315 Battery Meter

Calif. Ted · May 11, 2022

Are the house batteries not connected in parallel so they would read as a single battery, so Batt 1 is start and Batt 2 is the house "bank", both batteries ?

jssailem · May 11, 2022

Skipper John.
what happens when you switch from Batt1 to Batt 2?

It is a guess, you would get the Voltage for Batt2 the Start Battery.

This is a scientific guess. You will need to inspect the battery connections for your boat. See where all the wires go. Tte crazy thing, previous owners can change the connections. So better not to guess and inspect your boat taking notes about how and where the wires ho.

Ralph Johnstone · May 11, 2022

I suspect your wiring is pretty much as described by @jssailem and @Calif. Ted .

An easy check is to get out your multimeter and see what each battery voltage is compared to your battery monitor. This will confirm if your system is wired as it should be. I got two nickels, a dime, and a ball of pocket lint that says it is.

Siamese · May 12, 2022

Ditto on what Ralph said regarding checking with a multimeter. My 315 (2014) has just the two 4D batteries and I have the same meter as you that switches to measure 1 or 2.

If I had that third battery, I suppose it would be nice to add a meter. Or I might be happy just checking it with my multi-meter now and then. If I was doing more extensive cruising and overnights, I'd add the extra meter.

P.S. To check your's, instead of using the multimeter to see which batteries the meter measures, you could just disconnect the starting battery and see if you get two readings. But you probably already thought of that.

Calif. Ted · May 12, 2022

Fwiw my 320 came from the factory mislabeled, the battery labeled #1 was really #2 on the meter and vice versa, suspected in use I confirmed by disconnecting a negative terminal and seeing result on VM.

stephen_i_w · May 13, 2022

My boat, orginally came with two 4D batteries. They were pretty worn out when I took posession of the boat. I decided to go with 2 LiFePO batteries and an AGM starter battery. I had to isolate the LiFePO batteries from the AGM. The easiest way to do this was to connect the LiFePO batteries to switch positions one and two and not connect the AGM to the panel at all. Now, the LiFePOs charge through a DC-DC charger connected to the AGM. The DC-DC charger has a meter that I use to monitor the state of the AGM.

Anyway, my point is that the electrical system of the C315, at least in 2012 when my boat was built, was not designed for 3 batteries. Perhaps Catalina used a similar solution to my own.

Benny17441 · May 13, 2022

It depends on how are the batteries wired. You could have the two house batteries wired in parallel to make up one battery bank and the starting battery sitting alone as a 2nd battery bank. House batteries are usually deep cycle batteries rated in Ampere/hours (Ah) while Starting Batteries are rated in cranking amps. The deep cycle batteries are designed for slow and deep discharges while the starting batteries are designed for large but short bursts of power. For those designed features these batteries are rarely mixed. While monitoring the house batteries yields a lot of useful information having to do with discharge limits, duration of power availability and scheduling recharges, while the monitoring of the starter battery is questionable. The starter battery uses a short power burst to start the engine and charges right back from the alternator. They are usually fully charged or faulty which you will notice with the speed that they will crank the engine. You mention two large batteries for your house but do not indicate the voltage. Many boats carry two 6V batteries which wired in series will give you 12V. These are big heavy batteries rated for around 225 A/h while the 12V ones are rated for 115A/H. Two of each will produce a battery bank of around 225-230A/h. You say the boat is brand new and I don't have any issues with how you say the batteries are monitored so I would recommend before making any changes that you familiarize yourself with your batteries and system and get to use the boat and see how the monitoring works for you. Simply put the starter battery should be always fully charged so monitoring it is irrelevant. Even when a starter battery goes bad it may still show fully charged to the monitor but receive a deep drop in voltage when subjected to a load. Usually listening to the starter cranking speed is the best monitor for the starter battery.

valcour · May 14, 2022

Two 4D batteries were common on the C310 also. I replaced mine with four 6V batteries, and added a reserve (start) battery. If you will use your boat such that you are at anchor for several days in a row, with no charging source, you should consider wiring both 12V house batteries in parallel as a single bank. This will reduce the depth of discharge, and would also allow you to monitor both banks on your meter.

