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Monitoring lithium batteries


Dr Bob

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Its not been a sunny day here, I have been rebuilding my Rayburn with a bigger backboiler so the central heating and battery warmer will work better! ? I have had the lights on the kettle on the power tools going and now at nearly 10 at night my batteries are showing 13.3 volts, which in my world means everything is ok. I did plug the puter into the batteries and looked at the BMS they were showing 80% ish will all cells balanced, its been over a month since I last looked so again all is ok in my world.

My BMS circuit board doesnt cut off for high voltage I do that with the midnite controller and if that fails a voltage operated solenoid.

The drive batteries are going to have a voltage operated solenoid to divert the solar to the immersion heater as I will have 179 volts coming in it should operate the 3 kilowatt immersion as a dump load, seems a shame to waste all that sunlight doesnt it?

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49 minutes ago, cuthound said:

I have no practical experience of any Lion batteries beyond iPod,  mobile phones and power tools.

Interestingly, phones and the like do no cell balancing which is why the batteries deteriorate relatively quickly. The public accept that because they’re now programmed to expect redundancy in consumer goods. I’m not sure if Li-ion batts in power tools are the same. 

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9 minutes ago, WotEver said:

Interestingly, phones and the like do no cell balancing which is why the batteries deteriorate relatively quickly. The public accept that because they’re now programmed to expect redundancy in consumer goods. I’m not sure if Li-ion batts in power tools are the same. 

I would be surprised if a phone actually contained more than one cell.

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4 minutes ago, Robbo said:

I would be surprised if a phone actually contained more than one cell.

The iPhone X certainly has two cells. I don’t know about others 

I believe the iPad has several although information is scarce. 

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1 minute ago, Mike the Boilerman said:

I’d have thought batteries in series would be likely to stay in balance indefinitely as the current through them is precisely the same. 

No. Each cell’s efficiency will be very fractionally different. The manufacturers try to match the cells but nothing’s perfect. A well matched set of cells is unlikely to require regular balancing. 

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3 hours ago, Robbo said:

Well I can do that with LFP’s as well?   You don’t have to design your own - these things are available off the shelf just like LA’s!

 

With decent LA’s I need to charge at a high voltage which probably too high for the starter battery.   I need to fully charge regularly to get the best out of them as well an equalise every month at a even higher voltage that may potentially damaging my electronics.   Once LFPs are wired up correctly you just use them. 

You just use them if you wish to pay thousands of pounds out were low hundreds of fla batteries do a great job. What happens when the boat off grid is minus ten degrees which has often happened over the years and you need to charge the lion batteries? As a long term liveaboard I have any bit of kit that improves life afloat but these batteries are simply not one of those cases.

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9 minutes ago, mrsmelly said:

 What happens when the boat off grid is minus ten degrees which has often happened over the years and you need to charge the lion batteries?

 

I think most people keep them in a heated area of the boat.

 

Not sure where it has gotten to -10c often? Is that what it's like "up north"? ?

 

Edited by eid
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4 minutes ago, eid said:

 

I think most people keep them in a heated area of the boat.

 

Not sure where it has gotten to -10c often? Is that what it's like "up north"?

Naah it's warm oop Norrff. Coldest winter I have had was on the Oxford. My batteries are in the back engine ole so another expense then to reposition them and find a way to keep them warm if boat is unattended for a while?

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10 minutes ago, eid said:

 

I think most people keep them in a heated area of the boat.

 

Not sure where it has gotten to -10c often? Is that what it's like "up north"? ?

 

 

Here in Wiltshire, last winter. On plenty of occasions.

(But not inside my boat, obviously :) )

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A couple of questions to see if I understand correctly:

 

1) I currently have 4 FLA batteries in my domestic bank. If I replace 3 of these with Relion Lithium batteries, leaving the fourth in place, will the BMS on the Relion's kick in at a certain voltage/charge, disabling further charge from the alternator/solar, leaving the remaining FLA to soak up the charge and thus saving my alternator from sudden death?

 

2) I've forgotten question 2 due to wine intake.

 

regards...

 

 

 

 

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6 minutes ago, eid said:

A couple of questions to see if I understand correctly:

 

1) I currently have 4 FLA batteries in my domestic bank. If I replace 3 of these with Relion Lithium batteries, leaving the fourth in place, will the BMS on the Relion's kick in at a certain voltage/charge, disabling further charge from the alternator/solar, leaving the remaining FLA to soak up the charge and thus saving my alternator from sudden death?

 

2) I've forgotten question 2 due to wine intake.

 

regards...

