Constant heavy charging

[KJoeZ61]

This spring I installed a Holley Sniper and HyperSpark system along with a new in tank electric fuel pump. It all works fantastic! At the same time I installed a new 800 amp battery. I have a 360 engine in the Scamp. I replaced the alternator about a year ago with an Autozone 65 amp alternator.
My concern is that after the Sniper install the alternator gauge is always showing very heavy charging even on a half hour run. And the battery always tests about 12 volts with both a tester and the sniper monitor. But it always fires up. Does this sound like a bad battery?

 

[Mattax]

It sounds like the sniper, hyperkspark and 'lectric pump are tapped into the battery side of the ammeter.
Normally this side only has the battery on it. So the ammeter shows either battery charge or discharge.
But if you've added other items on it, then the ammeter shows the current flowing from the alternator to those items as well as battery charging.

Basic power circuit on most years is something like this:

If you really like having an ammeter, you could probably wire a fuse/breaker box for the new equipment off of the alternator.
Then use a heavy duty relay to connect the battery to the sniper-pump fuse box when the key is in start.
This way the fusible link, ammeter and all the connections in-between would not be subject to the additional power draw of the new equipment during start or run.

 

[Mattax]

Might want to consider copying the '73 (to '75?) wiring for the optional high output alternators.
I mention that because the extra loads on the battery during start may result in higher charging currents for longer periods of time.
It basically consists of two heavier wires and a grommet.
That scheme is shown here:
Another Ammeter bypass question

This would be in addition to supplying the new equipment direct from alternator.

 

[KJoeZ61]

Thanks Mattax for you response and I think I understand what your saying, just not clear on the modification you are suggesting. Holley wants it connected directly to the battery but didn't allow for this issue. Is there reason for concern that the fusible link might go out?

 

[Mattax]

Thanks Mattax for you response and I think I understand what your saying, just not clear on the modification you are suggesting. Holley wants it connected directly to the battery but didn't allow for this issue. Is there reason for concern that the fusible link might go out?

I think Holley & Autotronics (MSD) people had either one of two reasons for saying that.
1. These are relatively big draw items so they wanted a dedicated wire, and they assumed the battery and the alternator are closely connected in most cases.
2. Something inside their product is relatively sensitive to electrical noise or voltage ripple and the battery might act to dampen that.
3. A variation on the above two is the opposite concern. That these items won't turn on during start up because of the low voltage while starter is cranking. So they suggest the most direct connection to the battery.

OK. That's three possible reasons...
My guess is the first one is closest to the mark. Instructions are a generalization and don't account for systems like ours.

Concern about the fusible link. Yes a little. Even though its a short length, its only 16 gage wire.
Concern about the bulkhead connections. Yes. Depending on the year and options, it may be just one Packard 58 connector on the alternator feed, and same on the battery charge/feed.
Lets say the average current to the Fitech etc is 15 or 20 amps. Then that's 15 or 20 amps constantly though all of those connections and wires in addition to what they normally carry.

There could be enough resistance in the fusible link that it will get warm passing 20 amps for long periods of time.
Also, after start up, the link and attached wiring also will carry the current for recharging the battery. Add another 15 to 20 amps for a total of 40 amps. Even though the high charging rate may be less than a minute, IMO 40 amps is not something the circuit should see on a regular basis.

The alternator output connection through the bulkhead will also carry current for everything else that might be on.
Alternator field circuit - 0 to 3 amps
Brake lights
Heater fan
windshield wipers
etc.

This is why the alternator output side is probably the most vulnerable to overloading.
From around '66 to around '74 the alternator output through the firewall is a single wire with a packard 58 type terminal. That's probably the weakest point in the system.

The fact its all working for you right now is great.
These are things to look out for and I think you want to plan for addressing.

 

[KJoeZ61]

Mattax

What do you think about this idea? The Denso alternator. Wouldn't it be possible for this to work with the existing alternator? I'm not really worried about the amp gauge since the Sniper has a volt meter built right into it and it reads on the monitor.

Denso Alternator conversion Part-Number ?

