DIY lithium for novices!

[Neeves]

I think its the horror stories, most on the mainstream media, that scares, discourages, the many from looking at Lithium. A flat battery, the weight of lead, the acidic gasses etc etc are all 'mundane'. Lithium errors tend to be spectacular and catastrophic, or those that are reported are (catastrophic, spectacular) expensive.

Jonathan

 

[geem]

I think its the horror stories, most on the mainstream media, that scares, discourages, the many from looking at Lithium. A flat battery, the weight of lead, the acidic gasses etc etc are all 'mundane'. Lithium errors tend to be spectacular and catastrophic, or those that are reported are (catastrophic, spectacular) expensive.

Jonathan

All of the fires associated with lithium are a different lithium technology to lifepo4 used on boats. Phones uses different lithium tech. Electric cars have used different lithium tech but the entry level Tesla cars are now using lifepo4 for its safety aspect. They don't get the same range or performance but they also don't get fires.

 

[mattonthesea]

OK so I am now a complete LifePo4 convert. Three days at anchor, with fridge, in hot sun, and our remaining PV panel charging at 0.5A, and the batteries hardly noticed. A little bit of motoring and an hour or so on the shore power and we're back up to charged. The only of thing is that we've had to set the Sterling B2B to half power; it's supposed to be 30A but it was charging the batteries at 40 - or so the app said!

Thanks to all but particularly Geem and Poet, and the parishioner who introduced to The Off Grid Garage

M

 

[Neeves]

All of the fires associated with lithium are a different lithium technology to lifepo4 used on boats. Phones uses different lithium tech. Electric cars have used different lithium tech but the entry level Tesla cars are now using lifepo4 for its safety aspect. They don't get the same range or performance but they also don't get fires.

I knew that but the public image is that Lithium is Lithium and it is well know that Lithium catches fire. When there is a fire its a Lithium fire.

Lithium needs a new image.

I recall Geem mentioning on another thread that he had installed an acrylic cover on the top of his, Lithium, battery and I think he posted a picture. He has mentioned the same precautionary treatment again here. I wonder how many others have done the same (or something similar). Its not only the horror stories but the precautionary treatments (which imply danger).

I'm a convert, to LiFePo (which is why I'm taking my time and sucking up knowledge and experience, but many are going to take a lot of convincing. Emphasising, and re-emphasising, that there is Lithium, Lithium and then there is LiFePo - would be a good start.

I confess guilt - in threads here when I refer to LiFePo - I'm lazy and use the word 'Lithium'

Jonathan

 

[Kelpie]

It's standard practice to cover the cells in some way. You'd be crazy not to really.

 

[geem]

I knew that but the public image is that Lithium is Lithium and it is well know that Lithium catches fire. When there is a fire its a Lithium fire.

Lithium needs a new image.

I recall Geem mentioning on another thread that he had installed an acrylic cover on the top of his, Lithium, battery and I think he posted a picture. He has mentioned the same precautionary treatment again here. I wonder how many others have done the same (or something similar). Its not only the horror stories but the precautionary treatments (which imply danger).

I'm a convert, to LiFePo (which is why I'm taking my time and sucking up knowledge and experience, but many are going to take a lot of convincing. Emphasising, and re-emphasising, that there is Lithium, Lithium and then there is LiFePo - would be a good start.

I confess guilt - in threads here when I refer to LiFePo - I'm lazy and use the word 'Lithium'

Jonathan

Covering the cells to reduce the risk of short is belt and braces. In the same battery box is the class T fuse and BMS. I can safely replace a fuse or change a BMS with little risk of shorting a cell, due to a dropped spanner. The massive amps that lifepo4 can pull in a direct short is what I am protecting against. In addition to the perspex protector 30mm above the battery cells we have a 10mm perspex battery box lid. Belt and braces. I would rather be risk adverse than blasé

 

[Neeves]

Interesting.....

