13.7v - is it enough?
Discussion
OK - some of you will remember the failed battery thread from a couple of weeks ago where I had a battery die and Halfords wouldn't exchange it under warranty as they claimed it had been over or under charged...?
Well, since then I've been keeping an eye on my charging voltage with a peak hold multimeter every time I've been anywhere and the highest voltage recorded has been 13.76volts so I was fairly happy that I wasn't getting overcharging.
Anyway, I drove into Southampton today (about 20 miles) to go see a man about maybe getting my door tops recovered and on the way in my temperature gauge showed excessively hot so I pulled over and stopped the engine. I did the usual bloke thing (give it a couple of minutes to notionally cool) and then bleed the pressure from the cooling system by cracking the swirl pot plug slowly but still ended up with a good but brief geyser which covered the windscreen, roof and wings with water so had to wander off and get some more water from the nearest sign of life which was about 1/2 mile away.
Now, I'll admit to one mistake - I left my sidelights on - but they're only a handful of watts per bulb and not a massive drain (18watts total for two front and two rear bulbs IIRC so 1.5 amps - battery should support that for a good day or so) but when I went to start the car again half an hour later the bloody thing was flat (or at least not enough juice to fire the starter).
RAC arrived, jumped my battery and she started first time ... he checked the charging current (a smidge over 25a at 13.7 volts) and declared it to be charging OK albeit a tad down on voltage but nothing to worry about. I'm dropping a little less than half a volt between alternator and battery terminal and as the battery is in the boot it's a longer cable run than standard.
Now, obviously I'm now concerned as to why the damn battery went flat so quickly (it's used every day but only for about ten minutes each morning and evening) and this was straight after a 20 mile drive so there should have been plenty of juice in it ... I'm just worried that I may have lost *ANOTHER* battery after less than two weeks and that I might have a duff alternator...
Thoughts? Opinions? Wild theories?
Phil
Well, since then I've been keeping an eye on my charging voltage with a peak hold multimeter every time I've been anywhere and the highest voltage recorded has been 13.76volts so I was fairly happy that I wasn't getting overcharging.
Anyway, I drove into Southampton today (about 20 miles) to go see a man about maybe getting my door tops recovered and on the way in my temperature gauge showed excessively hot so I pulled over and stopped the engine. I did the usual bloke thing (give it a couple of minutes to notionally cool) and then bleed the pressure from the cooling system by cracking the swirl pot plug slowly but still ended up with a good but brief geyser which covered the windscreen, roof and wings with water so had to wander off and get some more water from the nearest sign of life which was about 1/2 mile away.
Now, I'll admit to one mistake - I left my sidelights on - but they're only a handful of watts per bulb and not a massive drain (18watts total for two front and two rear bulbs IIRC so 1.5 amps - battery should support that for a good day or so) but when I went to start the car again half an hour later the bloody thing was flat (or at least not enough juice to fire the starter).
RAC arrived, jumped my battery and she started first time ... he checked the charging current (a smidge over 25a at 13.7 volts) and declared it to be charging OK albeit a tad down on voltage but nothing to worry about. I'm dropping a little less than half a volt between alternator and battery terminal and as the battery is in the boot it's a longer cable run than standard.
Now, obviously I'm now concerned as to why the damn battery went flat so quickly (it's used every day but only for about ten minutes each morning and evening) and this was straight after a 20 mile drive so there should have been plenty of juice in it ... I'm just worried that I may have lost *ANOTHER* battery after less than two weeks and that I might have a duff alternator...
Thoughts? Opinions? Wild theories?
