not charging on engine

[Gugi47]

Originally Posted by crus

is there an easy way to determine if the battery(s) are being charged when running the motor?

like measue the voltage at some location in the circuit?

I have 2 of this:

https://www.ebay.com/itm/DC-12V-24V-...r=640972634728

instal close to the batteries with a switch, what give me the option to check on each individual battery. But is a good idea to have a multimeter on board all the time. I do.

[jparsons121]

Also. WRT charging. Each engine(alternator) charge runs from the alternator to the main starter post via the orn wire. Then the current flows back to the battery thru the main red cable. Since the selector switch is in between these two points, charge will go wherever the selector is pointing.
With twins, it gets a bit more complicated as you have two charging sources and two batteries. Each of the alternators has a regulator and can (will) start fighting each other if on 'Both'. Also, if left on 'Both' when engine is not running, the batteries will try to equalize and the lower charged battery will charge off the other. All of this assumes OEM installation without aftermarket isolator or combiners.

So, back to what an old-timer told me back when there were just On-Off switches. Select a battery for engine 1, the battery for engine 2 and only use both only in an emergency to connect both batteries when they are all discharged and won't crank by themselves.

That way, each main is isolated and any issue with charging, etc is easily seen on the gauges.

To keep thing balanced when off shore power, I run the portside according to the date. Odd days are 1, even days are 2. Stbd is then set to the opposite.

Sorry for the rant, but this topic has kept multiple message boards alive for years and there is a lot of misguided info out there...

John

[Phillbo]

Originally Posted by jparsons121

This is the typical process that most boating classes teach. At least the part about switching loads to run off a single bank when moored. Theory being that one battery is held in reserve for starting and not drained by typical house loads.

I don't disagree with that. I'm just not sure it's a good idea to use BOTH unless you have an issue with drained batteries and need to use BOTH to get the engine started.

Again, my process.

Start the engine and cruise on #1 (starting battery) - both batteries are being charged.
On the hook use battery#2 (deep cycle battery).
In the morning switch back to #1 before starting and cruising - starting battery is used to start engine and both batteries are charged while cruising.

I have never had my switch in the BOTH position.

[jparsons121]

Phillbo. Agreed.. BOTH should only be for specific circumstances where individual batteries are too low to crank independently.

How are both charging both while your selector is only in position 1?

John

[mmwjr]

Originally Posted by Gugi47

So if you end up with one good battery and no charging system, what you going to do?....Everybody should keep eye on the gages all the time. If you see something wrong, you can turn back to home. Two 1000 cca battery should be good for more than 4 hours run. That's why I always buy over size batteries and suggest everybody in the site to do.

Well a lot of people don't watch the gauges all the time. With one good battery and no charging you have a chance to make it to a safe port.

[jparsons121]

Yep.. And having a fully charged booster pack doesn't hurt.. (Don't ask why I carry one now) 8-)

[shrew]

If you're going to attempt to charge both batteries off of the alternator there should be a charging relay in place.

There is a lot of write-ups about the problems caused and premature death of batteries as a result of attempting to charge both simultaneously.

Generators and shore power can charge the hose bank which can be multiple batteries and much larger anyway.

[Gugi47]

Originally Posted by shrew

If you're going to attempt to charge both batteries off of the alternator there should be a charging relay in place.

There is a lot of write-ups about the problems caused and premature death of batteries as a result of attempting to charge both simultaneously.

Generators and shore power can charge the hose bank which can be multiple batteries and much larger anyway.

That is in your alternator. And always , the weaker battery will get the charge first, never overcharge.
I always check my batteries before I start the engine and after I run for 1/2 hour, with the engine ON.

The older system can use a split-charge diode is an electronic device used to enable simultaneous charging of multiple batteries from one power source. The device prevents current from flowing from one battery to another while enabling the batteries to be continuously connected.

While the original devices used diodes to charge the two batteries, while keeping them separate from each other, most devices now use other configurations in order to avoid the 0.7V drop which reduces efficiency and increases power dissipation. Here:

https://www.ebay.com/itm/Sterling-Pr...kAAOSw1RVaggou

https://www.ebay.com/itm/Car-Auto-Tr...YAAOSwk8RbMGYs

[jrsick]

Originally Posted by mmwjr

Agree, charging voltage is typically around 13.5VDC

Mike, 13.5v when on the alternator amounts to a trickle charge. You need to run the engine for a while to get a good charge with 13.5v. This is probably fine for the cruiser types that have destinations. Us ski boat guys that start the engine 15 times per outing need over 14v to keep a good battery.