 

 

 

 

1) No

2) A duck is a far better bet than a chicken

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33 minutes ago, mrsmelly said:

Naah it's warm oop Norrff. Coldest winter I have had was on the Oxford. My batteries are in the back engine ole so another expense then to reposition them and find a way to keep them warm if boat is unattended for a while?

Mine are too, but I was thinking I could open an access door to let some warmth in now and then if needed. If the boat is unattended though, you wouldn't be charging the batteries?

 

 

29 minutes ago, Mike the Boilerman said:

 

Here in Wiltshire, last winter. On plenty of occasions.

(But not inside my boat, obviously :) )

I've been living in London where it hasn't frozen for more than a night or two for about 15 years, and then only just below zero C. I had assumed this was more widespread.

21 minutes ago, Dr Bob said:

1) No

2) A duck is a far better bet than a chicken

Could you elaborate?

(mostly on 1))

edit:

The reason I thought this was that I read of Jono connecting a FLA battery in parallel to save his alternator from this problem.

Edited by eid
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8 minutes ago, Dr Bob said:

1) No

2) A duck is a far better bet than a chicken

Could you elaborate on 2 too! A chicken is clearly more versatile than a duck. Feel free to start a new thread if you don't want to taint this one! 

5 minutes ago, eid said:

Mine are too, but I was thinking I could open an access door to let some warmth in now and then if needed. If the boat is unattended though, you wouldn't be charging the batteries?

 

 

I've been living in London where it hasn't frozen for more than a night or two for about 15 years, and then only just below zero C. I had assumed this was more widespread.

Could you elaborate?

(mostly on 1))

 

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1 hour ago, eid said:

A couple of questions to see if I understand correctly:

 

1) I currently have 4 FLA batteries in my domestic bank. If I replace 3 of these with Relion Lithium batteries, leaving the fourth in place, will the BMS on the Relion's kick in at a certain voltage/charge, disabling further charge from the alternator/solar, leaving the remaining FLA to soak up the charge and thus saving my alternator from sudden death?

 

2) I've forgotten question 2 due to wine intake.

 

 

Just remembered no.2:

 

2) Or, will I need something to switch the charge to my extra battery (what did Jono do?)

Edited by eid
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9 hours ago, mrsmelly said:

You just use them if you wish to pay thousands of pounds out were low hundreds of fla batteries do a great job. What happens when the boat off grid is minus ten degrees which has often happened over the years and you need to charge the lion batteries? As a long term liveaboard I have any bit of kit that improves life afloat but these batteries are simply not one of those cases.

But LFPs are cheaper long term than any LA’s that’s one of the major the points of getting them.   LA’s do a very poor job if your off grid. My boat has never been below 5 degees.  It’s cold!

Edited by Robbo
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9 hours ago, eid said:

I've been living in London where it hasn't frozen for more than a night or two for about 15 years, and then only just below zero C. I had assumed this was more widespread.

Ah, the well known phenomenon of London's weather being the weather for the whole country. I understand how this misconception comes about - in the same way that London's news is the news for the whole country

Edited by George and Dragon
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10 hours ago, WotEver said:

Interestingly, phones and the like do no cell balancing which is why the batteries deteriorate relatively quickly. The public accept that because they’re now programmed to expect redundancy in consumer goods. I’m not sure if Li-ion batts in power tools are the same. 

 

I was led to believe that is heat whilst charging that kills phone and laptop batteries early.

 

Some people leave them on charge for hours even when they are charged.

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10 hours ago, WotEver said:

No. Each cell’s efficiency will be very fractionally different. The manufacturers try to match the cells but nothing’s perfect. A well matched set of cells is unlikely to require regular balancing. 

 

Correct.

 

Ericsson were using transistors to shunt charged lead acid battery cells for quicker charging in the early 80's. 

 

Worked well and shortened charging times by an hour or two but the shunt components were mounted on top of the cells and vulnerable to damage ehen topping up.

9 hours ago, rusty69 said:

Yes. You have surely heard of a battery chicken? 

 

Have you heard of a battery duck? 

4357614219_52a29e09f2_z.jpg

 

Has the bunny been made redundant? ?

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1 minute ago, cuthound said:

 

Correct.

 

Ericsson were using transistors to shunt charged lead acid battery cells for quicker charging in the early 80's. 

 

Worked well and shortened charging times by an hour or two but the shunt components were mounted on top of the cells and vulnerable to damage ehen topping up.

 

Has the bunny been made redundant? ?

He's on holiday til Easter! 

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8 hours ago, eid said:

Just remembered no.2:

 

2) Or, will I need something to switch the charge to my extra battery (what did Jono do?)

2) Ducks have better memories so would have reminded you of the question sooner. The answer to 2) of course is 'yes' which explains why the answer to question 1 was 'no'.

Edited by Dr Bob
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