Instantaneous, full battery discharge
 

Dear friends, this is a real puzzle.

The car:
Volvo 940 2.3i estate (1995), 210k mi. Regularly serviced.

The problem:
Twice now, the car has discharged its battery completely inside one minute, only to be rendered fine again with a jump start.

Instance 1 happened in seriously heavy rain round a roundabout which made me think it must be water and electricity not making friends.

Instance 2 dashes this theory as it was a beautifully warm day, car used 4x before the fault. Sat to listen to radio for fewer than 5 mins (no rain, engine not running) and it was dead to the point the radio reset itself etc. A jump and it was fine.

Battery reads great voltages cold and running but whenever this problem surfaces, the car won't even click the starter solenoid it is that weak.

I wondered if it was a loose earth so have been throwing it over speed bumps and round roundabouts and sharp corners to see if I can replicate the fault with cruel treatment; I can;t.

There seems no commonality in instances where the car chooses to fall over.

Fuel gauge only worls 2% of the time. Fresh plugs and bougicord leads fewer than 10k mi ago.

https://www.volvoforums.org.uk/showthread.php?t=313229

The above thread is realy insightful and details the tracking of a similar electricity demon.

I love this car and don't want to hear 'scrap it'. Any advice really appreciated. Stuff I've ruled out is fuel as it has happened once with the engine running, once with it just providing power to radio. Battery itself - this is healthy.

Cheers,

F

To discharge a battery that quickly would create a hell of a lot of heat!!!

Battery voltage is not really a good check on its condition.

Try to borrow a good known battery.

Well, this is the double mysterious thing - the car behaves as though it is dead (lights on dash dim, not enough grunt to even click the starter motor etc) but as soon as you show it a jump start, it is absolutely fine again.

For your advice, I say thanks and will change the battery out to see what it does and report back. It is most annoying as the problem only surfaces occasionally and seems to have no particular reason for showing up.

Cheers,

F

PS it doesn't mind being left for a few days, starts first crank etc. but has shown this fault once whilst driving and once whilst stationary with the ignition and radio on for less than 5 mins.

Possibly no capacity left in it, sulphated and charging ok but seriously depleted after initial starting.

When you fit the new battery, use a multimeter to check the alternator is charging at around 14 volts.

James.:thumbs_up:

Check your battery leads and earth points !

Agree, check and/or remake battery leads and earth points.

OK chums.Thanks for all chiming in. I have done some things today:


1) Checked battery with car switched off. Good voltage.
2) chucked a Snap on Rapid discharger on it for 15 seconds (it gets f'kin hot)
3) Car started beautifully and voltage on batteryu running is a solid 14.01v
4) checked (visually) all earth straps and cables. All seem ok and unsnapped.

Next up I will be:

1) flopping a new battery in
2) Redoing all the earth cables and maybe even adding a fresh one for good measure.

I will report back. In the meanwhile I am carrying a spare battery, jump leads and one of those little boxes of devil technology that weigh as much as a vole and claim to be able to jump start the titanic; let's see.

I do not begrudge the 210k mi car a wobbly. It is a venerable old thing, I like it and I want to see it carry on. What I do dislike is that at work, there is a fanatacism for brand new, financed, hybrids, electrics etc. Despite that, we all worship the volvo for its good reliability record and also its ability to deliver anything up to and including 0.5t of antique doors which none of the new metal can. This is an unsightly skidmark on what is an otherwise clean white y-fronted record.

Cheers,

F

If you try a new battery, ensure it is NOT a calcium/silver-calcium variety. Your alternator is NOT capable of charging this type, try a Halfords HB096, it's a traditional lead-acid battery that uses lead-antimony as a coating on the plates to help prevent sulphation. Newer batteries use silver-calcium which increases the necessary charging voltage to 14.7V MINIMUM just to start the charging process!

