One battery bank

Thinking out loud...

I've been casting about for a while on ways to simplify the battery system on our 37 year old boat. We haven't changed anything other than buying new batteries about five years ago, buying a Hamilton Ferris 100 amp alternator, and putting in a SmartGauge.

Badger has a 4D wet cell starting battery and four 6 volt wet cell golf cart batteries in series parallel, controlled by three 1-2-both-off switches.

I was toying with the idea of a single house bank and spring starter. While that would remove the need for a starting battery and reduce complexity, it would be annoying having to wind it up in cramped quarters.

Thinking further outside the box, I looked at Genius Boost lithium ion jump starters. They barely lose charge in a year, can be used dozens of times between charges, can be charged in a few hours through a 12V cigarette lighter, and have USB and phone charging ports.

One bank. No complexity. Backup starting via the Genius Boost. Top choice of batteries would be 12V Firefly carbon foam because they aren't as sensitive to sulfation or to deep discharges.

https://no.co/products/power/jumpstarters

Plausible?

"Plausible?"

Sure

The question is do you need to deeply discharge , if not ,,good old 6v golf carts and a SOC meter should cost 1/2.

FF said:

"Plausible?"

Sure

The question is do you need to deeply discharge , if not ,,good old 6v golf carts and a SOC meter should cost 1/2.

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Do we need to deeply discharge?

Not so much right now because I'm still working and on our vacations we tend to wander, not staying in one place for too long.

Upon retirement we may stay anchored in a bay for up to a month or more, to photograph. When we move and charge up the batteries it could be for only an hour or two, then who knows, maybe find another beautiful spot and hunker down for another month.

That's where the Firefly batteries come in...they don't have to reach full or be held on a float charge. (Treating them this way will shorten their life, but nothing like regular batteries).

Having one bank of Firefly's will probably save money. Instead of four house batteries, a starter battery and all the bits & bobs they require, we could get three Firefly 12 volt batteries, one ON-OFF switch, and have more house bank amp hours to play with because they can be taken down to 20% without harm.

Hopefully, a Genius Boost would serve the same function as the 9.9 kicker on our swimstep...a self reliant backup...that provides peace of mind but never gets used for its intended purpose. We have no towing service here and will be wandering to the ends of long, twisting, mountain lined inlets where there's no radio reception and you don't see other boats for a week, or more.

Our electrical needs are small. We have an extra 40 gallon tank for diesel (140 total) but will need it for heat during the colder months. The ultimate goal is to simplify and to stay "out there" without coming back for fuel as long as possible.

Think it's a bad thing to put all you battery needs in one basket. Is solar a viable option that far North? Maybe a simple small panel to charge and maintain the start battery and let the alternator charge the house bank. Pretty simple and user proof. Maybe a parallel switch to jump the start battery off the house battery.

Ted

O C Diver said:

Think it's a bad thing to put all you battery needs in one basket. Is solar a viable option that far North? Maybe a simple small panel to charge and maintain the start battery and let the alternator charge the house bank. Pretty simple and user proof. Maybe a parallel switch to jump the start battery off the house battery.

Ted

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That could work and avoid the different charging needs of a dedicated starting battery and the Firefly's. Would be dodgy in the winter though, when it's dark for 16 hours and it could rain/drizzle for a week.

MurrayM said:

That could work and avoid the different charging needs of a dedicated starting battery and the Firefly's. Would be dodgy in the winter though, when it's dark for 16 hours a day and it could rain/drizzle for a week.

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It might be worth running a test to see how many "starts" you can get without recharging the battery. I'm not advocating draining (and damaging) the battery down till it won't start, but seeing if you can get maybe 4 starts on 4 consecutive mornings during the coldest month you will be boating. Mine will start 5+ times (only did the test 5 times). Based on your extended anchoring plans, 4 starts should give you ample reserve.

The panel required to recharge a start battery should be pretty small. Making the mount adjustable would likely make a big difference (pointing it toward the sun) during the Winter months.

