Start battery setting

[DinghySailor]

The starter for my Yanmar began intermittently working over the summer. The engine now starts only with All or 1 selected.

• BMS indicates full charge on both banks.
• All connections (dashboard, selector, starter solenoid, # 2 terminal) are tight and corrosion free.
• Voltage meter on start shows normal amperage at all connections.

With battery selector on Bat 2 (start), start button results in clicking at the starter and some weak engagement.
My guess is starter solenoid is bad. Confirm?

 

[Timm R Oday25]

With out being there with a meter, it sounds like you have worn contacts in the battery selector switch.
I would check for resistance in the switch itself

 

[dLj]

I'd guess your start battery is bad or not charged for some reason. If you selenoid was bad, it wouldn't work no matter the battery selector.

Have you put a volt meter on your start battery to see what voltage you are getting with it?

dj

 

[Davidasailor26]

BMS indicates full charge on both banks.

What BMS is it? Usually a BMS is something associated with managing a lithium battery, but I presume you mean some sort of monitor? Even then most monitors check state of charge of one bank and just voltage of the other. Voltage may not be a good indication of state of health.

What types and number of batteries are banks 1 and 2?

Since it starts fine on bank 1 my guess is battery 2 is going bad and just has a surface charge, but not enough capacity to actually start the engine anymore. The other possibility is that the Yanmar wiring harness, a common weak point, has a failing condition and only bank 1 has the excess capacity to overcome the extra resistance.

Checking voltage at the battery posts and at the starter terminals with a multimeter could help narrow things down.

 

[DinghySailor]

Good suggestions. I’d heard about that start cable weakpoint. I could try a bypass. I’ll also put the meter on the terminal. I’ve been using the readings from a Victron BMV 712 (not BMS, sorry). Boat is on shore power now with smart charger.

 

[dlochner]

The starter for my Yanmar began intermittently working over the summer. The engine now starts only with All or 1 selected.

• BMS indicates full charge on both banks.
• All connections (dashboard, selector, starter solenoid, # 2 terminal) are tight and corrosion free.
• Voltage meter on start shows normal amperage at all connections.

With battery selector on Bat 2 (start), start button results in clicking at the starter and some weak engagement.
My guess is starter solenoid is bad. Confirm?

A bad solenoid is unlikely. What is likely is a known problem with the Yanmar wiring harness, and or a weak start battery.

Voltage is not a good indicator of the battery's condition or state of health. Over time a battery loses capacity and eventually reaches a state where it can not deliver sufficient current to start the engine even though the voltage looks fine. How old is your battery?

The solenoid gets its power from the battery cable attached to the starter. The wire then runs up to the key, through the key switch to the start button and then back to the solenoid. The wire is undersized and is subject to corrosion. This causes a voltage drop preventing enough power reaching the solenoid to engage the starter. The solution is to rewire that circuit.

 

[BarryL]

Hello,

if your boat is on shore power and you have a smart charger, you have no way of knowing the state of health of your batteries. You can't measure the battery voltage while the charger is connected and on.

Please try this simple test:
Disconnect your boat from shore power (or turn the charger off)
Turn off all loads on the batteries (or turn the battery switch to OFF)
Wait an hour
Measure the voltage of each battery.
My bet is that one battery will show 12.7 volts and the other will show much less.

If you want to do a better test you will need a helper
Select battery 1
Measure the voltage
Try to start the engine
Measure the voltage while the engine is cranking (or while the start switch is pressed if the engine won't crank)
Select battery 2
Measure the voltage
Try to start the engine
Measure the voltage while the engine is cranking

If you have a bad battery you will see a SIGNIFICANT voltage drop, like below 6V.