In fact, if your current battery is a calcium variety, this may be your problem....... :thinking:

https://en.wikipedia.org/wiki/Silver...alcium_battery

Have a read of that, you'll see what i mean. Also do some more research as you will find that 14.4-14.8V is a conservative estimate, it's normally 15.1-14.7V for a calcium battery but the point it does make in that Wiki page is that calcium batteries do deteriorate rapidly if they're not being fully charged at the correct voltage.

Sounds more like you either have a short or a bad connection, if the battery is good.

You cannot discharge the battery in 1min, something would go on fire, there would be smoke.

You need a better test for the battery than measuring the voltage, you need a load test like a high wattage bulb ideally..try not to blind yourself. Sparking the battery terminals can also work with a short piece of wire, but needs to be done carefully as if you allow it to contact for any length of time it will weld, overheat, go on fire, explode the battery etc,,.. thats a bad day.

A problem that has been reported before is the starter cable chaffing on the bulkheak, but I think that is more of a 740 problem than 940.

Try measuring the battery voltage at, say the cigarette lighter socket after measuring at the battery (with the ignition on).

Is it or is not Calcium?
 

Various posts on various threads mention calcium and antimony re batteries. The Lucas Classic and some Halfords batteries are apparently NON calcium and described as lead acid but how do we know that. All the batteries are lead acid. I’ve just had a browse in my local Halfords. Their calcium batteries are coded as HBC*** clearly marked as calcium, and their alternatives are coded HB*** lead acid and no mention of calcium. But other brands do not make it that obvious. My current Bosch battery silver 096 S5 008, which is now 5 years old, is marked as Silver, as was it’s predecessor, which lasted 12 years, but no indication as to whether there is calcium present. My current battery only shows 12.27 volts after standing overnight and sometimes less than that. I suspect that it is actually a calcium battery, but not marked as such. It still easily turns the engine over though. I’ve trawled around t’internet and have been unable to find any batteries marked as “non calcium” or “antimony” in their descriptions/specifications.

PS: I have a USB device, which also shows battery voltage, plugged into the cig lighter socket. I’ve compared it’s displayed voltage against the actual voltage at the battery whilst the engine is running and it is always 0.6 V less than the actual battery voltage. When driving it indicates a charge voltage of 13.1 or 13.2 so I presume that the alternator is providing 13.7 or 13.8. However, when the ignition is first switched on, prior to start up, it shows 11.9v or even less which would seem to indicate that the battery voltage is actually 12.5.

Just looked on the Tanya (Lucas) website and looking like they are no longer supporting lead-acid batteries as items discontinued and for the 745 its a lead/calcium jobbie!

Bob :)

Many good points there Ian - your Bosch Silver battery is Silver-Calcium and you must be one of the lucky ones that the battery has a lower concentration of silver-calcium than it should and consequently charges ok on 14.4V from your alternator - unless of course your alternator has been replaced with a later "smart" alternator.

As for the USB device, the calibration of those isn't great - i have two similar devices, one is a twin charging USB port with built-in voltmeter and the other is a combination voltmeter, clock and internal/external thermometer. Both are aftermarket items from Chinabay.

At 14.0V battery/system voltage, the latter of the two items reads 13.7-13.8V, at system voltage of 14.4V it reads 14.4V.

The other one can read anything up to 1V above the system voltage so i've seen it reading 16.1V but when the voltage drops to 13.7-13.8V, it's accurate - lower than that it shows 11.6 when the battery is showing 12.2V.

For reference, the former of these is on a system that charges at 14.4-14.0V and the latter on 15.1-14.7V, originally the latter was also 14.4-14.0V but i've boosted it to cope with the calcium battery that landed when i ordered a non-calcium variety.

Well, I didn't know that so thanks for enlightening me.

I will check current (electricity pun) battery to see if it is silvery.

