Submitted: Saturday, Apr 05, 2003 at 21:22
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With the advent of 36v veichles soon??,how will this affect the supply to 12v fridges,lights etc. in the van,will we need another mysterious black box to convert 36v to 12v. Peter
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Reply By: Deleted User - Saturday, Apr 05, 2003 at 21:24

Saturday, Apr 05, 2003 at 21:24
G'day Peter,
Interesting stuff indeed this new voltage. This will be happening because we are at the limit of 12v for cars. With modern entertainment systems and control modules cars sure require some wattage now. If you consider that say a wiper motor might draw 9amp @ 12v = 126watts that same motor @ 42v drops to 3amp for 126watts. Car makers will love
it .... smaller wiring looms smaller electric motors etc. Also makes way for hybrid cars with their combination elec/fuel motor systems.

BMW or Mercedes might have a 42v alternator with 36v system in a car this year ... but mainstream 36v I have read will come maybe 2010. Also the first systems would be combination 12v/36v then dedicated 36v. Imagine all the diagnostics for cars in workshops having to do both voltages .... gonna be a few fires around !!! <smile>

As our BT's dont really rely on power from the tow vehicle we dont have a problem. If I had a 36v tow vehicle I would use a transformer to connect to van and maybe one socket in car at 12v. One thing is for sure we will all have to get used to 12v and 36v being part of our lives for 30 years as it would take this long for 12v to go the way of T. Rex.
Might be quite some time before the big three (Holden Ford Toyota) get 36v into their product. Wonder when we will see the first 36v Bushtracker ?

AnswerID: 558466

Reply By: Deleted User - Saturday, Apr 05, 2003 at 21:25

Saturday, Apr 05, 2003 at 21:25

New systems with us much sooner than 2010!.

The new WV 'One Litre' already on sale in Europe has a Sachs' developed crankshaft starter/generator combined with an electrically actuated clutch - 110 mm diameter (the size of a CD!!) Is 36/42 volt.

Next Ford Explorer has a 36/42 volt system but I have no reliable details.

Various reasons for change:

An ongoing move to electrical actuation. This will extend to valve actuation, power steering, possible electronic control of dampers etc etc.

Electrical requirements of hybrid diesel/electric and other vehicles. greater possibility of using energy otherwise wasted in braking being utilised to charge battery.

In the same way that our 12 volt systems have >14 volt alternators, the new standard utilises 42 volt generation and 36 volt battery storage.

I would expect to see at least 50% of new passenger cars using 42/36 by 2005.

reason for higher voltage is that power demans is expected to be 5000 watts by 2005, and 10,000 watts by 2010. This is not feasible at 12 volts as it implies 350/700 amp alternators (which would be huge). If 42 volt then 120 amp and 240 amp respectively.

If this big then makes sense to combine with starter motor.

Repercussions for RVs? Probably beneficial - far less voltage drop for same size cables.

Intermediate problems - none really. The RV electrical industry may slowly move across but in the meantime there'll any number of 36/12 dc/dc converters.

As a matter of possible interest I'm currently writing a series on caravan and motorhome electrics for the Aust auto sparky's magazine 'Automotive Electrical & Air Conditioning News', following the wide global acceptance of my text book on the subject.

AnswerID: 558467

Reply By: Deleted User - Saturday, Apr 05, 2003 at 21:26

Saturday, Apr 05, 2003 at 21:26
G'day Collyn,
Could you post the ISBN of that book so I could obtain a copy. Although I'm not qualified in auto elec I have a great interest in it. I've been playing with car wiring for a long time .... I'd better read a book !!! <smile>

I liked your article re: caravan dynamics ... the old polar movement of inertia ... not many people know about that one. I found out about it the first time I drove my GTR street race car at Lakeside with a full tank of fuel in the rear. I have some interesting thoughts on caarvan stability. Busy at Easter.... I'll get back to you.

AnswerID: 558468

Reply By: Deleted User - Saturday, Apr 05, 2003 at 21:27

Saturday, Apr 05, 2003 at 21:27
Thank you for your comments re my piece on towing stability. It's caused quite a stir because, whilst there was a sort of general understanding that it's not a good idea to have too much weight at the end of a van, it seems not to have been realised that there's a square law involved.

It's also not generally realised that a van pitches around its centre of mass - not its axles.

It's all basic Newton - but a thorough search of the literature going back fifty years shows nothing previously that looked at the fundamentals.

Details my books are on
ISBN of 'Motorhome Electrics and Caravans Too!' is
0 9578965 14. Just released 'Solar That Really Works -Caravan Edition' is 0 9578965 2 2.
AnswerID: 558469

Reply By: Deleted User - Saturday, Apr 05, 2003 at 21:28

Saturday, Apr 05, 2003 at 21:28
'Scuse my ignorance guys, but from many moons ago I seem to recall looking at quite a bit of Marine gear in 24v. Lazy as I am I havn't looked at whether any still exists (it could be the industry standard for all I know). If available, would exploring a 24v rig be worth it? Thanks Griff
AnswerID: 558470

Reply By: Deleted User - Saturday, Apr 05, 2003 at 21:29

Saturday, Apr 05, 2003 at 21:29
G'day Griff,

24v gear is usually dearer than 12v because of production numbers so you would pay a penalty there .... and obviously would still have a mismatched system to car at either 12 or 36v. I still think it will be some time before a suitable vehicle to tow a BT comes in 36v.
Also the advantage is that 12v wiring is very suitable to carry 36v .... 12v uses three times the surface area in wire cross section than 36v to carry the same amperage.

This makes the wiring already in the BT walls able to carry 36v with ease. In 5-10years when the appliances change for the automotive and van industry (fridges lights etc) it will just be a matter of changing the appliances in BT. The batteries in van and input voltage from car becomes 36v. Solar will need some attention maybe replacing .... turning 4x 16v (app) panels in to 40v for charging needs a solar guru. Inverters become 36v/240v with 3 times less current draw on batteries to spin same microwave in BT

Stick with 12v in BT at this stage to keep costs down and shift with the 36v when we all have to somewhere way down the track. The costly thing would be totally rewiring the BT for 36v and as we dont have to do this the BT is reasonably future proof for 36v as are all vans now at 12v.


AnswerID: 558471

Reply By: Deleted User - Saturday, Apr 05, 2003 at 21:30

Saturday, Apr 05, 2003 at 21:30
Thanks, Anthony. Spot on. Griff
AnswerID: 558472

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