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The end of lead acid batteries


Dave_P

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Charging from an alternator shouldn't present much of a problem, providing that the battery itself has control of the voltage and current they put out, which is normal anyway with LiPo batteries. Manufacturers can easily produce a 'Sterling-style' alternator add-on which would add suitability for LiPo charging.

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Boaters totally abuse everything electrical......we fiddle with connections...overload things...draw too much power....invent ways of doing things....wait until our dogy alternator has gone to heaven.....and drop spanners across terminals....

 

I can see a lithium type battery lasting 10 minutes...

 

A boat...is not a smart phone... biggrin.png

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A fellow boater who is a flight engineer commented that the risk of a LiPo battery setting fire to your boat is very low.

 

Lithium burns so hot, it would just go straight down through the baseplate and into the water...

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There were incidents with the Dreamliner (B 787 ) where they got the charging wrong rather expensively. Probably just swapping a lead acid and a Li battery is rather fraught til the charging and discharging is controlled properly. AND when you have discharged them Li batteries DIE. the usual boat issue is that the batteries were never properly charged then they were emptied again so that will kill Li cells. You'd still need 1000ah because that's how much people try to take from any battery.

 

Now if you could get the cells from a Prius (or similar) so that three cells of huge capacity, and fitted with the correct controller per cell then there may be some benefit

 

BUT expect to need a new alternator and charger with completely new programmes built in.

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There were incidents with the Dreamliner (B 787 ) where they got the charging wrong rather expensively. Probably just swapping a lead acid and a Li battery is rather fraught til the charging and discharging is controlled properly. AND when you have discharged them Li batteries DIE. the usual boat issue is that the batteries were never properly charged then they were emptied again so that will kill Li cells. You'd still need 1000ah because that's how much people try to take from any battery.

 

Now if you could get the cells from a Prius (or similar) so that three cells of huge capacity, and fitted with the correct controller per cell then there may be some benefit

 

BUT expect to need a new alternator and charger with completely new programmes built in.

Nope, the charging and discharge cutoff is all handled by the electronics within the battery.

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It's getting there, but. Better to compare the Wh cost rather than the Ah since they're differing voltages - its still 2.4x (usually 4x) the lead-acid cost.

 

Agreed, although if you can use all not half, it is indeed getting closer. Assuming other factors like life/cycles are similar.

 

 

Daniel

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Nope, the charging and discharge cutoff is all handled by the electronics within the battery.

 

 

So how do you charge them then? Just connect them up to any old conventional 12v battery charger and the battery electronics sucks what it wants/needs?

 

(Dave P is being very coy about what he uses to charge his 5v Li Ion. Why would that be?)

 

Edit to add, having checked his link to what he purchased I see it comes with a mains charger that does all the managing. it can't just be connected to his engine alternator!

Edited by Mike the Boilerman
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So how do you charge them then? Just connect them up to any old conventional 12v battery charger and the battery electronics sucks what it wants/needs?

 

(Dave P is being very coy about what he uses to charge his 5v Li Ion. Why would that be?)

 

Edit to add, having checked his link to what he purchased I see it comes with a mains charger that does all the managing. it can't just be connected to his engine alternator!

No but then for a start it is a 5v battery not a 12v one. I doubt the mains charger does the managing, it will be the battery's internal electronics. Have a look at the links to the Victron and Mastervolt products I posted.

 

Screenshot of the spec, you can see that the charging voltage is your average 13.75 - 14.6. It has an overcharge and over discharge shut off relay along with charge control, cell balancing etc all built in.

post-9028-0-82844800-1458812493_thumb.png

Edited by nicknorman
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Seen ones like this on Ebay, might help with MtBs battery problems:

 

http://www.ebay.co.uk/itm/like/111523898631

http://www.ultramaxbatteries.com/Product-Ultramax-LiFePO4-Battery-12V-100Ah_2943.aspx

 

Probably cheaper than the Mastervolt ones. Only 20A charge/discharge, but 1800 cycle life.

Edited by smileypete
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I’ve looking into the logistics of retrofitting lithium batteries and they are viable.

 

The ones to go for are the LIFEPO4 variant as they are non-reactive and almost as safe as lead acid.

 

Major advantages of lithium for us are greatly reduced charging times as it’s basically a flat charge curve with next to no Peukert effect so if you take 50AH out you can put back 50AH in an hour with a 50A charger with hardly any current taper.

 

They can also handle massive sustained current so you could even run fan heaters, electric cookers, microwaves, washing machines etc. [assuming you have a good inverter] without damaging them. You could even use them in a multi-function setup to crank start you engine no problem.

 

Another big advantage is energy density needing less physical space to mount them. Weight saving is a non-issue for narrowboats so this advantage is a non-issue.

 

One major thing to consider is you cannot charge them in sub-zero temperatures so they need them to be inside the boat and the stove needs to have warmed the boat up to keep them warm before any charging takes place. They don’t gas so are safe like AGM.

 

The batteries also don’t like being fully charged or discharged below 20%. They are best stored in a state of partial charge from 20-80% but are safe to leave in that state and don’t discharge.

