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An affordable way to fit Lithium Batteries?


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Interesting and thoughtful post, Dr Bobble.

 

I was broadly intending to do much the same and connect my 200AH 24v Li bank in parallel with my four knackered Trojanoids, then I rather lost interest as the Whispergen performs so well keeping them charged as it does it quietly, and the heat it delivers at the same time is broadly needed the most when the solar works the least, so peak whispergen use in winter and not much in summer works really well. 

 

The thing that prevents me from connecting up the Li bank is needing to put the effort in to designing exactly how to stop it over and under charging. From what you say I don't need to worry at all about undercharging as I can just keep an eye on the volt meter. Stopping the Li bank overcharging strikes me as almost as simple given I'm happy to keep a weather eye on the volt meter. All I really need is a whopping great Li bank master switch next to the voltmeter if I understand you correctly, and the terminal voltage barely rises during charging, so can be relied upon to indicate SoC even during charge. 

 

The bits I still need to think about are what charging profile to set on the solar Tracer and on the Whispergen. 

 

Given it's not easy for me to turn the solar off when I'm not there, I think I still need some sort of over-voltage automatic cutoff. Or maybe the solar can be programmed not to go over 13.7v...

 

 

 

 

 

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1 hour ago, Mike the Boilerman said:

Interesting and thoughtful post, Dr Bobble.

 

I was broadly intending to do much the same and connect my 200AH 24v Li bank in parallel with my four knackered Trojanoids, then I rather lost interest as the Whispergen performs so well keeping them charged as it does it quietly, and the heat it delivers at the same time is broadly needed the most when the solar works the least, so peak whispergen use in winter and not much in summer works really well. 

 

The thing that prevents me from connecting up the Li bank is needing to put the effort in to designing exactly how to stop it over and under charging. From what you say I don't need to worry at all about undercharging as I can just keep an eye on the volt meter. Stopping the Li bank overcharging strikes me as almost as simple given I'm happy to keep a weather eye on the volt meter. All I really need is a whopping great Li bank master switch next to the voltmeter if I understand you correctly, and the terminal voltage barely rises during charging, so can be relied upon to indicate SoC even during charge. 

 

The bits I still need to think about are what charging profile to set on the solar Tracer and on the Whispergen. 

 

Given it's not easy for me to turn the solar off when I'm not there, I think I still need some sort of over-voltage automatic cutoff. Or maybe the solar can be programmed not to go over 13.7v...

 

 

 

 

 

Mine is mike and it works well, I have a cheap MPPT controller on my electric truck and that turns off the solar as well when fully charged.

John V has his LifePo4s in parallel with his LAs and that has been on the go for the same amount of time as mine, and its working very well,so go for it!

Today solar wise its been a scorcher here so my immersion heater has got the water that hot its turned on the central heating!! so I have lashings of hot water and hot towels as well, I think I will alter the stat on the central heating though.................

Forgot to say whispergen is easy go into settings and alter them to 27.6 abs and 27.2 float will work fine like mine

Edited by peterboat
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1 hour ago, Mike the Boilerman said:

Interesting and thoughtful post, Dr Bobble.

 

I was broadly intending to do much the same and connect my 200AH 24v Li bank in parallel with my four knackered Trojanoids, then I rather lost interest as the Whispergen performs so well keeping them charged as it does it quietly, and the heat it delivers at the same time is broadly needed the most when the solar works the least, so peak whispergen use in winter and not much in summer works really well. 

 

The thing that prevents me from connecting up the Li bank is needing to put the effort in to designing exactly how to stop it over and under charging. From what you say I don't need to worry at all about undercharging as I can just keep an eye on the volt meter. Stopping the Li bank overcharging strikes me as almost as simple given I'm happy to keep a weather eye on the volt meter. All I really need is a whopping great Li bank master switch next to the voltmeter if I understand you correctly, and the terminal voltage barely rises during charging, so can be relied upon to indicate SoC even during charge. 

 

The bits I still need to think about are what charging profile to set on the solar Tracer and on the Whispergen. 