Please could you tell me where all the earth leads are? As I see it, there is an earthing point just behind the battery on the chassis rail (left hand side, front of engine bay as you stand in front of car). There are a pair of plaited or braided earth cables from bulkhead to block (middle of engine bay and closest to the scuttle/windscreen). I assume there is something meaty hanging from the gearbox or something?

Cheers,

F

Thats the main earth points in the engine bay. But all electrical problems are not earth faults. Probe with a meter first, if you don't have one, buy one they are about £5. Start with the starter solenoid, stuff the probe down the back of the cover fot the little spade clip, negative on the battery negative look for a voltage when you activate the starter.


As for the calcium battery story, there are differing information sources on the internet. Daves wikipedia entry link features a curcular reference, whereby the wiki references an article page and the article page references the wiki page, I consider it untrustworthy. The story which makes more sense to me is that calcuim batteries have a higher charge "tolerance" than antimony batteries. This what experts like Yuasa say, meaning it works fine with lower voltage charge systems, it just charges slower than in modern cars designed for it. I use a Bosch S4 for several years in mny 360, and have now moved this to my daily 940. Its an excellent battery. I have had problems with my charging system running slowly (on a lead antimony battery), but this was due to voltage drop and resistance in the joints, the lights were also noticable dimmer than they should be. Fixing the charging restored the lights too.

Dave we have debated this before, to restate

There are many reference by trustworthy sources explaining that the calcium change increases the charge tolerance, this does not increase the starting charging voltage. 12V batteries will start charging at any voltage above about 12.6V or so, its just very slow. If there is energy going into the battery it is charging. Even the dodgy wiki states that the problem is the battery not getting fully charged, not that it starts charging at a higher voltage. It will not get fully charged simply if it is not given enough time to charge. This is a common today in new car bought by pensioners who drive the car for 5mins to the shop.
The history seems to be a vehicle manufacturer (Ford) stating that you cannot fit other types of battery other than the one supplied by them (requiring a specific calcium chemistry). There are many online reference specifically dissagreeing with this and that it is classic anti-repair misinformation.
There are also a number of people experiencing charging problems with newer batteries, this guy tells you all you need to know';
"I'm just going to ignore the science, we don't need facts", he then goes to show his charging system is working at 13V-13.7V, which he thinks is normal (although he doesn't show the load state of the electrical system, possibly this is just at idle with no other loads).
He blames the battery because its calcium, and upgrades his charging system to 14.5V and for some reason his high load loses are now only 0.4V instead of around 1V. His system is now working at the voltage it was intended for some of the time, other times its higher than it should be (14.1-14.5). Possibly it was just his brush/regulator module that was the problem.
https://youtu.be/RQFttbZnIfw

You are correct that we have debated it before Tony, however you are incorrect in almost everything else you state.

Firstly the nominally 12V battery fitted to most of our cars is 6 cells, each of 2.2V each = 13.2V. To even get those to charge, the voltage needs to be a minimum of 0.1V per cell above that, viz 13.8V but to get the battery to the gassing point which it needs to do to desulphate, it needs to be in the region of 14.4-14.0V consistently.

Using silver-calcium as a coating on the plates of lead-acid batteries instead of lead-antimony increases the gasing voltage by ~0.1V per cell so 15.1-14.7V to charge at the gassing point. Without reahing the gassing point, the battery will sulphate rapidly, rendering it fairly useless in very short order.

If i'm so wrong about this, why have so many manufacurers increased the charging voltages on their vehicles to cope with calcium technology batteries? They have been in use for ~25 years now and caught me out at first but i was 25 years younger then and found someone somewhat older that had already encountered them and was explained the facts to by them. These facts have not changed in a quarter of a century and neither have the laws of physics.

For other batteries that do not require any desulphation techniques during recharging, what you say is likely to be correct - however for automtive batteries and similar, it's not. :nah:

As for calling the wiki article dodgy, there are many of them, each giving similar information, are they all dodgy? As for the YT guy saying he's going to ignore the science, i'd call him a congenital halfwit but that would be over-generous by at least 7/16!

