry constantly monitoring the ring sensor for current running through that.
Your pre damaged battery might have been Ok for a fan, but a slow draw down with a small load to 10.7v is among the best ways to kill a battery, other than dumping baking soda in the cells.
Assuming your pre damaged battery was fully charged to its maximum dimnished capacity when you left the meter running, and considering 10.5v is considered 100% discharged, if the load of the meter itself were determined, which i will try and remember to do tomorrow or soon, then it would be fairly easy to somewhat accurately estimate the capacity your predamaged battery had before this latest damaging episode.
I'd likely not bother trying to charge this battery, if I had to pay for the electricity to do so. If you were to start your engine, the data you could gather, as to how much amperage the alternator is feeding it, would not erally be comparable to a new healthy battery that were also depleted to 10.7v. but it would be intetersting just to see how much amperage flowed for how long before voltage rose to the mid 14's.
It would rise much faster than a healthy battery depleted to 10.7v, and the healthy battery would gobble up much more amperage for much longer.
So if you plan to use this voltmeter/ammeter combo, put it on a switch so you can turn it off when not needed. I recommended it for its low price, its simplicity to wire up, and for the purpose of monitoring alternator current, which implies the engine is running, and that the meter is only live when the engine is running.
RE: dead battery? - Blacktank - 09-03-2018
so i went out and checked everything and could not find any draw so the 0.3-4 amp the meter is showing must be itself and not being zero'd in
hooked everything back up and the battery was at 12.6v so the meter drawing 10.4 milliamps? i believe thats what the 200m setting is,would kill the battery overnight
was hoping this battery would get me through the winter just running a led or two and since i wont run a 400cid everyday to keep the battery topped off, i dont see a reason to get another battery until i have some sort of solar
i have a cheap renogy controller so will keep an eye out for a cheap whatever temp panel
someday i will drive around to the commercial/residential solar installers and put my name in for the extra panel at bulk cost
getting these 20 year old tires replaced is the priority that will probably suck up all the winters extra cash
will let it go flat and the get stern some number then put it aside as a core,not like there isnt a 110 outlet two step from the rv door
RE: dead battery? - sternwake - 09-03-2018
This meter can toggle between volts or amps using the button on the back of the display.
Are you saying you did not bother charging the battery after the meter dragged it down to 10.7v, but now a day after you removed the only load on teh battery, the meter itself, it is now reading 12.6v?
I've got some other things going on today that take precedence so i will not be measuring the load of the meter itself, nor searching for the directions which I believe say how to zero the meter when it is know there is NO current flowing through the ring sensor.
But I cannot even remotely guess as to how much capacity is remaining in your pre damaged battery with the info you provided.
To guess at that i would need you to fully charge it on a grid powered charger, and apply a known load of 5 amps or so, for a period of time and report the voltage the battery held initially and over time.
Without this, it is futile to even guess, and hoping that the battery can provide what you require in the short term, well Hope and faith are not terms anyone ever describe me as being 'full of'
I need data and logic
RE: dead battery? - Blacktank - 09-03-2018
yesterday after the 3rd trip to 10v i noted when i put on my charger it would go straight to zero amps,left there for about an hour then declared the battery dead and moved the charger to the start up battery for topping off
the battery was dead and couldnt power a led light and the charger worked normal on my run down some truck battery
but without the meter hooked up it did hold voltage overnight
i'll start it up and see if i get the same not accepting amps from the alternator
i could try a miracle cure and see what happens,nothing to lose at this point
RE: dead battery? - sternwake - 09-03-2018
A 10v battery, with a charger that actually starts on a sub 10.5v battery, that wuickly has voltage go high and amps drop low is like trying to fill a teaspoon with a 5 gallon bucket.
That teaspoon might have once held 5 gallons, but now it is a lowly teaspoon, and it is never going to be a 5 gallon bucket again.
You can still fill the teaspoon and it will hold those contents overnight( holding voltage overnight) but it is still teaspoon sized and will get even smaller.
If Someone said they'd give me a hundred bucks, regarless of sucess or failure, simply to try and restore this battery to some usable capacity, I would bring it up to 16.2v, and dip the hydrometer every 15 minutes and stop either when Specific gravity stopped rising or battery temperature went above 105F.
if Sg was rising and battery temp hit 105f, i would stop, let battery cool, then bring it up to 16.2v again.
But I would not have much hope. A battery shoes plates were exposed, well those exposed portion of plates never seem to provide anything ever again.
RE: dead battery? - Motrukdriver - 09-03-2018
If I lived closer I'd loan you my Stanley 25 amp charger with the battery reconditioning setting. Dunno if it would work but at this point like you say, nothing to lose.