battery overdischarge, possibly compounding issues. - PeachParts Mercedes-Benz Forum

ar300d · #1 07-02-2010, 06:24 PM

[B]update:saturday a.m. -- see stupidity below

[B]summary: [/

-completely discharged a basic duralast battery (was half a year old, probably started less than 50 times),
-no lights will come on,
-black terminal clamp on jumper cables began burning up in jumping process,
-began charging process with key in glowplug position for 20min @ at a 6amp charge (stupid)

details:
in my 83 300d, i certainly left the key in the position before turning on the glow plugs for a few days, and possibly a light or similar on. can't get so much as a light to come back on, even weakly. i know a hydrometer measurement, voltmeter would help in this case but i don't have one handy.

i tried to hook up cheap-ish jumper cables (thin looking clamps) between it and a running nissan murano. neg clamp on my car began smoking/melting whether it was grounded on engine block loop or on terminal, almost immediately and before any attempt to start (sidenote: considering getting heavy duty cables or two at once, but am worried about tiny looking murano battery and its electronics even being connected, would plan on disconnect during starting attempt).

if its relevant, my alternator brushes are worn down and i often have started using pliers to make the connection (below battery on wheel well), perhaps a few dozen times, 90% of starts in last 6 months.

checked fuses fwiw, they seem to be intact.

and fwiw, a few drives ago i had a brief electrical gremlin, at least blinker was double fast, i think dash warning lights were irregular in some way..

not likely relevant but -- last year had failing alternator that mightve stressed electronic systems? i likely abused the battery in that situation (at least an overcharge once and an overdischarge or two, replaced it after i stopped trusting it.)

questions:
-did i make this situation much worse possibly in any ways?
-is on 6amp charge now, any guess on when i should make an attempt at starting? (no lights/sound when charger was disconnected, car tested after an hour)
-should i just pick up a new battery and straighten this one out later?
-ive got aaa roadside; should i just have someone come out and try to jump it, test the voltage who knows what they're doing?

hopefully ill understand enough about these cars to help someone else here. any altruism in the form of responses is greatly appreciated. worst part was i was about to go on a sort of vacation from farm work.

leathermang · #2 07-02-2010, 07:02 PM

If you really completely discharged it...
depending on the type of charger you have you might need to put another battery in the circuit to get the charger to ' register' it has a load and charge it..
if the charger face shows charging you are ok... just thought I would mention this to others since it makes it look like the discharged battery is not rechargeable.... when it may well be. I had a charger like this.... what a pain...

ar300d · #3 07-02-2010, 08:15 PM

update:
got a hold of a multimeter, after ~3-4 hours of charging at 6amps its at 6.65V ish, which to me is either coincidentally or suspiciously around half of what it would be at full charge.

should i be able to get at least a dash, interior light to come one with 6.6V?

*presently reading old threads*

y'all have a good weekend

ar300d · #4 07-02-2010, 08:28 PM

Quote:

Originally Posted by leathermang

If you really completely discharged it...
depending on the type of charger you have you might need to put another battery in the circuit to get the charger to ' register' it has a load and charge it..
if the charger face shows charging you are ok... just thought I would mention this to others since it makes it look like the discharged battery is not rechargeable.... when it may well be. I had a charger like this.... what a pain...

its a cheap little charger, but it seems to indicate its trying, popping the needle up to 6amp every so often for a span.

ar300d · #5 07-02-2010, 08:39 PM

ok ok

http://www.battery-chargers.com/charging_instructions.htm

according to that, at 6amp, a battery like mine will take 16-18 hours when fully discharged..

jkubica · #6 07-02-2010, 10:08 PM

Quote:

Originally Posted by ar300d

update: friday pm - based on source cited below it will take me 16-18 hours to get a full charge, maybe thats the problem at this point.. though no lights come on at 6.6V ?

summary: [/

-completely discharged a basic duralast battery (was half a year old, probably started less than 50 times),
-no lights will come on,
-black terminal clamp on jumper cables began burning up in jumping process,
-began charging process with key in glowplug position for 20min @ at a 6amp charge (stupid)

[B]details:
in my 83 300d, i certainly left the key in the position before turning on the glow plugs for a few days, and possibly a light or similar on. can't get so much as a light to come back on, even weakly. i know a hydrometer measurement, voltmeter would help in this case but i don't have one handy.

i tried to hook up cheap-ish jumper cables (thin looking clamps) between it and a running nissan murano. neg clamp on my car began smoking/melting whether it was grounded on engine block loop or on terminal, almost immediately and before any attempt to start (sidenote: considering getting heavy duty cables or two at once, but am worried about tiny looking murano battery and its electronics even being connected, would plan on disconnect during starting attempt).

if its relevant, my alternator brushes are worn down and i often have started using pliers to make the connection (below battery on wheel well), perhaps a few dozen times, 90% of starts in last 6 months.

checked fuses fwiw, they seem to be intact.

and fwiw, a few drives ago i had a brief electrical gremlin, at least blinker was double fast, i think dash warning lights were irregular in some way..

not likely relevant but -- last year had failing alternator that mightve stressed electronic systems? i likely abused the battery in that situation (at least an overcharge once and an overdischarge or two, replaced it after i stopped trusting it.)

questions:
-did i make this situation much worse possibly in any ways?
-is on 6amp charge now, any guess on when i should make an attempt at starting? (no lights/sound when charger was disconnected, car tested after an hour)
-should i just pick up a new battery and straighten this one out later?
-ive got aaa roadside; should i just have someone come out and try to jump it, test the voltage who knows what they're doing?

hopefully ill understand enough about these cars to help someone else here. any altruism in the form of responses is greatly appreciated. worst part was i was about to go on a sort of vacation from farm work.

