Charge voltage after startup

Submitted: Thursday, Apr 03, 2014 at 09:03
ThreadID: 107059 Views:2785 Replies:6 FollowUps:11
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After starting the battery voltage indicates 8 volts and stays there for a while eventually climbing to 13/14 volts. Seems to spin the motor normally, quite fast actually. I havent noticed this before. Vehicle is Toyota hj60. Is this normal or does it indicate a problem?
I have had the vehicle since 1996.
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Reply By: Member - Rosss - Thursday, Apr 03, 2014 at 10:14

Thursday, Apr 03, 2014 at 10:14
Seems to be normal, I have a 100 series and it does the same, I asked an Auto lecy about it and he said the voltage stays down for a while because the glow plugs do not shut off immediately the engine starts.
AnswerID: 529742

Reply By: Ross M - Thursday, Apr 03, 2014 at 10:23

Thursday, Apr 03, 2014 at 10:23
I had an HJ61 Turbo with the intake heater and not glow plugs.
When starting it would sit at around 12v with engine running and only rise slightly if, if, revved but hardly moved up at all.
When the heater time out was finished or the water temp was then sufficient in the block sensor, the system would then switch off and suddenly voltage would go from around 12/perhaps under 12 to 14, as the heater load was switched off.

Because the HJ60 has a smaller alternator output than a HJ61the voltage will stay low unit the time out period ends.

The HJ60 is around 45amp alt or 60amp, not sure never tested the output, while the HJ61 had an alt which would go better then 100 amp output so the "on heat" running voltage will be lower than the 61.
AnswerID: 529743

Reply By: pop2jocem - Thursday, Apr 03, 2014 at 11:03

Thursday, Apr 03, 2014 at 11:03
Sounds a bit odd to me. Maybe slightly different for other models. My 1HZ engine would drop when cranking but as soon as the engine fired up the voltage would begin climbing to 14+ volts almost immediately. I know the glow plugs stayed on for some time because of emission requirements, or so I was told. The 1HD-FT engine that now inhabits the engine bay starts fine on the coldest mornings where we are so I have never bothered to connect the toaster element in the intake manifold.
I guess if it ain't broke don't fix it. If it's been like that for the last 18 years and starts ok.

AnswerID: 529744

Follow Up By: Ross M - Thursday, Apr 03, 2014 at 11:39

Thursday, Apr 03, 2014 at 11:39
You must live in a warmer area and so the heaters may not come on (depending on ambient temps or engine block temp) and so you may not notice what others do experience.

The glows may not stay on if the block/water temp is above a certain value or they may only be on for a short time and the voltage being low and rising may mask detection of what is happening when.

The "thermo time switch" in the block decides what happens and it is temp/time dependent. Above a certain water temp NO below Yes, very cold, on for long time.

Unless you add an indicator light to monitor things on or off, it is sometimes hard to identify what , where, when.
That is a far better indicator than just " so I was told".
FollowupID: 812522

Follow Up By: pop2jocem - Thursday, Apr 03, 2014 at 18:48

Thursday, Apr 03, 2014 at 18:48

The "so I was told" was about the reason why the glow plug circuit remained energised for some period of time after start up.
Where we are the minimum overnight temps in winter quite often get down around the 0 degrees and occasionally a few below 0. I have often found a nice coating of ice on the windscreen.
No we don't get -20 type temps but cold enough to know that I had to give the glow system some time before cranking or no start.
Not sure why others are seeing such a low voltage for so long but I know mine climbs to around the 14+ v in a few seconds after start up.

After spending a lot more years than I care to remember with my head under the bonnet of every conceivable petrol or diesel powered beasty I have got a rough idea what makes them tick or refuse to.

FollowupID: 812553

Reply By: Allan B (Member, SunCoast) - Thursday, Apr 03, 2014 at 11:09

Thursday, Apr 03, 2014 at 11:09
I think that you will find that the voltmeter is connected to the ignition circuit 'downstream' from the battery and is reading the voltage where the heater or glow plugs are causing some voltage drop in the wiring. The voltage at the battery terminals is probably somewhat higher than you are observing. Even so, 8 volts seems particularly low and I suspect the voltmeter lacks accuracy at that reading point.
With a multimeter you could check directly at the battery terminals.

The typical alternator would be capable of holding the battery at 12 volts or higher even with glow plug load, rising to about 14v eventually.


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AnswerID: 529745

Reply By: oldtrack123 - Thursday, Apr 03, 2014 at 14:04

Thursday, Apr 03, 2014 at 14:04
8V does seem a little low & hopefully is not the true battery voltage
That would be my first check, with a multi meter ,check voltage DIRECTLY on the BATTERY terminal poss[not on the connecting lug]

If it is 8V , with just the glow plug /manifold heater it is quite possible the battery is sick, lost capacity due to age or abuse
Next check would be heavy a load test on the battery

If the battery Voltage is much higher than 8V , you could have some bad /dirty connections between the battery & the voltmeter[voltage drop under load.]
To find that you need to check voltage progrresively from the battery to the point where the meter is connected
A likely area is the actual battery connections, followed by the MAIN neg to chassis connection

Diesels do have an after glow temp dependent delay relay,depending on the engine block temp, that could hold in for some time.
AnswerID: 529752