Ted

O C Diver said:

It might be worth running a test to see how many "starts" you can get without recharging the battery. I'm not advocating draining (and damaging) the battery down till it won't start, but seeing if you can get maybe 4 starts on 4 consecutive mornings during the coldest month you will be boating. Mine will start 5+ times (only did the test 5 times). Based on your extended anchoring plans, 4 starts should give you ample reserve.

The panel required to recharge a start battery should be pretty small. Making the mount adjustable would likely make a big difference (pointing it toward the sun) during the Winter months.

Ted

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Problem is, if we're in an eastward tending inlet like Gardner Canal, the sun is so low on the horizon that mountains would block direct sunlight. (Gravel casts a long shadow at mid-day here in the winter).

The GB70 is rated to start forty 6 litre diesel engines. That's quite a bit of wiggle room with our 1.8 litre Yanmar 4JH2-UTE.

MurrayM said:

Problem is, if we're in an eastward tending inlet like Gardner Canal, the sun is so low on the horizon that mountains would block direct sunlight. (Gravel casts a long shadow at mid-day here in the winter).

The GB70 is rated to start forty 6 litre diesel engines. That's quite a bit of wiggle room with our 1.8 litre Yanmar 4JH2-UTE.

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With the parallel switch, when you start the engine to recharge the Fireflies, you could throw some amps back in the start battery if you think the sun hasn't been hitting the solar panel.

Ted

O C Diver said:

With the parallel switch, when you start the engine to recharge the Fireflies, you could throw some amps back in the start battery if you think the sun hasn't been hitting the solar panel.

Ted

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Apparently, the Firefly’s need a 14.2 bulk charge.

I’m no whiz when it comes to anything electrical (part of the reason I’m trying for simplicity) but wouldn’t the different charge rates involve more complexity/components?

MurrayM said:

Apparently, the Firefly’s need a 14.2 bulk charge.

I’m no whiz when it comes to anything electrical (part of the reason I’m trying for simplicity) but wouldn’t the different charge rates involve more complexity/components?

Click to expand...

Right now we have a 100 amp Hamilton Ferris Powermax LT self regulated alternator. Hoping it could easily be derated for the Firefly battery...

http://www.hamiltonferris.com/products/Alternators/PowerMax_LT_Small_Case/9

MurrayM said:

Apparently, the Firefly’s need a 14.2 bulk charge.

I’m no whiz when it comes to anything electrical (part of the reason I’m trying for simplicity) but wouldn’t the different bulk charge rates involve more complexity/components?

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My golf cart batteries bulk charge higher than that. A quick search on the web indicates a maximum starting charge rate of 14.5. If you felt it was necessary, you might combine them for a half hour or so. Again this wouldn't be the primary means of changing.

Ted

If you set it up to infrequently charge in parallel, borrow a clamp amp meter to get an idea of the charge rate going into that battery. That would give you a better idea of how long to leave them in parallel.

Ted

MurrayM said:

Right now we have a 100 amp Hamilton Ferris Powermax LT self regulated alternator. Hoping it could easily be derated for the Firefly battery...

PowerMax LT Small Case

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According to their PDF, the battery can accept 250 amps @ 14.4 volts. I don't think you will have a problem hooked to 3 of them.

Ted

When we bought our boat seven years ago, the PO had it set up with one house/start bank (two 8Ds at the time), and a single Group 31 12V start battery for just the genset. We now have four Fireflys as the house/main engine bank, and have been running with this configuration for more than 3,500 miles.

Other than the fact our generator is currently down (we have a Honda 2000 as backup), this set up has worked just fine. I was a little skeptical at first, as all my previous boats had the house and main engine start batts separate. But I wasn't in the mood to reconfigure, so we kept it as designed. Seven years later, no problems.

Moonfish said:

When we bought our boat seven years ago, the PO had it set up with one house/start bank (two 8Ds at the time), and a single Group 31 12V start battery for just the genset. We now have four Fireflys as the house/main engine bank, and have been running with this configuration for more than 3,500 miles.

