Electrics: Should I fit a bigger battery?

[BlueRubber]

The battery on my car seems to be coming to the end of its life.
As it discharges when the car is not in use quite quickly, and I have checked for parasitic drain when the car is locked is less than 50mah.
But the battery drops down to about 12.4v after a couple of days after being fully charged.
The battery voltage drops down to 10.2v when starting the engine, which isn't terrible but is on the low side.

So it seems that I need a new battery.
Currently, it has a Yusa 75Ah 650A, which is slightly higher capacity than the recommended 72Ah battery.

Should replace it with the same battery or pay £10 more and get a 77Ah 760A battery:
https://www.amazon.co.uk/Exide-Premi.../dp/B00UJ90U2A

Details of my car in the signature below.

[cheshired5]

£10 extra..... It won't make a difference but if you want to, sure.

[AndyV7o]

That battery is not really an upgrade, its better, but not notably.
If you want an upgrade you want an 019 battery as used in the D5's.

[oragex]

The way to test it is drive the car, then disconnect the positive, let sit 1h to stabilize, then measure at the posts. If you see 12.4 or so, it's not that bad. Your problem may rather be a parasitic drain which will damage a new battery as well. How much drain do you read when leaving the multimeter connected for 10 min (to have all computers shut down). If you see 0.01 or 0.02 is ok, 0.04 or higher there is drain. Have you tried removing the alarm siren fuse ?

[BlueRubber]

Thanks for all the replies guys. I will look into the 019 battery.

Originally Posted by oragex

The way to test it is drive the car, then disconnect the positive, let sit 1h to stabilize, then measure at the posts. If you see 12.4 or so, it's not that bad. Your problem may rather be a parasitic drain which will damage a new battery as well. How much drain do you read when leaving the multimeter connected for 10 min (to have all computers shut down). If you see 0.01 or 0.02 is ok, 0.04 or higher there is drain. Have you tried removing the alarm siren fuse ?

I used a UNI-T UT210E clamp meter to measure the drain after the car had been locked for 30mins ( and while it was still locked ).
It was showing between 10 > 25 Mah drain.
I also tested with a different clamp meter and got similar results, as well as testing both meters against a multimeter* connected in-line in a different DC circuit.

Also why do you suggest to remove the positive battery terminal, I thought usually it's recommended to remove the negative terminal as it's safer?

* I tried testing with the multimeter inline in the car, but the meter is only supposed to have up to 10amps going through it and the car uses more than that when reconnecting the battery and I was worried about damaging the meter.
Initially after reconnecting the battery is was pulling over 20amps, then it settled down to 16amps, then I removed the meter to prevent it being damaged.

[marcb]

I thought the 019 was standard in P2 V70s. It's the one in both the 2001 and 2005 models we've had. It's a big battery.

I put a Volvo OEM 019 in the 2005 2 years ago and it's now going flat after 2 days. It has a 3 year guarantee so I'll be checking the drain and taking it back if all is in order.

[cheshired5]

Originally Posted by BlueRubber

I used a UNI-T UT210E clamp meter to measure the drain

I have the UT216C but wouldn't trust its accuracy on such low currents due to the inherent margin of error.

A regular multimeter in series with the negative lead and negative post will be more accurate.

[BlueRubber]

Originally Posted by cheshired5

I have the UT216C but wouldn't trust its accuracy on such low currents due to the inherent margin of error.

A regular multimeter in series with the negative lead and negative post will be more accurate.

I tested my UNI-T UT210E against two different mutli meters and it was within 2mAh of the results from the multi meters.
Tried it with a DC circut pulling 15mAh and 80mAh, the other clamp meter I had was accurate within about 5mAh in the same tests.
Results from watching youtubers with more accurate equipment shows simular results.

I actually looked at buying a UT216C after seeing it in one of your videos but it's less accurate in measuring DC current than the UT210E.
The stated accuracy of the two are ±(2.5%+5) (2%+3) respectively.
Thats not to slate your meter, it has some nice features such as showing highest and lowest values.

As mentioned earlier in the thread I did try to use a multimeter inline on the car but the car uses too many amps when reconnecting the battery, which risks damaging the meter.

[cheshired5]

Originally Posted by BlueRubber

I actually looked at buying a UT216C after seeing it in one of your videos but it's less accurate in measuring DC current than the UT210E.
The stated accuracy of the two are ±(2.5%+5) (2%+3).

That margin of error has never be an issue for any of my uses. .

Originally Posted by BlueRubber

As mentioned earlier in the thread I did try to use a multimeter inline on the car but the car uses too many amps when reconnecting the battery, which risks damaging the meter.

If you see my parasitic drain video, the only risk is central locking and door openings so just avoid those.
You can leave doors, bonnet and boot open by closing their microswitches and tricking the CEM.
The current in that state won't blow the meter.

[BlueRubber]

Originally Posted by cheshired5

That margin of error has never be an issue for any of my uses. .

If you see my parasitic drain video, the only risk is central locking and door openings so just avoid those.
You can leave doors, bonnet and boot open by closing their microswitches and tricking the CEM.
The current in that state won't blow the meter.

The margin of error isn't huge, I mainly went for this clamp meter as it was much cheaper and slightly more accurate.

Thanks, I saw your very helpful video and followed the advice to close the boot and door micro switches etc.
My issue is that to connect a multi meter inline I first need to disconnect the battery. But when I re-connect the battery there is significant amp draw for a while as all the computers etc boot up, initially over 20amps, then down to 16amps, then I disconnected the multi meter as I was worried it would be damaged due to it only be rated for 10amps.