Storage batteries

[Donald Tyson]

Good morning.
Is there any advantage to using all storage batteries on a boat to save batteries that are often discharged significantly on a regular basis. For a mostly mild weather boating/trolling can’t I just do the starting with a storage bank?

[Robert H. Wilkinson]

Is your question - can you use deep cycle batteries for starting?

The short answer - starting a small outboard with a large deep cycle bank in a warm climate will usually be ok. The problem arises with larger inboard motors and/or cold climates. They can draw the voltage of a deep cycle battery down significantly while cranking and this can and will cause damage to the starting motor over time.

Attempting to start a motor with any battery that has been drawn down below 50% can also cause damage to starter.


Rob

[thataway]

I have owned several boats which came with an all purpose (start and storage) battery. Most of those i put in a house battery with a device to charge the second battery after the first battery has begun to charge. I have owned my Caracal cat (18' catamaran center console) for 17 years with only one battery. It took a heavy rain and unusual tides to sink the boat, partly because the only battery drained the bilge pump overnight. Then the water accumulated to the point where more water came over the gunnel and a "total loss" of the boat. (Insurance paid off, and I bought the boat back on a salvage basis.). One of the first things was to put in a second battery, battery chargers, and an alarm for high water.

Some of my sailboats came with only one battery. If you drained it down, you could not start the inboard engine--and then you had to sail home--not bad, unless no wind!.

[ssobol]

I use dual purpose batteries. I have two. One is used for all loads and the other is held in reserve for starting the motor in case the #1 battery gets low.

[Donald Tyson]

While in a Marina in Watertown NJ years ago we had a line of severe storms come through and had 13" of rain far in one hr. Many boats sank do to not having the batteries and pumps set up in the right fashion. It wasn't completely calamitous as many of the slips were very shallow. It would have been very expensive had they all Been deep slips. I fish and I need juice for trolling motors, and I hope to run more 12V appliances. Is there an argument for more deep cell batteries on board Instead of hybrids.

[tsturm]

[Donald Tyson]

Bingo! 11 yrs.

[thataway]

True deep cycle batteries, like L16 floor sweeper or traction batteries, and Rolls, single cells are way too heavy to be used in a C Dory.

In today's world those that need more trolling motor batteries are all going to LiFePO4 batteries, and same for the "appliances".

I did this with our last 25 with the chest freezer and chest refrigerator, plus microwave and induction hob for cooking. Running air conditioning is possible, but going to be expensive. There are 12 Volt air conditioners which are slightly more efficient than the 120V AC mains power.

Many of the professional bass boat group have gone to the Li batteries for their trolling motors. It is not unusual to use 24 volt or 36 volt, 50 amp hour batteries for trolling motors on many of the larger boats--similar in size to our C Dorys. There are some negitative issues with trolling motors and the C Dory with its rails nad deck configuration.

[Donald Tyson]

Bingo! 11 yrs.

[gulfcoast john]

Don,

The ‘Starting’ batteries referred to in the looper forum are required for some diesel and large (45ft) gassers. You’ll find a ‘Dual Purpose’ battery that can provide the specs required by your outboard engine maker. Then, that same battery can help power all your overnight needs while anchored out or combined with a House battery. A Starting battery can put out a huge slug of current for a short time, but will be damaged by lower demands overnight, so there is no advantage, but significant disadvantage, in using one on an outboard trailer boat.

After meeting the outboard starting specs, the next question is how much will you anchor out, what power draws will you have all night, and how will you recharge the drained batteries?

A battery monitor or ‘coulomb counter’ is almost mandatory to figure that out and gives Ah in and out, watts, an accurate State of Charge %, etc. I installed this one; fancier versions even have Bluetooth. This is a DIY install for most folks with basic 12v skills. In general, you don’t want to drain your lead acid batteries more than 50% (roughly 12.2V but the meter is more accurate).

https://www.victronenergy.com/battery-monitors/bmv-702

For long distance cruising, I’d avoid a boat that doesn’t have a 110v shore power panel with a battery charger and a couple of 110v outlets including one for a 12/110v fridge at a minimum. For the most basic 12v systems, the typical fridge with Danfoss compressor will be the biggest energy hog. After the last opening before bedtime, we turn the thermostat warmer…it won’t need to run as much but still keeps the ice cube trays hard frozen if the door stays closed. Our other loads are a couple of LED reading lamps, a small Pure Sine Wave inverter to power the laptop, the LED anchor light, and sometimes a 12v fan or two. On our Tenn Tom adventure, the SOC was 100% on all three Group 31 FLA batteries at sunset. At sunrise the Combined S Eng + House SOC was 86% each day with the P Eng isolated. A simple rooftop Renogy 100w solar panel charged them back up to 100% before 3PM. That’s an easy DIY install under $250 with the circuit breaker and Victron MPPT controller, assuming you don’t end up putting a bunch of other stuff up there that shades it.

