Electrical Troubleshooting - Batteries/Starters/Wires

[jonelli]

I understand that I should be able to start the M25XP engine off of one battery.
I have yet to be able to. I would very much like to be able to run off one battery and use the other as a backup.

I replaced the 4 year old batteries that came with the boat with brand new G27 deep cycles (the most "deep cycle" they can possibly be). and aside from not having a completely bad battery like I had before, there's no real change with a charged up single battery being able to start the engine.

I put a meter directly on the battery, and another one directly at the input of the starter motor (not after the solenoid) and cranked the motor. There was almost a 2V drop between those to points during cranking. So, at the battery while cranking I'd get an average of 11V, at the starter it was about 9V average. At rest they measured the same.

I then put a meter between the NEG of the battery and the engine ground and saw just under 1 V while cranking.

Then, I put a thick jumper cable between the NEG of the battery and the engine ground and saw no difference with the above behavior.

I put the jumper cable from the POS of the battery to the INPUT of the starter solenoid and saw an increase in over 1V at the starter and the engine was able to start. I then re-tested by jumping the NEG to engine ground and starting the motor, and it was a no-go.

So, it would appear that my positive connections from the battery to the starter are not as good as they should be. Next, I'm going to measure the OFF/1/B/2 switch.

----On a not-so-funny side note, earlier I had tried to turn on the hot water heater (110V) and noticed it wasn't working, so I pushed the reset button on it, and while I was doing all of this battery testing the hot water hose exploded under the rear berth and scared the crap out of me. lol

 

[jonelli]

I brushed clean all of the connections from the battery to the switch.
I tried starting the motor, and it was the same as when the starter has a lower voltage.

I used the jumper cable paralleled between the battery POS and the output of the OFF/1/B/2 switch essentially bypassing the switch and it still didn't solve it.

Is it possible I'm chasing something that isn't really broken? Is the long run of 4 gauge wire just too resistive? Is all of this normal?
I can't start the motor off one battery unless I jumper the POS straight from the battery to the solenoid.

 

[Jethro411]

Curious how long you heat glow plugs. Manual says up to 30 seconds or a minute, I believe. (I know that sounds like a lot). But the gauge of wire and run may not make that excessive. What happens if you get them real hot, crack the throttle and crank?

 

[jonelli]

It doesn't matter, that's what I'm saying. The engine can have been just running and still one battery won't crank it back on most of the time. The starter just doesn't crank fast enough. I've verified that there's a significant voltage drop during cranking at the 15 foot 4 AWG wire that goes from the starter to the battery. If I add a jumper cable between those two points then the single battery cranks the engine.

There was no difference when I jumped the negative side so I'm thinking to replace the main positive run with thicker gauge wire.

 

[Capt jgw]

4ga sounds pretty small, the cables on mine are I think 2-0 ga, the bare wire is around 5/8" diameter. The original engine in this boat was an Albin AD2 which is a real beast, it cranked just fine.
I had a similar problem one spring after putting the batteries back in, I found I had missed connecting one of the ground cables. Sounds like you've checked all of that though.

 

[Maine Sail]

As I have said many, many, many times 4GA is under sized. 1V of drop on ground or pos is 100% unacceptable.

Also:

Make sure starter case to engine block mating surfaces are clean and rust free. Use a product such as Penetrox A or Permatex Copper Anti-Seize Lubricant to mate the two together in order to minimize rust/corrosion while not inhibiting conductivity..

Better yet run the engine negative wire directly to one of the bolts that holds the starter to the motor. Be sure where the lug attaches is bare clean metal then coat with the above items.. This is where the engine negative really should attach but rarely if ever does.

Why pass hundreds of amps of current through a rusty engine and multiple poorly conducting metals...???

Check the wire lug that leaves the solenoid to power the starter motor. This is the opposite terminal of where the battery cable connects. Folks often ignore this terminal.

Be sure to make your new cables with the proper crimp tool.. If in doubt measure carefully and order premade to your spec from Genuine Dealz...

 

[jonelli]

Thanks MS. Good suggestion on the ground wire placement. As soon as I can, I"ll be replacing the primary battery wires with larger gauge wire and probably the main ground wire too.

@Maine Sail, Do you recommend larger than 2 AWG wire? 1/0? 2/0?
I would like to "overkill" by at least one size.

 

[JK_Boston_Catalina310]

@Maine Sail, Do you recommend larger than 2 AWG wire? 1/0? 2/0?
I would like to "overkill" by at least one size.

Our Catalina 310 has 2/0. Seems to be adequate and I wouldn't really want to run much thicker. I have also done other upgrades as suggested by Maine Sail including the redo on the ground and wiring the alternator direct to the battery bank.

 

[dj2210]

When I first got my C30, I was replacing the batteries and the black jumper wire connecting both batteries pulled out of the crimped terminal, I knew it was time to upgrade the wiring. The old crimped on terminals could also be a source of resistance as was my case. I cant remember which size wire I went with though it was either 1 or 2 awg.

