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15-04-2021, 00:40
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#1
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Registered User
Join Date: Nov 2009
Location: Dartmouth and Bristol, England
Boat: Northwind 50 - 50ft - Camille
Posts: 40
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Lithium to power thruster
Should I use a bank of lithium cells to power my bow thruster. Might there be overheating or problems with the battery management system?
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15-04-2021, 01:05
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#2
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Registered User
Join Date: Mar 2019
Location: Live aboard in Simonstown (Cape Town) - now Grenada having crossed the Atlantic.
Boat: 1986 Bruce Roberts 45 raised saloon
Posts: 374
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Re: Lithium to power thruster
That would depend on the capacity of your LiFe bank and the current draw of your bow thruster.
I personally try to limit the current draw on my LiFe bank to 50% of capacity (so 200amps from my 400Ah bank), for this reason I keep a lead acid start bank that also runs my windlass. No bow thruster but if I did have it would also be off the lead acid bank.
Having a lead acid bank also makes charging via alternator safe and easy (alt - lead acid - dc/dc - LiFe)
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15-04-2021, 06:11
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#3
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Registered User
Join Date: Mar 2019
Location: Live aboard in Simonstown (Cape Town) - now Grenada having crossed the Atlantic.
Boat: 1986 Bruce Roberts 45 raised saloon
Posts: 374
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Re: Lithium to power thruster
My own lithium bank is rated at 1C, I choose to limit it to 0.5C for longevity.
I also charge to max 90% (13.6V) when on the boat and max 70% (13.2V) when not on the boat - discharge is electronically limited to 20% SOC even though they can be fully discharged without immediate (noticeable) damage.
All the above is done in the name of longevity because they cost a lot of cash and I want to look after them as best I can.
So can you run your bow thruster off your LiFePO4 bank? In my opinion yes if the operating current of all concurrent loads remains below 0.5C, otherwise I would advise against it.
If you have a lead acid bank for starting then use that for your bow thruster. If you only have LiFe and it is rated to start your engine then by all means use it to run the bow thruster as well (but not at the same time!)
From Solarcity INC -
How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries
"How fast those lithium ions get yanked hither and yon has an effect on cycle life as well. In light of the above that should be no surprise. While LFP batteries will routinely do charging and discharging at 1C (i.e. 100 Amp for a 100Ah battery), you will see more cycles out of your battery if you limit this to more reasonable values."
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15-04-2021, 09:39
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#4
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Registered User
Join Date: Jun 2018
Posts: 48
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Re: Lithium to power thruster
Another thing to check is the voltage of the bow thruster. A LiFePO4 battery will maintain a much higher voltage and higher current than a lead acid battery will. This will produce more power to the thruster which can result in higher temperatures of the thruster motor.
Another thing to consider would be to use a remote battery bank closer to the load for the windlass and the bow thruster. Nigel Calder does this so he doesn't have to run large cables to the front of his boat. Might do some research on what Nigel is doing as he is very familiar with LI battery usages and backs it up with experience.
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15-04-2021, 10:35
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#5
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Registered User
Join Date: Mar 2019
Location: Live aboard in Simonstown (Cape Town) - now Grenada having crossed the Atlantic.
Boat: 1986 Bruce Roberts 45 raised saloon
Posts: 374
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Re: Lithium to power thruster
Actually P=VI=I2R, so higher voltage will result in lower amps and less heat.
This is one of the main reasons why voltage drop is a big problem for motors, low volts + high amps to produce required power = high heat = burnt motor.
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15-04-2021, 11:43
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#6
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Registered User
Join Date: Mar 2019
Posts: 36
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Re: Lithium to power thruster
from a technology standpoint, a lifepo4 bank that powers the thrusters is almost an ideal set up. High amperage output, high amp restore. Bow thrusters arent meant to be run much, but when they do, its pretty high amperage - which is why a lot of thrusters have battery banks near them for minimizing heavy cable runs with the high amperage they need.
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15-04-2021, 12:05
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#7
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Marine Service Provider
Join Date: May 2011
Location: Cruising Mexico Currently
Boat: Gulfstar 50
Posts: 1,979
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Re: Lithium to power thruster
LiFePO4 is great for this application. Lithium Titanate perhaps even better.
I've done some testing with Headway HP cells. One reason if you are assembling your own to use something like the HP cells is that the internal construction is such that they are optimized for heavy current pulses (less than oh say 20 seconds per pulse).
I do not have a thruster but do have a windlass. I did measure the total AH draw for pulling in my entire 230' chain and 85# anchor in 25' of water. The draw was minimal, Something like 6 AH if I remember correctly. This was pulled from a 32 AH Headway battery I assembled.
With a remote battery powering your thruster and a dc to dc charger for the remote battery you could use a 24 volt or 48 volt thruster. The dc to dc charger takes care of any voltage change ( e.g. 12 house to 24 v thruster). This would reduce the current needed for any given HP thruster.