 

Given it's not easy for me to turn the solar off when I'm not there, I think I still need some sort of over-voltage automatic cutoff. Or maybe the solar can be programmed not to go over 13.7v...

 

 

 

 

 

In summary yes. Once you start charging at 50A, with an at rest voltage around 13.0V (60% full), the Li's will immediately rise to 13.4V ish. As the charge goes up, the voltage rises so you can disconnect the bank at 13.5V (say 70%) at 13.7 (say 85%) or at 13.9% (95%). Watching voltage is all you need. No need for a smartgauge. It is totally different to Lead acids where you get to the constant voltage state of 14.2+V. Voltage rises as SoC increases.

I am not sure yet about solar and if your solar was putting in 20A, would that take you up to and over 100%? For me its easy. I just estimate how much is likely to go in and disconnect if you are away for the day and think too much would go in.  My solar MPPTs can be set for a max of 13.7V bulk and 13.2v float. I dont let my Li's go above 80% SoC with the alternator so lots of room for solar to go in.

I would use an over voltage cut out and the BEP switch coupled with the BMV works great......but there are cheaper solutions to keep the cost down.

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3 hours ago, Dr Bob said:

 

Is it possible to get all the benefits from Li's for £500? ….........It may be!!!

I am not going to go into all the benefits of Li's here. Suffice to say that during Oct/Feb when the sun is on strike and the solar isnt doing its job, you could reduce your engine running to 1 to 2 hours a day and save 6-10 hours engine running a week.....much less noise.....much less diesel....much less faffing. They should last 10 years. They are really easy to look after and even in the summer I am so much more relaxed about power now. I am sure that will generate a big debate. Bottom line is the benefits are significant and much less faffing.

.

 

But only need to run my engine for 1 to 2 hours per day anyway.

 

I think there is another option: Get a decent set of lead/acid domestic batteries and set your boat up for low power consumption when away from shore power. LED lights throughout, gas fridge, small flat screen TV that draws 1 - 2 amps, 12v car stereo that draws an amp, etc.

 

I don't use my laptop when I'm away and just go online on the phone. It's all about reducing electrical power consumption, but I really don't feel that I'm deprived in any way.

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3 minutes ago, blackrose said:

 

But only need to run my engine for 1 to 2 hours per day anyway.

 

I think there is another option: Get a decent set of lead/acid domestic batteries and set your boat up for low power consumption when away from shore power. LED lights throughout, gas fridge, small flat screen TV that draws 1 - 2 amps, 12v car stereo that draws an amp, etc.

 

I don't use my laptop when I'm away and just go online on the phone. It's all about reducing electrical power consumption, but I really don't feel that I'm deprived in any way.

Doesnt work for me I have a washer, dishwasher all mod cons, I didnt take up boating to camp out I want to live an easy life and let technology do the hard work. Solar is cheap and reliable, so are LifePo4s combine the two and things a re great in my world

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I agree with Blackrose that a good set of LA's with low power usage is a good solution....if you want to live with low power.

2 hours ago, peterboat said:

Doesnt work for me I have a washer, dishwasher all mod cons, I didnt take up boating to camp out I want to live an easy life and let technology do the hard work. Solar is cheap and reliable, so are LifePo4s combine the two and things a re great in my world

I'm with Peter on this. Why give up all your mod cons when you move to live on a boat? We havent. We have most stuff we had at home except for a dishwasher. Ok, the washing machine only works on cold water (unless you bung some hot in before you close the door) but otherwise we are pretty much all 240v.

A lot of peeps on here seem to think that you must go 12V (and gas fridges etc) to conserve power and eek out that scarce commodity. We use 100-140 Ahr per day and  thanks to LiFePo4s we can put it back in quite easily and not worry about replacing LA's every 2-3 years.

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4 minutes ago, Dr Bob said:

So a day without a response. Other than Blackrose who argues to use lower power, can anyone see any flaws in my thinking on the affordable route to lithium's?

 

Well yes, the solar.

