Battery Fuse Protection

[steveg]

So you're not going to the next European Healey Meet?

The Norway meet? Doesn't include winter, does it?

No, but some of us plan on going to Death Valley next year.

 

[RAC68]

Hi Steve,

I believe it is even simpler then you may understand. Since the starter and its solenoid are extending from the battery as a singlet separate circuit, its components and the battery cable are only active for a short period and thereby pose a much reduced risk of causing a problem or having a disabling short circuit. This risk is further diminished by using a Ford Remote solenoid located near the battery to fully disengage this circuit from the battery when not activated during engine starting.

The second cabin routed battery connection would be also connected to the battery terminal and routed directly to the B terminal on the voltage regulator. This connection would consist of an appropriately sized cable (10 Gauge or better) and could be protected by a 20-40 Amp fuse. Following normal operations, alternator/generator charging power as well as operating power demands would be satisfied through this battery path.

All in all, I believe a much safer arrangement baring unanticipated issues.

Ray(64BJ8P1)

 

[steveg]

Hi Steve,

I believe it is even simpler then you may understand. Since the starter and its solenoid are extending from the battery as a singlet separate circuit, its components and the battery cable are only active for a short period and thereby pose a much reduced risk of causing a problem or having a disabling short circuit. This risk is further diminished by using a Ford Remote solenoid located near the battery to fully disengage this circuit from the battery when not activated during engine starting.

The second cabin routed battery connection would be also connected to the battery terminal and routed directly to the B terminal on the voltage regulator. This connection would consist of an appropriately sized cable (10 Gauge or better) and could be protected by a 20-40 Amp fuse. Following normal operations, alternator/generator charging power as well as operating power demands would be satisfied through this battery path.

All in all, I believe a much safer arrangement baring unanticipated issues.

Ray(64BJ8P1)

Hi Ray - If you press the bump button on the stock solenoid, how does it work unless the battery cable is hot all the time?

How does it energize the rear solenoid in order to energize the main cable to the stock solenoid?

 

[Keoke]

Important: by making such radical changes, we may be in fact decreasing the reliability of a known-reliable system which has worked well for generations.

-True: Steve

Increasing the number of parts in a system tends to reduce its reliability.

What is easy to do here in order to prevent damage to the starter cable, is to armor it with metal conduit against scrapes. If correctly executed, this adds no potential for failure into an

False: Steve

Enclosing the cable in a metal conduit alters its thermal characteristics which causes its overall resistance to increase.

From a Electrical / mechanical standpoint:

The conduit must be reliably insulated from the cars chassis over its total length which is difficult to achieve and if not accomplished places chassis ground in the immediate close proximity of the cable potentially enhancing its susceptibility to failure'​

 

[RAC68]

Steve,
​

1. If you press the bump button on the stock solenoid, how does it work unless the battery cable is hot all the time?
​

First, the bump button on the stock solenoid will not work when the remote solenoid is not activated (by the ignition switch) to provide power to the cable. As a result, the bump button on the original starter solenoid become useless.

The remote solenoid and the original solenoid will activate simultaneously through power provided to the key via the voltage regulator and second cabin-routed lower amperage (20-40 amps) power line from the battery. However, as you have suggested previously, the local starter solenoid could be bypassed (eliminated from any circuit but kept in place for future use) in favor of using only the remote starter solenoid.

In either case, power is sent to one or both solenoids simultaneously with the remote activating power to the cable and the original activating the starter. In a single remote solenoid arrangement, both tasks would be performed by the one solenoid. Once the car is started and the key/button released, one or both solenoids are deactivated along with power to the cable. However, in all cases, you would loose the bump button but gain a higher level of power security.

Keep in mind that if the remote solenoid is NOT present with all else in place, power would be always present through the cable. engine starting would take place as normal with the use of the original solenoid, and the bump button would be available. Although this configuration remains more vulnerable then our proposed configuration, it still has the potential of providing Volvo type continuing power during a catastrophic cable short.

