CDI Electronics and AGM Battery Compatibility

[Terrapin]

Can I utilize a sealed 12-volt NorthStar AGM battery with the CDI Electronics system I have in my 1986 Johnson 150 HP outboard (J150TXCDC)? I believe this engine has a 9 AMP charging system.
I vaguely recall seeing a post somewhere that this is not recommended by CDI Electronics. Is this true? Isn’t 12-volt DC 12-volt DC whether it comes from a 12-volt battery or a 12-volt AGM battery?

 

[racerone]

The ignition on that engine does not use 12 volts from the battery to make spark.

 

[Faztbullet]

That rect/reg is designed for a wet cell battery and the AGM will not work

 

[cyclops222]

What happens to CDI garbage when the alternator is recharging a slightly run down battery ? KABOOMM ?
I tried CDI on my old Evinrude's Rectifier. Always failed new and after 1 long run at WOT. Other boating friends had similar repeat failures.

 

[Faztbullet]

Yep...along with using wing nuts

 

[cyclops222]

You are looking into my small boat Battery Box.

 

[Terrapin]

I looked into this a bit further, and it seems the AGM batteries require a specific regulated voltage range 14.1 to 14.8 to properly charge them. The recommended CDI Electronics rectifier/regulator seems to output an acceptable 14.5 volts reading their technical info in my OEM service manual.
However, the CDI Electronics instructions state (see below image), "Do not use a maintenance free, AGM or dry cell battery with this type regulator/rectifier as this will void the warranty" associated with CDI regulator/rectifier. Any thoughts on why an AGM battery would be problematic with the CDI regulator/rectifier?

 

[saltchuckmatt]

Well ...and I'm taking an educated guess here, because at low speed your not getting 14.1 volts.

 

[cyclops222]

What are you getting ? At different levels of battery capacity ?

 

[Terrapin]

Just to clarify, currently I am running a standard lead acid battery with caps I can pull to check and confirm fluid level. It's important to note that I do not have a problem with my engines charging system or battery. The system is functioning just fine.
The question I have and originally posted is, why can't a sealed 12-volt AGM battery be used with the CDI Electronics system I have in my 1986 Johnson 150 HP outboard (J150TXCDC)? Said another way, why does CDI post the above warning (voiding warranty) in their rectifier/regulator instructions?

 

[saltchuckmatt]

Don't believe your motor is undervolting at slow RPMs?

Get your meter out and test

 

[airshot]

Yep...along with using wing nuts

Wing nuts are fine if mechanically tightened...approved by my local Coast Card inspection...

 

[dingbat]

Wing nuts are fine if mechanically tightened...approved by my local Coast Card inspection...

Just because USCG doesn't recognize it as a safety violation, doesn't change the fact that wing nuts are a well documented source of charging systems failures.

The only advantage to a wing nut is cost and the ability to tighten ot loosen w/o tools.
If you're going to "mechanically" (use a wrench) secure it, why not use the appropriate Nylon insert or serrated flange nut with "best practice" in mind?

​

 

[Faztbullet]

ABYC 10.8.3
Battery cables and other conductors size 6 AWG (13.3 mm²) and larger shall not be connected to the battery with wing nuts. There is a TSB from OMC to replace all engine connectors with locking nut and discard wing nuts.

 

[saltchuckmatt]

Yeah.....I'm a "no wing nuts" guy. Why risk it?

 

[airshot]

In an emergency, I don't have time to look for a wrench, I have a lexan tool for wing nuts cable tied to the battery where I would not allow a metal wrench to cause an issue. Have had a couple battery emergencies over my 60 years of boating, by the time I scrambled to find a wrench it would have been to late. But to each his own, I understand the safety concern as many would not tighten wing nuts properly...

 

[saltchuckmatt]

I used to use my "hook out" needle nose plyers while fishing....usually cussing because my motor wouldn't start.

I was much younger then!

 

[Terrapin]

Don't believe your motor is undervolting at slow RPMs?

Get your meter out and test

I agree the motor would not be providing the AGM specified 14.1 to 14.8 volts for charging at lower RPM's. This would lead to an under-charging condition for the battery. Why would this void the warranty of the CDI Electronics rectifier/regulator?

 

[saltchuckmatt]

I have no idea but it's below their parameters.

 

[cyclops222]

NEVER EVER put anything between the cable compression lug surface and the cleaned LEAD POST surface.
The washer goes between the nut surface and the lug surface.