[mmwjr]

Originally Posted by jrsick

Mike, 13.5v when on the alternator amounts to a trickle charge. You need to run the engine for a while to get a good charge with 13.5v. This is probably fine for the cruiser types that have destinations. Us ski boat guys that start the engine 15 times per outing need over 14v to keep a good battery.

I said typical, this includes runabouts, cruisers, ... agree water sport folks put a more frequent draw on their batteries.

[crus]

i measured voltage on both batteries with motor on and off.

in both caes it reads 11.8 volts... so looks like its not charging, right?

did this test with the battery selector on all positions (1 - all - 2)
same result.

just saw a video how to test the alternator continuity with the mutimeter so i will try that next to see if the alternator is bust.

the black device i was talking about is a battery isolator. it has 3 big red wires attached and a small blue one.

there is a green indicator but it never lights up.
the problem could also lie in this battery isolator, right?

anyway to test an isolator?

[crus]

for now i just want to charge the two parallel connected domestic battery set with a ctek trickle charger on a 1000W gasoline generator.

can i just attach the charger to the set of paralel connected batteries or should i disconnect them first and charge them one after the other?

or simpeler,
plug the shorepower connector to the generator?

[jrsick]

Your battery is not charging, and is about 30% charged right now.
Consider getting your battery tested. In the states, we can take our batteries to an auto parts store and they will check the batteries and charge them.
I don't know how your battery system is configured. I think safest and surest approach is to charge one battery at a time to ensure it is taking a charge.
I have a battery charger that I really like. It will charge all battery chemistries, and has a restore capability for recovering heavily-sulfated batteries. I find myself using this charger regularly.

[mmwjr]

The isolator should be labeled; Batt1, Batt2, Alternator and wired with the alternator's output going to the Alternator terminal on the isolator. The Batt1& 2 terminals should be wired to the battery selector switch. Measure the voltage on the Alternator terminal to see what the it's putting out.

[crus]

well i tested the alternator for continuity with a multimeter and it didnt have any.

so i ordered a new one and replaced it. and when reving the engine now i get well over 14 volts so that seems to have been the culprit. also the volt meter in the dash came to life again... so that works just fine.

also i did a test which circuit was which.
turns out the starter battery is not on 1 but on 2.

i took out the starter battery and put it on a ctek trickle charger with reconditioning feature.

after several hours i got a red warning light which means that the battery is pretty much dead according to the manual. wasnt too surprised since one of the poles was already quite severly corroded.

so now i'm looking to get a new starter battery... i know i need an AGM type but what should be the minimum Ah for a 180HP L4 V6 Mercruiser? (boat also starts fine just on the non-agm house batteries)

[jrsick]

I recommend you get a single-purpose starter battery. Avoid the dual-purpose, deep-cycle starting, RV, or Marine-special. You probably only need about 500 CCA to start your motor, but should easily be able to find batteries with 800-1000 CCA. Also, don't be fooled by marine cranking amps vs cold cranking amps. MCA is measured at 32 degrees F while CCA is measured at 0 degrees F. MCA will be 20% higher at least.

[mmwjr]

What jrsick said.

[crus]

Originally Posted by jrsick

I recommend you get a single-purpose starter battery. Avoid the dual-purpose, deep-cycle starting, RV, or Marine-special. You probably only need about 500 CCA to start your motor, but should easily be able to find batteries with 800-1000 CCA. Also, don't be fooled by marine cranking amps vs cold cranking amps. MCA is measured at 32 degrees F while CCA is measured at 0 degrees F. MCA will be 20% higher at least.

whats the downside of a dual purpose battery?

this one seems reasonably priced (around 200 USD):
https://www.acculand.nl/accu-s/plezi...varta-lfd-140/

[jrsick]

It's not so much the downside of the dual purpose, but the upside of the starting battery. Starting battery will give you stronger starts and recover quicker. The starting battery will give you more starts over its life than a multi-purpose battery. Since you have two batteries, make one the starter so you can always get home. This is especially true if you are doing watersports with a lot of starts over the day.

[Gugi47]

Originally Posted by crus

whats the downside of a dual purpose battery?

this one seems reasonably priced (around 200 USD):
https://www.acculand.nl/accu-s/plezi...varta-lfd-140/

jrsick is right.

You need something like this:

https://www.ebay.com/itm/VMAX-XCA27-...nd!17601!US!-1

https://www.ebay.com/itm/DEKA-GENUIN...gAAOSwUKxYhVzV