Phil
13.7 volts is fractionally below the voltage the battery starts to gas, so thats fine. The upper voltage limits on a 12 volt battery are controlled by the point that all the lead sulphate is is back in solution as sulphuric acid, but this is also the point the battery starts to gas off so you loose fluid, so an alternator holds it just below this point. The voltage you are seeing is not a low battery charge voltage- so you have something else draining the battery. You need to disconnect the battery, and put a automotive type test meter that can measure a decent current (typically 10 amps) between the positive battery post and the connector, and see what the current draw is- Mind you anything that can drain a car battery in an hour should be getting pretty hot, thats around 500 watts draw .....
blitzracing said:
13.7 volts is fractionally below the voltage the battery starts to gas, so thats fine. The upper voltage limits on a 12 volt battery are controlled by the point that all the lead sulphate is is back in solution as sulphuric acid, but this is also the point the battery starts to gas off so you loose fluid, so an alternator holds it just below this point. The voltage you are seeing is not a low battery charge voltage- so you have something else draining the battery. You need to disconnect the battery, and put a automotive type test meter that can measure a decent current (typically 10 amps) between the positive battery post and the connector, and see what the current draw is- Mind you anything that can drain a car battery in an hour should be getting pretty hot, thats around 500 watts draw .....
Well that's a relief - sort of! 
Now to see what is draining the bugger...
Phil
I'm a mechanical ignoramus......but when mine was running fine in hot weather a few weeks ago, I pulled over because the driver was overheating and took the roof off.......and when I got back in and tried to start it again there wasn't a peep from the starter motor, not even a click. Battery was fine.....
If you are getting total silence from the starter motor in those circumstances, not even a slight whirr, yet it will start 15 minutes later for any other bugger, then it may be the well known hot start problem - fix is £40 from Modwise. Mine never fails since I got it and had it fitted by someone who knows one end of a battery from the other. Full instructions come with it if you have the brownie spanner badge.
If you are getting total silence from the starter motor in those circumstances, not even a slight whirr, yet it will start 15 minutes later for any other bugger, then it may be the well known hot start problem - fix is £40 from Modwise. Mine never fails since I got it and had it fitted by someone who knows one end of a battery from the other. Full instructions come with it if you have the brownie spanner badge.
Quietlybonkers said:
I'm a mechanical ignoramus......but when mine was running fine in hot weather a few weeks ago, I pulled over because the driver was overheating and took the roof off.......and when I got back in and tried to start it again there wasn't a peep from the starter motor, not even a click. Battery was fine.....
If you are getting total silence from the starter motor in those circumstances, not even a slight whirr, yet it will start 15 minutes later for any other bugger, then it may be the well known hot start problem - fix is £40 from Modwise. Mine never fails since I got it and had it fitted by someone who knows one end of a battery from the other. Full instructions come with it if you have the brownie spanner badge.
Cheers QB...If you are getting total silence from the starter motor in those circumstances, not even a slight whirr, yet it will start 15 minutes later for any other bugger, then it may be the well known hot start problem - fix is £40 from Modwise. Mine never fails since I got it and had it fitted by someone who knows one end of a battery from the other. Full instructions come with it if you have the brownie spanner badge.
Thanks for the suggestion - it's definitely worth considering but I've had her nearly three years now and she's not suffered at all from the infamous hot start issue to date.
The reason why I don't think it's the old hot start issue is she not only wouldn't even turn over "standalone" off the key but also when you did try to start then the alarm would often do it's low voltage bipping and buggering about - as soon as the RAC bloke hooked up his jumper cables then she popped to life almost immediately (took a couple of seconds turning to clear the excess fuel from the priming pulses from all the previous start attempts) so I'm pretty sure it's not the hot start issue - but, again, thanks hugely for the suggestion.
Phil
I had similar, would start some times, not others with anything from ten minutes to a week between attempts. It was traced back to a starter motor on its way out after being cooked by the hot manifold for years. Had it reconditioned and wrapped in some heat shield and it's been fine since (apart from when the trigger wire fell of some months later).
Not sure how this fits with it working with jump leads but I'm wondering if the RAC just caught it in a good mood! Either way, starter motor itself might be worth a look.
Nick.
Not sure how this fits with it working with jump leads but I'm wondering if the RAC just caught it in a good mood! Either way, starter motor itself might be worth a look.
Nick.
blitzracing said:
13.7 volts is fractionally below the voltage the battery starts to gas, so thats fine. The upper voltage limits on a 12 volt battery are controlled by the point that all the lead sulphate is is back in solution as sulphuric acid, but this is also the point the battery starts to gas off so you loose fluid, so an alternator holds it just below this point. The voltage you are seeing is not a low battery charge voltage- so you have something else draining the battery. You need to disconnect the battery, and put a automotive type test meter that can measure a decent current (typically 10 amps) between the positive battery post and the connector, and see what the current draw is- Mind you anything that can drain a car battery in an hour should be getting pretty hot, thats around 500 watts draw .....
