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Old 22-10-2022, 22:21   #61
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Re: Low priced LiFePO4 Batteries vs High priced

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Originally Posted by mitiempo View Post
Yes, many of the cheaper drop-in's do use 10 AWG internally. 10 AWG 105C wire is rated for 60 amps ampacity. Many of these batteries BMS's allow only 50 amps continuous charge or draw which is within this rating, just. That means you end up with a battery that can be out performed by a quality AGM battery. Usually at a much higher price.

I would never install a cheap drop in battery on a boat. There are a few very good ones - Lithionics for one. Note though it is very expensive.

My thought is that these less expensive batteries will end up giving Lithium batteries a bad name over time.
How do you generate more than 50A on a 27ft yacht? without say an over sized alternator that can probably be dialled back.

Surely if you were planning to draw a heavy load like boiling a kettle then you would read the specifications to see what the limits are and if they are suitable to meet your requirements? Or do people just buy lithium because some bloke in the yacht club bar or Defender said you should

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Old 22-10-2022, 22:27   #62
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Re: Low priced LiFePO4 Batteries vs High priced

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Originally Posted by Pete7 View Post
How do you generate more than 50A on a 27ft yacht? without say an over sized alternator that can probably be dialed back.

Surely if you were planning to draw a heavy load like boiling a kettle then you would read the specifications to see what the limits are and if they are suitable to meet your requirements? Or do people just buy lithium because some bloke in the yacht club bar or Defender said you should

Pete
I am just describing the limits of low end drop-in batteries.

My system is 400 AH of Calb cells with a BMS that is not current limited in either direction. And my inverter is 1200 watts which at max will pull about 100 amps.
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Old 22-10-2022, 22:54   #63
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Re: Low priced LiFePO4 Batteries vs High priced

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I am just describing the limits of low end drop-in batteries.

My system is 400 AH of Calb cells with a BMS that is not current limited in either direction. And my inverter is 1200 watts which at max will pull about 100 amps.
We have a similar. 120Ah of drop in with 170Ah of FLA in parallel and 1600w of inverter power. There are only a couple of things that won't run. One is the air fryer and the other a vacuum cleaner, neither have been used much this year unless even when we had shore power available. Everything else is about 1Kw (75A) max, so well within the 150A BMS limits.

I did consider upgrading the inverter etc, but instead chosen a different route and stick with what we have. Seems a bit pointless spending a lot of money to run something occasionally. A new battery powered vacuum cleaner would be more convenient to use and the air fryer? we have plenty of alternatives so won't starve.

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Old 22-10-2022, 23:27   #64
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Re: Low priced LiFePO4 Batteries vs High priced

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Originally Posted by Pete7 View Post
How do you generate more than 50A on a 27ft yacht? without say an over sized alternator that can probably be dialled back.

Surely if you were planning to draw a heavy load like boiling a kettle then you would read the specifications to see what the limits are and if they are suitable to meet your requirements? Or do people just buy lithium because some bloke in the yacht club bar or Defender said you should

Pete
I can draw well over 50 amps easily via my 2512 inverter not that I do very often but I can easily .

I did my lfp as there was basically a blank slate when I got my defender.. was actually cheaper for me than similar usable capacity of t105s.
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Old 23-10-2022, 00:45   #65
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Re: Low priced LiFePO4 Batteries vs High priced

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I did my lfp as there was basically a blank slate when I got my defender.. was actually cheaper for me than similar usable capacity of t105s.
My case is similar. 400 AH of new, matched Calb cells and a very good BMS came to $1060. Same usable capacity as 6 Trojan T-105.

The solution is to buy right.
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Old 23-10-2022, 01:00   #66
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Re: Low priced LiFePO4 Batteries vs High priced

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Interesting. Having just renewed my insurance with Pantaenius, there is absolutely no mention in any of the policy documents of lithium, LiFeP04 or even batteries.



What does your policy say, and were about in the policy?



Pete


Correct no mention in mine but there is a stipulation that if you mod the boat you tell them
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Old 23-10-2022, 01:23   #67
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Re: Low priced LiFePO4 Batteries vs High priced

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Correct no mention in mine but there is a stipulation that if you mod the boat you tell them
Long bow to draw there champ

Changing batteries is a consumable
Antifouling is a consumable
Hell, even a paint job is a consumable

Moding the boat is cutting your cat in half and adding 5 ft in the guts.
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Old 23-10-2022, 02:08   #68
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Re: Low priced LiFePO4 Batteries vs High priced

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Long bow to draw there champ

Changing batteries is a consumable
Also has this statement. Does LifePO4 increase the risk? Think we know the answer to that one.

