Hi, a couple of weeks ago I had to change my parking light bulbs. To do this I disconnected the batteries -one at a time- to access the bulbs. A few days later whilst driving at night, several warning lights came on on the clock panel and my headlights were very dim. I got home but next day it would not start. I charged the batteries and started the engine. I put a multimeter on the batteries and revved the engine and the voltage increased but only to 12.8 V. Next day I checked the voltage in the batteries again and only had 12.2 V. The batteries were new 3 years ago supplied by Toyota main dealer. The ignition light is not on when the engine is running so to me that indicates it is charging. Anyone got any helpful comments please ?
Don't like the adverts? Click here to remove them
Charging Problem
- Thread starter Piquet
- Start date
Hi, check your connections to your batteries are tight and that none of the wires have become broken or damaged. Terminals sometimes need loosening, opening out slightly then tapping on gently before tightening. Terminals also need to be clean and free of darker great lead oxide.
Charging voltage should be 14.2 just up off idle measured at the battery terminals. If it's anything less then the alternator may be faulty or a connection to it may be corroded. Check the plug on the rear of the alternator and give it a wiggle while watching your volt meter on the battery. See if it has any effect on the voltage there. If it jumps up to 14.2 then you need to stop the engine and remove and clean the plug before refitting it with a dab of Vaseline on the contacts. If it's the sealed type then check the seal is good.
Let us know how you get on.
Charging voltage should be 14.2 just up off idle measured at the battery terminals. If it's anything less then the alternator may be faulty or a connection to it may be corroded. Check the plug on the rear of the alternator and give it a wiggle while watching your volt meter on the battery. See if it has any effect on the voltage there. If it jumps up to 14.2 then you need to stop the engine and remove and clean the plug before refitting it with a dab of Vaseline on the contacts. If it's the sealed type then check the seal is good.
Let us know how you get on.
Hi, Star Cruiser, thanks for your reply. I was reading your advice to someone on another thread where you told him his alternator could be U.S. as he had disconnected the batteries. I was`nt sure what volts I should get at batts but thought 12.8 was low. The batt terminals look very clean and tight. I will however remove them tomorrow clean and re-fit. If that fails I will check that plug. Many thanks for advice.
Regards.
Pete.
You're welcome Pete, if they're tight and more or less clean then they should be fine though there's no harm in them being cleaner. Check chassis earth cables and block earth straps too. If they're not easy to get to you can test voltage across from battery -ve to a clean patch on the engine or alternator body on volts, should be zero across anything that is meant to be connected. Also check your fuses both under bonnet and internal if you have both and just look for the silly things as there is a voltage sense wire that should go direct to one of the batteries. I'm not sure if the alternator is run from the ECU on your truck as some of the more modern ones are. Robson and Francis may be your next call for a new alternator if it's not charging. Mike will likely be able to tell you if that one is controlled by the ECU or is a standard one.
Hi Star Cruiser, today I took all the battery connections off (one at a time) and wire wooled the terminals. I cleaned inside the lugs as well, then applied some paraffin wax and re-assembled. I checked voltage across -ve to engine block with engine off. 00.00 volts but with engine running there was 9.00 mv on near side battery and 1.00 mv on off side battery. I checked the charging voltage and that was 13.0 volts. Is the millivolt reading significant ? Thanks for your help. Regards. Pete.
The milivolt reading is insignificant Pete. If you had a bad connection you would get a reading somewhere closer to 12v. At millivolts you're only reading the error in the multimeter combined with voltage drop in the cables. 13v on the other hand is significant; your alternator is not putting enough in. Charging voltage should be 14.4v for bulk charging. At 13v it's not got the battery to start charging.
Try the plug wiggling and if all your fuses and fusible links right by the battery are intact then there's a good chance your alternator is duff. It may have a faulty diode which can drain batteries pretty quickly. Or it could have dirt in the brushes stopping them making good contact.
Two options, take the alternator off and refurb it yourself. Contact Mike at Robson and Francis and see if they can supply you the bits. If not, contact Mike and obtain a replacement alternator. In any case, if you explain your symptoms to Mike he will probably recognise them and advise accordingly.
Try the plug wiggling and if all your fuses and fusible links right by the battery are intact then there's a good chance your alternator is duff. It may have a faulty diode which can drain batteries pretty quickly. Or it could have dirt in the brushes stopping them making good contact.
Two options, take the alternator off and refurb it yourself. Contact Mike at Robson and Francis and see if they can supply you the bits. If not, contact Mike and obtain a replacement alternator. In any case, if you explain your symptoms to Mike he will probably recognise them and advise accordingly.
Don't like the adverts? Click here to remove them