Well - new battery in my multimeter as it died over the weekend (seems to be every bloody battery that gets near that car gets nuked - the one in the speedo is dead too so I have a zero mile Chimaera!) and checked the "standby" current draw this evening......380mA.
Now to start working through the fuseboard to see what's drawing power...
Phil
Bassfiend said:
Well - new battery in my multimeter as it died over the weekend
Yup - told ya so! 
The high voltage reading was your early warning sign of needing a new battery. The last time I measured 16V I bunged a new one in (borrowed from a smoke alarm) and got a more sensible 12-point-something.
Dr Mike Oxgreen said:
You need to change the battery.
The battery in your multimeter, that is.
You shouldn't be seeing 16 Volts anywhere, and I very much doubt that's a genuine reading. Put a new battery in your multimeter and try again.
The battery in your multimeter, that is.
You shouldn't be seeing 16 Volts anywhere, and I very much doubt that's a genuine reading. Put a new battery in your multimeter and try again.
pearly said:
I bet it looks 
, i haven't had the bottle to alter instruments in case I upset something 
It does look rather cool after the rather dull tan glow of the original fitment bulbs even if I do say so myself. Been an interesting "journey" as are most things to do with these cars ... have got through quite a few sets of LED bulbs getting to here I can tell you!, i haven't had the bottle to alter instruments in case I upset something I also wanted to do white rather than blue as it's a blue car with an all blue interior and - well - I also work in the HiFi industry where everyone and their brother stick as many bloody blue LEDs to everything as they can! (All the kit that we make is a very tasteful black and green thankyou.
)There are some that are absolutely useless for lighting gauges - the ones that have a single LED and actually look like a bulb might say that they're designed to disperse light but don't, and the ones that have lots of LEDs mounted on the sides are quite often significantly wider than the bulb base and so will either simply not fit by a mile or will snag on the way in or out but they do produce a much better blast of light to bounce around inside the gauge can.
Phil
Dr Mike Oxgreen said:
Bassfiend said:
Well - new battery in my multimeter as it died over the weekend
Yup - told ya so! The high voltage reading was your early warning sign of needing a new battery. The last time I measured 16V I bunged a new one in (borrowed from a smoke alarm) and got a more sensible 12-point-something.
Dr Mike Oxgreen said:
You need to change the battery.
The battery in your multimeter, that is.
You shouldn't be seeing 16 Volts anywhere, and I very much doubt that's a genuine reading. Put a new battery in your multimeter and try again.
The battery in your multimeter, that is.
You shouldn't be seeing 16 Volts anywhere, and I very much doubt that's a genuine reading. Put a new battery in your multimeter and try again.
I had been keeping an eye on the charging voltage for the last week or so and had been seeing typically 13.6 - 13.7 volts at the battery (my meter has a peak hold facility) which appears to be OK so not sure where that 16v reading came from.
Would be interested to see what the quiescent current drain on a few other chims out there is so that I have a baseline to work off ...
Phil
Bassfiend said:
Would be interested to see what the quiescent current drain on a few other chims out there is so that I have a baseline to work off ... Phil
The answer to your parasitic drain question on other Chims is:"It typically varies between high & ridiculous high"
There are lots of potential causes but I would check your door pin courtesy light switches first.
Often they appear to be working correctly but are actually energising the dim delay courtesy light relay without you knowing.
Because it's a fibreglass car the pin switches are a twin wire design (live & earth).
On my car the passenger side switch gave me loads of grief, so I replaced it with a new switch and made sure both were open circuit with the doors closed by building up the pusher button on the doors.
But no matter what I did the fault on the passenger side remained, it seemed the circuit was finding an earth at will.
Frustrated, I temporarily resolved it by isolating that circuit, problem solved, being a lazy sod I just left it like that.
The microwave sensor on the alarm seems to be another significant drain, if I leave the car for longer than a few days I now lock it then disconnect the battery using my Battery Brain device.
