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Post by Nick RS on Feb 17, 2013 21:30:58 GMT
I need to replace the ailing battery in my 18/85 but before doing so I thought it worthwhile seeing if there was anything that might have caused the decline of the old one. No point in buying a new one only to have it go the same way in a few weeks time. Feeling my way through car maintenance I find the articles in Practical Classics and similar a great help. The one on the use of a multimeter lead me to discover a current drain. Following the guide I set about removing the fuses one by one. The collection in the driver's footwell made no change so I then went for the ones in the AMP box on the bulkhead. The circuit protected by the middle fuse is the culprit, and Mr Haynes says it covers items independent of the ignition being on. The draw is 0.6amps and my first thought is to the radio installation. - any tips or suggestions for other things I should be testing? I am sure there there could well be a long list.
Nick
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Post by dave1800 on Feb 18, 2013 0:08:57 GMT
Sounds like fun! 0.6 Amps is quite a lot and enough to discharge the battery over a few days. The obvious things to check first are: boot light switch problem (take the bulb out ) radio/CD player etc - disconnect in case on/off switch not working properly if you have an alternator a leaky diode could allow discharge - disconnect plug if a dynamo also disconnect - could be control box the clock is on all the time but it should only take a very low current. Some clocks I recall were mechanical but wound up electrically. If like that you could have read the current while it was winding - check again to see if it is still showing 0.6 amps. Then carefully check all wiring that look as though it has been changed and and non standard accessories including a car alarm. Sorry forgot - you have an electric water pump. I believe some of these may be programmed to continue circulating the water for a short while after the engine is turned off. 0.6 A wouldn't be enough to turn the pump unless it is going very slowly - but you will have a computerised control box managing this pump I guess so that's on your list too - not sure how far down the list though - sorry! After that unless I have missed something it's a methodical check of all the wiring. regards David I need to replace the ailing battery in my 18/85 but before doing so I thought it worthwhile seeing if there was anything that might have caused the decline of the old one. No point in buying a new one only to have it go the same way in a few weeks time. Feeling my way through car maintenance I find the articles in Practical Classics and similar a great help. The one on the use of a multimeter lead me to discover a current drain. Following the guide I set about removing the fuses one by one. The collection in the driver's footwell made no change so I then went for the ones in the AMP box on the bulkhead. The circuit protected by the middle fuse is the culprit, and Mr Haynes says it covers items independent of the ignition being on. The draw is 0.6amps and my first thought is to the radio installation. - any tips or suggestions for other things I should be testing? I am sure there there could well be a long list. Nick |
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Post by Nick RS on Feb 18, 2013 21:04:05 GMT
Thank you David, a good list to have a go at over the next few days. The water pump does run on for a minute or two after switching the engine off so I will check the control box too. There is a lot of additional wiring on this car, I may be some time.
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Post by Penguin45 on Feb 20, 2013 1:12:18 GMT
Off the wall thought, Nick - diode in the rectifier pack. I got caught out with this many years ago with a Cortina. I knew little about cars back then - various friends and experts looked at it and no-one solved it. Just came home every evening and stuck it in charge. Eventually it conked and the charging light came on when driving, so got a recon alternator and the problem disappeared. And my neighbours stopped tripping over the cable running out across the pavement!
Chris.
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Post by Nick RS on Feb 20, 2013 21:55:06 GMT
Chris, that's definitely a good call which I will add to David's list for my weekend's activity. My charging light has sometimes been coming on at mid revs only to go out again when I slow down. At least I assume it is the charging light as it is yet another non standard fitment, this time in the middle of the wood panel shared with the ignition slot.
all part of my education....
Nick
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Post by Penguin45 on Feb 21, 2013 20:10:43 GMT
I really will have to pay more attention when posting late/tired/outside beer........... David has already mentioned the alternator. Doh!
Chris.
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Post by dave1800 on Feb 22, 2013 1:13:29 GMT
Nick IF it is the charging light and not something to do with your electric water pump or another intriguing mod this could suggest it's worth checking the alternator first - disconnect it and see if the parasitic drain falls. If it does, this may not be totally conclusive however as someone could have wired something else to the battery voltage sense connection to the alternator ie the wire that is connected to power with the ignition turned off (they shouldn't have done this but who knows?). At the very least it will point you in the right direction. You can quickly check the alternator function without having to insert an ammeter if you have a digital voltmeter. Switch on everything electrical and note the voltage at idle and through the engine range especially when the charging? light comes on. If it falls below a minimum of around 13.4 volts above 900- 1000rpm this suggests the alternator diode pack / voltage regulator and possibly brushes need replacing. Good luck! David Chris, that's definitely a good call which I will add to David's list for my weekend's activity. My charging light has sometimes been coming on at mid revs only to go out again when I slow down. At least I assume it is the charging light as it is yet another non standard fitment, this time in the middle of the wood panel shared with the ignition slot. all part of my education.... Nick |
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Post by Nick RS on Feb 23, 2013 11:15:33 GMT
Interesting.
I tried to be as methodical as possible with this.
Checked battery voltage - 11.9v (normal for this battery, I know I need to replace it).
Checked current drain - 0.6AMP same as before.
Disconnected alternator, tested again 0.05AMP once water pump woke up and went to sleep again.
Reconnected alternator, tested again 0.05AMP - huh?
