odd battery behaviour

[mr.tourette]

So i fitted a new battery when i bought the car and its been performing fine starting wise, now during the fitting off the new 6 speakers amp and sub I've been doing a fair bit of testing on the drive and not much actual driving so wasn't too surprised during the cold weather when the battery light briefly came on, a quick multimeter test showed 12.16 so popped on the battery charger using the under bonnet lead i fixed on when first bought, took 36 hours and 2 green lights showing fully charged.

So checked with multimeter just out of interest and only reading 12.5 straight off charge which i thought a bit low for a new battery so i started monitoring, 6 hours later at rest its reading 12.36, following day after a wee drive (30 mile round trip) I'm getting 12.26. This morning I go out and its 12.45v however when i take the battery off the car its reading 12.61 put it back on and back to 12.45 . I've tried this back and fore with a different battery and always get this .15 drop with the battery connected.

I'm far from expert on this kind of stuff but is this anything like normal behaviour..is maybe the canbus causing the voltage difference between battery connected and not. The fact its 12.61 off the car today suggests the battery may not be a problem at all but these readings being all over the shop I've confused myself a bit here I think

 

[flybobbie]

Well the car is live all the time.
Otherwise the alarm or roof wouldn't work.
I have just fully charged an aircraft battery. That shows 12.5 volts, fully charged.
I'll check it again when back at work later today see if it has changed.

 

[Anonymous]

You’ve got to remember that whilst the battery is electrically connected to the car as opposed to on a bench or just with one side disconnected you’re not reading an off load voltage..there is always at least one ECU running all the time..even If it’s in ‘sleep’ mode, so the voltage rail is dragged down by these ECUs..

To compound matters various ECUs may or may not come online based on ‘interrupts’ from events like doors opening, time passing, controls being touched, the computed state of the battery, the predicted state of the battery based on recent history etc

So I don’t think there is anything intrinsically strange there...IMHO..

If you wanted to check the battery the best thing would be to disconnect it from the car, fully charge it and then measure the volts then put a known load across and measure voltage against time

As a corroborating aside I swapped my original battery out last year despite not obviously being ‘bad’ even though it was 7 years old.

We had a scheduled power cut so thought I would use a 12v inverter to drive a few lights during the outage using that battery.

Despite being fully charged within 20 minutes of being used the inverter tripped off line due to low volts..

It’s sister battery, new in 2019 but 90ah rather 70ah lasted over 6 hours on the same load when mains power was restored..

Point being you can’t really tell (without very clever electronics) what state the battery is in without doing a structure discharge test measuring volts against time..

 

[flybobbie]

The aircraft battery i charged was because the aircraft cranked once and stopped. Flat battery? 1 year old?
Measured volts 11.2. One hour later and charger said fully charged 12.5 volts.
Went to aircraft, starter motor is hanging off, lose bolts.
Not always a battery fault.

 

[Anonymous]

The aircraft battery i charged was because the aircraft cranked once and stopped. Flat battery? 1 year old?
Measured volts 11.2. One hour later and charger said fully charged 12.5 volts.
Went to aircraft, starter motor is hanging off, lose bolts.
Not always a battery fault.

Was that starter motor under an EASA CAME or CAA CAME based maintenance program?

Your battery still sounds off..fully charged the volts should be better than 13.2 at least immediately post charging off load..

Fully charged 12v lead acid battery should be still at 12.6 after a 12 ish hour period..

https://www.batterystuff.com/kb/frequently-asked-questions/powersports-batteries-faq/12-volt-battery-reading-13-volts.html Refers

 

[flybobbie]

Well going to work now to drop on charge again. Gill sealed, don't like it as you can't see them bubbling under charge.
But second aircraft we have had with lose starter bolts. Can't see why they are not tab washers.
And now other aircraft on 75hr checks, bonkers.

 

[Smartbear]

Well going to work now to drop on charge again. Gill sealed, don't like it as you can't see them bubbling under charge.
But second aircraft we have had with lose starter bolts. Can't see why they are not tab washers.
And now other aircraft on 75hr checks, bonkers.

Do aircraft use lock wire on any fasteners like racing cars/bikes? I’m surprised they can just drop off
Rob

 

[Anonymous]

Well going to work now to drop on charge again. Gill sealed, don't like it as you can't see them bubbling under charge.
But second aircraft we have had with lose starter bolts. Can't see why they are not tab washers.
And now other aircraft on 75hr checks, bonkers.

Do aircraft use lock wire on any fasteners like racing cars/bikes? I’m surprised they can just drop off
Rob

Rob, they use lots of it in various key places..obviously the starter was not a key place..

single use nylocs are used in some areas..not sure how old flybobbie's aircraft are but the GA fleet is on average I think over 40 years old..

So that gives a lot of opportunity for interesting interpretation of maintenance regimes..

I think I told you about a certain organisation that was maintaining GA aircraft is such a good fashion the CAA suspended their licences and priviliges until I got my marigolds and bleach and cleaned them up (for a while).

 

[Smartbear]

Well going to work now to drop on charge again. Gill sealed, don't like it as you can't see them bubbling under charge.
But second aircraft we have had with lose starter bolts. Can't see why they are not tab washers.
And now other aircraft on 75hr checks, bonkers.

Do aircraft use lock wire on any fasteners like racing cars/bikes? I’m surprised they can just drop off
Rob

Rob, they use lots of it in various key places..obviously the starter was not a key place..

single use nylocs are used in some areas..not sure how old flybobbie's aircraft are but the GA fleet is on average I think over 40 years old..

So that gives a lot of opportunity for interesting interpretation of maintenance regimes..