You are required to notify us as soon as reasonably possible of any modification to the Sailing Yacht which increases the risk or any significant change in the information provided prior to the commencement of this insurance.
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Old 23-10-2022, 02:33   #69
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Re: Low priced LiFePO4 Batteries vs High priced

Insurance companies always cover themselves and try to put their "clients" (cash cow?) at fault.
I had another case recently when I had a car accident. Following a pile-up, a car hit the back of my vehicle. Very little damage to me, being "protected" by my hitch ball which was distorted in the impact. No apparent problem to get me repaired, not being at fault.
Except that the insurance company told me that since the trailer hitch was an accessory, it could not be taken into account in the repair...
I had to fight for 500€ of repair.

Personally, an LFP battery is much safer than an AGM or LA battery that can spray hydrochloric acid and release hydrogen, the only thing that is not safe is the BMS. Here, I get stuck on this electronics especially when I hear about "low cost".
But to think that you're going to turn your boat into a bomb because you replace the LA battery pack with LFPs, no, honestly. Maybe sound out the insurance company first?
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Old 23-10-2022, 02:33   #70
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Low priced LiFePO4 Batteries vs High priced

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Originally Posted by Simi 60 View Post
Long bow to draw there champ



Changing batteries is a consumable

Antifouling is a consumable

Hell, even a paint job is a consumable



Moding the boat is cutting your cat in half and adding 5 ft in the guts.


Misleading your insurance is a exercise in self delusion. Better inform them and deal with the consequences.
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Old 23-10-2022, 06:00   #71
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Re: Low priced LiFePO4 Batteries vs High priced

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Originally Posted by T1 Terry View Post
With 11 yrsexperience in a lot more than a single system, let me assure you that setting the end of charge at 13.6v will result in a progressive loss of capacity and the BMV wandering further and further out of range compared to reality. If you doubt this, charge the battery to the 13.6v 100% SOC, then adjust the BMS to 3.6v per cell and measure just how many Ah go into the battery and see if that matches 10% of the over all capacity .....

T1 Terry
You are correct, 3.4V/cell termination voltage during charging would undercharge the battery. But what if this is taken as an absorption voltage for let’s say 2-4 hours?

I’m not sure how they charge to that voltage, but I do know that you can fully charge (or 99.5% or so) at 3.4V/cell when it is held in absorption long enough.

The wish to use a CC/CV charge regime as described by cell manufacturers looks great on paper but it is designed for EV applications, where you charge the car and then it sits until driven. This is not how boats work, they use power continuously and when the battery is full we want to keep using solar power, not switch that off and use battery power instead. We only want to use battery power when the sun comes down and we lose solar power for the night.

The only way to achieve that is by configuring a float voltage that isn’t so low that power from solar is wasted. During years of living aboard with LFP and solar, I have found that 3.3V/cell is the ideal float voltage. It does discharge the battery to 92% but most of the solar power is used.

Our charge settings:

Absorption voltage: 3.45V/cell
Absorption current: I can reach 0.5C, have 1,875W solar for a 10.5kWh battery.
Absorption time: fixed 2 hours

Float voltage: 3.3V/cell

When the absorption charge finishes and the controllers switch to float, you see all power coming from the battery instead of solar. This is good because it’s better for the LFP to not be kept at full charge. When they are down to 97% SOC, solar delivers most of the power again and at low 90’s SOC solar takes 100% of power consumption.

The BMV is configured to trigger “fully charged” a couple mV below absorption voltage as described in the manual. It works perfect.

So here are the results: maximum cell deviation after battery was installed was 4mV. After two years of cycling with settings as described above, with no cell balancing of any kind, maximum cell deviation was 8mV. I packed my cell balancer because I don’t think it’s useful to do this for 4mV.

I must add that this battery is an 8s configuration with perfectly matched cells.
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Old 23-10-2022, 12:15   #72
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Re: Low priced LiFePO4 Batteries vs High priced

Quote:
Originally Posted by Pete7 View Post
Also has this statement. Does LifePO4 increase the risk? Think we know the answer to that one.
Actual testing has shown no risk with lifepo4
Other lithium ion chemistry is different
Quote:
You are required to notify us as soon as reasonably possible of any modification to the Sailing Yacht which increases the risk or any significant change in the information provided prior to the commencement of this insurance.
Replacing batteries, applying antifoul, painting, changing anchor type , putting on starlink are not what I would call modifying a boat.

Cutting a catamaran in half and adding 5 ft is a modification
Cutting the cabin and fishing gear off of a commercial trawler and making it into a cruiser is a modification.
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Old 23-10-2022, 12:20   #73
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Re: Low priced LiFePO4 Batteries vs High priced

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Misleading your insurance is a exercise in self delusion. Better inform them and deal with the consequences.

Misleading them how?
Batteries die and batteries get replaced
They were LA, then Gell, then AGM - do you tell them at every change?

