Mystery of intermittent battery light illumination in van - Page 1
Forum section: electronics / beginners

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 19, 2025, 10:39:46 am
content: I will preface that the electronics of the whole van is pretty weird. Sometimes the cd player power, yea it is an older vehicle, will go off for weeks then suddenly come back on again requesting pin code. Also the electric window on the driver's side would randomly roll itself down constantly. For this latter issue I have just unplugged the socket from the switch as it was distracting, and also inconvenient, to have it suddenly wind down when I am driving. I have sometimes still heard the mechanics clicking away behind the panel.Those other things I am not bothered about and just leave them as they are. The battery light issue however has been concerning.Sometimes it will come on while driving and stay on for random intervals, from a few seconds to perhaps 30 to 45 minutes or more. Depending on how long I am driving it may go off in between these intervals.I have checked the connections at the terminal and the alternator and neither seem loose. The battery itself does not seem to be discharged, having checked it when I got back when I first noticed it. The battery read full power. Are there other reasons that battery light comes on other than low voltage? Would it come on for overvoltage for instance? or some other reasons? as it doesn't seem to be a charging issue and if it is nothing else then it seems to be a false positive.This happened a few weeks ago but then seemed to settle down and went off and thought it might have sorted itself out.I now think though that this may be related to longer drives, and maybe hotter weather, as when I stopped noticing it I was back to only doing a 30 minutes or so drive a week. On this latest drive of a couple of hours or so though it kept coming on and off as described above.Of course the first thought is an alternator issue but I am now wondering if it is just a false positive related to the aforementioned overall screwy electronics. I am thinking this may be the case since on this latest longer drive, while I was mid journey and saw it staying on, I stopped in a layby and started engine again while parked and looked under the hood with my multimeter in hand and the alternator was turning as normal and checking on the battery terminals it was showing it was still charge with 14.1/2 as the output.My biggest concern would be the battery draining but given the above it seems that the light coming on is not functioning normally right? As such I am thinking to just peg it as another faulty thing, while of course keeping an eye now and then directly at the battery terminals with the multimeter myself. Not ideal because I don't want to be lulled into a false sense of security, a la 'crying wolf', and it really is draining at some point.Any suggestions how to get to the bottom of the overall electrical weirdness?

author: Sorama
author_rank: Frequent Contributor
timestamp: June 19, 2025, 10:58:44 am
content: Replace the battery.

author: golden_labels
author_rank: Super Contributor
timestamp: June 19, 2025, 11:36:11 am
content: Note:I’m not a car mechanic or expert. What I write below is based on my experience with cars and basic understanding of how various sytems work.Assuming we’re talking about this symbol:If yes, it indicates the car is using the battery, not a battery malfunction.(1)(edit: asexplained below, I missed that OP’s voltage check was done while the indicator was on. This points away from the alternator or serpentine belt)You said alternator connections are fine, so the next thing to check is the alternator itself. If it’s an interminnent failure, you’ll have trouble detecting it. May be an overheating rectifier, may be some liquid (engine oil?) spilled into the alternator, may be corrosion, may be a small fracture. However, before changing the alternator, make sure serpentine belt is not worn out or soiled. If it’s not quite new, I’d just replace it. It’s a perishable item after all, and the kind of perishable that gives a ton of headache when fails.If it’s not the alternator, I’d just drive to a shop specializing in car electric system. Let them diagnose it. My rationale here is simple. With all the symptoms you describe, something seems to be causing huge interference or shorts. The next thing to randomly switch off while driving may be power steering or brakes.(1)If a deplated or damaged battery causes voltage to drop, it may coincidently trigger this light. In a similar fashion something draining a lot of power or poor connections can make it light up. But I’d call it a useful side effect, not the primary function.

