Battery question on R21EC

N

Newf

Well-known member
Joined
Apr 10, 2014
Messages
319
Fluid Motion Model
R-21 EC
Vessel Name
Saltwater Joy
Had my boat out yesterday for the first time in about 3 weeks. It sat on the trailer for that timeframe with temperatures as low as 2 degrees C. I had the main switch in the off position so nothing should have been powered up.

The engine fired up with no issue but nothing tied to the house battery had power. I connected both batteries with a small set of jumpers and power was restored to everything immediately. I took the jumpers off within 20 seconds and everything stayed powered up.

I understand why it would power when I had both batteries connected but why did it stay powered up after being only connected for 20 seconds or less? Was there something that was triggered or switched on in the charging system when I connected both batteries that then allowed the components to be powered by the alternator until the house battery was charged again?

Probably a simple answer but I'm at a loss with anything electrical.

Newf
 
I'm not sure why the house battery went dead, but I can explain why it didn't charge when you started the engine. Your boat has a thing called an automatic charging relay that prevents the alternator from being connected to a really dead battery, for fear of dragging down the overall system voltage to the point where the engine electronics don't work and the engine stalls. Thing is, the little diesels in our boats will run with no electricity, but I guess that's another story. What you did is the right way to get things back to normal.

As to why the house battery went dead, that can be hard to figure out. My boat, as wired by the factory had the fuel gage always connected. I don't know if that would drain the battery in two weeks. The radio preset memory draws a little current. My Subaru car doesn't go much over two weeks without ending up with a dead battery. This is common and no one really seams to know why.

Good luck.

Larry
 
Once again for the new members....
Everyone should have a good quality DC clamp meter. They cost around 100 dollars and up. They allow you to measure the current in any line. Does not matter if it is a positive or negative cable. It can measure down to decimals of amps up to hundreds of amps. It is the best way to determine where current is going. The only other way is to stare at a device or wire and wonder. To test for phantom current, with the engine off, turn off all switches. Go to the house battery and clamp the red line. The current shown is what you are interested in. Now move to various line downstream from the house battery to find which devices are using this current.
A clamp meter will tell you how much current your alternator is putting out. Or you solar panel or your charger!

One thing to check is the white negative wire on the ARC, it is connected to a spade connector on the ARC and to the negative terminal on the battery. It does have the habit of slipping off and without it the ARC will not connect the alternator current to the house side. You can tell this is happening by looking at the voltage on your chart plotter when the engine is running. Before you start up the plotter voltage should be 12.6 ot so and after startup it should rise to 13.8 or up to 14.1.

So get a clamp meter, Fluke make one of the best and make sure it has a DC current setting. The AC only ones are cheaper so keep looking till you find a DC one!
 
lproulx":b9dufx6o said:
I My Subaru car doesn't go much over two weeks without ending up with a dead battery. This is common and no one really seams to know why.

Larry
Click to expand...
Most cars today have numerous computers in them, they go to 'sleep', but they don't fully power down. So they are a small drain on the battery all the time. It doesn't take much of a continuous drain over several weeks to kill a battery.
 
Thanks for the explanation on the charging relay. I learn something everyday on this forum.

I will look into getting a DC clamp as it sounds like a useful tool to have.

My batteries are 6 years old, so it probably wouldn't take much of a draw on the house battery over a 2-3 weeks period to run it down. I usually use the boat a couple of times a week so a dead battery had not been an issue before.

Again, thanks for the feedback and suggestions.

Newf.
 
Fluke 325 has the dc current measurement, it should last you many years and you can pass it down to you children! I am sure it would make a great Christmas gift to yourself!
I found that the current on my 21ec load when all off was 0.02 amps.
Enjoy!
John
 
I have had good luck with Extech equipment, which I believe is now owned by Fluke.
I have their electric meters and pH/salinity testers and they are very well made compared to Harbor Freight stuff.
 
Pilotnavigator":3hj07jss said:
Fluke 325 has the dc current measurement, it should last you many years and you can pass it down to you children! I am sure it would make a great Christmas gift to yourself!
I found that the current on my 21ec load when all off was 0.02 amps.
Enjoy!
John
Click to expand...
I was told you can check your draw with a multimeter by removing the battery ground cable and then connect the multimeter probes, one on the cable and the other on the battery post. Not sure if the accuracy would be the same. In any case I tried this out of curiosity and it shows a draw of 0.05 amps with everything off. I then removed the fuses one at a time to see if I could trace the current draw to something but it did not change from the 0.05 amps.

Any thoughts??

Remember, as I previously mentioned, I know practically nothing about electricity so what I was doing may make no sense. The clamp meter is on my Christmas list.
 
It was the radio memory (Standby Mode) that was draining mine. Once I switched that off, no more problems. The Fusion info indicates Standby Mode draws 150mA.