Other than the fact our generator is currently down (we have a Honda 2000 as backup), this set up has worked just fine. I was a little skeptical at first, as all my previous boats had the house and main engine start batts separate. But I wasn't in the mood to reconfigure, so we kept it as designed. Seven years later, no problems.

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That's very useful real-world feedback....Thanks. When I next have to replace my x8 6v Crowns House bank, I plan to move to Fireflys and reconfigure to the system you describe. Right now, in addition to the House bank, I have a Start/Cracking bank and a dedicated Genset Start battery. All can be fully or selectively interconnected. Works perfectly but Fireflys would permit simplification.

Moonfish said:

When we bought our boat seven years ago, the PO had it set up with one house/start bank (two 8Ds at the time), and a single Group 31 12V start battery for just the genset. We now have four Fireflys as the house/main engine bank, and have been running with this configuration for more than 3,500 miles.

Other than the fact our generator is currently down (we have a Honda 2000 as backup), this set up has worked just fine. I was a little skeptical at first, as all my previous boats had the house and main engine start batts separate. But I wasn't in the mood to reconfigure, so we kept it as designed. Seven years later, no problems.

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Have any situations where you depleted the bank further than you intended? If so, how did you get up & running again?

MurrayM said:

Have any situations where you depleted the bank further than you intended? If so, how did you get up & running again?

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Yes. My boat has two Lehmans with no starting batteries. They are started from the 932 AH (nominal) house bank, Deka wet cell golf car batteries. Those engines once started normally, defined as quickly, with the batteries having been depleted to 20% which I certainly did not intend. My starting options are two: (1) start a generator which have their own starting battery and sufficiently recharge the house bank, or (2) use the jumper cables I keep aboard to jump from the generator start batteries. A depleted house bank is simply something I don't worry about because it is highly unlikely and I have two good alternatives for getting the engines started.

Some guys here will say that one "should" have separate starting batteries. I'm not certain why but it is another way that works. But then, what are the alternatives when those starting batteries fail? Anyway, there is more one one good answer to this question. Just one guy's opinion.

Some good advice here Murray. OCDiver mentioned the solar panel option, and from my experience up your way, I really think you should consider it. You will rethink how many batteries are necessary. I’m contemplating reducing the amount of lead I carry in the house bank as we seldom drop below 90% SOC in summer months. With a 250 amp hour daily demand, 435 watts of panels together with travelling , we almost never need to run the genny, except for hot water when at anchor.

I think you could safely just use the house bank for starting, or perhaps just go down to a single, smaller group 24 for starting, proving you have an ACR or other unit for charging the starter battery. A 4D has to be overkill for your engine.

I would first test test the waters with your winter cruising plans and see whether they materialize. I think you will really need a genny for that option. Heat will be an issue and we find we are happiest at the dock in winter, particularly with getting a dog/dogs to shore. Solar isn’t really useful in winter in BC.

Jim

One battery bank.
One G31 battery to wart engine.

JDCAVE said:

Some good advice here Murray. OCDiver mentioned the solar panel option, and from my experience up your way, I really think you should consider it. You will rethink how many batteries are necessary. I’m contemplating reducing the amount of lead I carry in the house bank as we seldom drop below 90% SOC in summer months. With a 250 amp hour daily demand, 435 watts of panels together with travelling , we almost never need to run the genny, except for hot water when at anchor.

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Yup, a solar panel is also in the plan, although somewhat smaller than yours.

JDCAVE said:

I think you could safely just use the house bank for starting, or perhaps just go down to a single, smaller group 24 for starting, proving you have an ACR or other unit for charging the starter battery. A 4D has to be overkill for your engine.

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The 4D is what the boat came with, and I was so new to boating at the time that I just replaced what was there. Would prefer a single bank.

JDCAVE said:

I would first test test the waters with your winter cruising plans and see whether they materialize. I think you will really need a genny for that option. Heat will be an issue and we find we are happiest at the dock in winter, particularly with getting a dog/dogs to shore. Solar isn’t really useful in winter in BC.