I know you use your Chim regularly Phil, so you really shouldn't need a Battery Brain.
Put your meter on the battery and start pulling fuses till you find the drain.
Just watch those pin switches
Edited by ChimpofDarkness on Tuesday 17th July 10:03
Bassfiend said:
Well - new battery in my multimeter as it died over the weekend (seems to be every bloody battery that gets near that car gets nuked - the one in the speedo is dead too so I have a zero mile Chimaera!) and checked the "standby" current draw this evening...
...380mA.
Now to start working through the fuseboard to see what's drawing power...
Phil
Phil, 380mA is only 4.5Watts at 12V. That was probably the interior light bulb assuming you had the door open when you were making the measurement. If so, try turning the lamp off at the switch and then making the measurement. In any case, that's a pretty small current drain, it should take a few days to drain a large battery at that level....380mA.
Now to start working through the fuseboard to see what's drawing power...
Phil
A simple way to check the charging system is:
1) Start Car and run at a normal idle
2) Connect a voltmeter directly across the battery terminals
3) Turn on headlights to main beam
4) Check the battery voltage
The battery voltage should read between about 13.8 to 14.2 volts
5) Increase engine speed to 1500 RPM
The alternator should now produce a battery voltage between 14.2 and 14.6
volts
If it is lower than 14.2 volts, the alternator probably has one or more bad diodes (This could be part of your problem)
6) Now, maintain the 1500 RPM and turn off the headlights (Run this test for one full minute)
"The battery voltage should NEVER Exceed about 14.8 Volts"
If it does, the alternators voltage regulator is probably Faulty, OVER CHARGING the Battery (I doubt this is your problem)
My guess is you are slightly under charging, this combined with a significant parasitic drain is causing your problem.
Run the charge tests, check the door pin switches, and start pulling fuses to isolate any other significant drains and you should be well on the way to sorting it out.
It's also worth doing a heavy discharge test on your battery, this is the best way to establish the true health of your battery.
Most decent old school mechanics will have a heavy discharge tester in their kit, it's well worth bunging him a drink to get the battery tested properly.
Just dont take it to one of the KwickFit type places, they typically just condemn every battery they see to get a sale
1) Start Car and run at a normal idle
2) Connect a voltmeter directly across the battery terminals
3) Turn on headlights to main beam
4) Check the battery voltage
The battery voltage should read between about 13.8 to 14.2 volts
5) Increase engine speed to 1500 RPM
The alternator should now produce a battery voltage between 14.2 and 14.6
volts
If it is lower than 14.2 volts, the alternator probably has one or more bad diodes (This could be part of your problem)
6) Now, maintain the 1500 RPM and turn off the headlights (Run this test for one full minute)
"The battery voltage should NEVER Exceed about 14.8 Volts"
If it does, the alternators voltage regulator is probably Faulty, OVER CHARGING the Battery (I doubt this is your problem)
My guess is you are slightly under charging, this combined with a significant parasitic drain is causing your problem.
Run the charge tests, check the door pin switches, and start pulling fuses to isolate any other significant drains and you should be well on the way to sorting it out.
It's also worth doing a heavy discharge test on your battery, this is the best way to establish the true health of your battery.
Most decent old school mechanics will have a heavy discharge tester in their kit, it's well worth bunging him a drink to get the battery tested properly.
Just dont take it to one of the KwickFit type places, they typically just condemn every battery they see to get a sale
In terms of drain, both the ECU and alarm will draw some power all the time, but never enough to drain the battery in the time spans you are seeing- this makes little sense- even an amp standby draw would give you a couple of days. I think the point above about loading up the alternator with the lights on is very valid to do a load check.
blitzracing said:
In terms of drain, both the ECU and alarm will draw some power all the time, but never enough to drain the battery in the time spans you are seeing- this makes little sense- even an amp standby draw would give you a couple of days. I think the point above about loading up the alternator with the lights on is very valid to do a load check.
I do usually get three or four days - it was just that for some reason last weekend the battery was killed much more quickly. That one I'm not wondering about too much given that it sounds like the alternator is charging OK. Now just trying to get a handle on what it is on mine that kills the battery in four days when some people are getting several weeks out of theirs. Phil
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