They also don’t like being held at float voltage as they will overcharge so you need a way of cutting the voltage and that can be complicated with solar setups.

 

They are also difficult to measure the state of charge as they basically hold their voltage at 12.8V until they suddenly drop and if you are not quick you can over-discharge.

 

Some good reading can be found here with relation to boats.

http://www.pbase.com/mainecruising/lifepo4_on_boats

 

And here’s a good place to buy LIFEPO4 packs

http://www.ev-power.eu/Winston-40Ah-200Ah/

Edited by CaneyJ
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I’ve looking into the logistics of retrofitting lithium batteries and they are viable.

 

The ones to go for are the LIFEPO4 variant as they are non-reactive and almost as safe as lead acid.

 

Major advantages of lithium for us are greatly reduced charging times as it’s basically a flat charge curve with next to no Peukert effect so if you take 50AH out you can put back 50AH in an hour with a 50A charger with hardly any current taper.

 

They can also handle massive sustained current so you could even run fan heaters, electric cookers, microwaves, washing machines etc. [assuming you have a good inverter] without damaging them. You could even use them in a multi-function setup to crank start you engine no problem.

 

Another big advantage is energy density needing less physical space to mount them. Weight saving is a non-issue for narrowboats so this advantage is a non-issue.

 

One major thing to consider is you cannot charge them in sub-zero temperatures so they need them to be inside the boat and the stove needs to have warmed the boat up to keep them warm before any charging takes place. They don’t gas so are safe like AGM.

 

The batteries also don’t like being fully charged or discharged below 20%. They are best stored in a state of partial charge from 20-80% but are safe to leave in that state and don’t discharge.

They also don’t like being held at float voltage as they will overcharge so you need a way of cutting the voltage and that can be complicated with solar setups.

 

They are also difficult to measure the state of charge as they basically hold their voltage at 12.8V until they suddenly drop and if you are not quick you can over-discharge.

 

Some good reading can be found here with relation to boats.

http://www.pbase.com/mainecruising/lifepo4_on_boats

 

And here’s a good place to buy LIFEPO4 packs

http://www.ev-power.eu/Winston-40Ah-200Ah/

 

 

Interesting, thanks.

 

The article you link to starts off well but for me, de-generated into being nigh on impossible to read due to all the ranting and waffling padding out the technical commentary. The article could be halved (or more) in length if he just stuck to the subject in hand, I gave up reading it.

 

As usual with any battery type, buying the battery is easy, designing the charging system is the hard bit. To save me the pain of reading his article all the way through, have you actually installed a LIFEPO4 battery system in your boat?

 

How do you monitor SoC of your LIFEPO4 batteries?

 

And how do you charge them, ensuring they remain permanently inside that critical 20%-80% SoC range?

 

The viability of LIFEPO4 batteries depends on the answers to these difficulties in my opinion.

 

Thanks...

Edited by Mike the Boilerman
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For SoC you need a AH counting function. The Mastervolt battery I linked to has this built in, it send the SoC data (amongst other things) out on Masterbus and you can display it on a Masterview or the like. It also has the charge control and low voltage cutoff - in two stages, one being a Masterbus event telling stuff like a generator that the battery is nearly flat or generating an alarm, and a final cutoff being a relay that opens before the battery reaches a damagingly low SoC.

 

So for me it would just be a case of dropping the battery in and wiring it up as usual. There is nothing fancy to do apart from finding the £2k!

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I wanted to design a small LIFEPO4 system that is as basic and cost-effective as possible. Whilst it’s still theoretical, it should work and I will try to break it down based from what I’ve taken from the articles wafflings.

 

To start with; my boat is small and for leisure use only. I’ve calculated I just need a 90AH ‘Balanced’ Dumb LIFEPO4 pack [about £490]. This is about equivalent to a 135-150AH lead-acid battery [when used very conservatively in its 15%<->90% power band] and can power constant 1KW sustained loads such as a Microwave and small hair dryer.

 

The pre-built packs I’ve linked to before are ‘pre-balanced’. In theory; if you don’t over-charge or discharge a LIFEPO4 pack you don’t need a BMS [internal control electronics] which makes the system a lot easier to manage.

BMS PCB’s can fail and the ones I’ve looked at cannot handle high charge and discharge currents beyond 90-Amps constant.

 

The first part of my planned setup is a standard arrangement of having the alternator connected to a starter battery with a VSR connecting the starter battery’s positive to the service batteries.

My system simply uses 2x voltage monitors which each control a high-amp ‘normally-open’ 12V relay.

One controls the incoming charge current from the VSR and cuts it when the voltage monitor reads a pack voltage of over 14.1V and requires a manual reset.

The other relay goes on the master load output cable and cuts the load output when the pack goes below 12.6V and re-enables load when pack voltage recovers through charging to 12.8V+.

 

Keep a pack within that voltage range [12.6V-14.1V] and you should be gravy. Bare-in-mind there is no voltage sag with LIFEP04 so straight-up voltage monitoring is easier. An Amp-Hour counter is also good due to the flat charge curves allow you can simply add more-or-less what you took out.

