Batteries - Lead acid or Lithium?

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SailingDoc

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Not that I'm in the market for either, but baffled by conflicting views/facts in the latest PBO (October 2017).
The article on 'Going Electric' states that lead acid batteries can, 'if needed to get you home' go right down to zero capacity, and may even recover a little. Whereas lithium batteries 'cannot be taken down to zero capacity' and the battery management system will lock them out at 10% - not what you want when manoevering in a tight space or keen to get back before closing time.
On the next page 'Charging ahead!' reckons that lead-acid batteries, while cheaper than lithium, 'can't be discharged as far', while lithium batteries 'can be totally discharged without damage', and no mention of the dastardly battery management system that could make you miss that longed-for pint, or the lock-opening time!

Any experiences here, or enlightened views?
 
SailingDoc said:
Not that I'm in the market for either, but baffled by conflicting views/facts in the latest PBO (October 2017).
The article on 'Going Electric' states that lead acid batteries can, 'if needed to get you home' go right down to zero capacity, and may even recover a little. Whereas lithium batteries 'cannot be taken down to zero capacity' and the battery management system will lock them out at 10% - not what you want when manoevering in a tight space or keen to get back before closing time.
On the next page 'Charging ahead!' reckons that lead-acid batteries, while cheaper than lithium, 'can't be discharged as far', while lithium batteries 'can be totally discharged without damage', and no mention of the dastardly battery management system that could make you miss that longed-for pint, or the lock-opening time!

Any experiences here, or enlightened views?
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Firstly, don't believe anything you read in PBO, it has a history of getting things wrong.

Secondly, lithium ion batteries are expensive and require a very carefully-controlled charge regime. For the vast majority of leisure boaters, lead-acid batteries are still the best choice.
 
I haven't read the article but aren't they different ways of saying the same thing?

Lithium batteries deliver 90% of their charge and are then switched off by the management system - but can then be recharged and the the same again without being damaged. Lead acid can keep delivering power until deeply discharged but doing so damages them and regularly discharging by anything like 90% will cause deterioration over time.
 
The problem with that article is that it tried to cover far too much and was therefore very short on real facts. The reality is that there is very little experience of using lithium batteries in boats for the obvious reasons, mainly cost for little perceived benefit.
 
SailingDoc said:
the dastardly battery management system that could make you miss that longed-for pint, or the lock-opening time!
Click to expand...

A dedicated drinker would surely just switch on the donk?

bedouin said:
I haven't read the article but aren't they different ways of saying the same thing?

Lead acid can keep delivering power until deeply discharged but doing so damages them and regularly discharging by anything like 90% will cause deterioration over time.
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My understanding is that using lead-acids at all "damages" them in the sense that it erodes some of their liftetime capacity. The notion that routinely running lead-acids down to, say, 20% is particularly damaging should also be qualified. It's certainly true of typical automotive and "leisure" batteries, but not batteries specifically designed for deep cycling. The latter includes many large industrial batteries, but also some batteries commonly used on boats. Trojan, for instance, claim their T105s will release quite similar lifetime Ah, whether cycled to 80% or 20%, producing graphs to that effect.

(Haven't seen the article mentioned, but presume it's referring to LiFePO rather than any of the other Lithium technologies?)
 
Differences are not only how you can discharge them, but even more on how you can charge them. LiFePo4 batteries will swallow everything your charger can produce, while a Lead-acid battery will need 3-4 times longer to charge the same usable amps.
But a large(!) bank of LiFePo4 may very well also burn your generator, since they will have much less resistance, and the generator may or may not be solid enough for this piece of work...
 
SailingDoc said:
Not that I'm in the market for either, but baffled by conflicting views/facts in the latest PBO (October 2017).
The article on 'Going Electric' states that lead acid batteries can, 'if needed to get you home' go right down to zero capacity, and may even recover a little. Whereas lithium batteries 'cannot be taken down to zero capacity' and the battery management system will lock them out at 10% - not what you want when manoevering in a tight space or keen to get back before closing time.
On the next page 'Charging ahead!' reckons that lead-acid batteries, while cheaper than lithium, 'can't be discharged as far', while lithium batteries 'can be totally discharged without damage', and no mention of the dastardly battery management system that could make you miss that longed-for pint, or the lock-opening time!

Any experiences here, or enlightened views?
Click to expand...

What they don't tell you is that lithium will only last 500 recharges if you totally discharge them and then recharge to 100%.

My son tells me , from his own personal experience , that modern chargers will only allow you to go from 30%-70% charge which will give approx 10,000 recharge cycles. So lithium total capacity is only 40% of their quoted capacity; very similar to lead acid bulk charge from 50%-80%, but of course lithium is many times more expensive.
 
Thanks for all the comments, so far. As per the articles (we're talking of pure electric propulsion here, not hybrids), generally we're assuming that recharging is done back at the pontoon and will have plenty of time to take place, until your next visit to the boat anyway. A different story, of course, if you're relying on a generator, or maybe panels , out on a mooring.
 