If you want to get all nerdy on this you can buy a battery tester like this one:

https://www.amazon.com/FNIRSI-BTM-24-Automotive-Alternator-Resistance/dp/B0FN79DGW6/ref=sr_1_3_sspa?adgrpid=190077438167&dib=eyJ2IjoiMSJ9.3zyonjO-UuH_egW6qHIuI9W96ojk2T6atW1BYKisvjrMrouR8n4MC0TTKzVEAHDyooTFJwwOY_tRswKndYoMjo6bFCbNskHjxW33SnfmYrCT9DL8I1QrbRGedIOArUIcVM1y8sQIaofY3VOKVCKgILUhzf8FHtU35kg4E_dfN5-A5gv6IegoJhF7TNvYYVd8Qe3GMWl8qUqoX6SgF7QoDgRkGonpdG4unAOnfeENbyeRXj73XHt5jmkDH4d-c-Vt6qznO6oIFDyjSJ5f0qzufrN2mN3xVQz86layW5Lh4mQ.WrS7a8Okp15ZKBBFh_6G_R5E0HWbdOfyfvJxme5ZxPk&dib_tag=se&hvadid=792708364222&hvdev=c&hvexpln=0&hvlocphy=9004539&hvnetw=g&hvocijid=5537567951175116596--&hvqmt=e&hvrand=5537567951175116596&hvtargid=kwd-2418875843724&hydadcr=6365_13571929_2418524&keywords=fnirsi+battery+tester&mcid=6e5456a5617734eabcd75755bcfbd6f1&qid=1769613542&sr=8-3-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

I'm not hawking fnirsi products but I have the battery tester and the volt meter and they are both great devices.

Good luck,
Barry

Good suggestions. I’d heard about that start cable weakpoint. I could try a bypass. I’ll also put the meter on the terminal. I’ve been using the readings from a Victron BMV 712 (not BMS, sorry). Boat is on shore power now with smart charger.

 

[DinghySailor]

Thanks. If that wire from the key/button to solenoid was compromised wouldn’t the same issue occur with starting from the house bank?

Going to get a better assessment of #2 today using the method Barry recommends. Thanks again!

 

[dLj]

Voltage is not a good indicator of the battery's condition or state of health. Over time a battery loses capacity and eventually reaches a state where it can not deliver sufficient current to start the engine even though the voltage looks fine. How old is your battery?

While true voltage can sometimes be misleading, generally it works well. It's rare a battery in bad health will not show a decrease in standing voltage.

What Barry described is an excellent way to figure this out.

dj

 

[Don S/V ILLusion]

• All connections (dashboard, selector, starter solenoid, # 2 terminal) are tight and corrosion free.
• Voltage meter on start shows normal amperage at all connections.

With battery selector on Bat 2 (start), start button results in clicking at the starter and some weak engagement.
My guess is starter solenoid is bad. Confirm?

my guess is that “all connections” aren’t good. If you base that perception on visual inspection, don’t! Remove, clean and tighten all.
A voltage meter won’t show “normal amperage”.
The solenoid isn’t the problem. It’s either a weak battery under load or bad connection(s).

 

[JoeWhite]

Measure the voltage at the solenoid coil contacts while starter button is pressed. A chattering sound indicates insufficient voltage. The solenoid drops out as a result of low voltage. It does not need much current to be energized. You can use an external battery to energize it for a test.

 

[Hayden Watson]

Also, the best way to test for a battery issue when starting is to test the battery voltage while actually starting. You can have plates in the battery that have lost their lead, and the resting voltage will be fine. Then when you put the large demand on it by attempting to start, the voltage will fall on its face. Normally, a good battery will sag 0.5v to 1v. A bad battery will drop to 9v or below.

 

[FastOlson]

my guess is that “all connections” aren’t good. If you base that perception on visual inspection, don’t! Remove, clean and tighten all.
A voltage meter won’t show “normal amperage”.
The solenoid isn’t the problem. It’s either a weak battery under load or bad connection(s).

Amen! Every 5 or (10 at most) years, we remove all the Ground connections , clean up posts and lugs, oil 'em lightly, and reattach/retorque.
Probably just me, but it's easy to fall into the diagnosis trap of focusing on the positive connections because we imagine all those industrious electrons needing to hurry to their duties. Easy to overlook that the return path (Neg.) is Just As Important. Having done their work they then have to return to the battery for some soul renewal. (Actual electricians are likely hitting their heads on their keyboards at this point, but we amateurs do enjoy our simple motivations and mantras.)