Other common CD recharging options include running the outboard at fast neutral, or carrying a Honda generator.

I deeply respect Bob’s lithium systems knowledge and expertise. We hope to run Cat O’ Mine competently on the road and in the water until age 80, which is only 10 years away. Until then, our strategy is to buy FLA-31 batteries ($112 each on sale) and replace them every 36-48 months from mfg date, regardless of how well they pass a load test, if we will be cruising in remote areas like Georgian Bay.

Lithium is the future, but the future is not yet here. Even the standards are evolving or not even set yet.

In our experience with 13 trailer boats over 40 years, a typical AGM will last 6 to at most 10 years, a typical FLA last 3-5 years and no experience with Lithium batteries.


Good luck and tap the Brat experts in your journey to find a CD right for you and your crew!

John

[thataway]

John's post is accurate and good. I do disagree that LiFePO4 batteries are:

[Donald Tyson]

You folks are amazing.


John,
I am getting my ducks in a row in areas that are important to me. Knowledge is the first thing I'm gathering...its hard to store but easy to expand on.
I live right near the Deka and Interstate Plants and lead acid batteries are Cheap! One just has to know precisely what is needed.
From a moral standpoint I still have trouble patronizing the LI markets as they are slave driven industries from countries that don't clean up well after the bank runs dry. But I'm sure, in time, we will all have some of the new technologies.
I pretty much hate Electricity. I grew up on an old farm and was always getting shocked somewhere. Freaks me out to this day.
Recently, at a seminar, Captain Chris made a very clear but basic presentation and explained boat electronics in such a way that I believe there is hope for even me. I ordered "Nigels 4th" and hope to gain more confidence there.
Someone said recently that there can be alarms or switches installed to keep flooded batteries from discharging to much. Is that so? I like the Idea of the bluetooth monitor but It makes me thing there is more to set up than necessary.
Though I don't currently own one I've been using Honda Suitcase Generators on and off since they came out in the 80s sometime. I remember it was so Magical then...I could run a hedge trimmer with 200 feet of chord or two hedge trimmers with 50' ea. of chord. It was a miracle back then. I hope to have one aboard but will wait a bit. Has anyone really found a place to store these where they won't suffocate or electrocute you.
You mentioned that perhaps I'm sweating over the little stuff but I'm enjoying the path....I don't yet have a boat but will before long...too long I suspect. So these are the literal thoughts I'm thinking as I heal from surgery and enter into retirement Jan 1st.
Like I said you guys are amazing. Don't be surprised if Dr Bob Patents some new stuff soon.

[Tom Hruby]

I have been using LiFePO4 batteries as a primary source of power for 12 years and have not had any problems with them. I bought 40 180AH CALB cells in 2012 to power a small pick-up truck conversion I built, and used them for 8 years until the truck body gave out. I then transferred them into a box trailer I converted into an RV to provide off-grid power for it. They are still going strong (12 years). In 2013 I purchased an additional 48 CALB cells to power my St. Pierre Dories I used for cruising. These were working fine until 2023 when I lost the boat due to an accident. All told I have purchased 90 cells and only one of these has been defective and returned under warranty.

My new electric boat, a 22 ft C-Dory cruiser is also powered by LiFePO4 batteries (both for propulsion and house power), but since I have only used it this summer I don't know how long these batteries will last.

So I am a firm supporter of using LiFePO4 cells or batteries where you can.

[Donald Tyson]

You say 90 cells...do you mean 90 batteries?
My only area in electric is cooling/starting. Everything else can easily be either omitted or figured out without electric...not that I would.
how do you charge all these batteries.

[Tom Hruby]

In the early days of these batteries one could only buy the individual cells and I had to build a battery bank from scratch. My truck was running at 120 volts and my boats at 36. Between the two I had 44 kWh of storage.