Good/bad batteries or parasitic drain?

[PelicanHead]

Hi all.
I have a Toyota HiAce 2.5 D4D
It has two (never really known why?) 70ah batteries.
If I don't use the van for a week or two I can find the batteries are flat.
I take them off, charge them fully and leave them off for a couple of days to see if they hold their charge.
They appear to hold their charge well.
I was under the impression that if they were bad they would lose their charge?
If my assumption above is correct, could it be a parasitic draw?
Either way, could someone tell me, or point me to a tutorial on, how to do a full (ish) test?
I have a multimeter should it be needed.

Cheers.

[E-bmw]

It is likely 1 battery is for normal running & the additional one for starting.

Define "holding charge" and what/how are you measuring this?

I ask because a 12v battery that reads 12v is basically flatter than a flat thing.

A good battery fully charged should read about 12.6 volts and every 0.1v below that is a loss of around 15% charge capacity.

[PelicanHead]

Thanks for the reply.

Both batteries don't drop below 12.7 using the multimeter.
And that can be over two days sitting in the conservatory.

[JQ]

I can't help solve the problem, but I had a car with a parasitic drain. The previous owner had spent a considerable amount of time trying to source the drain without success. In the end they fitted a battery kill switch inside the car and you had to turn the battery on and off each time you used the car. It didn't bother me as it was a trackday car and would often spend weeks not moving, but a potential solution if you can't find the issue. Best of luck.

[PelicanHead]

Thanks JQ, that would do me, assuming it isn't bad batteries.

[ARH]

A duff battery doing nothing can easily read a good voltage. Try the voltage with the lights on. If it drops substantially then pop down to your local tyre shop or garage and get it tested.

Just reading voltages will give you an idea of condition but a proper tester is needed to check a battery.

[E-bmw]

^^^^ Wot 'e said.

After the OP's reply to my posting that would be my next suggestion, with the batteries fitted turn the lights on for a couple of minutes & check again.

If that is still showing 12.6/7v on each then check engine/chassis earth straps.

If they are OK check (properly, not just a quick look with a Mark 1 eyeball) all high current connections are good/clean/tight.

ETA.
Obviously this only really applies if you are saying they are flat after a while by the car not starting, if you have measured the voltages with them fitted/charged/left then it seems more likely a drain.

Edited by E-bmw on Tuesday 4th November 15:19

[PelicanHead]

Ok, thanks.
They are flat at the mo, so I'll get them off, recharge, refit and start the light test.

[PelicanHead]

Ok, so a bit more confusion for me.
I've just taken the batteries off.
I thought I'd test them before starting the charge.
One is reading 13.02 the other 13.03, the van hasn't moved for a week or so.
Why would they both read higher than the 'required' 12.6 but fail to turn the engine over?

[ARH]

Put them back on and try jump starting. As suggested it could be bad earths, a dud starter motor, faulty switch or any number of issues. A jump start will tell you if its batteries or something else.

[E-bmw]

PelicanHead said:

Ok, so a bit more confusion for me.
I've just taken the batteries off.
I thought I'd test them before starting the charge.
One is reading 13.02 the other 13.03, the van hasn't moved for a week or so.
Why would they both read higher than the 'required' 12.6 but fail to turn the engine over?

As I said & above you now need to find out why rather than assume they are flat/not.

First check is always battery/chassis/engine earths as this is most likely the issue.

Next is the Main 12v connections in the same light.

If your starter motor is accessible try directly jumping the starter itself to see if it turns the engine, if it does it is almost certainly a wiring/connection/ignition switch issue, if it does not then it is most likely a starter motor issue.

[PelicanHead]

Right, I can answer you now, I was limited to 5 posts!
Note to site owners, it would be good to make it clear that newbies only have 5 posts for the first 24hrs.
I didn't realise until I tried to reply last night (of course, I could have missed it and they do tell you?)
Plus, it would be good if when you reply you can see the thread you are replying to rather than have two tabs open.
Just sayin'!

ARH, I've done that before and it bumps with no issue.
It only needs a slow roll and a slight bump and away it goes.

E-bmw, I've been on to the place I bought them from and they say they just sound like they've had it.
I had a new alternator a while back and he said a dodgy alternator can damage batteries.
Plus they are around 7 years old.
I'll recharge, drive to the battery place and get them to test them.
At £80 a pop I'd rather not replace them (I'm very likely selling it in January) but hey!