I think I told you about a certain organisation that was maintaining GA aircraft is such a good fashion the CAA suspended their licences and priviliges until I got my marigolds and bleach and cleaned them up (for a while).

I should think that if an aero engine stalled & couldn’t be restarted due to the starter falling off, the pilot would swiftly refer to it as a key place!
Rob

 

[Anonymous]

With simple GA aircraft you can normally air start the engine by diving steep enough..great technique if you have enough height..

In the event of the starter motor /failing on the ground you can hand crank the prop to get them to start..

Don't ask me how I know that..

 

[flybobbie]

So 48hr later voltage is 12.33v. Put on charge and showed full 10 minutes later. 15 minutes after charging showing 13.5v.

Chap on our field pulled a prop through, struck his arm, sliced through the muscle. Wasn't even trying to swing prop.

Do aircraft use lock wire on any fasteners like racing cars/bikes? I’m surprised they can just drop off
Rob

Rob, they use lots of it in various key places..obviously the starter was not a key place..

single use nylocs are used in some areas..not sure how old flybobbie's aircraft are but the GA fleet is on average I think over 40 years old..

So that gives a lot of opportunity for interesting interpretation of maintenance regimes..

I think I told you about a certain organisation that was maintaining GA aircraft is such a good fashion the CAA suspended their licences and priviliges until I got my marigolds and bleach and cleaned them up (for a while).

I should think that if an aero engine stalled & couldn’t be restarted due to the starter falling off, the pilot would swiftly refer to it as a key place!
Rob

Funny we call that point, start of the glide "High key".

Would be quite simple to have the dog bone style washers with bendable tabs, used on motorbikes.

 

[Smartbear]

With simple GA aircraft you can normally air start the engine by diving steep enough..great technique if you have enough height..

In the event of the starter motor /failing on the ground you can hand crank the prop to get them to start..

Don't ask me how I know that..

I can’t believe you sent your wife outside the aircraft to hand crank the prop!
Rob

 

[Anonymous]

I didn’t ..all our aircraft were twin engined turbo charged, inter cooled diesels based on Mercedes engines ..

One of the founders had an old Cessna C172 we used for some basic instrument training..he went outside and did the biz..I sat there with the throttle etc

My wife wasn’t happy even with two engines...she thought it was bad news when they started to cross the Atlantic on two engines :thumbsdown:

 

[mcbutler]

36 hours to charge! I think that tells the whole story - I regularly discharge a 120A Lead acid battery to around 10.9 V, it takes less than 12 hours to recharge with my excellent Lidl C-Tek clone.....

 

[mcbutler]

The aircraft battery i charged was because the aircraft cranked once and stopped. Flat battery? 1 year old?
Measured volts 11.2. One hour later and charger said fully charged 12.5 volts.
Went to aircraft, starter motor is hanging off, lose bolts.
Not always a battery fault.

Was that starter motor under an EASA CAME or CAA CAME based maintenance program?

Your battery still sounds off..fully charged the volts should be better than 13.2 at least immediately post charging off load..

Fully charged 12v lead acid battery should be still at 12.6 after a 12 ish hour period..

https://www.batterystuff.com/kb/frequently-asked-questions/powersports-batteries-faq/12-volt-battery-reading-13-volts.html Refers

Might be nice to discuss aeroplane stuff by email fellas, over complicates and lengthens the thread otherwise

 

[flybobbie]

36 hours to charge! I think that tells the whole story - I regularly discharge a 120A Lead acid battery to around 10.9 V, it takes less than 12 hours to recharge with my excellent Lidl C-Tek clone.....

So was that direct on battery or via the under bonnet contacts?

 

[Smartbear]

36 hours to charge! I think that tells the whole story - I regularly discharge a 120A Lead acid battery to around 10.9 V, it takes less than 12 hours to recharge with my excellent Lidl C-Tek clone.....

So was that direct on battery or via the under bonnet contacts?

I doubt that battery’s fitted to Marks e89, it’s 120A so probably wouldn’t fit? :?
Rob

 

[mr.tourette]

36 hours to charge! I think that tells the whole story - I regularly discharge a 120A Lead acid battery to around 10.9 V, it takes less than 12 hours to recharge with my excellent Lidl C-Tek clone.....

im using a motorcycle battery smart charger using a lead at the under bonnet connector, designed to charge much smaller batteries but as a trickle charger works fine if somewhat slower than a car specific charger.

Ive removed the battery this weekend and charged it directly, its holding fine now at 12.9v a day later.

I think what caused my initial concerns was lower voltage when connected to the car and it still does have me wondering if thats the same on all e89s with a pull from the canbus, I wasn't expecting the increased voltage when removed from the car

 

[flybobbie]

36 hours to charge! I think that tells the whole story - I regularly discharge a 120A Lead acid battery to around 10.9 V, it takes less than 12 hours to recharge with my excellent Lidl C-Tek clone.....

So was that direct on battery or via the under bonnet contacts?

I doubt that battery’s fitted to Marks e89, it’s 120A so probably wouldn’t fit? :?
Rob

Yes i realised after i should have directed the remark to the first poster, as suspected used a low capacity charger.
I have one of those M/c chargers, they only push out about 1 amp. max.

 

[mr.tourette]

So was that direct on battery or via the under bonnet contacts?

I doubt that battery’s fitted to Marks e89, it’s 120A so probably wouldn’t fit? :?
Rob

Yes i realised after i should have directed the remark to the first poster, as suspected used a low capacity charger.
I have one of those M/c chargers, they only push out about 1 amp. max.

actally 0.6 amp according to the manual