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StationMaster

Battery Charging 'Concept' advice

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OK after some views on a concept - please try to focus on the concept rather than give me loads of detailed advice - the detailed advice can come later if the concept appears to be worth considering.

 

Background - live aboard narrowboat, fairly standard modern set up, long term mooring without hookup. Mainly looking at winter charging as solar provides much in the summer.

 

Radio, TV, Laptop + various sundries are all charged via either running the engine (via a 3kw travelpower or 1.6 inverter) or a 2.2kw generator - both the TP and Gen will also charge the standard domestic batteries and run the washing machine all at the same time. This means I hardly ever have to turn the inverter on during day by day operation unless the engine is running.

 

This leads me to think that when the washing machine isn't running and the engine/generator is running, lots of power is being wasted. Was thinking maybe I could store this power in a Lifepo/lithium type of battery connected to the 240v and say connected via a switch to run the freezer or fridge which run on 12v. I don't want to convert the whole boats battery system and charging system until prices come down for people who would need others to take on that level of work.

 

Does any of the concept make any sense (not sure I've explained myself well) - would using a 'modern' battery to provide leccy to fridge/freezer reduce the load on the lead acid batteries and result in reduced engine or generator running time?

 

eta - the radio, tv and sundries all have there own internal batteries that last well above my use and don't need charging outwith domestic battery charging times.

Edited by StationMaster

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The simplest way to achieve what I think you’re after is to have a LifePo4 battery which would be charged quickly and that you then switch over to finish off the charge into the LAs. This can be done relatively cheaply but requires all of the usual protection guff that Lithiums need. 

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Thanks.

 

What I was actually considering was charging a specific 'battery bank' that would charge quickly from 240v and could be wired in to power a specific bit of equipment for most/all of the rest of the day when I wouldn't be charging via engine/generator thus reducing the daily load on the domestic bank. Something like this

https://www.amazon.co.uk/Goal-Zero-Yeti-Universal-Power/dp/B00EVV24LM/ref=lp_10256628031_1_10?s=industrial&ie=UTF8&qid=1578175040&sr=1-10

although that one wouldn't suit as takes too long to charge.

 

Probably a silly idea but always worth an ask.

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12 minutes ago, StationMaster said:

What I was actually considering was charging a specific 'battery bank' that would charge quickly from 240v

 

LA batteries NEVER "charge quickly" to full, their chemistry simply doesn't allow it. 

 

The specific type of battery bank that does, is, as Wotever said, lithium.  

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24 minutes ago, Mike the Boilerman said:

 

The specific type of battery bank that does, is, as Wotever said, lithium.  

It was also what the OP intimated in his query:

 

"Was thinking maybe I could store this power in a Lifepo/lithium type of battery connected to the 240v and say connected via a switch to run the freezer or fridge which run on 12v"

 

Possibly not dissimilar to what you do.... (not the same :) )

 

What he wants to do would definitely work in principle. He could buy one or two of these:

 

https://www.ebay.co.uk/itm/668-CYCLE-VALENCE-LiFePO4-12v-BATTERY-130Ah-1-6Kwh-U27-12XP-LITHIUM-SOLAR-T4/264559694701?hash=item3d98fc936d:g:DRIAAOSwPn1dvW4h

 

Pretty sure the seller has more than he has advertised as he bought a whole pallet and seems to be selling them a few at a time. I've got 4, but collect only meant a trip to Market Drayton.

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1 hour ago, StationMaster said:

Thanks.

 

What I was actually considering was charging a specific 'battery bank' that would charge quickly from 240v and could be wired in to power a specific bit of equipment for most/all of the rest of the day when I wouldn't be charging via engine/generator thus reducing the daily load on the domestic bank. 

The problem with this is that you’re never fully charging the domestic bank. So they’ll sulphate in no time and you’ll be replacing them every few months. Far better I’d have thought to use the lithium to finish the charge into the LAs. It also avoids rewiring everything. 

 

The principle is that you run the engine for a couple of hours. This gets the LAs to around 80% full and the Lithium up to whatever you set its maximum as - say 90%. You then charge the LAs from the lithium over the next 10 hours. That’s just the basic principle but the timings need to be studied and as I mentioned earlier you’d require all the safety kit to protect the lithium from low temp, low voltage, high voltage etc.  

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Your perfect Concept Battery system would be a Li-Ion battery bank from an electric car. These hold around 50kwh+ of power, enough to run a narrowboat for a week. This could be charged by a 50kw generator coupled to the engine in an hour. Just imagine only running the engine one hour once a week. Of couse most engines could only run a 10kw generator but this would still only need to be run for an hour or two every 3 or 4 days.  14hp is about 10kw.  Of course a proper generator would need to be coupled to the engine with a clutch system at a 1 to 1 ratio running at 1500 rpm.  Batteries from crashed electric cars are available for a couple of thousand and generators are cheap. Lets see who will be first to build it???

