Bow Thruster Battery
- Thread starter Twinboat
- Start date
The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
Comodave
Moderator Emeritus
- Joined
- Jul 2, 2015
- Messages
- 21,273
- Location
- Au Gres, MI
- Vessel Name
- Black Dog
- Vessel Make
- Formula 41PC
Starting. High current draw for a short time.
While I agree with Comodave above, I don't think it makes that much difference. If you have a decent sized house battery bank then you can use it to power the bowthuster as it draws maybe 200 amps and a pair of GC batteries can easily supply that much current.
But if you are installing a dedicated battery in the bow, then use a starting battery. A Group 27 in the bow with the proper sized charging wiring, fuses on both ends and an ACR would be perfect.
David
But if you are installing a dedicated battery in the bow, then use a starting battery. A Group 27 in the bow with the proper sized charging wiring, fuses on both ends and an ACR would be perfect.
David
Maerin
Guru
I recently replaced the batteries for my thruster. Because the thruster is 24V, it has a dedicated bank in the bow with its own smart charger. The batteries I replaced were Optima Blue tops, they were on the boat when we purchased it, and were trouble free for over 8 yrs. I replaced them with new, same configuration. The blue tops are a dual purpose spiral wound AGM, and easily handle the high amp short draws. I'd use them again. Otherwise, I'd use a starting battery. Better suited for high current short duration as others have recommended.
FF
Guru
- Joined
- Oct 12, 2007
- Messages
- 22,552
Starting , the loads are short term as most thrusters have a very short ON time allowance ,
THe thruster batts may be the easiest to grab for an emergency engine or noisemaker jump start.
THe thruster batts may be the easiest to grab for an emergency engine or noisemaker jump start.
O C Diver
Guru
- Joined
- Dec 16, 2010
- Messages
- 12,865
- Location
- USA
- Vessel Name
- Slow Hand
- Vessel Make
- Cherubini Independence 45
Interesting. When (2015) I converted my bow thruster from 12 to 24 volts (swapped motors), I installed 2 Optima red top batteries. Contacted Optima for guidance and didn't think they fully grasped what the duration pulse was. So I went with the red tops. For my application, 3 second pulses are about all I ever need. On rare occasions I might do 2 or 3 of those when in a lock.
This pic is during the conversion process. Had voltage loss problems with the original 12 volt setup, so converted to 24 volts and moved the batteries to the thruster compartment. Already had the 4/0 cable, so figured there was no reason not to use it.
Ted
Last edited:
what_barnacles
Guru
whats the pvc thing in the pic?
stubones99
Guru
I think it is an gravity feed oiler for the thruster.
stubones99
Guru
It looks like a fusible link and the insulator mounting for the link. Those wires probably jump when he hits the thruster just from the starting current and it needs to be secured and fairly solidly built.
O C Diver
Guru
- Joined
- Dec 16, 2010
- Messages
- 12,865
- Location
- USA
- Vessel Name
- Slow Hand
- Vessel Make
- Cherubini Independence 45
The original oil reservoir cracked (cheap plastic, oily mess to clean up
). The replacement was pricey. So I made my own out of PVC pipe fittings. You can see the clear hose going to the lower unit.The black object is a fuse holder. The ANL fuse is in the tray to the left of the battery.
Ted
TugYacht_33
Veteran Member
- Joined
- Nov 12, 2017
- Messages
- 81
- Location
- USA
- Vessel Name
- Mhyzhen
- Vessel Make
- Custom 33' Glen-L design "union jack"
well, i can tell you from my own personal experience that using a deep cycle for hi amp short bursts can and most probably will kill the battery
i was about 2 or 3 months into an "emergency" deep cycle in my f150, had to have one, was in middle of nowhere right before closing, only thing the auto parts had in the size/post configuration i needed....
then it sort of became out of site out of mind, it was working great so i said forget it and forgot it, lol
until it left me stranded in a parking lot one day, worked great until it never worked again......