Gassing is the bit you need to avoid. Anything above 12.9V (2.15V per cell) is fine according to my research. 14.4V just happens to be the max stated for most batteries to avoid gassing. 12.9 to 13.3V isn't worth arguing about. A 940 charging at 13.3V would be slow charging and considered faulty at 13.3V.

The datasheets for Bosch S4 and S5 both state for standard charging (meaning continuous) that 14.4V is the "maximum". Sadly most battery datasheets are rather limited, it seems this information is privelaged, but I can say for certain that either Bosch batteries have reduced their charging range or they are perfectly compatible with old volvos despite them using Calcium.

https://www.ez-catalog.nl/Asset/3c4b...-S5-007-EN.pdf

My experience also says they work just fine, if you have a reasonably well working charging system, even over short journeys.

The reason I provided the halfwit link was to show a potential explanation for this "belief". Its more common now for old cars to have calcium batteries and faulty/poorly performing charging systems. Due to this type of misinformation rip-off mechanics will simply sell you a new battery, blame the calcium until you come back a year later with the same problem with a different battery that has calcium but doesn't state it.

There are also a number of different kinds, Yusas talk about Silver Calcium and Calcium/Calcium. It looks to me like all batteries now are Calcium instead of Antimony due to the reduced temperature aging characteristics, and increased voltage tolerance. The lastest types being AGM and EFB for start stop use, and you will want to drive those as hard as possible for recharging.

While it is hard to prove one way or another, I do think if there was a difference it would have to be stated in the datasheet. That is where the court will draw the line in a claim.

That data sheet is March 2008 Tony, i wonder if Bosch have updated it to reflect the correct charging voltage? To clarify, when i said it needed to be gassing, i should have said "just short of gassing", you don't want excessive gassing, that's certainly agreed!

The trouble is, most mechanics and most independent car accessory/spares shops don't actually know the correct charging voltage for calcium batteries. I had this argument with the owner of my local car accessories/spares shop and explained it to him and he wouldn't have it, kept insisting the customers alternator was faulty. I suggested a "normal" lead-acid battery with lead-antimony in stead and the next time i went in, the owner made a bee-line for me and thanked me for helping and apologised for not believing me. He had apparently got his battery rep to check and what i'd told him was confirmed after the rep found out as he didn't know at first.

For the record, i have diagnosed many charging faults, stripped and reconditioned (not rebuilt, there's a big difference!) many alternators, starter motors and other things. When i say "many" i don't mean 50 or 100 but thousands that i never kept count of. During the various processes of testing and reconditioning, each alternator was tested on a test bench, purpose built for the job to maximum output and if the alternator on test didn't achieve 14V at maximum output, it wasn't working correctly. Please note this was before "smart" alternators that detect by some witchcraft i haven't looked into whether they have a "normal" or calcium battery and adjust the output voltage accordingly.

As for buying an "adjustable" voltage regulator for that Bosch alternator in that video, there is a more cost effective solution which is to cut the earth tag off the regulator and replace it with a 10A rectifier diode, forming a loop on the end to replace the ring on the end of the earth tag. It's fiddly to do but saves a few £££ but needs no separate setting up.

I did similar on my Rover alternator but as that is battery sensed and not machine sensed, i could do it by cutting the battery sense wire, fitting a 2-pin Supaseal socket and using two plugs, one with a simple wire link and the other with a 10A rectifier diode in it. With this arrangement i can switch between 14.4-14.0V (standard output) and 15.1-14.7V (boosted voltage for calcium battery) but as i currently have a calcium battery on the ROver, i'm obviously running with the boost diode in.

If/when i need to do the same to the Volvo, that's the method i'll use. :thumbs_up:

Evening chums,

I am keen to sort this but there has been no problem since the last.

At the weekend I will begin to figure it out and until then, I have a new battery in the footwell and a jumpy box and jump leads.

Cheers,

F