Daly Smart BMS 500A for bow-thruster?

[JeanF73]

I am just looking into this for myself.
- I plan to keep things simple: use as much existing cabling/equipment as possible

I found LEV60F 3.2v 74ah Lifepo4 Power Cells that can push 600A for 10 seconds (10 seconds burst is loooong when using a bow thruster), 180A continuous; Dimensions of the cells are approximately 2.16" x 6.73" x 4.53", 2.17Kg each. Would give ~8 minutes of use if used alone! Thermal protection of the bow thruster will activate way before that.
Measured amps to the bow thruster: 498A (500A ANL fuse) from main LiFePO4 bank

-Leave original cabling in place
-Small BMS for charging only through a DC-DC charger and/or active BMS
-Add the battery to the bow, connect to the bow thruster only when using it, through a relay, with cabling calculated for as small drop so that load is shared (maybe +-50% bow battery, +-50% house battery).

[CaptainRivet]

Originally Posted by JeanF73

I am just looking into this for myself.
- I plan to keep things simple: use as much existing cabling/equipment as possible

I found LEV60F 3.2v 74ah Lifepo4 Power Cells that can push 600A for 10 seconds (10 seconds burst is loooong when using a bow thruster), 180A continuous; Dimensions of the cells are approximately 2.16" x 6.73" x 4.53", 2.17Kg each. Would give ~8 minutes of use if used alone! Thermal protection of the bow thruster will activate way before that.
Measured amps to the bow thruster: 498A (500A ANL fuse) from main LiFePO4 bank

-Leave original cabling in place
-Small BMS for charging only through a DC-DC charger and/or active BMS
-Add the battery to the bow, connect to the bow thruster only when using it, through a relay, with cabling calculated for as small drop so that load is shared (maybe +-50% bow battery, +-50% house battery).

Can you post a link of the battery/cells please.

Well hownthe bowtruster and house share the load is mostly internal resistance and/or easier capacity based.
Assume from name is 60AH battery and house is 600 then 500A from bowtruster is shared 50A bow, 450A house.
Paralleling with a relay is suboptimal and the cost for this relay is on par with a DC2DC converter that the BMS can shut of via its remote. Also paralleling means if house is at 60% SOC your bowtruster bat is only charge to 60% SoC as well. Mostly bowtruster will be 95-100% SoC but your house below, so the same moment you connect both the bowtruster is charging into house and then on top comes the bowtruster load. Not really a clever solution....
As i described there are only 3 solutions to do it correct, your is not one of them. Every has it pro and cons, choose the one that fits you best.

How did you measure the amps? Special fluke meter that also has a surge setting?
Normal current clamps or bat monitors cannot measure the surge or inrush current as too slow.
If the 498A is the max surge correctly measure then 500A fuse is ok. If bat mon or clamp meter shows 498A the fuse is to small in dimension, you need to use 600A one then.

Are there ANL fuse for inductive loads type? not cable protection type which is wrong here or does your bow truster have a own inductive type device fuse and you are only protecting the cable. If so how big is the cable?

[Pete7]

Originally Posted by CaptainRivet

Permanent parallel of AGM and LFP is forbidden due to many reasons.

Oh I see, by whom?

Pete

[CaptainRivet]

Originally Posted by Pete7

Oh I see, by whom?

Pete

ABYC and ISO which in reality means if your boat is insured of you don't comply they bail out and you have to proof its not the root cause.
Only for emergency is the exception butbeven then is better to switch completely to AGM and not paralleling as LFP suck right away the AGM down. Better load on AGM and let Lifepo4 charge
You can charge it isolated with a splitting diode in parallel.

My install is not ISO complaint as i have starter and windlass connect to LFP house just with a breaker to disconnect, BMS can supervise the whole battery but cannot disconnect both. Get a warning at navstation and helm + LVC at 3.0V so i have still 80-100AH in my bank.
As you have to activly engage windlass or engine nothing can happen, no current is floati g and discharging bank further and i am fully aware that bank is low and can manual switch to backup or just use it when there is no time still use both. With 80-100ah i can yse them very long before i get into daamage zone, so highly unlikely that ever happen. Also when using even below 2.5V nothing can happen but i prefer to riun the bank before boat on the rocks.
Thats why my install was checked by insurance surveyors and documented that it is ok to make an exception of the ISO norm as the added security justify it with no downside to saftey and its not pissible to charge the bank if it is below 2.5V so its safe.

[Pete7]

Originally Posted by CaptainRivet

ABYC and ISO which in reality means if your boat is insured of you don't comply they bail out and you have to proof its not the root cause.
Only for emergency is the exception but even then is better to switch completely to AGM and not paralleling as LFP suck right away the AGM down. Better load on AGM and let Lifepo4 charge
You can charge it isolated with a splitting diode in parallel.

