Running boat electrics with a soon to be replaced battery.

[XDC]

Not inflammatory at all Sandy but I'm trying to establish does the condition of a battery, from mine through to flat, impact on instruments when the battery is on charge and some people, trying to help me are telling me to buy led bulbs

Not upset with them in the slightest, just trying to reach an end goal.

 

[[70521]]

Not inflammatory at all Sandy but I'm trying to establish does the condition of a battery, from mine through to flat, impact on instruments when the battery is on charge and some people, trying to help me are telling me to buy led bulbs

Not upset with them in the slightest, just trying to reach an end goal.

Then I humbly suggest that you get a good book and read up on the subject. I'm an engineer and was suprised when an academic engineer (university lecturer with a PhD, and the brain the size of a planet, in my subject) got a thermometer out when looking at a power issue on the my boat over the summer!

If you have have power going in to the system and if that power is greater that what is going out then your electrics will work. If you have no power going into the system then it depends on what your batteries can hold and what the demands on that pool of energy that you hold in the battery. Instruments will work down to about 10.5 volts then stop. Those volts will depend on amps, temprature and power in the battery. Look at the spec of the insruments they usually say they work from from 10 to 15 volts.

 

[XDC]

Sandy, the only thing that I was unsure of was could an old battery affect the output current to an MFD even when on charge.

Secondly could a totally flat battery cause a bigger problem.

I've helped start enough cars with flat batteries in my time to understand that sometimes a car just won't start, the solenoid just clicks or the starter motor only just turns.

I recognise the difference between powering a starter motor and powering an MFD but I just wanted to clarify that given my circumstances it's not my battery causing the problem.

Did you look at the pictures? Did you read that the MFD powered down but didn't turn off? If you looked at the pictures you would see that the voltage figure actually disappears for a while.

Now that I have it 100% clear that the voltage leaving the charger reaches the MFD I have another problem ... not battery related. That's all I wanted to know.

 

[William_H]

OP may have heard stories of old fashioned current limited chargers. ie transformer rectifier with relatively large voltage output until loaded by the battery charge current. If a battery was really dead as in not taking a charge through total failure then the battery voltage when on charge can go really high possibly damaging instruments. My dad did this a long time ago on his car, smoking the electronic clock. However in this age many instruments are designed to take up to 30 volts so they can operate on 24v systems so immune from high voltage input from a 12v system and most chargers now are voltage regulated albeit with stepped charge voltage so no more thn 15v any way. And all this with OP battery that clearly is not too bad. So no worries re instruments when battery on charge. ol'will

 

[PaulRainbow]

Assume a 190ah battery capable of charging to and holding 12.8v but dying after 6 hours of 14 x 10w lights being turned on.

Then being charged and holding 12.8v again.

Turn on battery charger.

Voltage showing 13.9 at switch panel and instrument binnacle.

With the charger ON should the instruments work or drop in and out?

Make and model of charger please ?

 

[XDC]

 

[Caladh]

So if the battery state is irrelevant any idea why this is happening?

New MFD.

Start up screen insists you need to accept limitations by pressing OK

View attachment 81928

I never see that screen when the following happens which suggests to me that the MFD is not turning off, but suffering a low voltage.

See what happens. It goes from working fine to appearing to turn off but then recovers through these stages:

View attachment 81929

No voltage showing on screen

View attachment 81930

View attachment 81931

Voltage showing on screen

View attachment 81932

If it's not my low battery that's on charge any thoughts on what the problem could be?

The MFD has been checked by the commissioning agents and passed as ok and the "power down" of course didn't happen when they were there.

You may be interested in this post from the RM forum...……
http://forum.raymarine.com/showthread.php?tid=6458

 

[XDC]

You may be interested in this post from the RM forum...……
http://forum.raymarine.com/showthread.php?tid=6458

Thanks a lot for the link. The last sentence says it all.

I didn't think for a second that the dealer was going to fob me off but it felt good being able to assert that with shore power connected the problem wasn't my battery.

A replacement MFD is on order and the tech and I will run some tests, one with just battery power and one with shore power to try to replicate the screenshots I've posted.

 

[Caladh]

Thanks a lot for the link. The last sentence says it all.

I didn't think for a second that the dealer was going to fob me off but it felt good being able to assert that with shore power connected the problem wasn't my battery.

A replacement MFD is on order and the tech and I will run some tests, one with just battery power and one with shore power to try to replicate the screenshots I've posted.

The bill is on its way!

 

[XDC]

The bill is on its way!

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