Reply By: Member - 178 - Thursday, Apr 03, 2014 at 15:55

Thursday, Apr 03, 2014 at 15:55
Thanks everyone for your comments. I have never looked at it after startup before so dont know if that is normal or not. Anyway I have just driven the vehicle and noticed my ctek controller for aux. battery is showing a fault and the voltage dropped right down into the red and stayed there for quite a whilebefore jumping straight up to 14.Starter cranked effortlessly and started no heaters so I guess its off to the electrician to find the bad connection if I cant. I will start with the battery terminals as suggested first.
AnswerID: 529762

Follow Up By: pop2jocem - Thursday, Apr 03, 2014 at 18:57

Thursday, Apr 03, 2014 at 18:57
If the starter is winding the engine over no worries I suspect you do have a bad connection from the meter sensing point and not a crook battery. As the other guys suggested, check directly at the battery with a multi meter. If the battery voltage is actually 8v after start up with a reasonably healthy battery and alternator I would be extemely surprised.
IMHO the standard Toyota gauges for volts, engine temp and oil pressure, if that is what you have, are about as useful as an idiot light. All mine got replaced many moons ago with proper gauges.

FollowupID: 812557

Follow Up By: Member - Phil G (SA) - Thursday, Apr 03, 2014 at 20:47

Thursday, Apr 03, 2014 at 20:47
The other possibility are the fusible links which hang off the pos terminal on the 60series - with vibration, they can progressively lose strands, and become a point of higher resistance.

I agree with pop - ignore the factory gauges - use a multimeter on the terminals before we come up with a solution for a problem that doesn't exist!
FollowupID: 812573

Follow Up By: Member - 178 - Friday, Apr 04, 2014 at 19:00

Friday, Apr 04, 2014 at 19:00
Exactly as suggested. Checked connections at Pos. battery terminal first and there was the culprit. Fitted a new wire terminal and now just drops to 10V on starting and quickly gets up to well above 12V also CTEK D250s is not showing a fault now. Once again thanks for all the help.
FollowupID: 812616

Follow Up By: Member - Phil G (SA) - Friday, Apr 04, 2014 at 20:45

Friday, Apr 04, 2014 at 20:45
Good work Johnn. Glad we helped you find the problem. It helps to cable tie the ends of the links to the thick starter cable, so no significant vibration can happen again.

I had a 47series with a similar issue many years ago - had an intermittent starting problem when camped in Innamincka. Ended up driving back to Adelaide non-stop, for fear of the vehicle not starting. It was a fusible link hanging by a thread.
FollowupID: 812619

Follow Up By: The Bantam - Saturday, Apr 05, 2014 at 18:59

Saturday, Apr 05, 2014 at 18:59
Good work 178...step by step systematic fault finding will usually get you there.

If you still have the fusable links, probably a good idea to replace them with maxi blade fuses.

The fusable links are prone to failure and are a very low performance fuse.

Cant remember the values..but I dug em up from a manual when I did one for a mate.

FollowupID: 812688

Follow Up By: Member - Phil G (SA) - Saturday, Apr 05, 2014 at 19:08

Saturday, Apr 05, 2014 at 19:08
Gday Bantam,
I've found the fusible links last fine as long as they are well secured and not flapping in the breeze. The problem with a maxifuse and it's fuseholder is that they suffer accelerated corrosion if hanging off a pos terminal. It then becomes a point of high resistance, which is a problem with big amps. The link to the HJ60 glow plugs pulls 60 amps, and the link from the alternator will deliver similar current from the 55 or 80 amp alternators in that model.
I guess all of this explains why manufacturers now do neither!

FollowupID: 812690

Follow Up By: The Bantam - Saturday, Apr 05, 2014 at 19:21

Saturday, Apr 05, 2014 at 19:21
start with fitting a sealed maintenance free battery..that will solve a lot of problems.
apply some anti corrosion spray when fitting the fuse.

There are a couple of problems with fusable limks in the form of wire.
#1 the actual wire is getting a little hard to lay hands on now
#2 The quality and behaviour of the fuseable likk is variable
#3 there is no consistent colour code

This is whay almost without exception the modern vehicles are fitted with cartridge type fusable links

At lease with blade fuse and holder you have an item that can easily be obtained and replaced

If ya don't like blade fuses, there are other choices...cartridge type fusable links like come on the modern vehicles are probably easier ANL fuses.

Thinking about it...if I had to do it again I'd fit an ANL fuse block and fuses.

FollowupID: 812692

Follow Up By: Member - 178 - Sunday, Apr 06, 2014 at 07:16

Sunday, Apr 06, 2014 at 07:16
Thanks Bantam for That advice.
On checking
1 I have a 800cca sealed maint free battery.
2 I have a in line fuse for heaters, looks like a Toyota upgrade as labeled for heaters and clips on starter cable very original looking.
3 I have a 60 Amp ANL fuse to second battery AGM with a CTEK 250s controller. Is that eneough or do I need a bigger fuse and where can I buy replacement fuses?
FollowupID: 812715

Follow Up By: The Bantam - Sunday, Apr 06, 2014 at 16:12

Sunday, Apr 06, 2014 at 16:12
both Jaycar and altronics stock ANL fuses as should most good autoelectrical suppliers.

The ANL fuse holders from jaycar and altronics are a bit HIFIish, more suitable blocks can be had from the autoelectrical suppliers or off ebay.

The fusable links we spoke about just look like pieces of wire attached to the positive battery terminal.

What they are and where they go varies from model to model. to feed the engine electrics and one to feed the cab electrics....diesels may have one specifically for the glow circuit.

FollowupID: 812775

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