Battery "What the ???"

[-Scott-]

My Paj hasn't been driven much lately, and this morning the battery died.

It was turning over reasonably well, then just stopped. Key off & on, dash lights dim, click - click - click but no attempt to start.

I figured I had a loose terminal which had gone high resistance, so I popped the bonnet. Battery was at 8.4V!

Last week was it's first outing in over a month, and I checked battery voltages before starting - main was about 12.3, aux 12.5. I figured the main was down due to computer, clock & stereo, but it started OK, voltmeter showed charging a little over 14V.

I now figure the main was on it's way out, and I'll check the new battery a few times to get a better feel for what voltages should be - but WTF happened this morning?

It was cranking reasonably well, then just stopped! And the battery was completely shagged! 8.4V suggests two cells farked, but how would two go at once? Anybody seen something like this before?

[drivesafe]

Hi Scott, the onset of cold weather is usually the time a battery that’s on it’s last legs finally gives up the ghost.

To loose two cells at once is a bit unusual BUT

How old is the battery and what type is it

Cheers.

[-Scott-]

It was a Century of some description, probably a little over 3 years old. I didn't think it had a terribly hard time - perhaps I didn't use it enough? Or is it just one of those thing?

[drivesafe]

Three years is not too bad but how often do you use it

[-Scott-]

Aside from a couple of big trips (with aux battery for the fridge, so it shouldn't have been a depth of discharge issue), it was a weekend car for a while, daily driver for about 4 months, used only once or twice a month for the last year (been slack about fixing a water leak, letting water in every time it rains - I think I found the source today. )

[drivesafe]

used only once or twice a month for the last year

And just out of curiosity, how long were these drives

Cheers

[-Scott-]

used only once or twice a month for the last year

And just out of curiosity, how long were these drives

Cheers

A few would have been about 10km each way, most 15-20km each way. I try to avoid using it for short trips - that's why I've got my Sigma.

[drivesafe]

used only once or twice a month for the last year

And just out of curiosity, how long were these drives

Cheers

A few would have been about 10km each way, most 15-20km each way. I try to avoid using it for short trips - that's why I've got my Sigma.

Unfortunately not enough to charge the battery.

There be your problem and your battery did well lasting a long as it did.

Could I make a suggestion, it would probably pay you to invest in a small solar panel, one of the trickle charging types.

Might just save your next battery

Cheers.

[tj81]

Batteries have a habit of dying, without the slightest notice !

A typical cold start, can take 15-20 minutes of driving (not idleing) to put back the charge that the start has taken out of it. This of course is only charging the battery bak to what it was charged to the last time it was turned off, so if it was slightly down, its easy to find yourself with a flat battery after a while.

Its most common with office workers etc who start their car, drive to work 15-20 minutes away, the car sits there all day, and then gets driven home again.

[its aford not a nissan]

No thanks. I'll stick with my electronics degree and years of experience recharging batteries for medical equipment. I think I know how to charge lead acid batteries, and I know when my batteries are charged.

In addition, I can recognise myths on the internet, and I've even followed a few of them back to a common source - which isn't wrong, just mis-interpreted. I can also recognise somebody who DOESN'T know how to charge lead acid batteries, and I get sick of people who DON'T know what they're talking about continuing to perpetuate incorrect advice.


just a copy and paste job seems a little amusing so soon after

unfortunate though

[tj81]

your referring to my post i take it ?

[its aford not a nissan]

no refering to scott i just copied and pasted something he wrote in another thread

[tj81]

no probs, no wonder i didnt "get it" thought it must have been a blonde moment

[-Scott-]

No thanks. I'll stick with my electronics degree and years of experience recharging batteries for medical equipment. I think I know how to charge lead acid batteries, and I know when my batteries are charged.

In addition, I can recognise myths on the internet, and I've even followed a few of them back to a common source - which isn't wrong, just mis-interpreted. I can also recognise somebody who DOESN'T know how to charge lead acid batteries, and I get sick of people who DON'T know what they're talking about continuing to perpetuate incorrect advice.


just a copy and paste job seems a little amusing so soon after

unfortunate though

OK, you're such an expert. Explain how my Sigma, which is harder to start and does shorter runs more frequently, is still going on the same battery I put in it 5 years ago?