edit: forgot to say.... yea, on those optima batteries, they are considered not much better than junk(or were anyway) in the after market any more..... they are nothing like the originals from before the sell out
i sold them for three years and in that time a solid 25% came back for warranty issues
maybe they got their **** together and fixed the issues, its been a few years since i dealt with them
i was about 2 or 3 months into an "emergency" deep cycle in my f150, had to have one, was in middle of nowhere right before closing, only thing the auto parts had in the size/post configuration i needed....
then it sort of became out of site out of mind, it was working great so i said forget it and forgot it, lol
until it left me stranded in a parking lot one day, worked great until it never worked again......
edit: forgot to say.... yea, on those optima batteries, they are considered not much better than junk(or were anyway) in the after market any more..... they are nothing like the originals from before the sell out
i sold them for three years and in that time a solid 25% came back for warranty issues
maybe they got their **** together and fixed the issues, its been a few years since i dealt with them
Last edited:
Ski in NC
Technical Guru
I use a basic flooded starting batt on my thruster. First one lasted about five years then performance got weak. Second one is at about four years and still doing ok. I watch the panel meter when thrusting, if it goes below 10v under load, it's getting to be batt time.
Other batt types might last longer, but at much higher cost.
I would not use a deep cycle for this.
Not worried about H2 generation. That is usually only an issue with gross overcharging that comes from a shorted cell or crappy charger. I have enough ventilation for what H2 is created. And when I leave the boat I check charger amps, close to zero and I know batts are happy and H2 not a risk.
Other batt types might last longer, but at much higher cost.
I would not use a deep cycle for this.
Not worried about H2 generation. That is usually only an issue with gross overcharging that comes from a shorted cell or crappy charger. I have enough ventilation for what H2 is created. And when I leave the boat I check charger amps, close to zero and I know batts are happy and H2 not a risk.
psneeld
Guru
I havent done the research or the math...based on responses...doesnt sound like many others did...
Golf carts with 4 guys and clubs seem to leap off the line when the pedal is hit....wonder how tbat compares to a windlass pulling up chain...not the whole boat into the eye of a hurricane.
It would seem to me deep cycles might be fine, but so would stating batteries....hmmmmm.
I have no thruster, but if I did, I might run the amp draw and average amp hr draw to see which battery specs best met the job.
Golf carts with 4 guys and clubs seem to leap off the line when the pedal is hit....wonder how tbat compares to a windlass pulling up chain...not the whole boat into the eye of a hurricane.
It would seem to me deep cycles might be fine, but so would stating batteries....hmmmmm.
I have no thruster, but if I did, I might run the amp draw and average amp hr draw to see which battery specs best met the job.
TugYacht_33
Veteran Member
- Joined
- Nov 12, 2017
- Messages
- 81
- Location
- USA
- Vessel Name
- Mhyzhen
- Vessel Make
- Custom 33' Glen-L design "union jack"
its not rocket science
a starting battery is designed for hi current short draw usage, it is also designed to be kept at or near a fully charged state
a deep cycle battery is designed to be drawn down over time to power parasitic loads, it is designed to "give over time" and to do so for extended periods of time
the dual purpose batteries are an attempt to fill both needs from one source, not a best of both worlds, but more like this is the best we can do for both
a starting battery is designed for hi current short draw usage, it is also designed to be kept at or near a fully charged state
a deep cycle battery is designed to be drawn down over time to power parasitic loads, it is designed to "give over time" and to do so for extended periods of time
the dual purpose batteries are an attempt to fill both needs from one source, not a best of both worlds, but more like this is the best we can do for both
TugYacht_33
Veteran Member
- Joined
- Nov 12, 2017
- Messages
- 81
- Location
- USA
- Vessel Name
- Mhyzhen
- Vessel Make
- Custom 33' Glen-L design "union jack"
Deep Cycle vs. Starting Battery
read_interesting
Have you ever wondered why there are different sizes or types of batteries? Did you know every battery type serves a specific functionality? Well when it comes to the battery world, the type chosen and its usage varies significantly. Depending on both how much power output you require, and for how long you need power being produced is how the correct option can be chosen.
The two primary battery options that you will find will either be defined as “deep cycle” batteries, or “starting” batteries. It is very important that you find the correct battery for your particular application, as the wrong choice can affect both the battery’s efficiency as well as its lifespan.
