Required battery voltage to start Vitesse

[daverclasper]

Hi. I noticed my cranking was slower than usual on two occasions, from cold, though battery had been charged and reading about 12.75 V.

Car is running a dynamo. I did about a 40 min drive in slow city traffic, plus traffic lights. This was with headlights on.

After stopping, no juice to restart. Battery V was 12.5, which I thought should be enough to start a hot engine (Car a very good starter).

Battery is about seven years old.

Time to get battery tested maybe?.

Charging system was faulty, though now appears a lot Better, after replacing Control Box, so thinking battery not good, even though still holds voltage.

Cheers, Dave

 

[Colin Lindsay]

Dynamos are usually less good than alternators at running ancillaries plus recharging the battery; on long steady runs they'll charge ok, but on short runs at lower revs they can sometimes struggle to power headlights and recharge the battery. A tired starter can also draw a lot of power; check the cables and maybe give the starter an overhaul. My 13/60 was very lazy even on a fully charged battery so I swapped the starter and there's a marked improvement in spins.

[NonMember]

A life-expired battery will probably still give 12.5V with no (or very little) load. It's what it does when you hit the starter that matters. A good battery will hold up above 11V, a dead one will nose-dive to below 6V. In between those could be on its way out or just not been charged recently.

[Chris A]

15 minutes ago, Mathew said:

possible to have the volts look ok but the umph missing

Sounds like me. 😒

[johny]

I believe batteries are made up of multiple cells connected in series and parallel. You can have the series ones working to give the correct voltage but lost some in parallel so reducing the amps available. Only way to test this is with a heavy duty discharge tester which are difficult to find these days so most people just stick a new battery on...

[Wagger]

If you have conventional lights, measure the battery voltage with Dipped lights 'On'. It should remain above 12v. If not, the battery is not charged enough or it is knackered.

If you have the kit (a voltmeter and a DC current clamp) measure the volts and current no load and with all lights on. Divide the difference in voltage by the difference in current and that will give you the internal resistance of the battery. A result of 0.05 is too high because a starter current of (say) 100 amps, would result in a battery voltage of 7v.

If you do not have current clamp, knowing the resistance of the battery negative lead will enable you to measure the volt drop across it and calculate the current. That would also enable you to find out if the starter resistance is too low due to a shorted winding.

Some of us used to have 'Shunt' resistors for our AVO 8 meters. Using a 0.01 ohm shunt will give a reading of 1 volt per 100 amps.

Series ammeters are best avoided, they cause voltage drop or blow  internal fuses. I welded two AVO 8 meters up in my teens before I learned this.

My current clamp cost a mere £50. Well worth it. It has 2 Amp and 200 Amp ranges ac and DC.

Hope that is of use and not too tricky to understand.

[dougbgt6]

3 hours ago, Wagger said:

My current clamp cost a mere £50

And it will tell you you need a new battery, which will cost around £40.

db

[Wagger]

I have used the current clamp for over ten years to test domestic supplies, cars, inverters and help find current drains on modern cars. It also tells me which way the current is flowing when the dreaded ignition light comes on.

I have used it to help others too, for diagnosis of domestic and car faults.

My battery on the main car is over £100, even for a 3 year warranty.

OK, you may not need one, so just do the simpler tests.

OK, we buy tools that we need only occasionally, like the Hub Puller.

 

[Ian Foster]

Dave

In my experience seven years is about an average innings for a modern battery, although some can perform happily for much longer.

I suspect it depends on usage and a battery on a daily driver will probably last longer than one that sees intermittent use, unless it kept permanently 'conditioned' on a smart charger.

You mentioned that you had had charging issues and this may have affected lifespan.

One other nugget...check the earth strap connections (battery to body/body to engine) as these can be a source of voltage robbing resistance.