[its aford not a nissan]

i was just havn a dig

geeze no need to get touchy about it

but seriously if your not driving a car much it is a good idea to charge it every now and then with one of the above methods

i would say due to lack of use or in between drives the battery voltage dropped low enough to affect the longevity of the battery

[-Scott-]

i would say due to lack of use or in between drives the battery voltage dropped low enough to affect the longevity of the battery

I think you may be right. I've also worked out what happened.

My isolator is a Jaycar unit with a pair of FETs as the switching element. These FETs work like diodes when the primary battery is sufficiently lower than the auxiliary battery, which allows the aux battery to "help" the main battery during cranking.

I guess my main battery has been struggling for a while, and the auxiliary battery was masking the problem. Yesterday, during cranking, the FETs blew - probably when the main battery dropped it's second cell. My isolator is now farked, and needs new FETs. I was in Jaycar yesterday, too.

I think my multimeter may be farked too. Before cranking, it showed the main battery at 12.73V.

Tonight, I'll have another beer.

[tj81]

aah yes, ive been reading lots about dual battery systems and masking one dead battery, looks like it all makes sense.

On a side note, can you see how to avoid that type of issue with your current DBS ?

[-Scott-]

aah yes, ive been reading lots about dual battery systems and masking one dead battery, looks like it all makes sense.

On a side note, can you see how to avoid that type of issue with your current DBS ?

Piss off the Jaycar unit and have a look at the voltage sensing relay system chimpboy posted about?

I have a 60A fuse in the line between main battery and isolator - I'm pissed that it didn't blow. I could pull the fuse occasionally, and see how it starts without the aux battery?

I could try a thermistor instead of the fuse - probably trip a little faster, and reset automatically, but I don't know if thermistors are available to carry that sort of current.

Short term, I'll probably fix the Jaycar unit - I'm going bush next month, and don't want to fark around with a new system. And I'm too cheap to pay somebody else to do it.

[nicbeer]

bugger on the unit.

another reason i dont like the "intelligent" units

Nic

[muzza_fattire]

used only once or twice a month for the last year

And just out of curiosity, how long were these drives

Cheers

A few would have been about 10km each way, most 15-20km each way. I try to avoid using it for short trips - that's why I've got my Sigma.

Unfortunately not enough to charge the battery.

There be your problem and your battery did well lasting a long as it did.

Could I make a suggestion, it would probably pay you to invest in a small solar panel, one of the trickle charging types.

Might just save your next battery

Cheers.

Do you have any more info on these solar trickle chargers? I leave my car for long periods and one of these on the dash might be a good idea.

[drivesafe]

Hi muzza, you can get solar trickle chargers from places like Jaycar which are specifically designed do just as you want but the battery must be fully charged before you leave it to by maintained by the trickle charger.

You can also fit an ordinary solar panel and have it slowly charge the battery, as long as you don’t go any bigger than a 10 watt solar panel, you won’t need a solar regulator as the the battery’s own internal resistance, even when full charged, will stop the solar panel over charging the battery.

If your out in the sticks and can’t get one, PM me and I’ll see what I can get and at what price but as I posted, the likes of Jaycar or even your local solar panel supplier would have something.

Cheers

[j-top paj]

any updates scott? with 2 cells fcuked you would have gotten a new battery wouldnt you? ive had a similar problem with my dual battery system

[-Scott-]

Easy fix!

But I'm a farkin' idiot at times. (No need to agree... )

This time it was the fuse, and not the FETs. One of the LEDs was on, so I figured it was still getting 12V - but it must have been through the "ignition on" circuit. A new fuse, and she's all hunky-dory.

And I checked my multimeter at work - better than 50mV everywhere I checked.

Either way, new battery controller goes back to the bottom of the list.

[muzza_fattire]

Hi muzza, you can get solar trickle chargers from places like Jaycar which are specifically designed do just as you want but the battery must be fully charged before you leave it to by maintained by the trickle charger.

You can also fit an ordinary solar panel and have it slowly charge the battery, as long as you don’t go any bigger than a 10 watt solar panel, you won’t need a solar regulator as the the battery’s own internal resistance, even when full charged, will stop the solar panel over charging the battery.

If your out in the sticks and can’t get one, PM me and I’ll see what I can get and at what price but as I posted, the likes of Jaycar or even your local solar panel supplier would have something.

Cheers

Thanks mate. I'm in Sydney, so I'll have a look around.