We have 2 x 200 amp/hr lead house batteries, a bit more than 50kg ...... each, and they sit together under part of the upholstery (these batteries are the subject of my Lithium, sorry LiFePo investigation and education). Next to them is the engine start battery. The 3 batteries can be easily accessed simply by lifting the upholstery base, the back of the same upholstery offers the rear of the navstatian and 2 of the fuse boards. The inverter, circuit breakers and battery management are under another part of the upholstery 'next door'.

I find I have no need to access the house and engine start battery - except when they need too be replaced. They are 'isolated' and there is no need to 'visit' them.

It maybe that a catamaran offers different solutions to location and storage of the 'electricity' but whereas I would follow Geem's addition of a cover for our 'future' LiFePo installation it would actually just keep the dust off the batteries -

or do LiFePo need more attention.......??

The batteries sit under the upholstery, port side (left of picture). The nav station is behind the 'back' and below the same section of upholstery. The battery management, large fuses, circuit breakers are under, or behind the centre section. Twin queens forward and galley in the starboard hull to the right. Whereas we might need to access the circuit breakers the batteries are stored and left in 'almost' splendid isolation. We might also need to access the fuses - but can do so without ever seeing the batteries.

Jonathan

 

[Trident]

A cover is useful but you can do the same with just the normal rubber caps on battery terminals - its just about ensuring that any metal tools you might drop don't short between the battery terminals and that should be standard with any type of battery. Ideally you want insulated tools for electrical work but most "users" don't. Even with lead acid a spanner dropped across the two terminals will make a big spark, melt the edge of the spanner and possible destroy the battery.

A rubber cap on each terminal or a cover over the terminals is essential - though personally I'd go with a cap on each terminal so that if you need to work on the battery you only need uncover the terminal you are using (say to add a new cable)

Also any exposed fuses or busbars should be covered the same way as they are just an extension of the battery terminal

 

[BashkoN]

A good understanding of electrics would be necessary otherwise get it done professionally. Some of the mistakes people have made dabbling in something they have no understanding of have lead to expensive and dangerous errors

oh I totally agree with that
my friend's mistakes cost him a "fortune")

 

[geem]

Interesting.....

We have 2 x 200 amp/hr lead house batteries, a bit more than 50kg ......

View attachment 158563

Our new lifepo4 560Ah battery (@12v) weighs 44kg.
You need no more access to it than lead. In my case less because my lead bank need topping up with water every month or two

 

[geem]

Our new lifepo4 560Ah battery (@12v) weighs 44kg.
You need no more access to it than lead. In my case less because my lead bank need topping up with water every month or two

Also, your 2 lead batteries give you about 200Ah useful capacity. My 560Ah lifepo4 battery gives about 450Ah useful capacity if we keep it between 10 and 90% charged.
You could build two 4 cell 280Ah 12v batteries with their own BMs each. This way you can run a 3kw inverter and an induction hob. You will likely almost double you solar output to the lifePO4 batteries and still be lighter than you are now

 

[Neeves]

Also, your 2 lead batteries give you about 200Ah useful capacity. My 560Ah lifepo4 battery gives about 450Ah useful capacity if we keep it between 10 and 90% charged.
You could build two 4 cell 280Ah 12v batteries with their own BMs each. This way you can run a 3kw inverter and an induction hob. You will likely almost double you solar output to the lifePO4 batteries and still be lighter than you are now

Its really a no brainer!



Jonathan

 

[Poey50]

or do LiFePo need more attention.......??

The batteries sit under the upholstery, port side (left of picture).

LFP thrives at the same temperature range that human beings prefer so having them right next to the main cabin is ideal. If you install them correctly you will never have to look at them again. And they will be the last batteries / cells you ever purchase.

 

[Neeves]

LFP thrives at the same temperature range that human beings prefer so having them right next to the main cabin is ideal. If you install them correctly you will never have to look at them again. And they will be the last batteries / cells you ever purchase.

That is comforting - I'd be careful of your final statement

Our cat is over 20 years old and we have managed our battery bank with extreme caution, never allowing the batteries to drop below 50% of full charge - amp managed by a Xantrec (I think that is the name) display (it works by adding amps used and added and is a bit inaccurate). I never look at the batteries themselves - they sit their quietly, uncomplaining. I do zero the display as it indicates when the batteries are full and zeroing is easy.