Then I ran the car at various speeds and the voltage was just over 14 regardless. The charging light came on, still 14. (the voltmeter in the car was very close to my multimeter reading so I used that). Then switched it all on viz: headlamps, spotlamps, fogs, heated rear screen, hazard flashers and got it down to about 13 to 13.5 volts, slow and fast speed running didn't make much difference with if anything slightly lower voltage at higher revs. Interestingly the indicators caused the voltmeter to flick back and forth in by one volt at each flash (normal???). I ran the engine until the fan cut in and with everything on got it down to 12 volts.
Let it all cool down a bit and switched off. Battery now reading 12.1 volts and the current drain 0.05AMP. Now I know that my IT department at work say "Have you tried unplugging it and switching on again?" but I didn't think this applied to alternators. I don't like ignoring warning lights so believe I may still have a problem but as you know I am no expert. May leave it a few days and test again.
I think my alternator came out of a Nissan Primera but if I were to replace it is a lucas 18ACR the or its modern equivalent the best to go for?
Still a bit confused but grateful thanks David and Chris for pointing me in this direction first and saving me a chunk of time.
Nick
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Post by dave1800 on Feb 23, 2013 12:00:32 GMT
Nick Without getting too technical - if you are measuring the voltage anywhere but at the battery it will be affected by what is connected to that particular wire. For example it appears as though your indicators are connected to the same wire as the voltmeter feed so they cause the 1 volt drop in that feed but not necessarily what is seen by the battery. Again the 12.1 volts when the fan cuts in may not indicate insufficient charging current, you would need to repeat this all electrics on test and see if there is 13+ volts at the battery. Your battery voltage when everything is off should settle around 12.6volts - leave it half an hour or so after running the car. You can't draw any hard conclusions about the battery unless you fully charge it, leave it overnight with nothing connected and see if it is still above 12.4v minimum. There are battery load testers but you generally know if a battery is failing. Another easy test is to switch on the headlamps, everything else off and see if the battery voltage falls off noticeably after half and then one hour. If it does it does need replacing. I will let others advise on the alternator but at a minimum it must be able to deliver sufficient current + about 20-30% reserve minimum - preferably 50-100% reserve - to drive all the electrics, which you need to add up. (Watts/13.8V=current Amps). No idea why disconnecting the alternator has cleared the discharge fault - are you sure the "charging light" is actually that and wired correctly. If the light comes on it should correlate with a fall in output voltage and normally indicates a failed diode pack in the alternator. But your readings suggest that may not be the case here. I guess one remote possibility is that a leaky diode finally went open circuit and stopped the 0.6A discharge through it but that's just speculation by me. They are easy enough to test once out of the alternator - low resistance one direction - very high (meg- ohms the other). The only computer you have on board I guess is controlling the water pump. I suppose it could have locked up, but not really very likely that it would discharge 6watts without getting very hot although it could be passing that current through the water pump motor ; the joys of car electrics.  Unfortunately you are going to need to monitor this and hope it is a one off issue. I think you should be able to do this by watching the in car voltmeter reading with the engine off but ignition on - each morning before starting the car if it falls gradually back down over a few days the battery needs replacing. Remember if it is very cold the battery voltage will fall. I guess your priorities are to (a) fully check out the alternator then (b) probably replace the battery If the 0.6 amp discharge happens again I would suggest leaving the alternator connected and disconnect the power to the electric water pump for a few minutes - this is just a guess of course. It's funny this thread is running; last night my neighbour called me to tell me I had left the Toyota's lights on. I went out and found the brake light switch had stuck on. Regards David |
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Post by Nick RS on Feb 24, 2013 22:13:49 GMT
Thank goodness for the wonders of the Internet. I managed to find a set of instructions on the Davies Craig site for my electric water pump and controller. This could be a whole can of worms and I may make it the subject of a future thread - "wot, no 'stat in your motor?"
Anyway it says part of the kit is a red test lamp to be mounted on the dash. So this is the red light that has been alarming me on drives. My excuse is that it is by the ignition key, comes on with the ignition and goes off when the engine starts. It is however a warning light and accompanied by the flashing lights on the control unit itself (they're not supposed to flash) point to what the likely fault is. Some of them relate to over or under voltage and this seems likely after my tests this weekend. I'll just have to wait till next weekend to take it on a run and see exactly which ones come on and off and I'll need to pull over as it's buried in the passenger footwell.
The real charge light in its original position has not lit during this episode.
Another day wiser - N
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Post by Penguin45 on Feb 25, 2013 0:45:36 GMT
What are you intentions for the car, Nick?
Some of this stuff, whilst interesting, is just plain unnecessary for a classic/occasional use or even moderate daily driver. You might consider converting back to a more standard set-up. Mechanical pump/belt/hoses are freely available.
Just a thought.
Chris.
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Post by Nick RS on Feb 25, 2013 19:23:05 GMT
I don't use the car as a daily driver so Chris your thought is a valid one. If the electric pump starts giving trouble I'll get all the bits and put it back to standard, along with the electric fan as the whole lot seems to go together as an integrated package. I think the radiator has different outlets to a normal one so this may prove a headache.
I bought the car to see if classic ownership was for me so I didn't spend a great load of money on it figuring that if I didn't like it, it wouldn't hurt too much to move it on at a later date. I want to enjoy it over the coming season and see how it goes. If I keep it then I will probably change a few things. The steering column as mentioned elsewhere definitely has to go. With hindsight I would have bought a standard spec car.
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