2. How does it energize the rear solenoid in order to energize the main cable to the stock solenoid?

The rear Ford Remote Solenoid is connected to the ignition key and powered by the second line coming from the battery terminal and going to the "B" terminal of the voltage regulator. Since this, possibly 10 gauge connection could be fused, less exposed by running through the cabin, supplies alternator/generator charging current to the battery, and carries less then 1/10 the power required of the battery cable, I believe it is a much safer transport of operational power to and from the battery. Also, the battery switch is still in place and can be used to deactivate the battery for storage or parking.

Ray(64BJ8P1)​

 

[steveg]

Ray - thank you for the explanation. I was thinking you were trying to save the bump button functionality. it's a lot simpler without.

 

[Michael Oritt]

Important: by making such radical changes, we may be in fact decreasing the reliability of a known-reliable system which has worked well for generations.

-True: Steve

Increasing the number of parts in a system tends to reduce its reliability.

What is easy to do here in order to prevent damage to the starter cable, is to armor it with metal conduit against scrapes. If correctly executed, this adds no potential for failure into an

False: Steve

Enclosing the cable in a metal conduit alters its thermal characteristics which causes its overall resistance to increase.

From a Electrical / mechanical standpoint:

The conduit must be reliably insulated from the cars chassis over its total length which is difficult to achieve and if not accomplished places chassis ground in the immediate close proximity of the cable potentially enhancing its susceptibility to failure'​

I think Keoke is correct and still feel that if one uses best-quality battery cable, connectors and harnessing the likelihood of a dead short of the cable between the battery and the starter is low--absent a catastrophic collision, in which case you have other and bigger problems.

As to running a separate circuit to power lower-amperage appliances such as lights, etc. with its own fusing--absolutely, and locate fuses as close as possible to the source, as in at or very near to the battery or common buss.

 

[Novamonte]

If I understand it correctly, this rather complex change requires two cables to be run through the cabin - one "backward" to power the rear solenoid and one "forward" to provide power to circuits other than the starter. It also seems that the key risk associated with the original configuration would be a damage to the unfused cable running under the car causing it to short, e.g. if the car hits a bump or a rock. Wouldn´t it be much simpler and nearlas effective to re-route the main cable between the battery and the solenoid and run it inside the cabin? Admittedly it is a bit thicker that the two other cables proposed to go there, but I believe it would still be feasible and solve the main problem. I admit that a cable running through the cabin is not immune to damage, but correctly installed the risk should be much lower, and the risk for failure of all the new equipment would be eliminated.

 

[RAC68]

Hi Novamonte,

The use of 2 wires (10 gauge 20-40amp Fused Operational power line and 16/18 gauge Fuse key actuated remote solenoid line) should be easily placed through the cabin without taking up substantial room and could be well hidden for the change not to be obvious. The original cable and starter solenoid would be left as is with the connecting line between the starter solenoid and voltage regulator box disconnected at the voltage regulator end. Since the battery-based remote solenoid disconnects power from the battery through the cable before and after starting the car, in an accident or any condition that could cause a cable short, no detrimental result would probably be caused as there would be NO power flowing or connection after the short period of start-up through or connected to the cable.

Other then routing and connecting the both (2) wires, the installation of the remote solenoid (which could be placed in the space under the battery) and its intervention on the battery cable represents the most difficult and time consuming task involved in this change. As a result, I would expect properly routing the cable through the cabin, as you have suggested, would be much more difficult and take quite a bit more time to implement. Although I feel you are correct and rerouting the cable from its exposed location under the car to a path passes through the cabin would reduce risk, with its continuous high power flow, I would expect it to still hold more vulnerability and risk then that presented with the proposed alternative. Additionally, since both added lines are fused, should a catastrophic condition (cable short) happen during engine start-up and cause both new battery line fuses to blow, I would expect the remote solenoid to deactivate and fall back to its inactive state that would sever power to the shorting battery cable.

All in all, all changes should be easily hidden, giving a near concourse presentation.

Keep in mind that these are my thoughts as I have not installed these changes or plan to run tests as proof of concept.
Ray(64BJ8P1)​

 

[steveg]

Keoke -
I'd like to understand the metal conduit issue better from an electrical standpoint.