I think we are a long way from pure electric being appropriate for cruising sailors. As a technology to put an engine in a boat that will primarily be daysailed from the marina it is great but I am too used to being able to fire up the diesel to get me home in a reasonable time to go for an engine that doesn't have the range to run for at least 12 hours.

I like the idea of hybrid with enough battery for a day sail but with diesel in the background but that is essentially installing 2 engines to expensive and heavy
 
rustybarge said:
What they don't tell you is that lithium will only last 500 recharges if you totally discharge them and then recharge to 100%.

My son tells me , from his own personal experience , that modern chargers will only allow you to go from 30%-70% charge which will give approx 10,000 recharge cycles. So lithium total capacity is only 40% of their quoted capacity; very similar to lead acid bulk charge from 50%-80%, but of course lithium is many times more expensive.
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Please, what do you mean by "lithium" batteries? It's little more specific than "Heinz".
 
macd said:
I fear that contributes little to the issue. There are many distinct types of lithium battery, each with their own distinct characteristics. The type generally used for main battery installations in small craft is LiFePO.
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Which specific lithium batteries work well with 0-100% recharge cycles with no degradation of capacity ?
 
rustybarge said:
Which specific lithium batteries work well with 0-100% recharge cycles with no degradation of capacity ?
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None that I know of, but that is not the point. You referred to characteristics of a specific but unknown type of lithium battery. To have added usefully to the debate we'd need to know what type that was.

Incidentally, if the figures you mentioned do indeed apply to LiFePo batteries, they suggest a lifespan of something like ten times that of even a very durable lead-acid battery. So even if the useful cycle range is as limited as you suggest, that would be a strong argument for them on lifetime cost grounds.

All the information I have read about LiFePo batteries suggests they do indeed suffer faster degradation with deep discharging, but their useful life is still far in excess of any lead-acid battery likely to be fitted to a small craft.
 
SailingDoc said:
Thanks for all the comments, so far. As per the articles (we're talking of pure electric propulsion here, not hybrids), generally we're assuming that recharging is done back at the pontoon and will have plenty of time to take place, until your next visit to the boat anyway. A different story, of course, if you're relying on a generator, or maybe panels , out on a mooring.
Click to expand...

The main point to be made about the conflicting information is that the first one promoting gel batteries was by Emrhys Barrell of Electric Boat, who most definitely knows what he is talking about and gives solid reasoning for his recommendation. The author of the second is not named and looks like the result of an Internet search for information.
 
Tranona said:
The problem with that article is that it tried to cover far too much and was therefore very short on real facts. The reality is that there is very little experience of using lithium batteries in boats for the obvious reasons, mainly cost for little perceived benefit.
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Nigel Calder has done some serious work with them. His project didnt work out apparently but here are some of his thoughts on the subject http://jnj.design/wp-content/uploads/2017/01/Hybrid164-Final.pdf
Stu
 
We recently looked at buying a Lithium battery for a motorbike.
Price is high, even if you are prepared to accept much lower Ah. For most bikes, CCA is usually all you want, but I'd be wary of not being able to start after a reasonable time of being stopped with the lights on.
Weight is a huge saving, but a displacement yacht is the most obvious application where this really does nor figure.
In the end we decided to stick with what we know for now.
But the way things are going, Lithium will keep getting cheaper. Next time maybe?
One thing that put me off was the vague documentation regarding the effects of charging from typical bike alternator which does not have great regulation.

I think there are few yachtsmen who have a genuine case for using Lithium batteries at the moment.
For propulsion, unless you just want to get your racer from the marina to the start line, IMHO it's a nonsense.
For sure there are a significant handful who are making a big thing of it and flogging magazine articles or hoovering up grant/research money, and a few who have made notable passages with battery power etc.
But plenty of people have done equally well with no engines.

For domestic, it's expensive and people will need to up their game in terms of charging control etc. Putting kilowatts into a lithium battery is not a trivial issue. AIUI, we'd need better charge control than even top-end stuff currently in use for lead-acid.

It is early days yet, as electric cars and stored solar power etc become more mainstream, the technology will improve and get cheaper.
 
Lithium batteries are great if carefully managed, but currently cost about 10x as much per Ah, and therefore about 5x as much per usable Ah, as lead acid. When they come down to 4x/2x, I think they'll be well worthwhile.
 
JumbleDuck said:
Lithium batteries are great if carefully managed, but currently cost about 10x as much per Ah, and therefore about 5x as much per usable Ah, as lead acid. When they come down to 4x/2x, I think they'll be well worthwhile.
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Just to chuck in a thought, repeating myself, but my batteries lasted nearly nine years with a rapid decline only in the last part of this year. Bog std Numax leisure. Always been topped up with solar and a smart Sterling mains charger and a Sterling alternator booster. I did something right! Why pay more?
Stu
 
JumbleDuck said:
Lithium batteries are great if carefully managed, but currently cost about 10x as much per Ah, and therefore about 5x as much per usable Ah, as lead acid. When they come down to 4x/2x, I think they'll be well worthwhile.
Click to expand...

A good summary.
But in CCA they are already down to about a 2x price multiplier.
 
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