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We used to sea kayak in the winter, so having to tough it out next to a diesel heater with a coffee in my hand and a warm place to take a crap doesn't seem daunting at all

Will definitely try to avoid those -15C to -20C cold snaps with northerly outflow winds though...we could get frozen into an anchorage for a couple weeks!

Well, now...this is interesting:


You'd need a bigger one for diesel engines, but it does suggest one could dispense with a regular starting battery altogether and just use something like a Genius Boost completely separate from the single house bank.

Think I would stick to the original plan and use the house bank for starting and keep the Genius Boost for jump starts.

And yes Mr. RT, I know the GB70 is for sale at the Canadian Tire in Terrace

MurrayM said:

Have any situations where you depleted the bank further than you intended? If so, how did you get up & running again?

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That's where the separate genset battery bank comes in. It's always fully charged and is only ever used to start the genny. Although I've never depleted the main bank down enough to create a starting problem when out cruising, all I would need to do is fire up the genny. It would only take maybe 30 minutes to charge up the Firefly's to where they would be able to crank over the Lehman 120s.

Greetings,
Mr. MM. Yup, aisle 3. Second shelf from the bottom I think...Not only FOR sale but ON sale as well!

RT Firefly said:

Greetings,
Mr. MM. Yup, aisle 3. Second shelf from the bottom I think...Not only FOR sale but ON sale as well!

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Say, you’re not some high tech shill directing customers to Canadian Tire, are you?

(Thanks for the “on sale” tip)

Certainly not a consideration for Murray, but for those of us that have electronic engines such as the Cummins, Tony Athens (Seaboard Marine) strongly recommends that nothing be connected to the start battery except the engine.

The reason for this is possible electrical interference making the engine run poorly. I found this out the hard way, simply in how I was charging the start battery. It cost me thousands of dollars, months of down time, countless hours of aggravation, unintended anchor testing in a high current waiting for a tow, and ultimate the privilege of getting a new engine.

So while using a single bank makes a lot of sense, I wouldn’t consider it with a modern Cummins.

RT Firefly said:

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Weird...all I get is a little blue box with a question mark in it.

dhays said:

Certainly not a consideration for Murray, but for those of us that have electronic engines such as the Cummins, Tony Athens (Seaboard Marine) strongly recommends that nothing be connected to the start battery except the engine.

The reason for this is possible electrical interference making the engine run poorly. I found this out the hard way, simply in how I was charging the start battery. It cost me thousands of dollars, months of down time, countless hours of aggravation, unintended anchor testing in a high current waiting for a tow, and ultimate the privilege of getting a new engine.

So while using a single bank makes a lot of sense, I wouldn’t consider it with a modern Cummins.

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Egad...that sounds like it was the definition of frustrating to trace!

MurrayM said:

Well, now...this is interesting:

You'd need a bigger one for diesel engines, but it does suggest one could dispense with a regular starting battery altogether and just use something like a Genius Boost completely separate from the single house bank.

Think I would stick to the original plan and use the house bank for starting and keep the Genius Boost for jump starts.

And yes Mr. RT, I know the GB70 is for sale at the Canadian Tire in Terrace

Click to expand...

The problem with videos like this is that you have no idea of the current condition of the engine. If the engine has been running before the video and is already warmed up, it will probably take a lot less to crank it over. Cranking over a diesel that's 30 degrees Fahrenheit or less might take 4 times the energy or more.

Ted

I am in the process of doing this now. I am replacing two 8D house batteries with 3 L15 fireflys and each of the 8D start batteries with 2 group 31 fireflys. They will all be combined into one enormous bank. The engines’ two 115 amp Alternator’s will be controlled by Balmar 614 external regulators and a Balmar centerfielder which will allow both alternators two charge a single bank.

I was originally going to change just the house bank, but that became a complicated issue. I would not be able to combine the banks when at anchor if I had fireflys and something else.

I also must mention that I have two generators which have their own batteries. I think I have more than enough backup.

The fireflies have so much capacity and such a long life, I doubt I will ever have to monkey with batteries ever again. At least that is the hope.

Gordon