I am aware of those to organisations. Thankfully we can both ignore ABYC because we live in Europe.

The good news is that LFP and LA both work remarkably well in parallel and have a number of advantages. So having done so for 2 years we will continue to have a hybrid domestic bank until someone can provide clear evidence of why not to. To date I haven't nor has the 12volt FB group who are also strong supporters of the idea. It just works and fits our requirements rather well

This is a quote from the 12v FB Group which is rather good:

"If you think about it, using the old definition, then when you charge your phone on the boat you are mixing chemistries because the lead acid boat battery is connected to the phone but it is via a charger and a BMS in the phone. Now look at the Lithium / Lead acid hybrid. You are connecting the lead acid to the lithium but not directly, one of the most fundamental things is that you do so via a BMS which does exactly what the BMS in your phone does and protects the battery. In the case of the phone the input is 5v and it charges a battery to a max of 4.2v. In a boat system you don't need the actual 12v-5v converter because the lithium charge requirements sit within those of the lead acid. This gives another layer of safety to the system because a BMS failure will not expose the lithium to any excess / dangerous voltage. Ironically if the phone BMS dies then the phone battery can explode and if the 12-5v converter fails it can fry the phone and the phone uses a flammable battery technology."

[wholybee]

Originally Posted by Pete7

I am aware of those to organisations. Thankfully we can both ignore ABYC because we live in Europe.

The good news is that LFP and LA both work remarkably well in parallel and have a number of advantages. So having done so for 2 years we will continue to have a hybrid domestic bank until someone can provide clear evidence of why not to. To date I haven't nor has the 12volt FB group who are also strong supporters of the idea. It just works and fits our requirements rather well

I have not seen any evidence of a dangerous problem from paralleling them. However, everyone keeps talking about "advantages" and as far as I can tell, there are none. A pure LFP bank, or a separate AGM start bank and LFP house bank with both perform better than the hybrid.

In particular, for me the most significant improvements from LFP come from having virtually no Peukert factor, and the ability to charge at a high rate until they are fully charged. By paralleling with an AGM you lose both of those advantages.

How do you even program an SOC meter to work properly? I recently fully charged my battery and did a capacity check, having gone about 6 months without my meter syncing at 100%. Even after all that time, it was still withing 2-3% accuracy. You could never achieve that with lead-acid, or a hybrid. You could probably get better accuracy with pure lead than a hybrid, because a hybrid peukert and charge efficiency are now complex curves.

So for me it isn't a question of "why not" but a question of "why?" You just aren't gaining the advantages you think you are.

[CaptainRivet]

Originally Posted by wholybee

I have not seen any evidence of a dangerous problem from paralleling them. However, everyone keeps talking about "advantages" and as far as I can tell, there are none. A pure LFP bank, or a separate AGM start bank and LFP house bank with both perform better than the hybrid.

In particular, for me the most significant improvements from LFP come from having virtually no Peukert factor, and the ability to charge at a high rate until they are fully charged. By paralleling with an AGM you lose both of those advantages.

How do you even program an SOC meter to work properly? I recently fully charged my battery and did a capacity check, having gone about 6 months without my meter syncing at 100%. Even after all that time, it was still withing 2-3% accuracy. You could never achieve that with lead-acid, or a hybrid. You could probably get better accuracy with pure lead than a hybrid, because a hybrid peukert and charge efficiency are now complex curves.

So for me it isn't a question of "why not" but a question of "why?" You just aren't gaining the advantages you think you are.

First we are in europe,so ISO is valid. And due to ISo its forbidden to mix different battery chemistry means lead and lithium. And if ISO forbids that then there is enough proof thats dangerous and there are a lot reasons they forbid that.
I first thought Emily Clarks solution of paralleling lead and LFP is good but if look deeper into you only get the worst of both worlds. And this solution is ONLY paralleling when they are in the same voltage range...solving the biggest problem paralleling both.
People going over the atlantic in a barrel but because they do that doesn't mean its safe and recommended.....

I am just amazed about the hold on to lead for deer life...i was led down once by a LFP (the installation around excluded) in 20 years dealing with LFP, this was quite in the beginning and a pack scraped from a military vehicle, so unknown condition and even the exact chemistry plus we had limited know how about it. Yes we kill many but knowing we are at and above the limit doing competition car stereo but they work from beginning or didn't. And that a class T was arced during a internal bank short looking backwards that was most likely a fake and no Eaton original.
But the lead would fill several container....

Take a small 50AH LFP winston 12V thats 230Euro as starter and that is superior to any lead battery, even the AGM odyssey you can buy for the same amount of money.
no BMs needed just a BMV to do HVC/LVC which you should have for a lead too to monitor the starter.
No need for lead anymore other then then a cheap way to integrate LFP with A DC2DC but that installation in not aimed to have alternator as significant charge source. Its to integrate LFP so the alternator don't break...not more not less. Or having a small lead via an Argofet as surge protector, there are other way but its again a cheap way of doing it

[SOLAR SUPPORT]

LFP service battery support can be used when thick and long power cable is available. This cable pair run extending from the service battery to the bow to the windlass and/or bow thruster to transfer the energy needed.