I call this initial part of trouble shooting the Occam's razor technique.
(It's my general starting point for most trouble shooting where there is not an obvious failure point.)

 

[DinghySailor]

Following the method Barry mentions and armed with the tips here, I found the following on the start battery:
13.3 resting
11.80 when selected switched to 2
4.80 start

The 7V drop indicates a dying or dead battery, I think. Concur?

I also maintain my connections. That's why they're all tight and corrosion free

Thanks for indulging me in my process, gentlemen.

 

[dLj]

Did you have the battery charger on that battery when taking resting voltage?

Drop to under 5V when trying to start - bad battery.

dj

 

[DinghySailor]

yes

 

[jssailem]

focusing on the positive connections because we imagine all those industrious electrons needing to hurry to their duties. Easy to overlook that the return path (Neg.) is Just As Important. Having done their work they then have to return to the battery for some soul renewal.

Not to poke the bear, but.
During my study time, I was instructed that "Electrons carry a negative charge." This being the case, the electrons would be repelled by the negative terminal on the battery. They would hurry forward to the positive side of life, working along the wires to do the Load requested.

 

[marcham]

The starter for my Yanmar began intermittently working over the summer. The engine now starts only with All or 1 selected.

• BMS indicates full charge on both banks.
• All connections (dashboard, selector, starter solenoid, # 2 terminal) are tight and corrosion free.
• Voltage meter on start shows normal amperage at all connections.

With battery selector on Bat 2 (start), start button results in clicking at the starter and some weak engagement.
My guess is starter solenoid is bad. Confirm?

We'd need more information...

Battery / Starter issue troubleshooting 101:

What is the resting voltage of each battery? (after sitting for 12 hrs with no charging source)
What is the battery type/size on 1 and on 2?
How old is each battery?
How old is the starter?
What is the voltage at the starter with the ignition ON?
Pressing the start button, what is the voltage at the solenoid? (at the relay control wire)
Are all the battery cable connections perfectly clean?
Is it a flooded or AGM battery? If it's flooded, what is the acid level? When was it last topped off with distilled water? What are the hygrometer readings of each cell? When was it last equalized?

If the water is low and the cells are out of balance, it might be possible to bring it back with a distilled water top-off and equalizing the cells. (you'll need a power source that goes to 15.5V).

Have you checked the starter brushes ?
Have you inspectected the back of the battery switch?
Are all the wire connections and lug crimps secure?

The drop cannot be conclusively associated to the battery unless:
- all the wiring is checked
- the battery gets load tested

Loose/dirty/corroded connections will display the same symptoms as a week battery. I usually check all the "free" stuff before going through the trouble of pulling a battery and replacing it.

"Batteries don't die, they're killed!"

 

[Davidasailor26]

Following the method Barry mentions and armed with the tips here, I found the following on the start battery:
13.3 resting
11.80 when selected switched to 2
4.80 start

The 7V drop indicates a dying or dead battery, I think. Concur?

I also maintain my connections. That's why they're all tight and corrosion free

Thanks for indulging me in my process, gentlemen.

Assuming that’s 4.8V at the battery posts I concur - battery’s done.

 

[BarryL]

Hello,

Whichever battery is connected to switch 2 is bad.

I don’t know how your boat is wired but I suspect you don’t have a ‘start’ battery and a ‘house’ battery. I suspect you have 2 batteries and a typical battery switch with off, 1, both, 2 settings. With that switch one battery is connected to ‘1’ and the second battery is connected to ‘2.‘ When you go to start the battery, whichever battery is selected is the ‘start’ battery. In your case it seems that battery 2 is worn out and needs to be replaced.

It might be in your best interest to have both batteries checked. Your ‘good’ battery may not be so good after all.

Good luck,

Barry

Following the method Barry mentions and armed with the tips here, I found the following on the start battery:
13.3 resting
11.80 when selected switched to 2
4.80 start

The 7V drop indicates a dying or dead battery, I think. Concur?

I also maintain my connections. That's why they're all tight and corrosion free

Thanks for indulging me in my process, gentlemen.