Comparison of electronic ignition MMI vs Indigo

[romantic comedy]

It seems slow here tonight, so I thought I would ask this again.

A while back I asked about the differences between the MMI electronic ignition and the Indigo electronic ignition.

I remember a lot of great responses, but I dont think the question was really answered.

The mmi EI has just the parts that replace the points... the Indigo EI replaces the points but has an additional box.. I am wondering about the differences...

thanks guys

[ndutton]

The two systems use different triggering mechanisms. Both have greater dwell than points, both are non-contact systems eliminating wear issues and both are known to be reliable. Increased dwell means you have to be sure your ignition system is up to snuff.

I don't have any experience with the Indigo unit so I can't discuss anything beyond their product description. My opinion is you'll need to wire the 'R' bypass on the starter with the bundled Indigo retrofit kit. In the kit they have both a 4.3 ohm coil AND a 1.5 ohm resistor for a whopping 5.8 ohm ignition system. That's a lot. I'm sure they intend for both to be installed otherwise why would both be in the kit?

My Pertronix unit (same as MMI) has been trouble free for many years.

For the record, there's a third electronic ignition system for Atomic fours: the HotSpark. I'm trying one on my spare engine. So far so good

[romantic comedy]

Thanks Neil.
I still have points, and will most likely continue to do so. I am curious about why an addition box is included with the Indigo EI. I wonder why it is needed and what it does.

SO far, if I go with EI, I would get the MMI unit. Aside from that it comes from Don, it has less parts. That is always a good thing in a marine engine.

[ndutton]

I'll defer to Dave Neptune as he has an Indigo unit. I believe however that the Indigo has only the optical trigger under the distributor and the switching electronics are in the remote module. The Hall Effect magnetic systems (MMI, Pertronix and HotSpark) have everything under the distributor cap.

I'm sure you are but I have to ask. Are you up to speed on the voltage/amperage/resistance balance required with EI?

[joe_db]

I had an Indigo in the dark pre-resistor days. The optical trigger worked well and was easy to install. It does make a nice hot spark. The Indigo diagram does show the ignition bypass for starting. Indigo now includes the breaker plate so you can switch back to points easily.

Now the ballast resistor-coil resistance issue is known and solved by both types, I am not sure one would have a clear advantage over the other. In *both* cases the source company makes more sophisticated modules that IMHO have advantages worth pursuing. Hint-Hint Moyer and Indigo

* I can't swear Crane reads this forum, but now they have prominent warnings about the ballast resistor issue LOL

[Dave Neptune]

Ignition choices

There are a few types of ignitions out there and they all work fine doing "there" job.

First the Pertronix or an ignition style utilizing the "Hal effect" or more commonly known as a magnetic trigger. In these it is a magnetic pulse of the magnetic ring and the sensor inside the distributor does the switching that the points did. These units are usually more compact and a bit easier to install. The down side on this type of unit is the fitting of the magnetic ring can be a bit of a problem both off and on as they can be cracked and rendered useless. The problem is not so much the ring itself but the condition of the "cam" it is being installed over.

The Indigo or a "photo optic" style utilizes a photo cell (a lite) and a "shutter". The shutter fits over the cam (just like the magnetic ring) however it is a plastic piece and far more forgiving as far as getting it mounted on the "cam". This shutter has a flat disc with small slices cut out (4~6~8etc). These slices pass through the photo sensor and each time a slice or gap passes through the signal is sent to the externally mounted box to do the switching. One of the real plusses with the Indigo is that with the later models there is a red led indicator lite on the externally mounted box that can be mounted in view to confirm the switching signal, allowing you to see that it is getting the signal for diagnosing it ~ quite handy.

Volts and resistance: Both of these and most all systems like these were designed for the automotive market place. Now we in the marine market place have many different systems, types of batteries and charging systems. Most all things automotive were designed around the 13.8v that is used in almost anything automotive utilizing a single battery and a "stock" A-4. Now in our usage in the marine environment we have batteries that require higher charging voltages and demands. Another words we push the charging circuit far more than the automotive world and have experienced coil heating and some premature failures. This is not caused by Pertronix or Indigo but our taking them out of there designed voltage ranges. Then you add weak batteries that when grouped up can still start a puny A-4 and if isolated individually would not come close to starting your car!!!! These low batteries because of there weakness cause elevated charging voltages too and that also adds to the problems relating to coil voltages and failures. A simple resistor will fix this on either unit. Now don't think that points work better with these higher voltages as the points themselves will deteriorate much faster but not cook the coil~still a looming failure and constant adjusting to maintain ignition timing.

