is my battery "toasted"?

[shorty_f0rty]

hey guys,

went to go for a drive yesterday and noticed my battery was flat. I checked it with the multimeter and it registered about 4v. I'm pretty sure I didnt leave any acc's or lights on (done it before).. and I hadnt driven the 40 for a few days since coming back from fraser island.

anyway.. after not being able to jump start off the 2nd battery (12.4v) or off dibbz's main battery when he came around in his 60 (his battery went down to 8v with his car running, when I cranked the 40). I'm assuming because the voltage is so low that when you join the batteries, both are "equalised" and therefore have insufficient voltage to start?

anyway.. i removed the battery from the 40 and threw it on the charger. its been on there for about 24hrs now and it still hasn't reached "full charge" (as per the cheapish battery charger).. When i turn the charger off and check it with the multimeter, i notice the voltage drop of .1v every few secounds..

is this a symptom of a "dropped cell?" or something. i figure the battery is close to 3yrs old and has done a good service till now. there is a "battery condition" seeing eye on it and its blue indicating the water/acid levels are ok.

any pointers on what the issue would be appreciated.

thanks!

[chimpboy]

RIP, shorty_f0rty's battery, RIP.

[drivesafe]

Hi shorty, under normal conditions, there will not be battery “ equalisation “ ( for wont of a better word ) when you jumper connect to another vehicle while the other vehicle is running. The other vehicle’s alternator should bring the flat battery’s voltage up pretty quickly, not have the alternator’s voltage drop so dramatically.

To get a drop of between 6 and 7 volts when you connect to the stuffed battery points to more than just a flat battery.

As for the multi meter showing a .1 drop every few seconds. This will happen with any battery that has just had the charging supply removed ( battery charger disconnected or motor turned off ).

You didn’t post whether you finally got your rig going.

If not, try checking it out before you connect another battery to it because there has to be something very amiss to cause that sort of a voltage drop when you connected the jumpers from the other vehicle and normally you might put it down to cells shorted out in the battery but, even though you have not been able to fully recharge the battery, the fact that you are able to charge the battery at all, sort of rules it out for the massive voltage drop when you hooked up the jumper leads. So check around the engine bay for any potential cause.

I would start by looking at the starter motor and solenoid.

Cheers

[drivesafe]

One more point shorty, depending on how small your battery charger is, 24 hours may not be a long enough time to recharge your battery.

[bazooked]

sounds cactus, throw in a newy.

[shorty_f0rty]

thanks for the feedback so far guys..

i took the battery off the charger this morn as it was about 12.8v and threw it back in. THe 40 started up first crank no issues.. I did have a bit of a poke around and couldn't see any obvious signs of issues (burnt, warn, exposed wires, etc etc) and went for a solid drive this morning up to woodford and back.

During the drive there were no wierd issues, voltage meter read about 14.5-7v most of the time.

I'll check it out over the next week and see if it repeats itself if so I'll have to have a bit of a closer look.

thanks guys.

[chimpboy]

thanks for the feedback so far guys..

i took the battery off the charger this morn as it was about 12.8v and threw it back in. THe 40 started up first crank no issues.. I did have a bit of a poke around and couldn't see any obvious signs of issues (burnt, warn, exposed wires, etc etc) and went for a solid drive this morning up to woodford and back.

During the drive there were no wierd issues, voltage meter read about 14.5-7v most of the time.

I'll check it out over the next week and see if it repeats itself if so I'll have to have a bit of a closer look.

thanks guys.

That's good. From my experience, you might find now that your battery is fine if it's kept charged, but that it goes flat very fast if you don't drive the car, ie you can only leave it a day without driving before it's too flat.

Happened on my Mav shorty when I wasn't driving it often and the battery was already old. It just didn't have the charge capacity it had when it was a young 'un.

[shorty_f0rty]

yeh well ive only just recently (last month or two) replaced the alternator which left had me jumping the batteries more often than not and was a PITA! after that it i could put the jumper cables away for a while.. until now.

i just thort it was pretty strange that we couldn't jump start even with the other car running. and that it had gone down so much after only a few days. at least if it happens again i can be sure it wasn't me leaving something on... i hope

[Guy]

few years ago I was waved down by a straneded motorist on my way to swan hill late one night .. As there were three other largish blokes in the vehcile with me I decided I woould stop and help (car was well off the road in the middle of nowhere .. seemed a bit sus at the time) Apperently the guy had decided to pull off the road and have a nap for a few hours and left the parkers on, and radio, and fan ...

There was an Xe/xf falcon with a flat battery .. I had some pretty decent quality jumper cables with me (welding cable) and a fresh nz70 battery along with a 100+ amp alt on the GU .. figured it would start it easy..

we could barely get the starter to throw in, let alone crank ..

We let the patrol sit at high idle for about 10-15 mins .. tried again got the motor to turn over about half a turn .. .. so I disconnected the ford's battery lead from the battery, but left it hooked up to the jump leads .. tried again and it started it easy.. hooked the leads back up to the battery and listened to the alternator whine on the ford ..

Closed the bonnet on both cars .. chatted for a few mins .. he thanked us heartily we made sure he got going without stalling the vehicle and were all on our way again..

Seem's that the flat battery was soaking up all the avaliable juice and not letting enough get to the starter ... once the vehicles own alt was making power he had enough to keep the motor running as well as charge the battery..

[shorty_f0rty]

That's good. From my experience, you might find now that your battery is fine if it's kept charged, but that it goes flat very fast if you don't drive the car, ie you can only leave it a day without driving before it's too flat.

well.. i walked to work yesterday and went to drive to work this morn.. i got about 1--2 slow cranks out of it before it ran out of juice.

oh.. and ive pretty much driven the 40 every day cept then.. so i figure a bad short might be the go. i'll think i'll be spending the weekend looking for a bad short.

I spose i could swap in the 2nd battery but its an 100ah AGM.. how would this go as a cranking battery?