[E-bmw]

PelicanHead said:

ARH, I've done that before and it bumps with no issue.
It only needs a slow roll and a slight bump and away it goes.

He & I both said "jump" not "bump" start, as in try connecting another car/battery to yours & see if it starts, that will rule out your electrics in general.

[ARH]

E-bmw said:

PelicanHead said:

ARH, I've done that before and it bumps with no issue.
It only needs a slow roll and a slight bump and away it goes.

He & I both said "jump" not "bump" start, as in try connecting another car/battery to yours & see if it starts, that will rule out your electrics in general.

That saved me writing that, thanks.

[Richard-D]

E-bmw said:

PelicanHead said:

Ok, so a bit more confusion for me.
I've just taken the batteries off.
I thought I'd test them before starting the charge.
One is reading 13.02 the other 13.03, the van hasn't moved for a week or so.
Why would they both read higher than the 'required' 12.6 but fail to turn the engine over?

As I said & above you now need to find out why rather than assume they are flat/not.

First check is always battery/chassis/engine earths as this is most likely the issue.

Next is the Main 12v connections in the same light.

If your starter motor is accessible try directly jumping the starter itself to see if it turns the engine, if it does it is almost certainly a wiring/connection/ignition switch issue, if it does not then it is most likely a starter motor issue.

No, first check is the voltage of the battery when cranking. There's nothing wrong with checking connections if the battery voltage remains good but this is best done with a voltmeter, not randomly disconnecting and cleaning connections.

[ARH]

Richard-D said:

E-bmw said:

PelicanHead said:

Ok, so a bit more confusion for me.
I've just taken the batteries off.
I thought I'd test them before starting the charge.
One is reading 13.02 the other 13.03, the van hasn't moved for a week or so.
Why would they both read higher than the 'required' 12.6 but fail to turn the engine over?

As I said & above you now need to find out why rather than assume they are flat/not.

First check is always battery/chassis/engine earths as this is most likely the issue.

Next is the Main 12v connections in the same light.

If your starter motor is accessible try directly jumping the starter itself to see if it turns the engine, if it does it is almost certainly a wiring/connection/ignition switch issue, if it does not then it is most likely a starter motor issue.

No, first check is the voltage of the battery when cranking. There's nothing wrong with checking connections if the battery voltage remains good but this is best done with a voltmeter, not randomly disconnecting and cleaning connections.

We started with the advice to check volts under load.

[PelicanHead]

Sorry for any confusion.
I have both bumped and jumped, both resulting in the van starting with ease.
It's been a bit of a crazy day trying to test anything today.
A car rolled down the hill, hit our neighbours wall, knocked it over, which hit our car, so I've been clearing debris off the drive and speaking to scammers, sorry, insurance companies.

[E-bmw]

Richard-D said:

E-bmw said:

PelicanHead said:

Ok, so a bit more confusion for me.
I've just taken the batteries off.
I thought I'd test them before starting the charge.
One is reading 13.02 the other 13.03, the van hasn't moved for a week or so.
Why would they both read higher than the 'required' 12.6 but fail to turn the engine over?

As I said & above you now need to find out why rather than assume they are flat/not.

First check is always battery/chassis/engine earths as this is most likely the issue.

Next is the Main 12v connections in the same light.

If your starter motor is accessible try directly jumping the starter itself to see if it turns the engine, if it does it is almost certainly a wiring/connection/ignition switch issue, if it does not then it is most likely a starter motor issue.

No, first check is the voltage of the battery when cranking. There's nothing wrong with checking connections if the battery voltage remains good but this is best done with a voltmeter, not randomly disconnecting and cleaning connections.

Brilliant advice IF it were cranking.

[Richard-D]

E-bmw said:

Brilliant advice IF it were cranking.

If it isn't cranking it can tell you even more. If there's no voltage drop you don't need to be looking at the battery. If there is voltage drop you need to find out at which connection it's happening. The engine doesn't have to turn at all.

It's always good to try to help and I'm sure people appreciate it. But when you're trying to give people advice on a subject you don't understand you will end up causing the guy more problems.

[Panamax]

Richard-D said:

It's always good to try to help and I'm sure people appreciate it. But when you're trying to give people advice on a subject you don't understand you will end up causing the guy more problems.

You're kicking the wrong guy. E-bmw is pretty good on this stuff.

My personal opinion is these batteries need to undergo a proper high current drop test before anything else is done. I'd be interested to hear how old they are. If the batteries are fine then earth connections are next.