Issue with Electronics resetting when starting boat

[viper1216]

Having an electrical issue I am trying to chase down. Boat is an 01 Maxum 2400SCR. Bought it the beginning of last year. I installed a Raymarine Axium Nav unit and a new VHF Radio. Found if I had either of those items on while I was at anchor and went to start the boat...they would reset. Did a voltage drop test at end of year before I wrapped it and the voltage on my meter at the fuse box dropped from 12.5v to 8.2 when starting. Fuse boxes are both new and 10ga Red/Purp wire supplying fuse box looks good at connection. Ground connection looks good as well. Bought battery brand new at beginning of last season. It is a hybrid starter/Deep cell. I did try switching to my second battery which is 850cca starting battery and still had same issue. I did find one of my positive cables at the battery has some of the strands showing out of the connector....not sure if that could be the issue. But anything else I can check here? Not sure why I'm losing so much power. Any advice greatly appreciated.

 

[Scott Danforth]

start by cleaning the batter, cable, block connections.

you have a bad connection somewhere

 

[dingbat]

Zz

Having an electrical issue I am trying to chase down. Boat is an 01 Maxum 2400SCR. Bought it the beginning of last year. I installed a Raymarine Axium Nav unit and a new VHF Radio. Found if I had either of those items on while I was at anchor and went to start the boat...they would reset. Did a voltage drop test at end of year before I wrapped it and the voltage on my meter at the fuse box dropped from 12.5v to 8.2 when starting. Fuse boxes are both new and 10ga Red/Purp wire supplying fuse box looks good at connection. Ground connection looks good as well. Bought battery brand new at beginning of last season. It is a hybrid starter/Deep cell. I did try switching to my second battery which is 850cca starting battery and still had same issue. I did find one of my positive cables at the battery has some of the strands showing out of the connector....not sure if that could be the issue. But anything else I can check here? Not sure why I'm losing so much power. Any advice greatly appreciated.

Too lazy to dig up your units specification but doubt they are spec’ed to operate at 8.2 volt
Weak battery or the battery is too small (mca) for the motor

 

[viper1216]

Zz

Too lazy to dig up your units specification but doubt they are spec’ed to operate at 8.2 volt
Weak battery or the battery is too small (mca) for the motor

Definitely the reason they are resetting. I thought battery issue at first as well. But the starting battery is 1000mca and the Hybrid is 800. Engine is a 5.0 mercruiser, I believe the recommended is 500, so well above that spec. Both batteries were fully charged and I got the exact same readings regardless of which battery I used. It even happened when I had switch on BOTH.

 

[alldodge]

Both the above suggestions have great points, and I'm leaning more to Dings comment because your said

dropped from 12.5v to 8.2

If your readings are accurate, then your Bat is at 90% and should be 12.7 at full charge

 

[dingbat]

Definitely the reason they are resetting. I thought battery issue at first as well. But the starting battery is 1000mca and the Hybrid is 800. Engine is a 5.0 mercruiser, I believe the recommended is 500, so well above that spec. Both batteries were fully charged and I got the exact same readings regardless of which battery I used. It even happened when I had switch on BOTH.

Is that 8.2V at the axiom connector or on the battery? Axiom spec is 8 volts….

Compare voltage at battery to voltage at connector.

“1000 mca when new” doesn’t rule out a dying battery.
Have you had the batteries load tested recently?

I typically use this as a sign to replace my batteries

 

[viper1216]

Honestly I am going from memory on the readings. My apologies. I took them the end of Fall, and now that winter is hopefully coming to a close soon, trying to get a jump on things so they may be off a bit, but I do know it was quite a drop and did not seem right. I think I wrote it down somewhere, but will see if I can find the exact number. I can't unfortunately check for a few more weeks when the weather really stays warm a bit (I'm in RI). The batteries were fully charged. I have an onboard charger that is always on and plugged in on shore power. I did not load test them, but maybe I'll do that while I have them out. Like I said, one is brand new and this issue has been happening since that battery was first installed. That low reading was right at the main power cable going to the fuse box (red/purp) from engine plug.

 

[dingbat]

That low reading was right at the main power cable going to the fuse box (red/purp) from engine plug.

Powering sensitive electronics off/through the ignition circuit is just asking for problems. Power drops, noise, surges, etc.

My ignition powers nothing but the ignition switch. Everything else is either powered directly from the house battery or in the case of the components connected to the starting battery, off the accessories terminal on the battery switch.

