Coils sprung Land Cruiser system voltage?

[Guest]

Thanks Clive
So how does that work? Is the 12 v taken by using two batteries in parallel
and then switched to series to start?and then back again once started? The
12 v electrics being isolated during the start sequence?
We have a system like this on the British Aerospace Jetstream 31/32 series
aircraft, except is a 28/56 volt system. The batteries flick over to series
as the starter speed spools up the turbine at I think 10% rpm and then back
to parallel at 60% when the starters dis-engage and the engine becomes self
sustaining. The system voltage never actually reaches the true parallel
voltage due to the current being drawn by the starter.
Is this what happens in the Cruisers? Or is the second 12v battery solely
used for starting? Or does it parallel up with the primary battery once the
start sequence has finished?
Date: Sat, 12 Jul 2008 13:13:00 +0100
From: "Clive Marks" <[Email address removed]>
Subject: Re: [ELCO] LWB Coils sprung Land Cruiser system voltage?
Reply-To: [Email address removed]
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Neil,
They are 12volts with a 24volt starting system, or the 80 diesels are
anyway.
Regards,
Clive Marks
Home: +44 1293 514600
Mobile: +44 7821 491897
Crawley, West Sussex, UK.
From: "Neil Paisnel" <[Email address removed]>
Subject: [ELCO] LWB Coils sprung Land Cruiser system voltage?
Date: Sat, 12 Jul 2008 11:46:59 +0100
Reply-To: [Email address removed]
I have an old 1982 HJ60 cruiser that is all 24volt, including bulbs, trailer
wiring, the lot.
These modern LWB cruisers, are they 12v? or 24volt? My mate has a 10 year
old SWB that has twin batteries, but all bulbs etc are 12v. Have not looked
at it closely enough to see how it is wired up.
Is it all now 12v, or a split 12/24v system? Or what
Neil

 

[Guest]

Neil
| So how does that work
The "cold weather" diesel pack, standard in Euro spec models, has two
12v batteries which are normally wired in parallel giving a conventional
12v electrical system for the car.
The left hand (looking forward) battery wires go to a special (large)
changeover relay which normally connects it in parallel with the right
hand one. When you turn the starter this battery is "rewired" so that it
is in series with the right hand one, giving +24v at its +ve terminal
which runs the starter motor.
So you only have 24v when you turn the key to start, and then only to
the starter motor, all the rest of the electrics are bog-standard 12v.
It's a good system when it works: the engine fires absolutely instantly
and the starter has enough grunt to move the whole car uphill when you
(ahem) bury the exhaust pipe in earth so the engine won't start!
It's a bad system when one battery develops a duff cell, since the other
battery takes up the load during normal use in parallel and it's only
when they are wired in series and you try to start the engine that you
discover you have a problem.
Christopher Bell
Devon, UK
1996 1HD-FT (with 12/24v starting system)
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[Guest]

On Sun, Jul 13, 2008 at 5:02 PM, Christopher Bell
<[Email address removed]> wrote:
Chris,
I did find out some time ago that when the LC had been left for a few
days in the garage, battery voltage would drop to 12.10V. It would
start perfectly normal, though. When eventually I checked the
batteries (DMS 3500), I discovered that one of them had lost half of
its capacity.
After the bad battery was replaced, my LC spend some time sitting
idle. When I came six months later and turned the ignition key on, it
started first time as if it was driven only yesterday.
The system seems to be quite resilient.
Rgds,
Roman (London, UK)
'92 HDJ80 (auto)

 

[Guest]

Roman

| I did find out some time ago that when the LC had been left for a few
| days in the garage, battery voltage would drop to 12.10V. It would
| start perfectly normal, though. When eventually I checked the
| batteries (DMS 3500), I discovered that one of them had lost half of
| its capacity.
|
| After the bad battery was replaced, my LC spend some time sitting
| idle. When I came six months later and turned the ignition key on, it
| started first time as if it was driven only yesterday.
|
| The system seems to be quite resilient.
I think it's resilient when the batteries are in good nick, but not when
they are getting a bit past it, which was my point. If you do your
maintenance and check their health from time to time you should be fine,
otherwise the first symptom you get is "turn key, click" since there is
no intermediate "struggle a bit starting" phase to provide a warning.
I now treat the initial value of the dash volt-meter as a warning sign.
In the days when my air pre-heater still worked (it died about a year
ago) I reckoned that anything below about 3:30 o'clock on the meter
spelled trouble on the way.
Sadly, or perhaps happily, I'm not yet mentally recalibrated for the
"non-pre-heater impending failure voltage" case ... and I dropped and
broke my hygrometer the other day!
Funnily enough I *am* having lead-acid battery problems at the moment:
not with the car, but with the computer's UPS. I got two more redundant
ones from work, but they are both equally knackered - not surprising
given their similar ages and usage patterns. The capacity of a L-A
battery seems to nose-dive very quickly when it decides to fail.
CB
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[Guest]

Hi Guys
I think as has been said that the set up works very well but only when the
two batteries are very healthy.
If one or the other is ill then you will have trouble without warning.
For instance the cruiser started first time one day as it usually does, I
went to the shops and stopped and then tried to start it but all i got was
clicks.
No warning at all of the impending trouble.
cheers
john 92HDJ 80 1HDT

 

[Guest]

Landcruisers are definitely not all 12v. I have had my 1982 HJ60 since 1992
and it is most definitely 24v.
Thanks Christopher and Clive for letting me know how this system works. The
24v start system is a bit of a shame, as it means the batteries are not
permanently series wired, so I will not be able to jump start 24v trucks if
I bought a modern Cruiser.
Thanks
Neil,
Subject: RE: [ELCO] Coils sprung Land Cruiser system voltage?
Date: Sun, 13 Jul 2008 17:02:22 +0100
From: "Christopher Bell" <[Email address removed]>
Reply-To: [Email address removed]
Neil
| So how does that work
The "cold weather" diesel pack, standard in Euro spec models, has two
12v batteries which are normally wired in parallel giving a conventional
12v electrical system for the car.
The left hand (looking forward) battery wires go to a special (large)
changeover relay which normally connects it in parallel with the right
hand one. When you turn the starter this battery is "rewired" so that it
is in series with the right hand one, giving +24v at its +ve terminal
which runs the starter motor.=3D20
So you only have 24v when you turn the key to start, and then only to
the starter motor, all the rest of the electrics are bog-standard 12v.
It's a good system when it works: the engine fires absolutely instantly
and the starter has enough grunt to move the whole car uphill when you
(ahem) bury the exhaust pipe in earth so the engine won't start!
It's a bad system when one battery develops a duff cell, since the other
battery takes up the load during normal use in parallel and it's only
when they are wired in series and you try to start the engine that you
discover you have a problem.
Christopher Bell
Devon, UK
1996 1HD-FT (with 12/24v starting system)
____________________________________________________________
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