The current bank is about 8 years old now and I anticipate renewal in about 2 years (aiming for less) - so I have about 2 years to have a LFP ready to go.

A question

How do you determine the state of a LFP bank, or single LFP battery. With the current battery I can check voltage, which should be accurate (I have the Xantrec voltage amp display and a separate and independent meter for voltage.

Much is made of holding the bank at 60% of capacity (or that LFP will last longer if you aim for 60% capacity) but there is no mention of adding amps in and subtracting amps out - is voltage alone the measure for LFP. It may be that it is assumed amps in/out will be monitored as being obvious ..... Like Lead it seems that keeping LFP capacity within specific limits, much wider than lead, I distil 10%-90% for LFP, but I'm not clear how you know when you are at 60% - or critically getting near 10%.

Apologies if I appear a bit moronic - just dotting the i's and crossing the T's

Jonathan

 

[geem]

That is comforting - I'd be careful of your final statement

Our cat is over 20 years old and we have managed our battery bank with extreme caution, never allowing the batteries to drop below 50% of full charge - amp managed by a Xantrec (I think that is the name) display (it works by adding amps used and added and is a bit inaccurate). I never look at the batteries themselves - they sit their quietly, uncomplaining. I do zero the display as it indicates when the batteries are full and zeroing is easy.

The current bank is about 8 years old now and I anticipate renewal in about 2 years (aiming for less) - so I have about 2 years to have a LFP ready to go.

A question

How do you determine the state of a LFP bank, or single LFP battery. With the current battery I can check voltage, which should be accurate (I have the Xantrec voltage amp display and a separate and independent meter for voltage.

Much is made of holding the bank at 60% of capacity (or that LFP will last longer if you aim for 60% capacity) but there is no mention of adding amps in and subtracting amps out - is voltage alone the measure for LFP. It may be that it is assumed amps in/out will be monitored as being obvious ..... Like Lead it seems that keeping LFP capacity within specific limits, much wider than lead, I distil 10%-90% for LFP, but I'm not clear how you know when you are at 60% - or critically getting near 10%.

Apologies if I appear a bit moronic - just dotting the i's and crossing the T's

Jonathan

We use a Victron smart shunt. It will communicate via Bluetooth with a Victron smart solar MPPT solar reg. It provides super accurate voltage to the MPPT and to you as SOC

 

[Kelpie]

The BMS will give you a pretty accurate reading, assuming it has Bluetooth. Even better is a battery monitor.
You're right that using voltage to determine SOC isn't great, it's too flat. But it is useful for determining the very ends of the capacity curve, where it changes much more quickly.

 

[geem]

The BMS will give you a pretty accurate reading, assuming it has Bluetooth. Even better is a battery monitor.
You're right that using voltage to determine SOC isn't great, it's too flat. But it is useful for determining the very EVs of the capacity curve, where it changes much more quickly.

In my experience, voltage is useless at judging SOC at the upper end, as the voltage rises so quickly with lots of solar connected. You would have to be sat there watching it or you would miss where the SOC went from constant voltage to fully charged. It may be far slower with less solar panel capacity.

 

[ean_p]

There is some interesting reading around this subject on the various motorhome / RV sites as moving to LFP is a big issue there too......
Here's one particular thread that has some interesting thoughts on the 'drop in' ability or lack of of LFP batteries and how they can mesh with the existing infrastructure.....

Lithium batteries cannot just drop in and replace lead batteries can they?

 

[geem]

There is some interesting reading around this subject on the various motorhome / RV sites as moving to LFP is a big issue there too......
Here's one particular thread that has some interesting thoughts on the 'drop in' ability or lack of of LFP batteries and how they can mesh with the existing infrastructure.....

Lithium batteries cannot just drop in and replace lead batteries can they?

There are a lot of incorrect statements on that link

 

[ean_p]

I think that in many ways that that is the point of the thread........