Ian

[Wagger]

16 hours ago, johny said:

I believe batteries are made up of multiple cells connected in series and parallel. You can have the series ones working to give the correct voltage but lost some in parallel so reducing the amps available. Only way to test this is with a heavy duty discharge tester which are difficult to find these days so most people just stick a new battery on...

A 12v lead acid battery is six 2v cells in series. It was always considered bad practice to connect batteries in parallel, unless they were the same model, same age and in the same state of charge. You can find how to do it on other sites and it is done on motorhomes. However, they need to be left connected permanently or one will discharge the other until they are in the same state of charge. Must always be well ventilated too as they give off Hydrogen and Oxygen in a very explosive ratio.

[dougbgt6]

11 hours ago, Wagger said:

OK, we buy tools that we need only occasionally, like the Hub Puller

Wagger I sense I may have given offence, for which I apologise   Regarding the above, I'm a tight wad, I don't have a hub puller or spring compressor, I hire them from the Club. One of the benefits of membership. 

I did like my ammeter more direct, by the time you notice the voltmeter has gone into decline it's too late. Sadly I decided it had to go as the loom was getting overly warm. However, I now have a clamp like ammeter, cost £10. It's not ideal, it has LCD read out, but good enough to tell what's going on. 

Doug

 

 

 

[Clive]

the old fashioned test was to wait until dark (ish) but headlights on, then flick the starter. If the lights alll but go out, battery knackered. You are using the lights as a voltage indicator. 

But it is usually a cold spell that exposes a failing battery, warmer days they will be OK, cold, no-go. Time to replace.

I want to know where you can get a quality battery for £40... they seem to have gone up alarmingly, just like most things.

[Pete Lewis]

Dave  at 7 years old  i would take it to a battery supplier they will run a full sort of  semi computerised  test with a print out of the battery performance 

but at 7 years i fear its time to buy one for christmas 

12,5 volts is just not enough and  when sulphated will hold volts but no amps are available  in the cold this all gets worse 

so sorry think its wallet time  

Pete

[Wagger]

35 minutes ago, dougbgt6 said:

Wagger I sense I may have given offence, for which I apologise   Regarding the above, I'm a tight wad, I don't have a hub puller or spring compressor, I hire them from the Club. One of the benefits of membership. 

I did like my ammeter more direct, by the time you notice the voltmeter has gone into decline it's too late. Sadly I decided it had to go as the loom was getting overly warm. However, I now have a clamp like ammeter, cost £10. It's not ideal, it has LCD read out, but good enough to tell what's going on. 

Doug

 

 

 

No offence taken Doug, I am sometimes 'Over helpful' and go OTT on everything. My intentions are to assist, not appear as a 'Know it all'. I spend my money on tools, not chocolate. Wife does the opposite. I am forever hiding the stuff. Mice found it once. That's one way of dieting.

[dougbgt6]

38 minutes ago, clive said:

I want to know where you can get a quality battery for £40... they seem to have gone up alarmingly, just like most things

Euro car parts currently have a Lion 063  on 3 year guarantee for £36.84. You may not consider Lion quality, but I'm finding none of them last too long theses days!

Doug

[Clive]

7 minutes ago, dougbgt6 said:

Euro car parts currently have a Lion 063  on 3 year guarantee for £36.84. You may not consider Lion quality, but I'm finding none of them last too long theses days!

Doug

Hmm, no, wold not be on my shopping list. But a couple og years ago £40 would have bought a proper batery. I think £50 now. Only 25% more... ouch. Wish my income had gone up 25%.

[Wagger]

Made another really stupid mistake way back. Left door open on my classic for a week. In my 'Hurry' I connected the charger the wrong way round. Two days later engine turned over with much popping and banging. I then noticed it was turning the opposite way. So, I left door open for another week, recharged it the correct way round and the battery lasted another five years.

I never tried it again, but might have discovered something at the time. Accidental de-whiskering of de-sulphiding it internally.

