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BobHorvath
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I must be missing something, what is the advantage?
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Slow day at the Triumph forum, so here it goes.
I think (get second, third, fourth opinions) that it mainly so you could fit a newer and higher output alternator and that most modern accessories are negative earth.
These may not be advantages depending on how you look at it...
I think (get second, third, fourth opinions) that it mainly so you could fit a newer and higher output alternator and that most modern accessories are negative earth.
These may not be advantages depending on how you look at it...
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Re: frosh asks what is the advantage to negative g
<div class="ubbcode-block"><div class="ubbcode-header">Quote:] I think that's about it. If you don't want or need upgraded audio, and are happy with the generator, well, why bother? [/QUOTE]
That's a good question. There is no fundamental advantage to negative ground over positive ground; the main reason to change is for compatibility with later equipment, such as electronic ignition or radios. It's not that hard to do, so a lot of us make the change, just in case it might come in handy at some point in the future.
Perhaps the best reason for switching to negative ground, in my opinion, is a safety issue: someone could easily assume that a positive-ground car is negative ground, without checking, and hook up jumper cables backwards. Since positive-ground cars are quite rare these days, it's an easy mistake to make, and the consequences are scary.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:] I think that's about it. If you don't want or need upgraded audio, and are happy with the generator, well, why bother? [/QUOTE]
That's a good question. There is no fundamental advantage to negative ground over positive ground; the main reason to change is for compatibility with later equipment, such as electronic ignition or radios. It's not that hard to do, so a lot of us make the change, just in case it might come in handy at some point in the future.
Perhaps the best reason for switching to negative ground, in my opinion, is a safety issue: someone could easily assume that a positive-ground car is negative ground, without checking, and hook up jumper cables backwards. Since positive-ground cars are quite rare these days, it's an easy mistake to make, and the consequences are scary.
OP
BobHorvath
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Re: frosh asks what is the advantage to negative g
Thanks for all the input. Does anyone have info on beefing up the stock generator?
Thanks for all the input. Does anyone have info on beefing up the stock generator?
BlueRidge2
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Re: frosh asks what is the advantage to negative g
Perhaps the best reason for switching to negative ground, in my opinion, is a safety issue: someone could easily assume that a positive-ground car is negative ground, without checking, and hook up jumper cables backwards. Since positive-ground cars are quite rare these days, it's an easy mistake to make, and the consequences are scary.
Is the proper hook up when jumping a positive ground system with a negative ground system pos to pos and neg to neg as long as the two vehicles donot make contact with the other?
Also when hooking up a charger on the positive ground on my car I 've been hooking pos to pos and neg to neg. I do utelize a battery disconnect on my grounded wire and have that circuit opened when charging. Is this correct? I havent blown any thing up ...yet. Thanks Bob
Perhaps the best reason for switching to negative ground, in my opinion, is a safety issue: someone could easily assume that a positive-ground car is negative ground, without checking, and hook up jumper cables backwards. Since positive-ground cars are quite rare these days, it's an easy mistake to make, and the consequences are scary.
Is the proper hook up when jumping a positive ground system with a negative ground system pos to pos and neg to neg as long as the two vehicles donot make contact with the other?
Also when hooking up a charger on the positive ground on my car I 've been hooking pos to pos and neg to neg. I do utelize a battery disconnect on my grounded wire and have that circuit opened when charging. Is this correct? I havent blown any thing up ...yet. Thanks Bob
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Re: frosh asks what is the advantage to negative g
The later BJ8 already has a "slightly" higher output generator. I doubt if it is very practical to change to a larger generator from another car.
Alternators are much more compact for their output. For really big bucks, you can get an alternator that is built into a generator housing.
D
BR Bob,
I think you have it about as correct as possible.
D
Hi Bob H,BobHorvath said:
The later BJ8 already has a "slightly" higher output generator. I doubt if it is very practical to change to a larger generator from another car.
Alternators are much more compact for their output. For really big bucks, you can get an alternator that is built into a generator housing.
D
BR Bob,
I think you have it about as correct as possible.