I have grounded 1/2" ID EMT in my garage with wires running through it. That was the origin of my thinking re the conduit.

If I run a 5/16" D cable through 1/2" ID EMT or Raceway on my car frame and use the starter motor for a few seconds, is the cable in danger of melting in that short time due to the close proximity of the grounded conduit?

If so, is this because of the large size of the cable relative to the open space inside the conduit -- compared to the small size of a 2 - 3 #12 wires running through my garage EMT?
Or is it because of an induction between the cable and conduit?

 

[Keoke]

Sufficient to say your garage which is wooden uses a relatively large- conduit-- No BX which places the wire in close contact with the conduit. which may not protect your garage from an electrical short in the wire .


Steve:
All wire / cable is current rated as a single wire in free space SO :

Even when we bundle wire into a harness those wires can't dissipate heat like they were rated to do for a given current and they run at higher temps and lower current which like I
said will cause their resistance to increase per unit length., under fault conditions simply reduces the insulations dielectric strength and a total failure which is enjoined by the close fitting conduit.

 

[Keoke]

I think that fella

Ray(64BJ8P1)​

done made his self a hand crank wid a lectric motoer--HI Ray--LOL

 

[steveg]

Sufficient to say your garage which is wooden uses a relatively large- conduit-- No BX which places the wire in close contact with the conduit. which may not protect your garage from an electrical short in the wire .


Steve:
All wire / cable is current rated as a single wire in free space SO :

Even when we bundle wire into a harness those wires can't dissipate heat like they were rated to do for a given current and they run at higher temps and lower current which like I
said will cause their resistance to increase per unit length., under fault conditions simply reduces the insulations dielectric strength and a total failure which is enjoined by the close fitting conduit.

Keoke - I think you're saying conduit large enough to be rated for that cable would be too large to be practical.

Anyway, looking at the bottom of my car (2-seater) the only places the cable would need to be armored are a few inches each, under the axle, where it crosses under the x-members. Most of the run on my car is above the rear brake line and out of danger from objects scraping on the frame. IMO problems with this setup are extremely unlikely.

 

[steveg]

Ray, Novamonte, Keoke and others - I've enjoyed studying this issue as we have done. It makes me appreciate not only how well the stock setup works, but why most cars have the battery in the front near the starter motor!

When I was in the Alfa club, many racers would move their batteries to the trunk in the interest of weight distribution. I can now see there are significant safety and reliability issues with this.

 

[Keoke]

Keoke - I think you're saying conduit large enough to be rated for that cable would be too large to be practic

No Steve:

That is not what I meant .
.
I meant do not put metal conduit over wiring used in DC circuits on Cars, the enhanced susceptibility for failure falls outside of good electrical engineering design.
​

 

[Novamonte]

Steve - in a way you can say that Austin-Healey was ahead of the game when they put the battery in the boot/trunk. Few cars had that configuration back in the day whereas many have today. All modern cars I have had in recent years (currently an Alfa Romeo Giulia QV and a BMW X5) have the battery in the rear. Today the main reason is weight distribution but for the Big Healey I would assume that the lack of space under the bonnet/hood was at least as important, if not more.

 

[John Turney]

Thank you Reid.

 

[RAC68]

Steve,

After all the years of playing with and addressing the many issues presented by my Healey's engineering, I have come to see my Healey as a plethora of enjoyable dynamic puzzles incased in an enigmatic envelope. What better learning vehicle could you find?

Ray(64BJ8P1)​

 

[steveg]

Keoke - I think you're saying conduit large enough to be rated for that cable would be too large to be practic

No Steve:

That is not what I meant .
.
I meant do not put metal conduit over wiring used in DC circuits on Cars, the enhanced susceptibility for failure falls outside of good electrical engineering design.
​

Keoke - I'm just trying to get you to explain what you mean instead of a version of "don't do it". How about some reasons?

 

[Legal Bill]

After further reading and further study, I'm still doing nothing. But carry on fellas. I enjoy reading the dialogue.