In order to support the high peak current of the bow thruster and/or windlass DC motors, a 70-100Ah capacity LFP battery capable of providing 600-1000CCA and the service LFP battery are connected in parallel. Since they have the same chemistry, it is possible for these batteries to be constantly connected in parallel. In the worst case scenario, the Soc%20 of LFP batteries connected in parallel does not prevent this plan from working. This is the power of LFP chemistry.

Paralel connected big LFP batteries with their BMSs that have large continous and peak discharge current capacity can be another solution to the problem if the boat need to have large Ah service battery capacity also. These large service batteries can also manage to cope with bow thruster and/or windlass high current energy demand.

If there is no thick power cable installation extending from the service batteries to the bow of the boat, an alternative LFP/LTO battery can be placed near the bow thruster to operate the bow thruster and/or windlass. With this solution, there is no need for a very thick and expensive power cable pair that is half or 2/3 of the boat's length. The windlass can also be operated with the same LFP/LTO battery located in the bow. This battery is kept constantly charged with energy taken from the service LFP batteries using a small DCDC charger.

An LA engine crank battery separated by a battery isolator is a safeguard for the alternator and other sensitive electronics when charging the LFP service battery with the alternator. When the battery isolator is used to charge battery groups with the same alternator, you do not need to use VSR and APD already.

[CaptainRivet]

You don't need a DC2DC charger for LTO or LFP, a much cheaper converter with adjustable voltage is enough, my go to device here is the orion TR 1212-20 or 30 galvanically isolated (non smart) which 130 or 160Euro.
This is necessarily so you keep the nasty spikes and noises the bowtruster produces from the house and therefor senstive nav electronics.
Like this as you wrote correctly the cable can be much smaller.
But if you have the possibility to run a thicker cable i would just buy more capacity and add that to house and run it from the house. This way you have much more use of the invested money and more capacity to use.
No battery on the bow needed. Thats how i do it.

[SOLAR SUPPORT]

There is a difference of approximately $40-50 between the cost of 1 meter length of 100 mm2 - 6 mm2 cable pairs. For the bow thruster, the energy loss occurring on thick cables and connection terminals that transmit current around 400-500A increases as the cable length increases. The heat energy generated in cables and connection terminals is equal to the energy lost. Prolonged bow thruster operation will cause the power transmission cables to overheat. This is also an undesirable thing. When the cable cost and losses in energy transmission are calculated, placing the LFP/LTO battery that operates the bow thruster and/or windlass at the bow of the boat and charging support transmitted to the bow with a much thinner cable pair reduces the total cost and increases energy efficiency.

[CaptainRivet]

Originally Posted by SOLAR SUPPORT

There is a difference of approximately $40-50 between the cost of 1 meter length of 100 mm2 - 6 mm2 cable pairs. For the bow thruster, the energy loss occurring on thick cables and connection terminals that transmit current around 400-500A increases as the cable length increases. The heat energy generated in cables and connection terminals is equal to the energy lost. Prolonged bow thruster operation will cause the power transmission cables to overheat. This is also an undesirable thing. When the cable cost and losses in energy transmission are calculated, placing the LFP/LTO battery that operates the bow thruster and/or windlass at the bow of the boat and charging support transmitted to the bow with a much thinner cable pair reduces the total cost and increases energy efficiency.

True. But lets say you have 300AH LFP house now and LTO or AGM costs you in total 400Euro then i can buy another 4x304AH EVE for that and have double capacity house. That i can use every day.
The bowtruster i use maybe a week twice for total 2-3min and that losses are ok. Windlass over same cable is much less only 100A surges to 250A.
The cable can be a welding cable, thats enough so a 4/0 cable is not that expensive. House is often in middle of the boat with monos or cats so cable is shorter.
Additionally the cable adds the resistance that protects the bowtruster as a lot of them rely on the voltage drop of lead to not overload, thats the reason youbvoid warranty with Lithium on some of the newer ones.
I had it this way in my old ketch mono with a even 800A bowtruster, no space for that big of a battery bank in bow so the former owner ran a 4x150mm2 from pilothouse to bow and had 4x140AH AGM as house and bowtruster/windlass. Changed to one LTO 6P6S 240AH bank after 3 of the AGMs had a runaway, where only 3 years old and must had an internal short, were not dry and regulator ok.