D
Keoke
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Re: frosh asks what is the advantage to negative g
Hi Bob, Check the generator on your car, if it is a CP42 unit it is capable of producing 35 Amps. I run a modern radio with a 500 watt power amp, Interior lights, Electronic fuel pump and ignition as well as driving lights. I have not found any reason to switch to an alternator but the radio forced the ground circuit change. The most significant change in the lighting system I made, was to install relays to switch direct battery power to the lighting systems. Additionally, I run effectively a slightly smaller pulley on the generator which upgrades its ability to charge at idle speeds.---Fwiw--Keoke
BobHorvath said:
Hi Bob, Check the generator on your car, if it is a CP42 unit it is capable of producing 35 Amps. I run a modern radio with a 500 watt power amp, Interior lights, Electronic fuel pump and ignition as well as driving lights. I have not found any reason to switch to an alternator but the radio forced the ground circuit change. The most significant change in the lighting system I made, was to install relays to switch direct battery power to the lighting systems. Additionally, I run effectively a slightly smaller pulley on the generator which upgrades its ability to charge at idle speeds.---Fwiw--Keoke
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BobHorvath
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Re: frosh asks what is the advantage to negative g
Thanks again for all the input. While going to collage I worked in the armature shop @ Sun Shipbuilding and Dry Dock in Chester Pa. I seem to recall that twisting the brush block in the direct of rotation increased the output voltage. The other idea relates to incresing the size of the generator output wire. For a boat/inverter installation I adjust the alt. output to 14.8V (at the battery terminal) for lead acid. The size of the battery cables could definately be increased. THese are some ideas that could help if you see a big drop (greater than 10% 1.2v) across the lead to lights, gen (voltage drop from neg source to appliance).
Thanks again for all the input. While going to collage I worked in the armature shop @ Sun Shipbuilding and Dry Dock in Chester Pa. I seem to recall that twisting the brush block in the direct of rotation increased the output voltage. The other idea relates to incresing the size of the generator output wire. For a boat/inverter installation I adjust the alt. output to 14.8V (at the battery terminal) for lead acid. The size of the battery cables could definately be increased. THese are some ideas that could help if you see a big drop (greater than 10% 1.2v) across the lead to lights, gen (voltage drop from neg source to appliance).
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Re: frosh asks what is the advantage to negative g
Some very old automotive & maybe some industrial generators used a third brush which could be moved to adjust the output voltage. Old Fords had the third brush. This was later replaced by a voltage regulator & the third brush was eliminated since the third brush couldn't automatically adjust for varying loads.
Some alternators have an extra "sensing" wire that reads voltage directly at the battery & compensates for alternator to battery voltage drop. Not really necessary for the average automotive application.
D
Hi Bob,BobHorvath said:
Some very old automotive & maybe some industrial generators used a third brush which could be moved to adjust the output voltage. Old Fords had the third brush. This was later replaced by a voltage regulator & the third brush was eliminated since the third brush couldn't automatically adjust for varying loads.
Some alternators have an extra "sensing" wire that reads voltage directly at the battery & compensates for alternator to battery voltage drop. Not really necessary for the average automotive application.
D
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BobHorvath
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Re: frosh asks what is the advantage to negative g
sounds like you know what i am leading to. I also recall that you can adjust regulators with an adjustment to the contacts with a bending to the gap. THe idea is to increase the voltage delivered to the bat. Do you see what I am saying about delivering 14.8v @ the the bat. terminal under load? If their is a big difference under load vs no load then the small leads are droping the voltage due to their resistance so drop the gauge of the lead and then adjust the voltage with the gap in the regulator to achieve the correct charging voltage. I think this would maximize the output of the generator system. HEALYBOB
sounds like you know what i am leading to. I also recall that you can adjust regulators with an adjustment to the contacts with a bending to the gap. THe idea is to increase the voltage delivered to the bat. Do you see what I am saying about delivering 14.8v @ the the bat. terminal under load? If their is a big difference under load vs no load then the small leads are droping the voltage due to their resistance so drop the gauge of the lead and then adjust the voltage with the gap in the regulator to achieve the correct charging voltage. I think this would maximize the output of the generator system. HEALYBOB
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Re: frosh asks what is the advantage to negative g
I guess that you could do so. The old Lucas generator regulators have screw adjustable contacts to set the voltage. They aren't very accurate by design, & at best, the voltage varies quite a bit from no load to full load. Maybe from 16 volts no load to 13.5 volts at full load.
On the other hand, alternators with built in regulators are not adjustable & usually run from 14.2 or so, to 14.8 volts. Depending on the particular alternator/regulator.
In any event, to put things in perspective, assuming a 40 amp generator or alternator output:
With three feet of 12 AWG wire from generator to starter solenoid & seven feet of #2 AWG wire from the solenoid to battery, there would be 0.196 volts drop in the #12 & 0.04 volts drop in the #2 AWG wire for a total drop of 0.24 volts from generator to battery. For a number 10 AWG wire from generator to solenoid the total drop would be 0.16 volts.