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29 minutes ago, rogeriko said:

Your perfect Concept Battery system would be a Li-Ion battery bank from an electric car. These hold around 50kwh+ of power, enough to run a narrowboat for a week. This could be charged by a 50kw generator coupled to the engine in an hour. Just imagine only running the engine one hour once a week. Of couse most engines could only run a 10kw generator but this would still only need to be run for an hour or two every 3 or 4 days.  14hp is about 10kw.  Of course a proper generator would need to be coupled to the engine with a clutch system at a 1 to 1 ratio running at 1500 rpm.  Batteries from crashed electric cars are available for a couple of thousand and generators are cheap. Lets see who will be first to build it???

Not that many 12V (or even 24V) electric cars around...

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Just now, Mike the Boilerman said:

 

And the cells tend to have spot-welded interconnects, so not easy to reconfigure to 12v. 

And none of the car’s battery maintenance electronics can be used, no BMS, no charge controller, no safety cutouts...

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Most electric car batteries are around 400v but they can be easily split and reconfigured to give you 48v say to run an inverter/charger. An electric car battery is just hundreds if not thousands of 4.2v li-ion cells.  BMS circuits are available, many people are doing this for their off grid houses.  Search Navitron Forum.

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Is your alternator set up for charging Li-on ?

A battery cell, is a battery cell, series, parrallel, you can increase amps, or volts, but you can never increase power. if the cells are movable, you can make it what you want.

If your alternator isnt setup for Li-on, then you will have a 'Thermal Incident'

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53 minutes ago, rogeriko said:

An electric car battery is just hundreds if not thousands of 4.2v li-ion cells.

Well I never...

38 minutes ago, rogeriko said:

Each battery module is 7.4v at 66ah.

So useless for 12V or 24V boats then. 

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9 hours ago, WotEver said:

The problem with this is that you’re never fully charging the domestic bank. So they’ll sulphate in no time and you’ll be replacing them every few months. Far better I’d have thought to use the lithium to finish the charge into the LAs. It also avoids rewiring everything. 

 

The principle is that you run the engine for a couple of hours. This gets the LAs to around 80% full and the Lithium up to whatever you set its maximum as - say 90%. You then charge the LAs from the lithium over the next 10 hours. That’s just the basic principle but the timings need to be studied and as I mentioned earlier you’d require all the safety kit to protect the lithium from low temp, low voltage, high voltage etc.  

This was the bit I wasn't sure about, I'm aware of needing to charge the domestic bank fully but was thinking that by reducing the amps taken out of the domestic bank I could reduce the charging time - this is probably correct but not enough (using my solution) to make it worthwhile.

 

I'll wait a few more years to see how battery technology improves before making any decision... putting in all the safety kit is beyond my level of expertise.

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23 minutes ago, StationMaster said:

This was the bit I wasn't sure about, I'm aware of needing to charge the domestic bank fully but was thinking that by reducing the amps taken out of the domestic bank I could reduce the charging time

You can recharge from (say) 85% to 90% in a fairly short time, it is the last 10% that takes many hours to achieve as you are only charging at a few amps (irrespective of how big your alternator is)

Discharging down to say 90%  will still take many hours to get back up to 99.9% which is why solar is so useful (in the Summer) run your engine for a couple of hours in the morning and get back up to a fairly high SoC and then let the solar give you a nice steady charge all day.

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1 hour ago, Alan de Enfield said:

Discharging down to say 90%  will still take many hours to get back up to 99.9% which is why solar is so useful (in the Summer) run your engine for a couple of hours in the morning and get back up to a fairly high SoC and then let the solar give you a nice steady charge all day.

And is why the lithium-topping-up-the-bank idea could work, but requires all the usual safeguards, leaving me very unsure as to whether it’s worth the bother of not going completely lithium. 

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3 minutes ago, WotEver said:

And is why the lithium-topping-up-the-bank idea could work, but requires all the usual safeguards, leaving me very unsure as to whether it’s worth the bother of not going completely lithium. 

I think you may be correct, if you (he) is going to the expense and complications of putting all of the infrastructure to charge one or two lithiums you may as well go the whole-hog.

 

However, I believe that the point I made is still relevant to the question he asked about reducing charging time on his FLA's, it will be the same time wherever the supply comes from (Engine, mains charger, solar or Lithium's)

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1 minute ago, Alan de Enfield said:

However, I believe that the point I made is still relevant to the question he asked about reducing charging time on his FLA's, it will be the same time wherever the supply comes from (Engine, mains charger, solar or Lithium's)

Yes, but with the caveat that Solar is useless in winter whereas the lithium solution works 365 days of the year. 