 

[JTPearson]

I had the exact same problem. Changed the batteries, cleaned all the connections. Still no help, had always use two batteries.
I changed my cables to 1/0. Never a problem again!! Even after sitting for a month, my m25xp started right up on one battery. Two years later, still perfect!

 

[jonelli]

Thank you JTPearson, that's exactly what I wanted to hear.

May I ask if you kept the wiring scheme as default or did you do any other mods?

 

[Capt jgw]

Eliminating the amp meter, it's wires, and the trailer connectors should be on your "fix it ten years ago" list if not already done. Lots of posts here and Mainsail's site describing that mod.

 

[JTPearson]

Thank you JTPearson, that's exactly what I wanted to hear.

May I ask if you kept the wiring scheme as default or did you do any other mods?

I added a Victron Battery Monitor. I can send you my schematic; in Powerpoint if you would like.

 

[jonelli]

1/0 Custom cables ordered.

Now, without going extravagant, which battery isolator/combiner would you all recommend to use if I wire the alternator directly to battery #1 as suggested?

There's so many choices out there, I wanted to find out what was recommended.

 

[Stu Jackson]

No isolators, 1980s technolgy.

Echo charger, Blue Sea ACR or Yandina combiner.

I have a combiner, lifetime warranty. Can't go wrong, great instruction manual, which BTW, is correct.

Echo charger is good for using large house bank with small reserve, but the directions s*ck. Here's why:

Echo Charger Use Warning from Maine Sail: http://www.sailnet.com/forums/electrical-systems/72295-xantrex-echo-charger-rant.html

I'd go for either of those before a Blue Sea. Good stuff, but just my opinion.

 

[jonelli]

Allright, so I think one of these will work:
http://www.yandina.com/c100InfoR3.htm

Another question if you don't mind!

From my 110AC source I have a West Marine 5Amp multi-stage charger which appears to have two white cables, one going to each battery, and a single black one that goes to one battery and obviously loops over to the other battery.

I can't find a manual for it, and so I'm curious if I wire the alternator to one battery, and use the combiner, do I need to remove the battery #2 output leg from the AC charger? I've attached a diagram how it would be connected:

 

[Stu Jackson]

Allright, so I think one of these will work:
http://www.yandina.com/c100InfoR3.htm

Another question if you don't mind!

From my 110AC source I have a West Marine 5Amp multi-stage charger which appears to have two white cables, one going to each battery, and a single black one that goes to one battery and obviously loops over to the other battery.

I can't find a manual for it, and so I'm curious if I wire the alternator to one battery, and use the combiner, do I need to remove the battery #2 output leg from the AC charger? I've attached a diagram how it would be connected:

Yes, that's right, remove it. It will avoid the relay from "chattering."

Yandina: size the unit based on what your charging sources MAY BE IN THE FUTURE. In 1998 I bought a 130A model (only 70 & 130 were available back then). I didn't install a 100A alternator until years later, but was glad I got the right sized combiner back then.

Good luck.

 

[jonelli]

Thanks! I thought so. I ordered the combiner. We'll see if it all makes it here by this weekend and I'll let you know how it goes, or it'll be another week before it all gets installed.

 

[jonelli]

So, another question about using battery combiners, and application of use...

If I'm plugged into shore power, my AC 5A charger will be running at 13.5V minimum which is above the battery combiner's sensing voltage, so it will ALWAYS be paralleled while charging/floating, and my house power will be running off both batteries at that moment which is okay since I'm probably not pulling more than 5 Amps unless I turn the TV on (which does happen).

But, if I'm off shore power and at the island, then I connect a solar panel to battery #1, I'm assuming that the battery combiner will be "open" and paralleling the batteries together, but this time, I'm running house power of 2-3 amps and the solar panel is only able to trickle about 1amp. That sounds like I could easily make both batteries low by accident by using the solar panel thinking I'm only using house power off one battery.

Is my logic correct? What do you do in the case off shore power and 15 watt solar panel? Don't use it?

 

[Stu Jackson]

Combiner operation

No.

You seem to be confusing amps and volts. The combiner only "closes" (combines) when the voltage is above the setpoint (13.5 or so). It knows NOTHING about amp flow.

In real life, here's what'll happen: If your house bank is low SOC, say after a night on the hook, regardless of what the charging source is, the house bank voltage will be low and start to rise with the charging. Only once it reaches the setpoint will the combiner "close."

You also need to understand the difference between "open" and "closed." It's like a switch: if it's OFF, it is OPEN.

You're correct about using the shorepower charger.

You might want to browse around this Electrical 101 topic and learn about battery charging:

Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html

It includes a link to the Ample Power Primer.

When I got my combiner, I had to read the manual a dozen times before "I got it!"

You will, too, and we're here to help. Good questions.