Calif. Ted · May 16, 2022

Posted below is typical Catalina wiring, note the Voltmeter is connected direct to the positive of both batteries at the selector switch so IT is independent of switch position. Also note the bilge pump is likewise connected so as to be always live independent of selector switch position.

leslie894 · Aug 19, 2022

Skipper John, it all depends on what position your selector switches are in. If the engine selector switch is in position 1+2 then the starting battery is in parallel with whatever battery or batteries are selected by the main selector switch. If you want to measure the voltage on your starting battery, you can move a wire.

Unscrew the switch panel (after disconnecting your batteries of course) and move the small gauge (orange on my boat, not purple) wire from position 2 of the Main Battery Selector switch to position 1 of the Engine Selector switch. The battery condition meter will show the starting battery voltage provided the Engine Selector Switch is in position 1 (and the panel is powered by the Main Battery Selector switch.)

If you want to be sensible, move the other small gauge (orange? Purple?) wire from position 1 to the C terminal on the Main Battery Selector switch. Then, when the Engine Selector switch is in position 1, one position of the battery condition meter will give the voltage of the starting battery and the other will give the voltage of the house batteries as selected by the Main Battery Selector switch.

If you want to just use a hand held volt meter, make sure both those switches are OFF. Otherwise, some or all of the batteries will be connected in parallel.

For the record, our boat is a 2018 Catalina 315, hull 61.

Stu Jackson · Aug 19, 2022

Skipper John said:
Brilliant! Thanks for finding that schematic.

John, are you suggesting you do NOT have a manual for your boat?
I strongly urge you to obtain one.
And for all the guessing going on here, just open the panel and your battery box and trace the wires. Ralph's right.

leslie894 · Aug 19, 2022

Stu Jackson said:
John, are you suggesting you do NOT have a manual for your boat?
I strongly urge you to obtain one.
And for all the guessing going on here, just open the panel and your battery box and trace the wires. Ralph's right.

Stu, the Catalina comes with a manual. John likely has that manual, a blue binder. Problem is the manual is generic. Every boat is built one at a time. Some options are added at the factory, some by the dealer. No guarantee it’s wired like the generic options given in the “blue manual” if it’s a dealer add on.

Yes looking at his batteries and switches is the only way to be sure. But it helps to know what other people have discovered and what they did to obtain a different result if one is desired.

Shutting down conversations about what other people did is unhelpful and unnecessary. I’ve solved a lot of problems by looking on forums just like this one.

Stu Jackson · Aug 19, 2022

leslie894 said:
Shutting down conversations about what other people did is unhelpful and unnecessary. I’ve solved a lot of problems by looking on forums just like this one.

I fail to see how anything I suggested could be remotely construed in such a manner.
I have owned my C34 for 25 years, and a C22 & C25 for 15 years before that. I understand how manuals work and am grateful to Catalina for assembling some of the best boat manuals in the galaxy.

The "basics" of the contents Catalina's manuala, in my more than limited experience, are 95-100% correct and valid.
For something as simple as this exercise, I simply suggested he go look, for exactly the reasons you mention.

leslie894 · Aug 19, 2022

I guess I misunderstood you.
We are huge Catalina fans. Had a Catalina 28 mk II. Manual covered everything because it was a pretty simple boat really. When we decided to buy a new one, it had a be a Catalina. Only decision was a brand new 315 or a used 355.
Modern Catalinas have become complex. Large option list. And as I said not always clear who installed what. So the manual covers some options but not everything and all bets are off if the dealer installed it.
Our batteries were not connected according to the manual’s wiring diagram. Maybe it was out of date. Maybe the dealer installed the starting battery. Warren the support guy at Catalina is wonderful but I decided not to bother him with it. We figured it out and figured out how we wanted to change it, right down to fixing the battery condition meter so it reads what we want it to.
I have to admit fixing all the new boat problems — and yes, there are always new boat problems and we are nowhere near any kind of business that services sailboats — has been an excellent learning experience. So years from now when we have old boat problems we will know where everything is

315 Battery Meter

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SBO Weather and Forecasting Forum Jim & John

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