Thread: flat battery problem

Jedo

Sounds like a job for a good auto electrician.

Sounds like a problem with your battery isolator. They are isolated aren't they? What is drawing if it is just sitting in your garage/carport.

Allelse fails, disconnect second battery, if it is still happening, maybe you do have a dud primary battery. Coincidence?

Originally Posted by Jedo_03

what's the chances I have a short or a leak or a discharge somewhere in the circuit\system that's draining the batteries overnight...Jedo

Slim and none. Looks like a newie. But a mechanic can test for the leak if you are determined.

Originally Posted by Big Shed

Sounds like a problem with your battery isolator. They are isolated aren't they? What is drawing if it is just sitting in your garage/carport.

Allelse fails, disconnect second battery, if it is still happening, maybe you do have a dud primary battery. Coincidence?

my knowledge of modern engines and esp modern auto-electrics is just about zilch... how do you mean "isolated" - the ignition key...
looking under the bonnet - is at least 8 or so wires running off the +ve terminal. few look like they been added on - not by me - one prolly for the spotties and another prolly for the uhf... neither the spotties or the uhf are working (too lazy\lack enthusiasm)...
now I don't really relish the thought of isolating each wire over an extended period to see if the batteries stay up...
might look at the spotty circuit and uhf circuit and see what...
buying a new primary battery this am and see what happens...
Jedo

Jedo,
the two batteries need to have some form of isolating switch. Either a two way switch as is often used on boats (battery 1, battery 2, both on, all off) or an automatic load sharing/disconnection/charging device. Otherwise one battery will drain the other flat and then when you get started the good battery gets overcharged as the alternator works full tilt to charge the flat battery.

Mick

Jedo,

What Mick said

Originally Posted by journeyman Mick

Jedo,
the two batteries need to have some form of isolating switch. Either a two way switch as is often used on boats (battery 1, battery 2, both on, all off) or an automatic load sharing/disconnection/charging device. Otherwise one battery will drain the other flat and then when you get started the good battery gets overcharged as the alternator works full tilt to charge the flat battery.

Mick

Thanks...
I didn't know that... I can't see any 2 or 3 way switch between the primary & secondary battery...
So I bought a champion NZ70ZZ - 660 amps cranking power - this morning and hooked it up,, then a good long run...
secondary battery is still connected... newish, 2yrs - 360 cranking
what do you reckon - disconnect it pending a switch... disconnect it altogether... or what...
I've been running two batteries on the vehicle since 2002 when I bought it over in WA and only had any trouble with it this winter

don't even need the 2 batteries - apart from the usual electrics that any vehicle has there's only a 12v DC double fluro light in the cab...
yehh - many thanks for edumucating me...
Jedo

If you don't need it disconnect the second battery, making sure you remove or at least isolate the terminals really well. I like a 2nd battery in a 4wd, especially when going bush, haven't been able to afford one of those fancy 2nd battery management units and use a switch.

Mick

you could disconnect the terminal then put a meter across from the battery to the lead and see if its reading anything.
but a bad starter motor can sound like a dead battery....

A couple of thoughts here. How old is the vehicle? A modern diesel has electronics, lots of them and you can do a serious amount of damage if you are not careful. If the Hi Lux had two batteries from the manufacturer then it won't have isolation switches and you need to look further into the problem. An auto elec is the best bet. Modern diesels are now completely computer controlled, so don't drown one either.

got up this morning -1 and frost all over the hilux...
turned her over and she sounded like a kid giggling...
hehehehevroooom......
so
duff primary battery seemed the cause
not enough cranking amps in the first solution
addition of 660 cca Champion solves problem
(at least for now - haveta wait and see what happens...)
will disconnect the secondary battery - isolate the terminals well
so wasn't a duff starter motor (thank goodness)
the hilux is a 97 model - the cab on the back is aftermarket - rigged for bush trips - so is the secondary battery fit...
this is the vehicle that explored the pilbara and sandy desert with us...
No ferrari - and hardly the epitomy of cab comfort - but a good workhorse
Thanks for your input.
cheers
Jedo

PS - Her car is an 11 month Nissan Patrol with electric everything... even the bloody seats raise and lower with a switch...