Neither of these voltage drops is out of the range that a normal battery & regulator can handle. Remote sensing alternators are not usually used until the outputs get over 100 amps.
At 300 amps starter draw the #2 AWG wire will drop 0.33 volts. Not very significant either.
D
I guess that you could do so. The old Lucas generator regulators have screw adjustable contacts to set the voltage. They aren't very accurate by design, & at best, the voltage varies quite a bit from no load to full load. Maybe from 16 volts no load to 13.5 volts at full load.
On the other hand, alternators with built in regulators are not adjustable & usually run from 14.2 or so, to 14.8 volts. Depending on the particular alternator/regulator.
In any event, to put things in perspective, assuming a 40 amp generator or alternator output:
With three feet of 12 AWG wire from generator to starter solenoid & seven feet of #2 AWG wire from the solenoid to battery, there would be 0.196 volts drop in the #12 & 0.04 volts drop in the #2 AWG wire for a total drop of 0.24 volts from generator to battery. For a number 10 AWG wire from generator to solenoid the total drop would be 0.16 volts.
Neither of these voltage drops is out of the range that a normal battery & regulator can handle. Remote sensing alternators are not usually used until the outputs get over 100 amps.
At 300 amps starter draw the #2 AWG wire will drop 0.33 volts. Not very significant either.
D
Ed_K
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Re: frosh asks what is the advantage to negative g
You were very correct. DC drops voltage quickly as wire length increases. Using Thicker wire is the only way to slow down the voltage drop per a given length of cable. If mine ever needs to be replaced, I will put in larger diameter cable.
/bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
You were very correct. DC drops voltage quickly as wire length increases. Using Thicker wire is the only way to slow down the voltage drop per a given length of cable. If mine ever needs to be replaced, I will put in larger diameter cable.
/bcforum/images/%%GRAEMLIN_URL%%/thumbsup.gif
Keoke
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Re: frosh asks what is the advantage to negative g
No Cutlass, you did not waste your time reducing the voltage drop between the battery and the load distribution point. That was a Plus. Whats being over looked here is the contact resistances of the connectors in the circuit. These resistances can exceed the resistance of your old #4 wire and they continue to grow with age.-Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
No Cutlass, you did not waste your time reducing the voltage drop between the battery and the load distribution point. That was a Plus. Whats being over looked here is the contact resistances of the connectors in the circuit. These resistances can exceed the resistance of your old #4 wire and they continue to grow with age.-Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif
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Re: frosh asks what is the advantage to negative g
D
Not at all. I used #2 in my examples & have #2 installed on my car. I think the question was about the wire size from generator to solenoid & regulator settings. Did I miss something.Cutlass said:
D
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Re: frosh asks what is the advantage to negative g
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Is the proper hook up when jumping a positive ground system with a negative ground system pos to pos and neg to neg as long as the two vehicles do not make contact with the other? [/QUOTE]
Yes, charger or jumping, always connect positive to positive and negative to negative. Doesn't matter if its positive ground or negative ground. But, as you say, make sure the bodies don't contact if the two cars are not the same. (Even if they are the same, it's a good idea not to let them touch. You want the current to go through the cables, not fry a hole in the nice chrome on your bumper!)
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Is the proper hook up when jumping a positive ground system with a negative ground system pos to pos and neg to neg as long as the two vehicles do not make contact with the other? [/QUOTE]
Yes, charger or jumping, always connect positive to positive and negative to negative. Doesn't matter if its positive ground or negative ground. But, as you say, make sure the bodies don't contact if the two cars are not the same. (Even if they are the same, it's a good idea not to let them touch. You want the current to go through the cables, not fry a hole in the nice chrome on your bumper!)
Re: frosh asks what is the advantage to negative g
Be a bit careful about trying to get too much power (amps) out of your generator. The BMC type units were designed to deliver around 20 or maybe 25 amps max. If you adjust the regulator to make them deliver much more you run the definite risk of overheating the generator and melting some of the solder joints (yes- this CAN happen!) and basically ruining the entire unit.
Bill
Be a bit careful about trying to get too much power (amps) out of your generator. The BMC type units were designed to deliver around 20 or maybe 25 amps max. If you adjust the regulator to make them deliver much more you run the definite risk of overheating the generator and melting some of the solder joints (yes- this CAN happen!) and basically ruining the entire unit.
Bill