 

[dingbat]

Both batteries were fully charged and I got the exact same readings regardless of which battery I used. It even happened when I had switch on BOTH.

I = v/r.
Current is directly proportional to the voltage and inversely proportional to the resistance.

If tying the two batteries together doesn’t reduce the voltage drop, demand is exceeding supply.

Dirty battery terminals, bad batter(ies), bad starter solenoid, bad starter....... typical voltage drop while cranking is @ 3.0V less.

 

[viper1216]

Oh they aren't powered to the ignition. They are straight to the fuse box. From the wiring schematic...the fuse box is powered by a 10ga red/purple wire that comes from a big plug at the back of the engine. From the schematic...that plug is powered B+ by a connection to the battery switch. I'll start with checking and cleaning up all the connections at the battery and switch and go from there .

 

[dingbat]

Oh they aren't powered to the ignition. They are straight to the fuse box. From the wiring schematic...the fuse box is powered by a 10ga red/purple wire that comes from a big plug at the back. From the schematic...that plug is powered B+ by a connection to the battery switch.

Power to the fuse box is coming off a 50 amp breaker on the motor and broken out on Pin 6 of the the main engine harness connector.

Wiring Diagram - Maxum 2400 SC3 Owner's Manual Supplement [Page 44]

Maxum 2400 SC3 Manual Online: Wiring Diagram. 38...

www.manualslib.com

The power for my primary instrumentation runs directly from the ACC terminal on the battery switch to a dedicated fuse panel at helm. A backup, redundant supply goes directly from the “house” battery post to the helm.

 

[viper1216]

Power to the fuse box is coming off a 50 amp breaker on the motor and broken out on Pin 6 of the the main engine harness connector.

Wiring Diagram - Maxum 2400 SC3 Owner's Manual Supplement [Page 44]

Maxum 2400 SC3 Manual Online: Wiring Diagram. 38...

www.manualslib.com

The power for my primary instrumentation runs directly from the ACC terminal on the battery switch to a dedicated fuse panel at helm. A backup, redundant supply goes directly from the “house” battery post to the helm.

Hmmm...interesting. So you have a power wire to your fuse from that 50amp breaker. Then an additional wire going from your ACC on switch and then another too battery? That was what I was originally going to do, run a separate wire between the fuse panel to the battery switch. I don't want to go straight to the house battery if I can avoid, as I like to be able to kill all power if needed with the only thing still having power being the bilge pumps. I am primarily plugged into shore power, but just in case. Appreciate the info and help!!

 

[dingbat]

Hmmm...interesting. So you have a power wire to your fuse from that 50amp breaker. Then an additional wire going from your ACC on switch and then another too battery?

I’m running a two battery setup with ACR and a Off/On/Both switch.

Primary (critical) circuit is wired to ACC post on switch with in-line breaker. Covers ignition, nav lighting, primary navigation devices, trim tabs, NMEA network, etc.

Secondary fuse panel is wired direct to house battery thru in-line fuse. Covers bilge pumps, raw water pump, live/bait well pumps, stereo, back up navigation devices, radar dome, etc.

Run offshore so getting home is paramount. I run redundant navigation electronics. Two Plotters, two sounders, vhf, radar all networked and powered separate power feeds.

Don’t care if I loose house battery for some reason. I can still get home.
Should I loose primary battery, I simply remove positive cable from battery and flip switch to both. House battery now powers the primary feed.

Understand the want for on/off switch. Have that function on primary battery. Everything on unswitched house supply is either on demand (bilge) or switched at the units themselves, ie chart plotter.

That was what I was originally going to do, run a separate wire between the fuse panel to the battery switch. I don't want to go straight to the house battery if I can avoid, as I like to be able to kill all power if needed with the only thing still having power being the bilge pumps. I am primarily plugged into shore power, but just in case. Appreciate the info and help!!

 

[viper1216]

Makes sense and helps a ton. Thank you!!

 

[sam am I]

EMC FLEX BLOG | Automotive Cranking Pulse

EMC FLEX BLOG - A site dedicated to Automotive EMC Testing for Electronic Modules - The Cold Cranking Pulse occurs when starting the engine in the morning and even worse in cold w

www.flexautomotive.net

 

[440roadrunner]

Powering sensitive electronics off/through the ignition circuit is just asking for problems. Power drops, noise, surges, etc.

My ignition powers nothing but the ignition switch. Everything else is either powered directly from the house battery or in the case of the components connected to the starting battery, off the accessories terminal on the battery switch.

^^THIS^^