[C320-list] Xantrex DC Controller - functions?

[David Hayes]

Hi all,
I have a Xantrex "C-Series Multifunction DC Controller" in the aft starboard locker. I've recently installed a separate starter battery and had the 2 x 230 AH batteries paralleled, so we turn the battery selector to No. 1 to use the starter battery and then turn to No. 2 to run the house. Plus we have a VSR installed to isolate the started battery to ensure we should always have power there.
Since the addition of the extra starter battery, the Xantrex DC Controller seems to think the batteries (it is connected to the house bank) are in need of charging, despite several hours of motoring on our recent trip. I have tested the batteries and all are currently showing about 13.1 volts so I'm not sure why the Xantrex thinks otherwise. The Xantrex is showing 1 green blink which indicates the batteries are well below what they should be (it blinks between 1-5 times depending on charge levels and then ultimately is on full green when the batteries are fully charged.
I understand there's a reset button on the Xantrex that is probably worth pushing so it can refresh since the house bank is now double the capacity it was previously, but I'd appreciate any help from the group to clarify what functions this unit performs...such as:

1. We have 2 x solar panels - I presume the Xantrex plays a role in bringing that charge into the batteries?
2. When we are motoring does the Xantrex regulate the charge going into the batteries?
3. We also have a Xantrex (Link Lite I think?) battery monitor in the saloon which reads the (correct!) charge for both the starter and house batteries, and shows the net charge coming into, or being drawn from, the batteries....is this connected to the DC Controller at all or just a source of info re charge status?

Thanks in advance for any feedback.
2006 Harlequin.

__________________
David Hayes
Mobile: 0478 956 056
20 Cooks Outlet Road
Loch Vic 3945
Australia

[Scott Lagerquist]

David,

I have been struggling with a start battery issue for the past two seasons. Voltage read well and all indicators pointed towards a good battery. The start battery would not start the engine. I checked wiring at each contact point all the way to the starter and voltage dropped dramatically when engaging the glow plugs or starter. The house batteries had no issue starting the engine. I replaced the start battery and it easily starts the engine. I believe the old battery would charge up in voltage but could not handle a load. I did do a load test and the battery was below the normal range but wasn’t completely shot. Maybe you have a similar problem?

Good luck.

Scott Lagerquist
1994 C-320, #39 “Sea Esta”
San Diego CA
Silver Gate Yacht Club

Sent from my iPhone

> On Oct 18, 2020, at 1:55 AM, David Hayes <david...@hotmail.com> wrote:
>
> Hi all,

[Jack Brennan]

Hi David:

The Xantrex is the controller for the solar panels. By the way, I believe it is a PWM controller, which is not nearly as efficient as the MPPT controllers. The price on MPPTs has become more reasonable, and it’s probably worthwhile looking at a new one that also has an LED showing battery charge info rather than just blinking lights.

A couple of thoughts:

• The 13.1 reading is probably coming as the solar panels are charging your house bank. That means the real state of charge is not 13.1, but more likely 12.3 or so. Try disconnecting the solar panels and letting the batteries sit for an hour with no load on them before checking the voltage.
• A 400-amp house bank takes a lot of charging to bring it up to full. You don’t say how large your solar panels are, but even a couple of 160-watt panels would take more than 10 hours in perfect conditions (and with an MPPT controller) to bring the batteries from half full to near full.
• Your diesel probably has a stock alternator originally designed for a car. This means it’s good at charging your batteries to about 80 percent, but the rate of charge drops sharply after that. I’ve read it can take 8 or 10 hours to fully charge a battery bank with the alternator.
• You are only getting a partial charge from the PWM controller when the batteries are above 80 percent because it is not very efficient. So even on a sunny day, it will be slow going for the solar panels to top off the batteries.

My guess is that your batteries are being somewhat undercharged, which can damage them in the long run. The Xantrex is probably giving you the correct information, but you’re not getting enough data to understand the situation because you don’t have an LED on it.

My recommendation would be to buy an MPPT controller (you can get a Renogy 20 amp for $100), install it and see what the LED screen tells you.

For some perspective, I have two 160-watt solar panels with an MPPT controller charging four golf cart batteries rated at 400 amps. I run the fridge 24/7, and it takes until about 1 p.m. in sunny Florida to bring the bank up to float stage at the dock with no other electric usage.

The panels put out close to 20 amps on a sunny day with the MPPT, but that goes into the batteries only when they are partly drained. The rate of charge drops to 4 or 5 amps as the batteries get close to full. It will be less than that with the PWM.

Good luck. Hope this helps.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.
Dolphin Cruising Club of Tampa Bay







Sent from Mail for Windows 10

From: David Hayes
Sent: Sunday, October 18, 2020 4:55 AM
To: c320...@lists.catalina320.com
Subject: [C320-list] Xantrex DC Controller - functions?

H

[Scott Thompson]

Had a similar experience last year when I discovered that my starter
battery, which I thought was sealed, did in fact need topping off with
distilled water. I had not been doing that and ruined the battery. It
would seem to charge up OK, but could not turn over the engine well
enough to start the engine.