C70 battery dead

[mark2410]

Originally Posted by Clan

That is because you didn't maintain it ... ie charge it ...
I dont know what's going on with modern batteries but they do loose their power when left for several weeks let alone months .

oh i realise i should have used it every week or two, but its an easy thing to forget, hence my wondering about those solar chargers, to keep it alive when i forget to.

[Clan]

Originally Posted by mark2410

oh i realise i should have used it every week or two, but its an easy thing to forget, hence my wondering about those solar chargers, to keep it alive when i forget to.

A modern solar charge panel connected up will do it in normal daylight but you will need one from a house roof size ... about 2 ft x 4 ft .

[mark2410]

Originally Posted by Clan

A modern solar charge panel connected up will do it in normal daylight but you will need one from a house roof size ... about 2 ft x 4 ft .

oh no no, i mean one of the trickle chargers to keep it topped up when i dont use it, this current battery is going in the bin

[Wgl2020]

Originally Posted by Clan

no volvos should draw more than 50ma when parked up .

Yup. Over time this adds up, if we are talking months.....

My electrical knowledge is distinctly average but aiui:

50ma is 0.05a.
0.05a being drawn for 24hrs is 1.2ah.
If you battery is 80ah this gives 66 days before it becomes flat.

(Don't take this as correct..... Like I say I'm no expert! Happy to be corrected).

[Dibble]

Buy yourself a CTEK. £60 or thereby and it will just trickle away. I have a 2003 C70 and have the same problem with a flat battery if I have not been near the car for a week or so. CTEK was the answer.

[Tannaton]

You do not need to remove the battery from the car to charge it - you can and should leave it installed and fully connected.

If you don’t fancy spending £60 plus on the c-tek get a £15 basic charger from Amazon and a £6 plug in timer from screw fix - have the charger come on for 30 mins twice a week. Just as good…..

[JohnM 855 T5R]

Originally Posted by Wgl2020

Yup. Over time this adds up, if we are talking months.....

My electrical knowledge is distinctly average but aiui:

50ma is 0.05a.
0.05a being drawn for 24hrs is 1.2ah.
If you battery is 80ah this gives 66 days before it becomes flat.

(Don't take this as correct..... Like I say I'm no expert! Happy to be corrected).

You are correct. The Volvo battery will be a 72aH which would give around 60 days in theory on a 50 mA constant drain. In practice, however, you would get much less useful battery standing time. Anything less than 50% charge would make starting very difficult and even then it will crank slowly, particularly if its a diesel with its high compression pressure.
At 30% charge, battery voltage will have degraded to the point that many of the systems in the car either shut down or give all sorts of confusing messages.
As a very rough guide, around 70% charge is needed for a reliable start, If I leave my T-5R (which has a 72aH battery) for 3 weeks, the cranking speed is noticeably sluggish and I keep my fingers crossed - so nowadays I take it out for a 20 to 25 mile run at least every 2 weeks. It's no good just starting it and idling for 10 mins or so as that puts very little charge in.

Regards
John

[Clan]

Originally Posted by Wgl2020

Yup. Over time this adds up, if we are talking months.....

My electrical knowledge is distinctly average but aiui:

50ma is 0.05a.
0.05a being drawn for 24hrs is 1.2ah.
If you battery is 80ah this gives 66 days before it becomes flat.

(Don't take this as correct..... Like I say I'm no expert! Happy to be corrected).

volvo state that when their new cars are in storage the battery must be charged fully every 3 months .. they do start after a couple of months no trouble. They certainly wont he hanging around in recent years, they can sell each car they make several times over the last few years .

[JohnM 855 T5R]

Originally Posted by Clan

volvo state that when their new cars are in storage the battery must be charged fully every 3 months .. they do start after a couple of months no trouble. They certainly wont he hanging around in recent years, they can sell each car they make several times over the last few years .

Absolutely no chance. Left for a couple of months they wont start! The quiescent current drain on any Volvo, modern or old, will take the battery down to an unusable level in 4 or 5 weeks. My T-5R is good for about 4 weeks max with a 35mA quiescent drain, my C70II T5 goes pretty flat in 5 weeks, as does my C30 T5. All have got 72aH batteries in good shape. Note, when manufacturers put cars into storage for any length of time they disconnect the batteries - well we most certainly did at Ford and Rover Group.

Regards
John

[iantowil]

My 2008 C70 draws about 13ma at rest and very stable. Compared it a few months back to a friend's Corsa that varied between 115ma and 60ma which was going dead after a few weeks.
Mine was left parked up without beng started for a month at the beginning of the 2020 lockdown and started as usual....was a little sluggish sounding but not bad at all really.

Works out as roughly 3 days per Ah, so around 3 months to 4 months to drain a 70-80Ah battery to half capacity where it should just about still work.....Volvo's calcs for new cars seem about right.