author: Rascal
author_rank: Contributor
timestamp: June 19, 2025, 11:48:42 am
content: Some years ago I had a similar problem with a car I owned. The battery light would come on for periods and go off again, until it eventually stayed on and no longer charged the battery.I traced the issue to the rectifier pack and replaced a few that were faulty/blown.I assumed that the periodic illumination of the battery light was related to the rectifiers slow demise over a few weeks.It might be worth checking, although it sounds like you have multiple electrical issues that maybe elated to the battery lightPaul

author: Sorama
author_rank: Frequent Contributor
timestamp: June 19, 2025, 02:25:04 pm
content: it cannot be the alternator, because TS wouldn't be able to start the engine as the battery would be depleted.

author: floobydust
author_rank: Super Contributor
timestamp: June 19, 2025, 03:22:07 pm
content: I've seen this problem before and it was due to bad grounding.In a vehicle, there are two grounds - the engine block, and the chassis/body. Then there is where the battery (-) cable connects.In old cars, battery (-) cable went to the engine block, and there was a smaller #10AWG ground wire from battery (-) to the body.Newer cars, battery (-) cable goes to the body, and there is a ground strap from the engine block (-) to the body.So I would check at where the battery is grounded, and look at the engine block ground strap (hard to find) it might be corroded.

author: golden_labels
author_rank: Super Contributor
timestamp: June 19, 2025, 05:52:07 pm
content: Quote from: Sorama on June 19, 2025, 02:25:04 pmI don’t get your line of reasoning. How is an alternator involved in starting the engine? What “TS” stands for?

author: themadhippy
author_rank: Super Contributor
timestamp: June 19, 2025, 06:02:03 pm
content: QuoteIf the battery is able to start the car it must have sufficient charge,and to maintain sufficient charge the alternator needs to be working enough to replace the power used starting the vehicle

author: Sorama
author_rank: Frequent Contributor
timestamp: June 19, 2025, 06:51:25 pm
content: Quote from: themadhippy on June 19, 2025, 06:02:03 pmExactly.TS=topic starter

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 19, 2025, 06:58:48 pm
content: Sounds like water might be getting into something.I have a cell phone charger that also shows the voltage. When it's not charging a phone, it shows the vehicle's voltage. Normally it's at 14V. Some times it drops down to 12 when at idle. If I leave the lights on for a long time, it will show 13 until the battery is recharged.Get one of these and see if the voltage is off when you're seeing strange things happen.Check you fuse boxes, all of them, and make sure they are dry. Also look for evidence of leaks elsewhere. Check the drains in the bottom of your doors and make sure they aren't clogged.

author: Sorama
author_rank: Frequent Contributor
timestamp: June 19, 2025, 07:08:43 pm
content: Quote from: JustMeHere on June 19, 2025, 06:58:48 pmNot completely right…14,4V is when alternator is running and thus charging car battery.When the cd-player or radio asks for its PIN code (anti theft), it means it loses its permanent 12V.There is another 12V connection on the cd-player that gets 12V when ignition key is turned.So there must be an issue with the permanent 12V power supply of the player.Either a bad contact in the fuse box with this particular fuse, or general disconnection of the battery wires or bad battery (voltage drops).Does the van has a start/stop functionality ?

author: Benta
author_rank: Super Contributor
timestamp: June 19, 2025, 08:58:48 pm
content: +1 for ground straps. There are several, and they tend to rot away, especially the braided ones.There are at least three: Engine to chassis, battery to chassis and battery to engine. But very often more, and they can all play tricks with the car.Those are priority #1 before even beginning other fault finding.

author: Benta
author_rank: Super Contributor
timestamp: June 19, 2025, 09:07:15 pm
content: Quote from: JustMeHere on June 19, 2025, 06:58:48 pmYour phone charger shows the voltage at the charger plug. Period. It does not show the "vehicle's voltage".

