Using a multimeter to check if battery charger is working?

[Someday*]

I recently purchased a multimeter and would like to check if my battery chargers are working. I am completely new to using the meter so even which ports to use on the meter and where to set the dial would be appreciated. (I've read and watched some videos but each hasn't seemed to clarify for me)

One is the standard charger you use to charge a 12 v car battery.

The second is verifying all 3 batteries (for a trolling motor) are being charged via the on board charger.(I think one of the three isn't getting charged)

Thank you.

 

[TylerFromEverett]

For 12 V batteries I set the multimeter to 20 volt DC. On most multimeters, this will be a number 20 with a strait or dashed line. The squiggly line means alternating current, batteries are direct current. Put the red lead on the positive terminal and the black on the negative terminal. With the battery chargers off, it should read 12.6 if it’s charged. Hook up the battery chargers and then test is should read like 13.6-14.2 I believe. I’m not sure if all batteries will read as being charged when you test, I think there’s a relay that distributes charging one by one.

 

[Martin610]

It's not easy to explain how to use a multi-meter in a text format. YouTube has some good videos that do a better job. Here's a link to one: https://www.youtube.com/results?search_ ... ulti-meter

There are a lot more.

Check each battery individually. One bad apple spoils the whole batch. Batteries in parallel, such as a house bank, function as one. So if one battery is bad it can bring down the other. Also, check the lights on the battery charger. If it's not working a light can indicate a failure, or you don't have any lights at all which indicates the charger is down.

You want to look into the type of battery you have, flooded, sealed, AGM, etc. The battery manufacturer's web site will indicate what the different charge levels should be. For example 12.8 would generally be fully charged. 13.5 and above would be 'float' which is good. Anything much over 14.5 the battery can gas out, you don't want that.

Once you've gained experience you can put your leads on the cables coming from the charger to the batteries and check for voltage.

Many of the Fluid Motion boats have ACRs or automatic charge relays. Shouldn't be an issue with that if your batteries are somewhere in the normal range.

-martin

 

[Martin610]

One important point. Tyler got you off to a good start, all that info he posted is correct in my opinion. Sorry I forgot to mention that Tyler.

-martin

 

[TylerFromEverett]

Thanks. I was reflecting on this a few minutes ago, thinking I was probably too brief and general for a technical question. I was answering while sitting and waiting for a virtual meeting to start. It’s incumbent upon us all to give good; thorough advice to keep with community standards.

 

[Someday*]

Thanks all…was able to check the 12 v (car) battery charger using the above and it seems to be working.

I’m working on checking if the three 12 v trolling motors are all getting charged.

 

[Someday*]

Thank you Tyler and Martin….just to clarify, I am expecting delivery of our 2022 R29 in a few months so I am trying to learn how to use the multimeter on my current bay boat which has a multi-bank battery charger.
Hoping to learn enough so I can us the meter for the tug when we get her.
Again, I appreciate and thank you for your help!

 

[rpmerrill]

Just a quick addition.
You can check all the battery conditions listed above on your car battery for practice.
In the case of voltage measurement it doesn't matter which lead you touch to which battery post. You'll just gea a positive or negative number on the display.
The ACR's on your boat (Automatic Charge Relays) are designed to monitor the voltage between the 3 battery banks. When one bank is receiving a charge (say from the engine alternator) and another bank is sitting at a lower voltage (say the house batteries) the relay will sense that and share some of that incoming engine charge current with the house. Then when the engine is shut down and the two battery banks settle down and equalize, the ACR disconnects them.

Besides sharing incoming charge (a good thing) the ACR's protect the 3 battery banks from discharging each other. A fault or mistake (leaving a switch on) in one bank will not be shared by the other banks. You wouldn't want to be anchored out somewhere and discover that your house battery usage had also drained the engine (start) battery.

And finally, I believe your new boat will have a voltage meter at the helm with a "1,2,3" switch so you can see your battery volts in each bank. Engine, House and Thruster.
You'll quickly find all this makes sense once you spend time with your boat.
Enjoy.

 

[S. Todd]

(And finally, I believe your new boat will have a voltage meter at the helm with a "1,2,3" switch so you can see your battery volts in each bank. Engine, House and Thruster.)
On the R29 this voltage meter gauge is located in the mid-cabin. Not the most convenient place to view it, but closer to the battery sources. R29 is a great boat!