[Colin Lindsay]

54 minutes ago, Wagger said:

Made another really stupid mistake way back. Left door open on my classic for a week. In my 'Hurry' I connected the charger the wrong way round. Two days later engine turned over with much popping and banging. I then noticed it was turning the opposite way. So, I left door open for another week, recharged it the correct way round and the battery lasted another five years.

I never tried it again, but might have discovered something at the time. Accidental de-whiskering of de-sulphiding it internally.

Interesting!! Never thought of it turning in reverse (maybe you should have left the opposite door open for a week?  ), but then I swapped over wiper motor terminals after reading that doing so would use the previously unused parts of the mechanism and so extend the life. Cost me a new loom, that did. 

I also blew my first alternator by connecting the battery back to front, too. Bit of a learning curve, these things!

[dougbgt6]

Ha! A son-in-law followed me around the garage wanting to help, I let him put my battery on charge. The next day I put the battery in it's box, re-connected and the alternator went Phut! My fault, I should've checked his work. A new set of diodes, a simple repair, but It took 4 hours with the lights on main beam to flatten the battery. One of my Uncles reckoned reverse charging was the way to revive a dying battery, but it didn't work for me. I charged the battery the right way round, but no joy, it was a ex-battery.

Doug

[dougbgt6]

18 minutes ago, Colin Lindsay said:

I swapped over wiper motor terminals after reading that doing so would use the previously unused parts of the mechanism and so extend the life. Cost me a new loom, that did.

That's one of Uncle Pete's tricks, but it's the spiral gear you have to turn over I think? He probably told you the wrong thing on deliberates. 

Doug

[Chris A]

1 hour ago, Wagger said:

I spend my money on tools, not chocolate. Wife does the opposite. I am forever hiding the stuff. Mice found it once

wife caught me out today! Got back with the shopping and put the bags in the 'cave' prior to sorting while she dealt with the stuff for the fridge. She found the bag with the 3 bottles of Scotch . . .OOPS! (it was on promo last day tomorrow)

[Pete Lewis]

me deliberate   ............only turn the spiral rack over not the terminals   

and turn the wheel boxe gears  180 deg  so your rack  runs on unused teeth 

Colin was just testing the physics of the triumph harness smoke alarm system

Pete

 

[JohnD]

14 hours ago, johny said:

I believe batteries are made up of multiple cells connected in series and parallel. You can have the series ones working to give the correct voltage but lost some in parallel so reducing the amps available. Only way to test this is with a heavy duty discharge tester which are difficult to find these days so most people just stick a new battery on...

Not so, Johnny.    Yes, multiple cells, because the most that a single lead/acid cell can produce, fully charged, is 2.1V.    Car batteries stack six of those in series to give the 12V that they are designed to run off.   Vehicles that use 24V will have two such batteries in series to get that.

Batteries, or cells, in parallel, would not sum their voltages, but can provide more charge to get a car started.   That's what you do when you use jumper leads from another car or an extra battery.

John

[Wagger]

4 hours ago, Chris A said:

wife caught me out today! Got back with the shopping and put the bags in the 'cave' prior to sorting while she dealt with the stuff for the fridge. She found the bag with the 3 bottles of Scotch . . .OOPS! (it was on promo last day tomorrow)

I once hid a tin of Cadbury's roses in the boot of the 'Spare' car. Man car had a puncture so my wife used the other one. She was caught on camera in a car park doubled over raiding the tin when loading in the shopping. Another shopper saw her and exclaimed. 'You must be desperate'.

[daverclasper]

Have a good Xmas everyone and thanks for all your input, very interesting and useful

Doug, are those Lions 063 suitable for 6 cylinder please?. Also, I assume, they are maintenance free (I guess they all are now?), if so, are they the ones that you can take the top covers off to top up if necessary? (I have been told they do exist?), as apparently useful, if running dynamo, as battery can get warm by overcharging, as not as accurate a Alternator setup?

Cheers, Dave