2015 ProXs - critical voltage issue

[mcguirt24]

Serial 2B091375. 2015 Optimax proxs 150.

I was running the boat almost wide open on Sunday and it went into guardian mode. Vessel view mobile showed two codes: critical voltage 601-5 and then water pressure sensor not working properly 411-25. I took the boat to the shop and it is no longer showing the codes. The battery connection was checked and the engine cable was not on first. That has been corrected.

When hooked to the computer, the voltage is showing 12.2-12.6. However, when the boat is cranked the voltage drops to 7.5-8.5v and then climbs back up to 13+ after. The battery is 800cca and is about 8 months old. Water pressure and block pressure were reading normal.

Has anyone had this issue? Is that a sign the starter is having issues? And is the water pressure sensor just a code that was thrown because of the voltage drop?

Thanks in advance!

[leonreno]

How old is the battery? Your battery is the bare minimum for the motor, if you are running many electronics off of it it’s probably not adequate. Voltage does normally drop while cranking but 7-8 volts is lower than normal, leads me to think your battery is weak. Might be some degraded cables also. Does your motor have a digital water pressure gauge/reading or a separate analog gauge? What does the battery voltage read at the battery terminals with volt meter while not cranked and after cranking?

[SilverFox579]

I was running the boat almost wide open on Sunday and it went into guardian mode. Vessel view mobile showed two codes: critical voltage 601-5 and then water pressure sensor not working properly 411-25. I took the boat to the shop and it is no longer showing the codes. The battery connection was checked and the engine cable was not on first. That has been corrected.

When hooked to the computer, the voltage is showing 12.2-12.6. However, when the boat is cranked the voltage drops to 7.5-8.5v and then climbs back up to 13+ after. The battery is 800cca and is about 8 months old. Water pressure and block pressure were reading normal.

Mercury specifies 800CCA for engine only so if you're running other items off the same battery you're tempting fate - "BATTERIES THAT MEET THE REQUIREMENTS"

Was the battery fully charged prior testing static and cranking voltage? SS Nyloc nuts on the battery terminals? If not, fully charge the battery and have it load tested then repeat the test. You should see 13.8 - 14.3vdc at idle.

Low voltage can indeed cause some screwy sensor readings.

[mcguirt24]

Thanks for the feedback. The battery was fully charged, but I am running my boat power (pumps, lights, etc.) and a helix 9 off the same battery. I will take a look at the battery list posted above. Thanks again.

[SilverFox579]

If you're running all those items off the start battery you need more capacity, any of the Enersys options in the top chart will be an excellent choice.

[mcguirt24]

Getting a new battery with 1000 cca. I'll report back once I get it installed the week after next. Thanks again for the replies and assistance.

[EuropeanAM]

You also need to ask that shop to provide a full report (Run History, Freeze Frame (Fault) History, and Fault Seconds Counters). Those faults didn't "disappear" unless someone intentionally deleted them.