Advantages~with either type once installed and set your done!! Unless you want to change the timing all that is needed is to replace the "hard" parts of the system like plugs, cap, rotor and occasionally wires. I replace my "stock" J-12 plugs every 3 years and cap and rotor at 5 years. My wires are now about 12 years old and may get replaced in a few years. I run just over a hundred hours a year and my engine is an original 1970 (one new Eaton exhaust valve replaced in 1983 when I purchased her) and very tired, She still runs great and I have never been stuck with a non-start episode in all that time~reliability is bliss.
I will state one advantage of the Indigo or photo optic trigger styles of ignition and that is they will switch or send the switching signal at a far lower voltage which could be a big advantage for hand cranking when the battery or batteries are to weak to spin the engine!!

Go electronic and be done with it.

Dave Neptune

[Rbyham]

Every time I see this topic come up it leaves me with a question. Can anyone point me to a step by step of what happens when I hit the key. I have indigo EI but if it ever goes bad I would not even know what to suspect. I simply do not understand basic ignition.

[joe_db]

http://en.wikipedia.org/wiki/Ignitio...rated_ignition

Testing the Indigo system is mainly sparking the coil with a test wire to see if the coil is dead or not. If the coil is not dead, then the EI module is.

Every time I see this topic come up it leaves me with a question. Can anyone point me to a step by step of what happens when I hit the key. I have indigo EI but if it ever goes bad I would not even know what to suspect. I simply do not understand basic ignition.

[ndutton]

I simply do not understand basic ignition.

Grossly oversimplified the coil builds and stores a massive charge (from ~12VDC to 25,000 ~ 40,000VDC), the points or EI tells the coil when to deliver the charge, the rotor and distributor cap sends the charge to the proper spark plug. Timing is exactly what it says, making sure the charge gets to the right spark plug at the right time.

Beyond that it's all a matter of quality and durability. Simple as that. If anybody starts throwing out multi-syllable words sounding like they barfed an electronics dictionary they're either getting into minutiae that has little effect on the subject or they're intentionally trying to confuse and impress. Shine 'em on.

That goes for me too.

[romantic comedy]

sing along with me

the battery is connected to the ignition switch
the ignition switch is connected to the coil, or resister, if so equipped
the coil primary is connected to the distributor and points
the points are connected to the ground when closed
the secondary center terminal of the coil is connected to the distributor cap
the rotor spins and connects the spark to the correct wire
the wire connects the spark to the spark plug
the spark plug makes the bang

it sounded better at practice today.

[Administrator]

These low batteries because of their weakness cause elevated charging voltages

I think weak batteries elevate the charging amperage and not the voltage. At least that's how it is on my boat.

Doubling back to the original question as to the difference between the Moyer Marine EI module and the competitor's, I presume both are fine at the end of the day. On the other hand, one helps pay for this forum, and one doesn't.

Bill

[Dave Neptune]

Bill, my reference was to an old "puffed out" battery that has very little reserve. When charging the amperage and voltage will rise higher to maintain a higher voltage that the battery can supply due to it's already low voltage level~this is not so with good batteries just a bit discharged.

Also the weak old puffed out batteries will really heat up even at a modest 14v unlike a "good" battery. With these old batteries it takes far more charge to see "normal" voltage levels. I am experiencing this now with my due to be replaced house bank, now at seven years old.

Dave Neptune

[ndutton]

When charging the amperage and voltage will rise higher to maintain a higher voltage that the battery can supply due to it's already low voltage level . . . . . . . I am experiencing this now with my due to be replaced house bank, now at seven years old.

What different voltages are you seeing out of the alternator Dave?

[Dave Neptune]

Neil my charging voltage is 13.8~14.2 and after running sits around 13.8~14 and all is well. Now that my house bank is in need of replacement after a few hours the house bank will get to 14.6 or more and be heating up~I even got them almost dry earlier in the season. These house batteries are at about half capacity (a guess) and will still run me for a long weekend and barely start the engine. If I isolate the start battery (2 years old) all is well at 13.8~14v. For my last few cruises I have isolated the house to charge and keep the higher voltage out of the start battery.

These 2 6v 235's are really abused (almost dry on two occasions) at this point and due to be replaced. I figured this out earlier in the season and just wanted to finish this season with them and start fresh next season. There at rest voltage is around 12.1 or less and really drop if I engage the starter far more so than the start battery a DS grp 27.

Dave Neptune

[ndutton]

Well, I'm at a complete loss to explain how a battery can achieve a higher voltage (14.6) than the alternator puts out under normal circumstances. It is also interesting that you are experiencing a relatively wide voltage output range from the alternator/regulator. The regulator strives to maintain a constant output voltage. There may be some minor wiggle room but your reports are not minor. This is from www.autoshop101.com

Voltage Regulation

The regulator will attempt to maintain a pre-determined charging system voltage level.

When charging system voltage falls below this point, the regulator will increase the field current, thus strengthening the magnetic field, which results in an increase of alternator output.

When charging system voltage raises above this point, the regulator will decrease field current , thus weakening the magnetic field, and results in a decrease of alternator output.

reference: http://www.autoshop101.com/trainmodu...or/alt131.html

You'll see it's the current that's variable, not the voltage. At least that's how it's supposed to be.