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 20, 2025, 01:05:24 am
content: Quote from: Benta on June 19, 2025, 09:07:15 pmOkay...First photo: car off and high beams onSecond photo: car off and lights offThird photo: car just after crankingFourth photo: with RPM up and 30 seconds after cranking.Not perfect, but good enough to tell the alternator is working and if the battery is charged enough to crank the car.There is a voltage leak in the car. Very common with a broken hands free link. As along as it's above 10.0 it will crank. Sometimes after 4 or so days it may be 9.8 but still strong enough to crank.The point is that if it doesn't show 14 while the battery is fully charged and the RPMs are up, the alternator is.working. If I've been driving for 30 minutes and it shows less than 14 then I need to check the alternator. Also, I don't have to stop and test with a DMM. I can make this evaluation at highway speeds.

author: Sorama
author_rank: Frequent Contributor
timestamp: June 20, 2025, 04:53:53 am
content: I don’t agree there is a leak per se.I really advice to try with a different battery.

author: golden_labels
author_rank: Super Contributor
timestamp: June 20, 2025, 05:26:54 am
content: Quote from: themadhippy on June 19, 2025, 06:02:03 pmQuote from: Sorama on June 19, 2025, 06:51:25 pm… and where from comes the assumption, that the alternator is unable to provide power? Certainly neither me nor the OP suggested this.I find your claim weird primarily because I experienced this scenario.

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 20, 2025, 06:18:07 am
content: Quote from: Sorama on June 19, 2025, 10:58:44 amI forgot to mention the battery is only 1 year old after buying new then. I also check it when switched off and shows high 12v to indicate full charge.As golden_labels states, I do not see what would indicate it was battery at fault when I have clearly shown otherwise from my testing.

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 20, 2025, 06:22:51 am
content: Quote from: golden_labels on June 19, 2025, 11:36:11 amYes that is the symbol I mean. You are in a different country, I am in the UK, so maybe there are different standards there? but from articles I read online it means there is a voltage drop/alternator issue if the light is working correctly.I did take a look in the user manual for the vehicle yesterday and it did indicate something about the belt being at fault.If that were the case though the battery would not be charging would it? and as I noted in the OP it is clearly charging even when I checked while this light was on which leads me to believe it could be a false positive.For vehicles in the UK that battery light should only be on for a second or so just after the engine is started and then go off if the vehicle is functioning normally.

author: Sorama
author_rank: Frequent Contributor
timestamp: June 20, 2025, 06:24:55 am
content: Quote from: golden_labels on June 20, 2025, 05:26:54 amyou are misunderstanding what has been said. No one said the alternator is unable to deliver, on the contrary. The alternator IS working as the battery gets charged and voltage goes up to the expected 14,4V.You really need to educate yourself on the basics of automotive electricity.

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 20, 2025, 06:25:15 am
content: Quote from: Rascal on June 19, 2025, 11:48:42 amFirst time I learn about rectifier packs.Yea the other issues does make me wonder what the root could be since there seems to be generalized electrical weirdness.

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 20, 2025, 06:31:25 am
content: Quote from: floobydust on June 19, 2025, 03:22:07 pmOh that is an interesting hypothesis and I wonder if it is related to the 'chasis ground' which I put into the leisure space to ground all my leisure battery electrics as the started battery is also connected to that via a wire from starter to the back negative busbar due to the dc-dc charger.I am trying to think now if I had random electrical issues before I connected that system up. I didn't for the battery light, but have to think about the other issues mentioned whether they only began when I made this starter to leisure battery circuit.For those who didn't read my other thread, you can find itherewhich has an electrical diagram by myself in the first one but was refined/cleaned up, apparently to make it more easy to understand for anyone else, by another member, with suggestions from others.

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 20, 2025, 06:32:58 am
content: Quote from: themadhippy on June 19, 2025, 06:02:03 pmBesides that I already wrote in the OP I checked that alternator and saw via the voltage on the starter terminals it is charging. Also when switching the engine off again the battery shows full charge.

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 20, 2025, 06:36:04 am
content: Quote from: Sorama on June 19, 2025, 07:08:43 pmYes, it started fine and as mentioned alternator is working and battery shows full charge.

author: Sorama
author_rank: Frequent Contributor
timestamp: June 20, 2025, 06:38:20 am
content: Quote from: electroniclearner820327 on June 20, 2025, 06:36:04 amThat was not my question...You don't know if your battery is fully charged: you only see its voltage. That doesn't mean she can hold all the charge.Stop making assumptions.