This link is to some options that we discussed here on CF.
https://www.cruisersforum.com/forums...ts-234714.html
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15-04-2021, 12:28
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#8
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Registered User
Join Date: Dec 2019
Posts: 18
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Re: Lithium to power thruster
Quote:
Originally Posted by anthem00
from a technology standpoint, a lifepo4 bank that powers the thrusters is almost an ideal set up. High amperage output, high amp restore. Bow thrusters arent meant to be run much, but when they do, its pretty high amperage - which is why a lot of thrusters have battery banks near them for minimizing heavy cable runs with the high amperage they need.
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As much as I dislike lead acid batteries, for engine starter motors and thrusters they are pretty much the perfect application. They deliver excellent short time high current capacity, easy integration into the boat electrical system and are also quite cost efficient. When going lithium look at the battery management system AMP rating which is generally the limiting factor. If technologically inclined you may want to look into a 48V thruster motor as used on electric boats which sits well with lithium but this is another can of worms.
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15-04-2021, 13:59
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#9
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Registered User
Join Date: Dec 2020
Posts: 750
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Re: Lithium to power thruster
Quote:
Originally Posted by tomsnrg
As much as I dislike lead acid batteries, for engine starter motors and thrusters they are pretty much the perfect application. They deliver excellent short time high current capacity, easy integration into the boat electrical system and are also quite cost efficient. When going lithium look at the battery management system AMP rating which is generally the limiting factor. If technologically inclined you may want to look into a 48V thruster motor as used on electric boats which sits well with lithium but this is another can of worms.
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Like Tom says ^^^^^
Li batteries for a bowthruster are a flagrant waste of money--for no benefit in the real world.
Of course it is YOUR money... so feel free.
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15-04-2021, 14:00
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#10
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Registered User
Join Date: Jun 2013
Location: canada
Posts: 4,634
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Re: Lithium to power thruster
Bow thrusters are around 500a.
So for the drop in ones you’d need 5-10 of them... as they Likly max out at 100a each.
External bms bank would handle it better if done right.
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15-04-2021, 16:12
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#11
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Registered User
Join Date: Aug 2011
Location: Queensland, Australia
Boat: Endeavourcat 30
Posts: 238
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Re: Lithium to power thruster
Quote:
Originally Posted by parachute
Lithiumm batteries have caughfire in planes and and cars and everything else with a Lithium battery including phones.
Lithium-ion batteries commonly used in consumer electronics are notorious for bursting into flame when damaged or improperly packaged. ... "If the battery is damaged and the plastic layer fails, the electrodes can come into contact and cause the battery's liquid electrolyte to catch fire
List of UK Lithium battery fires: https://resource.co/article/lithium-...llion-annually
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But seriously, only silly people would use other than LiFePO4 batteries on a boat and re-hashing old tales about lithium ion fires is also not useful.
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16-04-2021, 12:16
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#12
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Registered User
Join Date: Nov 2009
Location: Dartmouth and Bristol, England
Boat: Northwind 50 - 50ft - Camille
Posts: 40
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Re: Lithium to power thruster
Thanks, Guys for some really useful info.
I know lead acid has its plus points but I voyage around leaving my boat wherever I stop for the winter. Yards in the Med I have found will not allow you to leave your battery charger running on tick-over (Fire insurance risk for the yard) so this year, in particular, with no 2020 sailing my lead acids are all likely caput. I know,--- solar or wind generators. In the winter, I think wind may be best. I am fitting one now as I am moving back to Northern Europe.
Thanks again.
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29-12-2021, 05:48
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#13
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Registered User
Join Date: Jun 2013
Location: New England, USA
Boat: 45' SV
Posts: 75
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Re: Lithium to power thruster
It seems like the lower cost LFP cells have lower impulse current specs - as noted earlier in the thread. But Winston's are spec'd for up to 3CA continuous and 10CA impulse.
http://www.csl-battery.com/static/up...7920730755.pdf
For even a modest 300AH bank that is 900 and 3000 amps respectively. Seems like that would be more than enough for thrusters, windlasses, electric winches, etc. Thruster is probably the largest (say 500 amps).
Any recent thoughts on this topic?
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02-01-2022, 10:21
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#14
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Commercial Member
Join Date: Dec 2008
Location: St. Petersburg, FL
Boat: Gulfstar Long Range Trawler; 53'; BearBoat
Posts: 1,524
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Re: Lithium to power thruster
It really depends on your BMS. Some BMS's will consider a large impulse load as a short circuit and shut down the bank. As an example, Battle Born batteries have a difficult time coping with bringing an inverter/charger on line due to the high inrush current to charge the input capacitors. BB offers a soft start unit to mitigate this.
__________________
Charlie Johnson
ABYC Master Technician
JTB Marine Corporation
"The Devil is in the details and so is salvation."
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03-01-2022, 05:18
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#15
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Registered User
Join Date: Jun 2013
Location: New England, USA
Boat: 45' SV
Posts: 75
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Re: Lithium to power thruster
Thank you, Charlie. Yes for this I am planning on Winston cells and a high end BMS with 500+ amp external contactors.
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