 

A fully charged LIFEPO4 pack tops out at 14.4V but if one of the 12V packs 4 cells is out of balance a long way [+0.3V] and hits 14.7V, that cell will eventually die. Keeping the pack at 14.1V [which is still at a 90-95% complete charge] keeps all unbalanced cells below that critical 14.4V mark.

 

In the same way, taking cells below 12.2V is even worse and will kill them within an hour if left that way. Cutting a load draw when at 12.6V is around 10-15% of a packs final capacity and allows for lower balanced cells to not drop too low.

 

A BMS allows a pack to have a wider range being able to go down to 5% capacity [12.2V] to 100% [14.4V with a charge set to 14.6V]

 

If float voltage can’t be avoided; it should be at 13.2V and for no more than 2-3 hours.

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In theory; if you don’t over-charge or discharge a LIFEPO4 pack you don’t need a BMS [internal control electronics] which makes the system a lot easier to manage.

 

Sounds like a bit of an assumption to me!

 

This site seems to indicate the opposite:

 

http://www.wheelchairdriver.com/BMS.htm

 

Why use lithium instead of lead acid?

 

ETA: Just a thought: for people who just want some TV in the evenings and LED lights, how about buying a 360Wh 36V scooter batt and charger, run the TV etc via a converter and charge the batt at work or whatever.

Edited by smileypete
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Lithium Polymer 12V starter battery equivalent, are now available in whatever MAH you might desire, so apart from the difference in price between these & glass mat lead acid batteries, the balancing problem has been overcome I believe.

 

As to why bother there is the small matter that unlike lead acid batteries you can use nearly all the capacity of lithium polymer battteries, deep cycle lead acid batteries, won't wear being regulary dicharged, below 1/2 capacity without serious life degredation. And there is the obvious weight factor to be taken into consideration . Lithium polymer batteries are featherweight in comparison to lead acid batteries. We just have to wait for price parity & below & everyone is a winner...

Edited by charlie - uk
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I think the voltage profile thing is an important point. LiFePo4 batteries keep a pretty steady voltage until nearly flat. By comparison a lead acid battery varies from perhaps 12.8v down to 10.5v. Taking my Trojans for example, they will happily run the inverter on a high demand (electric kettle) when well charged. They can be used down to 20% SoC without major life impact, however once getting below say 50% SoC they start to struggle to deliver high currents at a reasonable voltage.

 

The inverter is a constant power device (for a given load) and so as the voltage from the batteries reduces the current taken has to increase and you get a bit of a vicious circle where a reducing voltage causes an increasing current which causes a reducing voltage. At some point well before the miminim SoC the inverter gives up due to under-voltage.

 

By comparison a LiFePo4 with its flat voltage profile will be able to service big loads right down to nearly flat. It is worth bearing in mind that an AH rating is pretty meaningless in terms of useful energy, since the voltage is also a factor in determining power and energy. So a 100AH 12v battery will be able to deliver much less energy than a 100AH LiFePo4 battery since the former only briefly has a voltage of 12.8v, and towards the end is well below 12v, whilst the latter can deliver 12.8v over most of its discharge profile.

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The theory is GOOD Lipoly batteries will supply lots of power and take reasonably deep discharge. The practise however may not be so easy, Most of the many chargers around for lead acid use have a float charge phase which will kill Li cells, Li cells do absolutely require the proper charge control and discharge end point determination.

 

I'm really not sure how the current automotive alternator and regulator will cope with the special needs of Li cells. If the alternator spins for 8 hours but the battery only needs charging for 4 hours will the battery turn off, will the alternator turn off or will the battery's clever electronics adjust the alternator's clever electronics? How will an engine alternator and a Li battery cope when running an inverter to power say a washing machine? The fluctuating load and he charge going into and out of the battery... ... will any alternator and controller keep a Li battery charged enough without exceeding the battery ratings and going to meltdown. -It happened to a Dreamliner (B 787 ) so I really don't see why it cannot happen to a narrow boat.

 

Also NO battery system will survive the users who don't actually charge their batteries - but Li batteries WITH individual cells monitored will close down in a sate that permits recharging ( but as they reach this state the electricity will just go OFF on he boat).

 

The industry has spent years and millions on making the automotive alternator fit for purpose with the lead acid battery til a car battery lasts 5 - 10 years, Lots of that fine tuning will need to happen to make engine powered generation suitable for long term boat use with Li cells

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Power tools live in a charge OR discharge lifstyle, so you can use the correct charger, then discharge them separately. Boat batteries live in a float type environment where a load may get fed from battery and/or generator in any proportion -and Li Batts really don't like float situations.

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The current automotive alternator and regulator won't cope with the special needs of LiPo cells, an additional unit is needed to take the output of the alternator & regulate it for the specific nneeds of the LIPO charging cycle. Gone are the days that the battery can be plugged straight into the alternator output. It's not a problem, just that additional kit will be required for a new LIPO install.

Edited by charlie - uk
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