How important is Battery control system?

[seapop]

I "think" I would like to install a good battery monitoring and usage and management and alarm system for the batteries in my Catalina 320.

Is this really a good thing or am I over reacting... I am kind of a control freak.

I would think that charge state, amps in/out, etc would be important.

If you think so too, then I would really appreciate suggested brands and models, and if I can do it myself (pretty capable with elec).

thanks

[smac999]

Every boat that shuts the motor off while away from dock should have a battery monitor. They are so cheap and useful.

I like the victron 702. I think they have a newer version now.

[john61ct]

Yes 712-BMV.

But for SoC specifically, far easier to use and best accuracy is Merlin SmartGauge. Only works with lead banks though.

[a64pilot]

I depends on the expected use of the boat.
If your just day sailing with the occasional overnight then you may not really need a battery monitor.
I don’t think an alarm is needed, battery SOC comes and goes gradually like fuel level, it’s not an all of a sudden thing.

[Sailnav]

Check Marine How-To for more than you want to know about battery monitors.
My C320 has two huge 4D wet cell batteries and it's on a mooring with a small (30-Watt) solar panel hooked to one battery. I installed a Smart Gauge two years ago to keep an eye on the whole system, and it works fine.

[seapop]

thanks all for the replies !

[CarinaPDX]

I'm going to take a contrarian position: you don't need a battery monitoring system. I cruised for many years without one - I just had an accurate voltmeter and approximate ammeters (and only the voltmeter was really essential). A battery monitor provides a clearer presentation of the SoC, but a good voltmeter is adequate for the purpose. If you are an obsessive-compulsive type that insists on getting the absolute longest life out of their batteries then closely monitoring the state of charge with a system should give a bit longer life. The real issue is not the quality of instrumentation, it is the attentiveness of the operator. It is a simple matter of paying attention to what is happening with the electrical system, and not letting any battery become too discharged. Most of the time there is charging power available, at the dock or under power, more often than needed. With a good solar system it is seldom that an operator needs to intervene and specifically run the engine to charge the batteries. But in those cases it is necessary to be aware and act on a timely basis. IMHO your money is better spent on proper charge regulators for all charging systems (alternator, solar, wind, battery charger), and on solar panels, to avoid low battery levels in the first place. Also make sure that you reduce power consumption to a minimum, both by design (LEDs, well-insulated refrigerator) and operation. Then buy the cute toy. Unless you don't plan on keeping track of the batteries (among all of the other things happening) and wish to rely on a system that will issue an alarm - not my way of doing things but YMMV.

Greg

[soloauditor]

Battery control is a good idea ,i allways like to know what is going on .insrtuments that monitor voltage and current cost about 8 pounds on e bay and a digital voltage meter with alarm costs about 2.5 pounds on ebay with free drlivery from china .works great had them for years .

[Capt.Don]

When we first bought out boat I made a label for the battery voltage at 50% discharge. Battery manufacturers provide this data. With my AGMs, these values were 12.32 volts open circuit and 11.8 volts load circuit. 100% discharge at 10.5 volts. I could easily see SOC and know when approaching 50% discharge just by looking at the installed volt-meter.

Later I installed the Victron BMV 702. I find it interesting to monitor amps in/out, AmpHours consumed, state of charge, etc. You'll find with a good battery monitor, you'll know how much the fridge, lights, electronics, autopilot,...consume. You start thinking in terms of a total battery capacity, how much each device uses and know when you approach 50% discharge.

Good investement - yes. I'm glad I installed.

Don

[john61ct]

Yes, voltage vs SoC relationship varies with mavy factors, an changes over time

[hzcruiser]

Originally Posted by seapop

I "think" I would like to install a good battery monitoring and usage and management and alarm system for the batteries in my Catalina 320.

Is this really a good thing or am I over reacting... I am kind of a control freak.

I'm a bit surprised you don't have one already if you want to be in control and you know the difference between Volts and Amps.


Get one and see if you're happy with it, there are many BMS out there, some can do more than others. You get what you pay for.

[Gmcgyvr]

OP asked for importance of a control system - many replies are for monitoring system.
Monitoring is imperative (if you want your batteries to last)
Control is optional.
BMS systems normally mean (management) control systems. Too many instances of control systems ruining batteries when components fail.
Minimum control (in my opinion for LiFePo4 banks) is HVC and LVC with good monitors. Don't concern myself with lead; as I have a cat.

[Cpt Pat]

Originally Posted by CarinaPDX

I'm going to take a contrarian position: you don't need a battery monitoring system. I cruised for many years without one - I just had an accurate voltmeter and approximate ammeters (and only the voltmeter was really essential). A battery monitor provides a clearer presentation of the SoC, but a good voltmeter is adequate for the purpose. If you are an obsessive-compulsive type that insists on getting the absolute longest life out of their batteries then closely monitoring the state of charge with a system should give a bit longer life. The real issue is not the quality of instrumentation, it is the attentiveness of the operator. It is a simple matter of paying attention to what is happening with the electrical system, and not letting any battery become too discharged. Most of the time there is charging power available, at the dock or under power, more often than needed. With a good solar system it is seldom that an operator needs to intervene and specifically run the engine to charge the batteries. But in those cases it is necessary to be aware and act on a timely basis. IMHO your money is better spent on proper charge regulators for all charging systems (alternator, solar, wind, battery charger), and on solar panels, to avoid low battery levels in the first place. Also make sure that you reduce power consumption to a minimum, both by design (LEDs, well-insulated refrigerator) and operation. Then buy the cute toy. Unless you don't plan on keeping track of the batteries (among all of the other things happening) and wish to rely on a system that will issue an alarm - not my way of doing things but YMMV.

Greg

The original post didn't specify the battery type. If you have a lithium battery -- terminal voltage tells you almost nothing about its SoC. 13.35 volts: it's fully charged, 13.2 volts: it's somewhere between 80 and 30% SoC. Look away... and it's "fallen off the knee of the discharge curve" -- sorry, too late, ruined battery. Lithium batteries absolutely require a battery monitor that totalizes amps in and out. And if you have a battery management system that disconnects the battery before it's ruined - you'll want to know how close you are to that threshold before your lights go out in the middle of the night.

With lead/acids you'll still want a monitor that totalizes charge/discharge so you can detect an unexpected drop in capacity - before you head out for a long voyage, and to monitor the SoC when loads are varying causing fluctuating terminal voltages. Trying to guestimate SoC by the terminal voltage with differing loads will drive your mind into circles, unless you enjoy calculating nonlinear regressions. I have 300 amp/hours of 6-year-old AGMs. Two Lifelines and two Odysseys. They've undergone about 500 cycles. I've monitored them carefully, and they still hold 95% of their rated capacity - and I wouldn't know that without a battery monitor. The monitor has paid for itself many times over. I have a Victron Energy monitor. Xantrex also makes a good monitor.

I'm a delivery captain, so I've seen quite a variety of configurations. Both monitors are good - and sure beat crouching down with volt meter probes trying to measure terminal voltages.

[john61ct]

I think it's safe to assume lead unless LFP is mentioned specifically.

And a full LFP-style BMS is overkill for lead, pretty sure the OP just meant monitoring, newer members aren't always up on the precise use of jargon.

[denverd0n]

Ask yourself how important is it to you that your batteries last as long as possible, and that you get the most beneficial use out of them. That is also EXACTLY how important a good battery monitoring system should be to you.