I hadn't thought of bakelite enclosures - I'll have a look about - thanks

Right - a basic electirickery question
 

Whilst I've been busy connecting the dots (so to speak) between each component I'm wiring and joining things up to a fuse box the thought about how much power I'm going to need has suddenly dawned...

...I mean so far my basic brain has been thinking - oh right that's a 50W bulb so over a length of X meters I need to make sure the wire is thick enough to make sure it won't act like a fuse and ideally thick enough to make sure the voltage drop isn't so great. Essentially - so far it has been easy to say "bugger it I'll use a thick wire and hope they all go through that hole".

Now I'm figuring out the fuses I'll be needing and more importantly how these groups of fuses (and relays) are going to be connected to the charging system (the alternator) and the battery.

If I have an electrical system that needs more power than the battery and the alternator can give I'm going to be in trouble.

I've had to make a spread sheet.

https://www.volvoforums.org.uk/attac...1&d=1550523287

Some of the values in the spreadsheet might not be 100% correct - I've had to guess - for me at the moment it is more understanding what I should be doing (even if I haven't got the right data)

I was thinking about the way in which the electrical components are connected in an automotive system and realised that the electrical loads / components are connected in parallel.

To calculate the maximum possible disaster situation of having everything switched on at the same time - I calculated the resistances of each of the loads and added then together in parallel - then this figure of total resistance got converted to a total current.

I'm not sure this is correct - can someone confirm?

A series calculation of the values in the picture above comes to 160 amps

But I think because it is all in parallel the total current draw would be 100 amps

Mini update
 

I'm still mulling over how I'm going to safely connect the power from the alternator and battery to the rest of the car.

I have decided not to wire everything through the ignition switch - I will be using at least two mini relays and strip fuses with just a token signal wire running from the ignition. I'm still a bit unsure about the amperage calculations and I really need to crack on and get some more accurate data.

Which ever way I look at it I'm fairly sure the existing alternator is a bit on the small side =>

https://www.volvoforums.org.uk/attac...1&d=1550590203

It is rated for 55W - I expect I don't need to have one that can supply everything in the worst case scenario but I need to check what's safest to fit (as in the most reliable)

The ignition switch was easy to find =>

https://www.volvoforums.org.uk/attac...1&d=1550590203

I thought I'd found the headlight switch but it turns out to be the demister fan =>

https://www.volvoforums.org.uk/attac...1&d=1550590203

I wonder where the headlight switch has gone?

####

In other news the reamer for the king pin replacement should be here soon so I've been a painting with Eastwoods rust encapsulator (after poo loads of angle grinder wire brushing as usual - followed by a good soaking in Rustyco rust eater before the rust encapsulator)

https://www.volvoforums.org.uk/attac...1&d=1550590203

Slowly

Slowly

I doubt you really need 100 amps. I have a 40 amp alternator and it seems to be adequate.

dean

I agree that for most of the time the amount of current draw would be much less. After hunting about for information it seems like the 55 amp alternator that came with the car is another upgrade (this is the car that keeps giving!) - this size seems to be about the maximum safe size you can fit to an original PV wiring loom.

Because I'm trying to plan ahead and I'm making up my own custom loom I'm thinking about how bad things could get if I decided to add on extras. I've decided to put in beefier wiring - I'm just finishing that off by designing the power route from the alternator. I think for the sake of getting on with the job (this project has taken too long) I'm going to fit a heavy duty wiring arrangement but re-fit the 55 amp alternator and see how it goes.

Army;

Your listing of all loads in the vehicle and totalizing of currents is much what went on, on the electrical engineer's desk during vehicle development...but you did not include one important factor...a column which might have been broken down to show if load use was 1. Continuous, 2. Intermittent, or 3. Occasional...and this column would determine "weight" of the current which would get added into the total...by adding all at 100% without this (including some generous "guesses"), you come up to the high 100A total.

Bottom line is: A 60A rated source will supply all the needs, and have plenty capacity and headroom for additional lighting, or other loads, while still keeping the Battery charged fully (and this has been confirmed by tests and numerous field experiences).

Cheers

I'm aware that my calculation is a bit high for normal use.

Do you happen to know where I can find out the weightings of "intermittent" and "occasional"?

I love to re-invent the wheel - this is after all a hobby!

Was looking at this earlier and came up with this. Didn't get round to posting it.

As I know no better let's assume your calculations are correct.

Analysing your disaster scenario I believe a few items can be removed as I imagine you'll be pulling over if these are running constantly. Washer -5, horn -10,* brake lights -7 (incl trailer), indicators -10.5 (incl trailer), radio-5 (if you do fit it but imagine if you had power concerns you would turn this off), interior lights-1.5. That is 39 off your 100 leaving 61w consumption. Assuming your alternator is supplying the 55w on the rating then that is a 6w deficit to* come from the battery. You have quite a few hours battery capacity before that becomes an issue and if you can turn off any of rear screen heater, main beam, fog lights you would be back in positive territory and charging the battery.

Army;

It's science, but not rocket science...so you can make an informed judgement call (much as the vehicle elec eng would have)...for instance I'd consider the modest current of Directional Indicators and Wipers as somewhere between Continuous, and Intermittent, so weigh them at 50%...High current of Fog or Driving lights, I'd weigh (for the purpose of Charging System sizing) at 80-90%...I'd add in Brake Lights at 20%...again you're making a bit of an academic exercise of this, but the 60A Alt will serve you well. Remember also, that the rated output of Alt is used only when called for...at other times, it is just available and on stand-by, and trickle-charging the Bat.

Cheers

Something different...
 

...need to order some more electrical stuff so I've moved back to things I find more enjoyable.

Hashtag PV ZF steering box time (!)

I got the epoxy bearing repair stuff a few weeks back and got round to applying and sanding it yesterday and today.

https://www.volvoforums.org.uk/attac...1&d=1550765837

Epoxy was easy to apply and quite easy to sand but difficult to get the contour correct (of course)

https://www.volvoforums.org.uk/attac...1&d=1550765837

For those of you who may remember removing the old ball bearings from the NLA bearing races was quite straight forward (that was done months ago). I found correct sized replacement ball bearings and fitted them today - just squeezed the bearing race back in place so the balls didn't drop out.

Also easy.

https://www.volvoforums.org.uk/attac...1&d=1550765837

The bottom bearing cup was still available so I bought a new one. I couldn't find the top one for sale so it had to be left in place (but it is much much much better condition than the old lower one).

The bit in my hand in the picture above is actually a spacer washer - the bearing cup is already in there.

Spray on Hylomar =>

https://www.volvoforums.org.uk/attac...1&d=1550765837

Good stuff to use on every side of the shims - should stop leaks for a bit

https://www.volvoforums.org.uk/attac...1&d=1550765837

The steering box is now back together (just need to fit two seals) and then it is more or less done for now.

There are still problems with this part however - the epoxy bearing surface repair has helped - it is way way smoother than before but not as nice as it should be. I'm going to use it as it is for a bit and see if use wears it smooth for me (!)

A bit dodgy - I'm not exactly tickety boo with how it is turned out. I'm going to keep an eye out for another steering box and see if that has better parts in it. (Probably not!)

Worse case scenario - I put in the extra shim like some one did previously to reduce the "correct" pre-load between the two ball bearing races so it feels smoother. I don't really want to do that though as it doesn't help with future wear on that pesky inner shaft...

[To be continued]