[SOLAR SUPPORT]

Originally Posted by CaptainRivet

True. But lets say you have 300AH LFP house now and LTO or AGM costs you in total 400Euro then i can buy another 4x304AH EVE for that and have double capacity house. That i can use every day.
The bowtruster i use maybe a week twice for total 2-3min and that losses are ok. Windlass over same cable is much less only 100A surges to 250A.
The cable can be a welding cable, thats enough so a 4/0 cable is not that expensive. House is often in middle of the boat with monos or cats so cable is shorter.
Additionally the cable adds the resistance that protects the bowtruster as a lot of them rely on the voltage drop of lead to not overload, thats the reason youbvoid warranty with Lithium on some of the newer ones.
I had it this way in my old ketch mono with a even 800A bowtruster, no space for that big of a battery bank in bow so the former owner ran a 4x150mm2 from pilothouse to bow and had 4x140AH AGM as house and bowtruster/windlass. Changed to one LTO 6P6S 240AH bank after 3 of the AGMs had a runaway, where only 3 years old and must had an internal short, were not dry and regulator ok.

If you have thick cable(s) going to the bow, you should use them. When you use isolated 6s LTO as a bow thruster-windlass battery, you should use a stepup dcdc charger to use them at their full capacity, because the full charge voltage of 6s LTO is above 4s LFP.

If you had chosen a high CCA LFP supporting battery, it would be possible to connect it directly in parallel with the service LFP battery. I think you use 6p6s LTO bank as all purpose. You have thousands of CCA capacity that is more than you need.

[CaptainRivet]

Originally Posted by SOLAR SUPPORT

If you have thick cable(s) going to the bow, you should use them. When you use isolated 6s LTO as a bow thruster-windlass battery, you should use a stepup dcdc charger to use them at their full capacity, because the full charge voltage of 6s LTO is above 4s LFP.

If you had chosen a high CCA LFP supporting battery, it would be possible to connect it directly in parallel with the service LFP battery. I think you use 6p6s LTO bank as all purpose. You have thousands of CCA capacity that is more than you need.

the problem with 6s LTO in 12V as all purpose is you cannot go to all the way up to 6x2.9V=15,4V as the common limit on 12V devices are 15V.
but thats no issue in reality as between 15 and 15.4V is 5% capacity loss, insignificant and LTO (after 1st initial charge) doesn't care at which soc you keep or charge it. Also you can balance it at any SOC as curve is not flat like Lifepo4. the majority of capacity is beetween 2.1 and 2,5V.
Additional the boat was from 1983, partly rewired but 15V with voltage drop 14,4V everywhere.

yes i had more then enough current for all which was the goal but wouldn't be the case with Lifepo4 with the space and with that huge bowtruster the only way to go. Maybe winston cells in Lifepo4 as only alternative but costs were higher then LTO in 2017 when i done that. paid 34Euro per 40AH grade A Yinglong LTO...today a good source 60Euro+.

for 24V in 11S LTO then fits perfect.

[Pete7]

Originally Posted by wholybee

A pure LFP bank, or a separate AGM start bank and LFP house bank with both perform better than the hybrid.

In particular, for me the most significant improvements from LFP come from having virtually no Peukert factor, and the ability to charge at a high rate until they are fully charged. By paralleling with an AGM you lose both of those advantages.

That isn't what happens in practise. The LA is invariably at 100% or very close, for the majority of the time. When charging all the power goes straight to the LFP.

Originally Posted by wholybee

How do you even program an SOC meter to work properly?

Our SOC meter is now 15 years old and doesn't have any ability to change the Peukert factor. Instead what we do is fully charge the hybrid bank which takes the SOC meter to 100%, every few days, effectively resetting it. The Sterling battery monitor doesn't show a percentage only Ah being currently being used or charged and the running total. It's this running total that is reset back to zero with a full charge. Is this a problem? in practise no, as its a guide only for a quick check or glance as I walk past, just as the SOC state of a LFP from the Bluetooth app is.

Originally Posted by wholybee

How do you even program an SOC meter to work properly?So for me it isn't a question of "why not" but a question of "why?" You just aren't gaining the advantages you think you are.

As I said earlier, we disconnect the LFP when not on board so the solar doesn't continually charge it. This leaves the LA sitting on float (plus the engine start AGM) from solar to run the bilge pump if needed. If I pop down to the yacht to check it particularly during the winter, often I don't switch in the LFP. Instead just use the power in the LA for lights etc. The LFP is currently sitting at a temperature of 5'c and 70% SOC, which is fine.

Finally, should the LFP shutdown for any reason whilst we are at sea, the LA will supply sufficient power to keep systems like VHF, running for a while.

Is it worth doing? suits our needs very well. The only thing that is worth mentioning and I suspect the reason why ABYC and ISO don't approve a hybrid bank. To be specific lead acid supported by LFP, isn't approved because someone will try to fix an old LA bank with problems by adding LFP, rather than doing the job properly. Clearly adding any battery to an existing bank requires the existing bank to be in very good condition.

Pete