Our first variety, deep cycle, is meant to provide a continuous current of the same intensity for a prolonged time span. Although they are certainly capable of providing surges of power, this is not their primary purpose. Because of the internal structure, they can be used for starting, but tend to provide a lower cranking output than similarly sized starting batteries. Also important to the deep cycle battery is that once discharged, it is best to recharge at a lower amp rating for a longer amount of time, and not to simply be “topped off” quickly. Quick charging could eventually shorten the cycle life of the battery.
Starting batteries occupy the opposite end of the spectrum, being designed to provide quick bursts of energy, such as a car would use while starting. This only discharges the battery by about 1-3%, which is then topped off typically by you vehicles alternator. This is perfectly acceptable for a starting battery, and ensures that they are always ready to provide maximal current on demand. The drawback being that in order to provide peak cranking power, a starting battery will trade off some of its reserve, and deep cycling capacity.
The bottom line. Deep Cycle batteries provide a greater reserve capacity, but cannot deliver as many peak CCA’s (cold cranking amps). Starting Batteries are made to provide high power for higher amp, more frequent short draws, and limited long term discharge. Ultimately, your primary need should determine your battery choice. Choosing the right battery always provides the right amount of power, and does so for the right amount of time.
read_interesting
Have you ever wondered why there are different sizes or types of batteries? Did you know every battery type serves a specific functionality? Well when it comes to the battery world, the type chosen and its usage varies significantly. Depending on both how much power output you require, and for how long you need power being produced is how the correct option can be chosen.
The two primary battery options that you will find will either be defined as “deep cycle” batteries, or “starting” batteries. It is very important that you find the correct battery for your particular application, as the wrong choice can affect both the battery’s efficiency as well as its lifespan.
Our first variety, deep cycle, is meant to provide a continuous current of the same intensity for a prolonged time span. Although they are certainly capable of providing surges of power, this is not their primary purpose. Because of the internal structure, they can be used for starting, but tend to provide a lower cranking output than similarly sized starting batteries. Also important to the deep cycle battery is that once discharged, it is best to recharge at a lower amp rating for a longer amount of time, and not to simply be “topped off” quickly. Quick charging could eventually shorten the cycle life of the battery.
Starting batteries occupy the opposite end of the spectrum, being designed to provide quick bursts of energy, such as a car would use while starting. This only discharges the battery by about 1-3%, which is then topped off typically by you vehicles alternator. This is perfectly acceptable for a starting battery, and ensures that they are always ready to provide maximal current on demand. The drawback being that in order to provide peak cranking power, a starting battery will trade off some of its reserve, and deep cycling capacity.
The bottom line. Deep Cycle batteries provide a greater reserve capacity, but cannot deliver as many peak CCA’s (cold cranking amps). Starting Batteries are made to provide high power for higher amp, more frequent short draws, and limited long term discharge. Ultimately, your primary need should determine your battery choice. Choosing the right battery always provides the right amount of power, and does so for the right amount of time.
TugYacht_33
Veteran Member
- Joined
- Nov 12, 2017
- Messages
- 81
- Location
- USA
- Vessel Name
- Mhyzhen
- Vessel Make
- Custom 33' Glen-L design "union jack"
pto driven hydraulics off of the main propulsion engine
Mule
Guru
On my MS 34MK 1 I put a big 8D next to the biggest Vetus thruster recommended. I then put a solar panel, controlled, as only charging source. I wired it up with much smaller gauge wire from the panel to battery so big wire, long run with high amp draw to feed thruster from the middle of the boat would not be necessary to carry the amps to power the thruster. Battery to thruster, 2 feet..about. Small wire to keep it topped from the solar panel. Worked great.
Currently, on my Present I have a main engine driven v belt driven hydraulic stern thruster. Were l starting from scratch, I would have a 12 volt hydraulic power pack pump off the house bank pushing thruster(s) and windlass, independent from the main. I think that would work really good.
Currently, on my Present I have a main engine driven v belt driven hydraulic stern thruster. Were l starting from scratch, I would have a 12 volt hydraulic power pack pump off the house bank pushing thruster(s) and windlass, independent from the main. I think that would work really good.