CN
 
Neuf... you were just measuring the internal resistance of the multi meter.
 
Pilotnavigator":24nkjzl6 said:
Neuf... you were just measuring the internal resistance of the multi meter.
Click to expand...


Please explain.

Not saying you are wrong but after being told by an auto mechanic friend of mine what to do I watched a couple of youtube videos and they show that you can check for parasitic draw in this manner. Red probe in 10A dc on multi meter, set dial to 10a, remove ground cable from battery post and connect multi-meter probes between battery post and the cable you just removed. Any draw on that battery would show on your meter. When I did this i got the reading indicated. Then pull fuses one at a time to narrow down where the draw is coming from. If you pulled a fuse from the radio for example that had a current draw for the memory, would that reading on the multimeter not drop?

What am I doing wrong if the videos I watched say this is how you check for drawdown on a battery when everything is turned off?
 
Newf, not every draw from that battery comes through the fuse panel (ie: bilge pump float switch).
I'm not sure if the bilge high water alarm is powered all the time or not. I thought you said what the age of your battery was and if it was more than 3 years for a deep cycle battery it's probably time to replace. Good luck Bob
 
You would need to have a milliampere plug on the meter to get accurate reading this low. Try using the formula method. Measure the resistance and the voltage and calculate the current. If there is no device that is on then the resistance would be real high. current is volts divided by resistance. The current part of your meter uses a very large resistor in the 10A setting. In this case accurate measure to of very low currents is appropriate.
Same with camp meters, they use a different way to measure current but you need a more expensive DC clamp meter to get accurate low readings.
 
Hi Bob, Yes I was aware of other fuses. There are two next to the panel that I pulled as well. One for the bilge alarm and one for the radio memory I believe. There's one at the batteries for the bilge pump and there may be others. And yes the batteries are the original ones from 2014 so I'm sure they are getting tired. I used the boat a couple of times most weeks so normally there is never an issue. They get a good charge and not draining in a matter of one week. After 3 or 4 days on the trailer they still show 12.4 to 12.6 volts so probably still OK for my purpose for awhile yet.

Right now the checks I'm making have more to do with me trying to learn something new so I appreciate all of the comments.

Pilotnavigator, I will check out your latest thoughts.

But for now I'm heading out to go fishing.. Maybe tomorrow.


Thanks again Newf
 
Did a few more check today, starting with the Ranger R21 manual. A sketch on PG. 17 shows the starting/cranking battery to be on the starboard side of boat. On my boat the Deep Cycle battery is in the starboard location with the Cranking Battery on the port side so opposite of what the manual shows.

However the engine starter is wired to the Deep Cycle battery. I confirmed by tracing the starter lead and also did a load test. I bumped the engine and it went from 12.65 V down to 10.45 V indicating "I believe" that it's still in fairly good condition.

Since this was the way that it was wired when I bought it new, is there a reason they would have done this or was it a mistake?

Like the electrical side of things I don't know a lot about batteries but from what I've read there's a design difference between the two for specific purposes so not sure what's going on with this set-up. Was wondering if anyone with the same boat and engine (Volvo Penta) can have a look to see how their's is set up. It must not be a major issue as it's been like this since 2014. I guess this would explain why I couldn't find any current draw on this battery when I did my initial checks by pulling the fuses.


On MY BOAT
The "house battery" is a Interstate Cranking Battery Model 24M-RD with 400-CCA and 500 MCA
The "starting battery" is a Interstate Deep Cycle Battery, Model SPM-24 with 558 CCA and 690 MCA
Would someone have installed the starter to the battery with the higher Cold Cranking Amps on purpose?

When I did the same multimeter checks on my house battery (which is actually a cranking battery) the only amperage draw I could find when pulling fuses was from the stereo memory. When I pulled that 15amp fuse the meter reading dropped from 0.47ma to 0.12ma. This was what I was trying to find originally but was doing the checks on the wrong battery.

This was quite the confusing exercise for someone like me who was already confused by this electrical stuff.
 
Are the battery draw down meters a reliable test of (flooded) batteries? I was thinking of buying a basic one to try out. It is basically a large resistance (heater) coil and a volt meter. Do they draw the amperage that simulates starting a motor?
 
harley":6skn22gw said:
Are the battery draw down meters a reliable test of (flooded) batteries? I was thinking of buying a basic one to try out. It is basically a large resistance (heater) coil and a volt meter. Do they draw the amperage that simulates starting a motor?
Click to expand...

Hi harley,,I'm sure others are more qualified than me to answer but from what I've read and the how-to videos I've watched, the multi-meter can give you a good indications of the overall condition of your battery. There are other meters that measure CCA's and perform better load tests but the multi-meter is a good starting point if you don't have one. They are fairly cheap and the check is quite easy to perform.

Also a hydrometer is a good tool to have to test the individual cells.
 
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