Originally Posted by journeyman Mick

Jedo,
the two batteries need to have some form of isolating switch. Either a two way switch as is often used on boats (battery 1, battery 2, both on, all off) or an automatic load sharing/disconnection/charging device. Otherwise one battery will drain the other flat and then when you get started the good battery gets overcharged as the alternator works full tilt to charge the flat battery.
Mick

I'm an auto elec, here are a few things to try.
Mick is partly correct, you need an isolation switch only if you are running something off the second battery such as a fridge so it won't flatten the primary battery overnight. If nothing is running off the second battery you can leave them connected with no problem provided both are in good working order because if one is faulty and has an internal leak it will drag the good battery down.
I suggest you put the biggest (highest CCA) battery as the primary if it will fit in the holder. To test for a leak in the system which could still be a possibility, first switch everything off eg. interior light and then remove the negitive terminals from both batteries, then carefully touch one of the terminals onto its battery if you see a spark no matter how small then you have a leak. If the spark is very small place an ammeter between the terminal and battery and see how much current is flowing, anything more than 200 milliamps means you have something draining the battery.
Also check that the secondary battery is connecting to the starter motor when cranking by disconnecting a terminal on the primary battery and then trying to start the car, if it starts, good, if not that means the secondary is not being used for starting. This could be because there is an isolation switch and it is off or the way the wiring is done the second battery isn't used to help with starting, and if this is the case I recommend you take it to someone and have it changed so the second battery is also used to help with starting. The advantage in having both batteries used for starting is that it combines the power of both batteries. So if you have a 330 cca battery and a 600cca battery combined you will have about 900 cca which is a good thing.
I hope this helps and is clear enough.

Posted by Speedy

I'm an auto elec, here are a few things to try.
Mick is partly correct, you need an isolation switch only if you are running something off the second battery such as a fridge so it won't flatten the primary battery overnight. If nothing is running off the second battery you can leave them connected with no problem provided both are in good working order because if one is faulty and has an internal leak it will drag the good battery down.
I was thinking along the same lines – that my primary battery was duff. Problems with duff batteries tend to raise their heads in winter when there is more demand on the battery with a cold start…
I suggest you put the biggest (highest CCA) battery as the primary if it will fit in the holder. I’ve done this – the Champion NZ70ZZ only just fits into the space. I went for the 660cca above the 600cca. An added surprise – to me – was to find that you can get Left handed and Right handed batteries. . !
To test for a leak in the system which could still be a possibility, first switch everything off eg. interior light and then remove the negitive terminals from both batteries, then carefully touch one of the terminals onto its battery if you see a spark no matter how small then you have a leak. Okay – will try this. If the spark is very small place an ammeter between the terminal and battery and see how much current is flowing, anything more than 200 milliamps means you have something draining the battery. Okay – I have an ohmmeter thingy that I think measures mA… So if this test is +ve then it’s a job for an auto-electrician, to find out what…
Also check that the secondary battery is connecting to the starter motor when cranking by disconnecting a terminal on the primary battery and then trying to start the car, yeah – I can do that… if it starts, good, if not that means the secondary is not being used for starting. This could be because there is an isolation switch and it is off or the way the wiring is done the second battery isn't used to help with starting, and if this is the case I recommend you take it to someone and have it changed so the second battery is also used to help with starting. The advantage in having both batteries used for starting is that it combines the power of both batteries. So if you have a 330 cca battery and a 600cca battery combined you will have about 900 cca which is a good thing. I first tried replacing the primary battery with an elcheapo 330 cca, which together with the secondary 330 cca battery brought the cranking amps up to 660 but all I got was a reluctant rrRRh…. rrrRRh… As you say – maybe the secondary is isolated from the starting circuit – or maybe the duff primary has (over time) dragged the guts out of the secondary. The test of disconnecting the primary and seeing if the secondary turns her over will determine whether the secondary is connected or not.

I hope this helps and is clear enough
Thanks – yeah, it helped a lot.
My ‘plan’ is to do all the above checks you recommend.
If I get a spark and an ammeter reading >>200 mA then consider an auto=elec consult
If I don’t, then replace the original secondary with the elcheapo 330 cca I just bought and see what happens…
I suspect though, that the Champion 660cca will have enough guts to get me through this winter – and probly the next – before I complain again about cold starting probs. And if it does – then that’s $165 well spent…
Jedo

Originally Posted by Jedo_03

If I get a spark and an ammeter reading >>200 mA then consider an auto=elec consult

Ermmm... one thing to consider... does the car radio have a clock? Or is there a clock anywhere on the dash? LCD, handed or otherwise. 'Cos many of them pull a continual draw, even when not actively displaying. They shouldn't be pulling that much, but, well, I've come across one that does! (Won't mention car type, except to say it seems Al has developed a dislike for the brand. )

Also, with remote central locking, the receiver has to be pulling current continuously, else it won't respond when you press the button on your key-ring, eh?

So if you do find a current draw, make sure it's not something as simple as that before consulting the auto-lec (ie. disconnect and retest) as it's a lot easier to spend a few mins resetting the clock, etc. than a few hours earning the auto-lecs fee.