Last edited:
psneeld
Guru
Ooops, meant thruster....
To me.... the logic could go either way..still interested in seeing the math....
OK, here is some math:
A midsize 12V Sidepower thruster such as what would be installed on a 34-38' trawler draws about 200 amps according to SP's literature and requires a minimum of a 300 CCA rated batttery, Notice that starting batteries have CCA ratings and deep cycle batteries typically don't. So SP is implicitly recommending starting batteries. A group 24 or 27 will meet this CCA spec.
If you were to use a group 24 deep cycle battery, these are usually rated at about 70 AH of capacity. So you would be drawing about 3 times its AH capacity in instantaneous amps. Ignoring the huge inefficency of doing this, such a battery would only last 20 minutes at this draw. Not that a starting battery would last any longer, but I suspect it would last a little longer at this rate. That is what it is designed to do.
As another data point, a small three cylinder diesel, the Yanmar 3GM that are commonly used in sailboats, draws about 200 amps starting and is often fitted with a group 24 starting battery.
Seems to me that a starting battery is the preferred type. But it won't hurt a deep cycle battery if it is a decent size one. Drawing 200 amps from a pair of GC batteries will work and won't hurt the battery (assuming it is immediately recharged) but won't power the bowthruster as long as an equivalent starting battery.
David
A midsize 12V Sidepower thruster such as what would be installed on a 34-38' trawler draws about 200 amps according to SP's literature and requires a minimum of a 300 CCA rated batttery, Notice that starting batteries have CCA ratings and deep cycle batteries typically don't. So SP is implicitly recommending starting batteries. A group 24 or 27 will meet this CCA spec.
If you were to use a group 24 deep cycle battery, these are usually rated at about 70 AH of capacity. So you would be drawing about 3 times its AH capacity in instantaneous amps. Ignoring the huge inefficency of doing this, such a battery would only last 20 minutes at this draw. Not that a starting battery would last any longer, but I suspect it would last a little longer at this rate. That is what it is designed to do.
As another data point, a small three cylinder diesel, the Yanmar 3GM that are commonly used in sailboats, draws about 200 amps starting and is often fitted with a group 24 starting battery.
Seems to me that a starting battery is the preferred type. But it won't hurt a deep cycle battery if it is a decent size one. Drawing 200 amps from a pair of GC batteries will work and won't hurt the battery (assuming it is immediately recharged) but won't power the bowthruster as long as an equivalent starting battery.
David
Last edited:
MYTraveler
Guru
It is, but the beauty of it is that by having the level of the oil above sea level, there will be slight positive pressure on the seal, so any leak would be of oil going out, not seawater coming in.
And my take on deep cycle or starting is that deep cycle is best (longer lasting), so long as they can put out the necessary amperage. In my case, ALL of the batteries are deep cycle, but the capacity is sufficient to put out the amperage necessary to run the high-demand stuff like windlass, thruster, crane.
dhays
Guru
- Joined
- May 26, 2015
- Messages
- 9,045
- Location
- United States
- Vessel Name
- Kinship
- Vessel Make
- North Pacific 43
My boat is setup with a dedicated thruster/windlass bank of 2 8D AGM batteries located in the compartment under the cockpit aft. This powers the bow and stern thruster as well as the windlass. This bank is charged by a dc-dc charger from the house bank.
Yes, there is a very large 00 cable that runs from the positive buss bar in that compartment that runs to an auxillary dc panel in the forward end of the ER. There, the power to the bow thruster and windlass are controlled by relays and 1/0 cables from the ER to the bow.
The system uses lots of heavy and expensive cable but it also means that one bank controls both thrusters and the windlass. All in all, I like the system a lot.
If I was going to start from scratch, I would certainly consider placing a battery in the bow for both the thruster and windlass. I would still use a dc-dc charger but that would mean running small gauge wire from the closest and most convenient buss bar from the House bank. I would still use a deep cycle battery, not necessarily for the bow thruster but for the windlass.
John mentioned earlier in this thread the idea of just upsizing the house bank and using it. I seriously considered doing this when I replaced my house bank. Just combine my thruster bank and house bank. However, the thruster bank was replaced by the PO so are relatively new and in good shape. No need to replace it at this time. However, if it does need to be replaced down the road, I may yet consider that.