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2 minutes ago, Alan de Enfield said:

I think you may be correct, if you (he) is going to the expense and complications of putting all of the infrastructure to charge one or two lithiums you may as well go the whole-hog.

 

However, I believe that the point I made is still relevant to the question he asked about reducing charging time on his FLA's, it will be the same time wherever the supply comes from (Engine, mains charger, solar or Lithium's)

Your point was relevant. However if I reduced drain on the LAs to 5% per day then charge time would be reduced - IF I found a simple solution to running the fridge and freezer with built in protection that would charge quick enough and could be simply wired in by a 2 or 3 way switch then this would feasibly reduce chardging time significantly. However I don't think there is that solution available yet.

 

I didn't think there was a tv that would run for 10 hrs on a 2 hour charge until someone here mentioned it - perhaps in the future a fridge that runs for 24hrs on a 1 hour charge to it's own internal battery will be possible.

 

Incidentally a sunny winters day does make a difference to how well the batteries are charged so solar is not completely useless in the winter ?

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43 minutes ago, StationMaster said:

However if I reduced drain on the LAs to 5% per day then charge time would be reduced

I don't believe that the chemistry of FLA's will allow that.

 

If you 'use' 5% per day and recharge daily then you need to replace 6%.

If you use 5% per day and recharge every two days then you need to replace 12%.

 

The actual total charge time between recharging in one or two days will be negligible.

The benefits start to accrue when you discharge to (say) 50% as you can get from 50% to 90% quite quickly but then the last 10% takes many hours.

However if you plan on only using 5% per day, then it would take you 10 days to get down to 50%, and during that 10 days the batteries would be slowly sulphating due to being in a state of discharge.

 

Batteries are a real 'tricky' thing to manage well, and the best way is to treat them as consumables and replace them every couple of years.

You can get 100Ah batteries for around £60 so if you have (say) 4 of them (£240) and they last 2 years they are only costing about 33p per day. In fact , less than that, as you can get £10 each from the scrap man when you dispose of them, so 27p / day.

 

Edit to add a link to the 1st cheapish battery I came across. In a similar discussion last week I found some at under £60

 

https://www.ebay.co.uk/itm/12V-110AH-LEISURE-BATTERY-HEAVY-DUTY-LOW-HEIGHT-100-AH-AMP-110-AMP-DUAL-PURP/301581095653?epid=20033959993&hash=item4637a252e5:g:FBgAAOSw6e1dhi2U

 

or 130Ah at £68

 

https://www.ebay.co.uk/itm/12V-130AH-130-AH-Leisure-Battery-DEEP-CYCLE-for-Motorhome-Caravan-Campervan/112427659033?_trkparms=aid%3D1110002%26algo%3DSPLICE.SOI%26ao%3D1%26asc%3D20190711095549%26meid%3D7df669edf7454cfe8bc21072e1d0ad26%26pid%3D100047%26rk%3D4%26rkt%3D12%26mehot%3Dpp%26sd%3D301581095653%26itm%3D112427659033%26pmt%3D1%26noa%3D1%26pg%3D2047675&_trksid=p2047675.c100047.m2108

Edited by Alan de Enfield

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16 minutes ago, Alan de Enfield said:

I don't believe that the chemistry of FLA's will allow that.

 

 

I pretty much now agree with this plus the rest of your post. was worth (for me) asking the question though

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On 05/01/2020 at 01:37, WotEver said:

Well I never...

So useless for 12V or 24V boats then. 

LOL

Edited by Pompey

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On 05/01/2020 at 08:44, StationMaster said:

This was the bit I wasn't sure about, I'm aware of needing to charge the domestic bank fully but was thinking that by reducing the amps taken out of the domestic bank I could reduce the charging time - this is probably correct but not enough (using my solution) to make it worthwhile.

 

I'll wait a few more years to see how battery technology improves before making any decision... putting in all the safety kit is beyond my level of expertise.

You go full Li-On or nothing really.

 

A complete waste of money mixing the two systems. 

 

Absolutely nothing wrong with Li-On, preferential imo, they can discharge to 0%, for starters. Which is actually 10% of capacity.

 

Very good for people who dont move much. Your mobile works on Li-On battery technology, or Ni-Cad, depending on your age.

Ni-Cad - has power memory issues. Unless flattened and then fully recharged.

Li-On -Excellent, will provide full voltage until battery management kicks in which is why, you must ensure, battery charging is suited for Li-On.

Led-Acid - Made of Lead rather then Lithium, discharge to 80 %, sulphating occurs past 11.6v

 

There are a few different battery types:

Li-On-the best and most expensive

AGM - The next best thing

Sealed - Both the above fit in this section: no maintenance required.

Led-Acid, wet cells, maintenance required ! Which is where most people go wrong. They produce Hydrogen Gas when charging.

 

 

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