Hi
If you have AAA roadside, it wouldn't hurt to have them come out and try to give you a jump. But if you need a new battery there are better places to get one.

The Duralast battery should still be under warranty if the battery is indeed bad.

Using a 6 amp charger, I would take the cables off and leave the charger connected to the posts for an least 24 hours - each hour you are puting 6 amp/hours into the battery. Then check the voltage with the volt meter - should be showing something like 12.75 volts. In this case reconnect the cables (after cleaning the connections) and try starting the engine

If the battery has removable caps, check the electolyte level in the cells and note if every cell is producing hydrogen bubbles at about the same rate. A cell that is gassing excessively or not bubbling at all could be defective.

Once you get the car started, take it to an auto parts store for a free battery/charging system check.

Your starter problem sounds more like a wiring problem or bad transmission interlock switch (to make sure you start in netrual or park)rather than worn brushes.

Good Luck,
Joseph

layback40 · #7 07-02-2010, 10:50 PM

X2 with Joseph.
The clicking & jumping you are seeing on the charger indicator is probably the charger overload protection cutting in.
Normally a dead flat battery will start to charge slowly for a while.
Only seeing 6.5V after some time makes me think the battery may have a fault. You should see it up to over 10V after about 20 minutes, it wont stay there for long if you remove the charger.
leaving it on the charger for 24 hrs should bring it back to life if it is recoverable.
Make sure you disconnect the battery from the car before you charge it. Its best to connect the charger to the battery before you turn the power on & turn of the power before you disconnect it from the battery. Sparks can ignite the hydrogen/oxygen produced in the charging process & destroy the battery & cause injury. I have pieces of battery casing jammed in my sheds ceiling from such.

good luck

Junkman · #8 07-02-2010, 11:23 PM

Confirm meter accuracy on another battery. Put charger on dead battery. Go to sleep. IF not charged in the morning, take to store for test &/or replacement. This part of the process isn't worth over thinking or worrying about.

If no crank with fully charged battery, see recent thread with all of the details.

leathermang · #9 07-03-2010, 12:26 AM

Remember that these batteries are not designed to be totally discharged...
For things like boat trolling motors you would get a ' deep discharge ' battery which was made for that... in other words... it is possible that a total discharge may ruin the battery.

ar300d · #10 07-03-2010, 02:28 AM

update

oh wow, i need to sell this and revert to a bicycle, at least i can fix everything on those.

so... i charged it up to over 9 volts, with it hooked up to the car, with the charger on the WRONG poles. for some hours @ 6amp..

yes.

based on a sort of moderate google consensus, it is apparently possible to charge a battery backwards if it is indeed utterly discharged in the first place... i had been conveniently ignoring that the multimeter was telling me -x volts. so now i need to completely discharge this, and recharge with a certainly damaged battery.

ah, so did i fudge up by car's electrical system? i have flipped the key to an early pre ignition spot several times during the 'charging' process.

its funny, im in this situation b/c of chronic mild sleep deprivation (why i left the keys in in the first place), so i doubt i should even try something as simple as installing the new battery i bought without getting decent sleep.

also, totally impressed by all the helpful responses. maybe ill repay the favor by putting my car up on here for a low price-- before i accidentally destroy it entirely.

edit: can i repay the assistance here by giving $20 to someone's favorite charity? there's clearly no way ill be contributing advice here anytime soon heh..

layback40 · #11 07-03-2010, 04:40 AM

Just buy your parts from fastlane on the site, that way they get rewarded for the sponsorship of the forum.

smiffy6four · #12 07-03-2010, 08:37 AM

You have well and truly buggered the battery. Quit buggering about and go and buy a new one.

Then clean all the connections on the charging circuit. Never charge with the key on...it's adds a load and slows the charging down. Lightweight jumper cables are NO use on a diesel. Get the heaviest pair you can find, you will save the cost of them the first time your car won't start. Once you have the car started, run the engine up to about 2000rpm and put a voltmeter across the battery. Look for it to show at least 14v. If it's any lower, have the alternator rebuilt/get another one.

leathermang · #13 07-03-2010, 11:50 AM

Why would anyone think of charging with the key on? I would never even think to tell someone not to have the key on....
As to cables... even the big ones often have terrible clamps... a bottleneck in terms of current flow..... clamps which have an amazingly small amount of contact area...

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