 

[Mattax]

Are you asking if changing the alternator will help with what you see on the ammeter?
If so, no. Still need to reroute the wiring so current isn't flowing through the bulkhead connector to the splice to the ammeter to the bulkhead, through the fusible link, hopefully through another fusible link or fuses to the new stuff.

If you don't care about having the ammeter to monitor battery charging, you have more options for wiring.
Watching the voltage can give you a reasonably good sense of how the system is doing.

Whatever you do, just make sure there is a fusible link between the battery and any non-fused circuits (except the starter itself).

 

[KJoeZ61]

Are you asking if changing the alternator will help with what you see on the ammeter?
If so, no. Still need to reroute the wiring so current isn't flowing through the bulkhead connector to the splice to the ammeter to the bulkhead, through the fusible link, hopefully through another fusible link or fuses to the new stuff.

If you don't care about having the ammeter to monitor battery charging, you have more options for wiring.
Watching the voltage can give you a reasonably good sense of how the system is doing.

Whatever you do, just make sure there is a fusible link between the battery and any non-fused circuits (except the starter itself).

So couldn't I just run a fused #8 from the alternator to the hot side of the starter relay? And leave disconnected the black wire on the alternator that goes to the bulk head. wouldn't it back feed through? 30-40 amp fuse?

 

[Mattax]

So couldn't I just run a fused #8 from the alternator to the hot side of the starter relay?

I don't know the details of what you've got there but conceptualy yes that should work.

And leave disconnected the black wire on the alternator that goes to the bulk head. wouldn't it back feed through?

Yes. Definately leave the direct feed to the main splice. Electricity will take the shortest path as long as the bulkhead connector doesn't have excessively high reistance.

30-40 amp fuse?

You mean for a fuse on the alternator feed?
I don't know. It's kindof an odd situation. Normally things are fused based on the weakest link downstream. But in this case the only things downstream of the alternator I assume you already have on fuses or breakers. But in this case, the biggest concern is a short to ground in the alternator and the battery sends as much joice as it can up that wire until something burns through. If attaching at the starter relay I'd go with a 16 gage fusible link since that's what the factory diagram ( for wiring the 60 amp alternator option) shows with an 8 gage wire. A 14 gage would probably be OK - its still going to burn up before the 8 gage wire.

Another way is to have the new stuff on a single terminal block with a fusible link between the block and the starter relay. Then the alternator feed has no restriction.
Something like this below.

It could be an auxilery fusebox or it could be individual wires each with a ring terminal on the stud.

73 B-body's with optional 65 amp alternator (for Taxi, Fleet uses) show another relatively simple way fusible links could be arranged.

The way I read this, there's a 10 gage fusible link protecting the 6 AWG wires going to the starter relay, an ammeter and the alternator.
A 16 gage fusible link protects the 10 gage, 12 gage wires.

 

[KJoeZ61]

I don't know the details of what you've got there but conceptualy yes that should work.

Yes. Definately leave the direct feed to the main splice. Electricity will take the shortest path as long as the bulkhead connector doesn't have excessively high reistance.


You mean for a fuse on the alternator feed?
I don't know. It's kindof an odd situation. Normally things are fused based on the weakest link downstream. But in this case the only things downstream of the alternator I assume you already have on fuses or breakers. But in this case, the biggest concern is a short to ground in the alternator and the battery sends as much joice as it can up that wire until something burns through. If attaching at the starter relay I'd go with a 16 gage fusible link since that's what the factory diagram ( for wiring the 60 amp alternator option) shows with an 8 gage wire. A 14 gage would probably be OK - its still going to burn up before the 8 gage wire.

Another way is to have the new stuff on a single terminal block with a fusible link between the block and the starter relay. Then the alternator feed has no restriction.
Something like this below.
View attachment 1715351378
It could be an auxilery fusebox or it could be individual wires each with a ring terminal on the stud.

73 B-body's with optional 65 amp alternator (for Taxi, Fleet uses) show another relatively simple way fusible links could be arranged.
View attachment 1715351395
The way I read this, there's a 10 gage fusible link protecting the 6 AWG wires going to the starter relay, an ammeter and the alternator.
A 16 gage fusible link protects the 10 gage, 12 gage wires.

I like the option of just adding to the existing system. I appreciate your help and will reply to this thread when it's complete, hopefully in a day or two.