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 20, 2025, 06:43:32 am
content: Quote from: Sorama on June 20, 2025, 06:38:20 amUmm, you ask if it has start/stop functionality, and I reply yes it started fine.How is that not answering your question?I have also written in my other replies that the battery is new and yes it shows full charge of high 12v when switched off - aka NO alternator powering it.

author: Sorama
author_rank: Frequent Contributor
timestamp: June 20, 2025, 06:50:17 am
content: Quote from: electroniclearner820327 on June 20, 2025, 06:43:32 amNo, it is not.Start/stop functionality is when the car shuts down when the car is idle, like waiting at the lights. The engine will crank again one you hit the gas pedal.It's for optimization of fuel economy.These cars, with such behavior, need special (commonly AGM) batteries and they are prone for more issues/life expectancy.But I noticed in an another topic of you that you have solar panel and other battery in that van.Sorry to say it that way, but this goes above your head.

author: golden_labels
author_rank: Super Contributor
timestamp: June 20, 2025, 08:06:33 am
content: Quote from: electroniclearner820327 on June 20, 2025, 06:22:51 amI missed, that your measurement was taken while the indicator was on. Yes, the voltage being 14.5 V points away from the alternator. Unfortunately I can’t recall what was it showing in my case. Sorry for the false lead; I will add a note to the post.Quote from: electroniclearner820327 on June 20, 2025, 06:22:51 amYes, same here.Quote from: Sorama on June 20, 2025, 06:24:55 amThen what were you trying to negate here:“it cannot be the alternator, because TS wouldn't be able to start the engine as the battery would be depleted?”Because to me this looks like implying that somebody said the alternator is not charging the battery.Do I need to educate myself in basic logic in addition to basic automotive electricity?

author: Sorama
author_rank: Frequent Contributor
timestamp: June 20, 2025, 08:15:10 am
content: Quote from: golden_labels on June 20, 2025, 08:06:33 amQuote from: golden_labels on June 19, 2025, 11:36:11 amYou were (and still are) telling TS how to check the alternator and other things regarding the alternator.I made you clear that the alternator has no role in this issue as it's charging the battery.The fact you don't seem to understand that relation or behavior, shows you do lack those basics.Another forum member explained it also to you.I can't keep repeating nor explaining over and over the same thing.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: June 20, 2025, 08:45:05 am
content: Quote from: Sorama on June 20, 2025, 08:15:10 amIf you're on Internet to just argue with people go play on Twitter.

author: golden_labels
author_rank: Super Contributor
timestamp: June 20, 2025, 09:01:02 am
content: Quote from: Sorama on June 20, 2025, 08:15:10 amNot sure, to whom this reply is directed. I’m being quoted, but to me the response doesn’t make much sense. In the post I clearly said, that I misread a sentence in their original post. Coincidently I think I’m not the only one. I also noted that it points away from the alternator hypothesis, and apologized for my mistake. Even more, I edited the post with original suggestion to make it clear. You quote me saying twice it isn’t the alternator, and argue… I still tell OP to check the alternator? And all this is a reply to the comment about the discussion content, which is also quoted, but never referenced?Unless OP observes something new or something pops into my memory, my role in this topic is over.If you wish to continue the side-thread with me, I expect posts being connected and related to each other.

author: Sorama
author_rank: Frequent Contributor
timestamp: June 20, 2025, 10:19:36 am
content: Quote from: JustMeHere on June 20, 2025, 08:45:05 amI don’t have twitter nor Facebook.If one doesn’t understand specific basics of car electricity than maybe it’s better for that person not say irrelevant things.Unless we want TS to spend lots of money on non relevant parts.I’m here to help TS, so let’s stick to the facts instead of ranting about belts and oil spills.