Yes, there is a very large 00 cable that runs from the positive buss bar in that compartment that runs to an auxillary dc panel in the forward end of the ER. There, the power to the bow thruster and windlass are controlled by relays and 1/0 cables from the ER to the bow.
The system uses lots of heavy and expensive cable but it also means that one bank controls both thrusters and the windlass. All in all, I like the system a lot.
If I was going to start from scratch, I would certainly consider placing a battery in the bow for both the thruster and windlass. I would still use a dc-dc charger but that would mean running small gauge wire from the closest and most convenient buss bar from the House bank. I would still use a deep cycle battery, not necessarily for the bow thruster but for the windlass.
John mentioned earlier in this thread the idea of just upsizing the house bank and using it. I seriously considered doing this when I replaced my house bank. Just combine my thruster bank and house bank. However, the thruster bank was replaced by the PO so are relatively new and in good shape. No need to replace it at this time. However, if it does need to be replaced down the road, I may yet consider that.
The idea that starter-type batts are "better" at feeding high-amp loads is only true at AH sizes tiny for house banks.
Vendors generally don't publish the CCA for true deep cycle batts, because rightfully suspicious buyers would think "aha that's just a pseudo-dc dual use starter batt".
Obviously all batts **have** a CCA rating, it scales along with AH, so get a large enough AH capacity bank CCA becomes irrelevant.
Actual starter cranking usage is so short and infrequent it does not draw even a small batt down more than a fraction of a percent.
For many thruster setups, and windlasses, that is not true, can be a lot of AH draw very quickly. If any high-amp usage is depleting a bank by say 10+% DoD on a regular basis, that is by definition a deep cycling use case.
Large say 8D bank can handle the loads, but if not true deep cycle plate design, their **longevity** will be a small fraction of what you would get from a true deep cycle bank.
If your thruster usage is very light, draws your starter-style batt down just a few percent, then it doesn't matter.
And again, if at all possible, create a single massive bank that feeds House and thruster loads, Peukert's law means a single 800AH bank has much higher total AH, shallower cycling and longer life compared to a 500AH House separate from a 300AH bow bank.
It may require very heavy gauge wiring over the distance, but a one-time expense that saves money on consumables is a good investment.
And if your installation space requires AGM, note that Lifeline, Odyssey and Lifeline batts have **huge** CCA ratings but are in fact excellent true deep cycling as well, even those in automotive BCI sizes like G31
e.g. Odyssey PC-2150 series
Excellent for AGM that is; unless you really need sealed, FLA are more robust, long-lived and of course much better value.
Vendors generally don't publish the CCA for true deep cycle batts, because rightfully suspicious buyers would think "aha that's just a pseudo-dc dual use starter batt".
Obviously all batts **have** a CCA rating, it scales along with AH, so get a large enough AH capacity bank CCA becomes irrelevant.
Actual starter cranking usage is so short and infrequent it does not draw even a small batt down more than a fraction of a percent.
For many thruster setups, and windlasses, that is not true, can be a lot of AH draw very quickly. If any high-amp usage is depleting a bank by say 10+% DoD on a regular basis, that is by definition a deep cycling use case.
Large say 8D bank can handle the loads, but if not true deep cycle plate design, their **longevity** will be a small fraction of what you would get from a true deep cycle bank.
If your thruster usage is very light, draws your starter-style batt down just a few percent, then it doesn't matter.
And again, if at all possible, create a single massive bank that feeds House and thruster loads, Peukert's law means a single 800AH bank has much higher total AH, shallower cycling and longer life compared to a 500AH House separate from a 300AH bow bank.
It may require very heavy gauge wiring over the distance, but a one-time expense that saves money on consumables is a good investment.
And if your installation space requires AGM, note that Lifeline, Odyssey and Lifeline batts have **huge** CCA ratings but are in fact excellent true deep cycling as well, even those in automotive BCI sizes like G31
e.g. Odyssey PC-2150 series
Excellent for AGM that is; unless you really need sealed, FLA are more robust, long-lived and of course much better value.
Last edited:
