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What I think is a quick dashboard/electrics question


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New wiring loom with sub-loom for overdrive ordered and on its way to replace the mass of tinkered spaghetti that currently exists so going back to basics and then adding a auxiliary loom from revington TR for the likes of the existing electric fan, spotlights etc. The car will never be 'stock/OE' just aiming to make it more usable and reliable. It already has an alternator conversion but the amp gauge remained, so here's the question is there an advantage/good data reason for swopping that gauge for a volt version or would you simply rely on the glow of the ignition light and pop an appropriate looking clock in the empty space which would be left in the nice newly made 'Classical Dash' from Ian Bond of Stokenchurch?

And finally, when replacing the wiring loom what relays etc would it be wise to replace at the same time

 

Ever learning

David

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Hi David,

 your simple question will get rather a lot of answers.

Keep the ammeter it will give good info and in my opinion better than the Voltmeter.

The old relays tend to survive very well - keep them until they need changing. Many of the relays can actually be taken apart to clean the contacts.

Do not rely on the Ignition warning light to give too much info.

Change the original Voltage stabiliser for a solid state unit. Consider changing the flasher unit for a modern one

 

Roger.

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And if you go to LED lights - sooo much better than Lucas Prince of darkness you don't need relays as the amps are so low but do need the correct flasher unit if you add led indicators.

Michael

Edited by MichaelH
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And just to add to the above, the only lamp not to change to an LED is the ignition warning lamp. The current from that helps to 'wake up' the alternator.  

Do you intend adding a 'logic unit' to the overdrive ?  It makes a good system even better. 

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35 minutes ago, MichaelH said:

And if you go to LED lights - sooo much better than Lucas Prince of darkness you don't need relays as the amps are so low but do need the correct flasher unit if you add led indicators.

Michael

Yes Michael, have already purchased from Classic LED in Cheltenham, remembered reading about keeping the ignition bulb as standard and ordered the new flasher relay as well. The old bulbs I couldn't change were the numberplate pair as the bulb is too tall

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27 minutes ago, RobH said:

And just to add to the above, the only lamp not to change to an LED is the ignition warning lamp. The current from that helps to 'wake up' the alternator.  

Do you intend adding a 'logic unit' to the overdrive ?  It makes a good system even better. 

I read about it on the revington site but for the time being just trying to get the basics done so I think that will need to wait until i've save a bit more pocket money

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50 minutes ago, RogerH said:

Hi David,

 your simple question will get rather a lot of answers.

Keep the ammeter it will give good info and in my opinion better than the Voltmeter.

The old relays tend to survive very well - keep them until they need changing. Many of the relays can actually be taken apart to clean the contacts.

Do not rely on the Ignition warning light to give too much info.

Change the original Voltage stabiliser for a solid state unit. Consider changing the flasher unit for a modern one

 

Roger.

Thanks Roger, solid state from the usual car autoelectric suppliers?

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No need to use the rather expensive Revington logic unit.  There have been several circuits posted in threads on here which use just a couple of cheap relays to get the same function. 

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1 minute ago, Cotswoldiver said:

I read about it on the revington site but for the time being just trying to get the basics done so I think that will need to wait until i've save a bit more pocket money

If your adding the Revington extra fuse box do not fit it where they say on top of the footwell as thats prone to getting wet, fit it on the inner wing next to the original.

Stuart.

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13 minutes ago, Cotswoldiver said:

Yes Michael, have already purchased from Classic LED in Cheltenham, remembered reading about keeping the ignition bulb as standard and ordered the new flasher relay as well. The old bulbs I couldn't change were the numberplate pair as the bulb is too tall

Re the number plate lamps from Classic LED, I've just done this on my 4a, they were supplying the wrong lamps, now corrected. Get in touch with them, really good customer service

Rgds

David

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4 minutes ago, qkingston said:

This is what Duncan suggested:

GLB207 BA15S 5W LED UPGRADE BULB 15MM BAYONET FITTING

Rgds

David

Thanks I'll drop him a note and see if i can exchange

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29 minutes ago, stuart said:

If your adding the Revington extra fuse box do not fit it where they say on top of the footwell as thats prone to getting wet, fit it on the inner wing next to the original.

Stuart.

Good suggestion - thanks

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14 minutes ago, qkingston said:

This is what Duncan suggested:

GLB207 BA15S 5W LED UPGRADE BULB 15MM BAYONET FITTING

Rgds

David

Just checked with Duncan, that is what I actually ordered but they are too tall for the glass dome, he says probably a few months before they produce a shorter version

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Hello David

                  Just fit one of these inside your old can!(10volt negative type)

Even cheaper from China

78xx 79xx Three Terminal TO-220 Linear Voltage Regulator IC 1.0A, Various | eBay

Qty 5: 78xx 79xx, 3 Pin TO220 1A Linear Voltage Regulator IC 1 Amp | eBay

Roger

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4 minutes ago, rogerguzzi said:

78xx 79xx Three Terminal TO-220 Linear Voltage Regulator IC 1.0A, Various | eBay

Qty 5: 78xx 79xx, 3 Pin TO220 1A Linear Voltage Regulator IC 1 Amp | eBay

If you use those you need the LM7810 for a negative earth car or the LM7910 for a positive earth one.   The TO220 case is easiest to work with and can be bolted to the metal case to act as a heat sink. 

Data sheet:

https://pdf1.alldatasheet.com/datasheet-pdf/view/105708/FAIRCHILD/LM7810.html

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A voltmeter WILL tell you whether the battery is charging or not. Indeed some are even marked in this way (on charge, off charge, normal etc. Above 13v and its charging, 12v or under and it is not charging. Simples.  It will also let you know the condition of the battery when you turn on the ignition which an ammeter can not do. Also means you can do away with 2 heavy, un fused, wires from behind the dash. You can get some all black with white letter face volt meters which don`t look out of place.

Having said all that, I have an alternator and still have the ammeter, because I am too lazy to change it, but as the ammeter only goes to 30amp I deliberately bought the lowest amp alternator (45 amp I think it was) which is still plenty better than the dynamo. I have also fitted a 40amp Maxi fuse between the battery and the car electrical system. Only the starter is un fused now on my car.

Ralph

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3 minutes ago, Ralph Whitaker said:

A voltmeter WILL tell you whether the battery is charging or not. Indeed some are even marked in this way

Sorry Ralph, but it doesn't - Irrespective of what the marking purports to show.  It really just shows what the generator voltage is and although most of the time that is a good hint of what is going on, you don't actually know for sure whether the battery is taking charge or not. Only an ammeter can show that. 

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16 minutes ago, RobH said:

 

Sorry Ralph, but it doesn't - Irrespective of what the marking purports to show.  It really just shows what the generator voltage is and although most of the time that is a good hint of what is going on, you don't actually know for sure whether the battery is taking charge or not. Only an ammeter can show that. 

Beg to differ.  If your voltmeter is saying 14v or above, it has to be charging your 12v battery . If reading 11v then you know you are depleting the battery.  I get your point about not knowing that it is shoving power into the battery. In any case why do you need to know, all modern cars manage quite well with a warning light, and unless you drive all the time looking at the ammeter you are more likely to see the red light first.

Edited by Ralph Whitaker
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16 minutes ago, Ralph Whitaker said:

Beg to differ.  If your voltmeter is saying 14v or above, it has to be charging your 12v battery

No, sorry but that is not always the case. The generator does not necessarily look at the battery voltage (a few do but most don't) and will bang out the 14v + whatever is attached to it.  It is possible to have a battery which has lost its capacity in which case its terminal voltage will rise very quickly and it will not take a proper charge even at 14Volts applied. The same thing would happen if there was a bad connection to the battery where the voltage drop would fool the meter. 

A voltmeter just makes the assumption that everything is OK and in most cases it is, but it does not tell the real story.  It infers the situation of one variable by measuring another. 

An ammeter tells you whether current is actually going into or out from the battery but it doesn't tell you what the generator voltage is.  However, if you know whether there is charging current it is debatable whether you need to know what voltage is driving it. The ideal situation is to have both meters if you want the full story, but most people don't want that information. After all, in a modern you just get a warning light. 

 

 

 

Edited by RobH
typo
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13 minutes ago, RobH said:

No, sorry but that is not always the case. The generator does not necessarily look at the battery voltage (a few do but most don't) and will bang out the 14v + whatever is attached to it.  It is possible to have a battery which has lost its capacity in which case its terminal voltage will rise very quickly and it will not take a proper charge even at 14Volts applied. The same thing would happen if there was a bad connection to the battery where the voltage drop would fool the meter. 

 

 

 

 

Hi, you make a good point, but so I can understand better, in a situation you describe above, where the battery reaches terminal voltage quickly and tricks the voltmeter into thinking all is OK, does the ammeter keep on showing a charge?, or does that also drop back to zero.

Is the situation different between an alternator and a dynamo? 

Ralph

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