author: floobydust
author_rank: Super Contributor
timestamp: June 21, 2025, 02:51:31 am
content: Quote from: electroniclearner820327 on June 20, 2025, 06:31:25 amIt's not a hypothesis, I actually had a car where the ALT/CHG light would come on dim at night when the headlights were on. Everything checked OK - battery, alternator, instrument cluster etc. it drove me nuts.I found it was a bad ground from the battery (-) to the car body. Headlights are at least a 10A load, they are grounded to the radiator support (body) - not the engine/alternator, and the potential difference caused problems. You could look for a voltage drop between engine block and battery ground and chassis.I think you need to visit the batteries ground connection, body steel corrodes/rusts or you just have done a poor job stacking the connectors etc. I don't know if your AUX battery is isolated or not. Or disconnect the AUX battery and see if the problem is still there.

author: darkspr1te
author_rank: Frequent Contributor
timestamp: June 21, 2025, 10:40:06 am
content: I worked in auto electrics fitting alarms and audio for years. We would often see issues like this , It is common for under dash circuits to have own power and ground and even more so now we have many ecu's.if I was diagnosing this the first thing i would look at is a vehicle schematic if it can be found , if not then next would be a visual inspection of grounds ( foot well kick panels often hide common grounds on both left and right side of car , not specific lefthand/rh drive car but all models) , also check under center console - *warning do not disassemble dash/console with battery connected or you can trigger airbags even if the car is not moving. ask me how i know :-p *you mentioned the radio requested a code every so often, my guess is around the radio area you will have a loose ground and can be checked with a dmm on the radio case and "body or battery ground" in ohms mode then start moving the wires around , i usually start by grabbing a loom and ragging on it.In the case of old ford transits the ECU/Radio and alarm all shared the same ground behind then dash under the air controls, this was a common failure point in uk as the winsheild would leak there and run down the firewall all over the grounds, even worse on the super base models as they had less insulation and condensation was a massive issue early on and would accumulate around grounding straps.Another area i've seen that can be a issue is hidden fuse boxes, I worked on a hino recently that you had to remove half the dash to get at the f/p and alarm fuses which were right under the dashboard cup holder (which had drain holes over the fuse box) ,this was a known issue to the vendor and the following year model did not have cup holders (a blank was added that you can clearly see) , so this cost cut they did lead to the early demise of these vehicles (also landrovers famous for this too, leaking drivers window on dash electrics)Body/chassis/engine grounding straps - this is a major pain-As a example i will take my 2001 Hilux , from the battery ground goes to the engine,from engine it goes to body and then onto chassis , normally not a issue except that rear tail lights connect to chassis ground as do trailer lights , normally not a issue except the body->chassis strap went next to the aluminum heat shield and would touch/rub and over time (say 10 years) and while it looked ok if you grabbed it then you would just have dust and it would break, the end result was a new ground was found through the circuit , this lead to a situation over time of another part of the car acting as ground and putting stress on an circuit not ment for that load, in my case my abs module gets fried as the abs pipe from the abs motor are connected to the chassis and this was the new ground route, now the abs had two grounds, one for motor which went to chassis and the other went to the ecu and it was this small ecu only wire which ended being the final grounding route. we found this issue manifested itself by burning the abs ground wire and is was not visibly burnt but when you played with that wire it broke up.Well i hope these tips help.*quick edit*in most automotive Alternator battery light systems ,that signal is a battery + feed into the dash bulb and then onto the alternator, if the alternator is not providing power then the alt. acts as a ground lighting up the light, as soon as that power feed equals battery voltage the bulb goes out - if you ever had a mk1 mini or rover metro you will remember the alt light dims over a short time as the old school alternator built up power after starting it and would often come on for short time on turning on headlamp main beams.however in some cars there is a signal to the ecu for OBD codes and this itself can act as a ground and in turn it illuminates the alt warning light (looking at you suzuki and your bad ecu caps)darkspr1te

author: electroniclearner820327
author_rank: Regular Contributor
timestamp: June 22, 2025, 05:24:31 pm
content: I just turned it on for a little bit after being parked for almost a week and the light went out instantly.It seems something to do with longer drives and/or heat.