I changed some shackles last week
And replaced a bulb.
Several months ago a replaced the anchor chain
And a water pump
Should I tell them about the "modification"?

Add: oh ****, I have Starlink now, I'd better spam them some more
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Old 23-10-2022, 20:41   #74
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Re: Low priced LiFePO4 Batteries vs High priced

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Originally Posted by s/v Jedi View Post
You are correct, 3.4V/cell termination voltage during charging would undercharge the battery. But what if this is taken as an absorption voltage for let’s say 2-4 hours?

I’m not sure how they charge to that voltage, but I do know that you can fully charge (or 99.5% or so) at 3.4V/cell when it is held in absorption long enough.

The wish to use a CC/CV charge regime as described by cell manufacturers looks great on paper but it is designed for EV applications, where you charge the car and then it sits until driven. This is not how boats work, they use power continuously and when the battery is full we want to keep using solar power, not switch that off and use battery power instead. We only want to use battery power when the sun comes down and we lose solar power for the night.

The only way to achieve that is by configuring a float voltage that isn’t so low that power from solar is wasted. During years of living aboard with LFP and solar, I have found that 3.3V/cell is the ideal float voltage. It does discharge the battery to 92% but most of the solar power is used.

Our charge settings:

Absorption voltage: 3.45V/cell
Absorption current: I can reach 0.5C, have 1,875W solar for a 10.5kWh battery.
Absorption time: fixed 2 hours

Float voltage: 3.3V/cell

When the absorption charge finishes and the controllers switch to float, you see all power coming from the battery instead of solar. This is good because it’s better for the LFP to not be kept at full charge. When they are down to 97% SOC, solar delivers most of the power again and at low 90’s SOC solar takes 100% of power consumption.

The BMV is configured to trigger “fully charged” a couple mV below absorption voltage as described in the manual. It works perfect.

So here are the results: maximum cell deviation after battery was installed was 4mV. After two years of cycling with settings as described above, with no cell balancing of any kind, maximum cell deviation was 8mV. I packed my cell balancer because I don’t think it’s useful to do this for 4mV.

I must add that this battery is an 8s configuration with perfectly matched cells.
If you use smart solar charging controller/s, they have a built in "rebulk" setting when/if the battery drops below this point.
By charging to 3.5v per cell and then dropping back to 3.45v per cell with zero absorption time allows the cells to balance and slowly top up the capacity using that 0.05v over fully charged rested voltage to finish off what the "bulk" voltage charge didn't achieve.
The rebulk function allows for systems that have less solar input than the peak current demand, so the battery acts as part of the supply until the load reduces, then the battery goes back into the recharging mode and balancing mode.

If you are not bringing the cells above 3.45v, you are fooling yourself that the cells are top capacity balanced, any voltage below 3.45v will be the same across the cells until they drop below 3v and are 0% SOC, then you will also see just how far out of balance they are.
This is called bottom balancing, useful for electric vehicle because they use all the capacity they can get out of the cells and want them to all run out of capacity at the same time.
Bottom balancing is not the best option for house battery use, too easy to end up with an over voltage cell, instead, top balancing and not allowing a cell to go over 3.6v, stopping charging at this point and allow the load and balancers to bring the high cell down, a time delay once the cell is below 3.6v before charging resumes, and it won't take long for the pack to top balance.

Using this method, it is very quick to see when a cell group is in trouble and an investigation can begin .... generally a loose link or dirt contact between the cell and the links is the cause. A properly set up 8 cell 24v battery or 16 cell 48v battery will remain in balance between service intervals, 3 yrs to 4 yrsis the general service interval and the battery generally dictates when this needs to be done, the cell group start to wander apart where they didn't over the last 3 yrs or so .... clean all the terminals, clear the memory voltage stop points and load test the battery to determine the capacity and see if any cell group needs further attention .... then the system will look after itself for the next 3 yrs, then repeat ..... We all have better thinks to do than baby sit our battery pack

T1 Terry
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Old 24-10-2022, 01:28   #75
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Re: Low priced LiFePO4 Batteries vs High priced

Quote:
Originally Posted by T1 Terry View Post
With 11 yrsexperience in a lot more than a single system, let me assure you that setting the end of charge at 13.6v will result in a progressive loss of capacity and the BMV wandering further and further out of range compared to reality. If you doubt this, charge the battery to the 13.6v 100% SOC, then adjust the BMS to 3.6v per cell and measure just how many Ah go into the battery and see if that matches 10% of the over all capacity .....

T1 Terry
When I get a chance I will do that.


The reason it is set to that is the the company that sells the BMV state to exactly that in the manual and also by email when I talked to them.


Why would they state that if its a major issue as you say?


Here is a Link to them:



https://123electric.eu/products/123smartbms-gen3/
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