 

On of the things the American bod says is lithiums don't like being left on float indefinitely. Whatever the float voltage, they carry on charging up to 100% and over, then eventually wreck themselves if left to their own devices. ISTR him writing that of all the wrecked seta of Li he encounters, its usually leaving them on flat that did the damage. LA batt owners simply cannot let go of the idea of having them on float.

 

When I leave the boat I often have no idea if I'll be back in 12 hours or 14 days, so I need to automate the solar properly as I leave the fridge on. Needs some more thinking about.  

 

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4 hours ago, Mike the Boilerman said:

 

Well yes, the solar.

 

On of the things the American bod says is lithiums don't like being left on float indefinitely. Whatever the float voltage, they carry on charging up to 100% and over, then eventually wreck themselves if left to their own devices. ISTR him writing that of all the wrecked seta of Li he encounters, its usually leaving them on flat that did the damage. LA batt owners simply cannot let go of the idea of having them on float.

 

With my 480Ahrs of lithium capacity, it isnt a problem as I am usually less than 70% SoC so still 120Ahr short of full therefore my 500W of solar will never get me to 100% and the MPPT should reduce to 13.2V after an hour of reaching the 13.7V bulk charge limit on the MPPT. If you only have 160Ahr of lithium then there is more opportunity to be up nearer full but in that case then set your disconnect at 13.5V. I am finding the solar is taking my voltage up to 13.5V at around 70-75% SoC if there is 20-25A going in. My disconnect has not disconnected in the 3 months as the voltage has always been below my trip level.

 

4 hours ago, Mike the Boilerman said:

When I leave the boat I often have no idea if I'll be back in 12 hours or 14 days, so I need to automate the solar properly as I leave the fridge on. Needs some more thinking about.  

 

We left ours for a week last week while it was being blacked and left the fridge on....but we just manually disconnected the Li's. The solar was happy keeping the LA's working and topped up. I monitored the voltage/amps remotely so checked each day how they were doing ...and no problem. When I got back, I just reconnected the Li's. The Li's are useful when you are on the boat, using lots of power and needing to recharge back up again. Just disconnect when away ....or when on shore power.

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On 21/05/2019 at 17:39, Mike the Boilerman said:

 

Way more than you need to.

 

With a small but decent solar setup you will not need to run your engine for nine months of the year.Your neighbours would be delighted!

 

Yes I still haven't fitted solar. One day I'll get around to it. 

On 21/05/2019 at 17:40, peterboat said:

Doesnt work for me I have a washer, dishwasher all mod cons, I didnt take up boating to camp out I want to live an easy life and let technology do the hard work. 

 

Me too. I have a washer, dryer, etc. I haven't given up anything. I don't like dishwashers and wouldn't even have one in a house. I run the washing machine straight from the generator. 

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On 21/05/2019 at 20:25, Dr Bob said:

I agree with Blackrose that a good set of LA's with low power usage is a good solution....if you want to live with low power.

I'm with Peter on this. Why give up all your mod cons when you move to live on a boat? We havent. 

Neither have I.

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  • 1 month later...
On 21/05/2019 at 14:21, Dr Bob said:

Option 4. Keep all your LA's ...say a 440/550/660 Ahr bank and just put one Lithium battery on top. Hence you buy a 2nd hand 160Ahr LifePo4 (cost around £330) and bolt it on top of your LA's.

Very interesting concept! I am soon planning on installing a proper bank and strongly considering Lithiums. Would you need 440Ah+ to make this "bottom tank" or could I get some of the benefits of the hybrid system by simply keeping my single 110Ah LA (and single starter battery) as somewhere for the power to be dumped?

 

I'd also taken it for granted that I'd get rid of the LA (especially as it has been hammered quite hard in its 9 months life). But if it could be beneficial to keep...?

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On 22/05/2019 at 21:35, Dr Bob said:

With my 480Ahrs of lithium capacity, it isnt a problem as I am usually less than 70% SoC so still 120Ahr short of full therefore my 500W of solar will never get me to 100% and the MPPT should reduce to 13.2V after an hour of reaching the 13.7V bulk charge limit on the MPPT.

What model of batteries do you use? The cheapest I could find on Bimble Solar are 706 GBP + VAT for 500Ah? Is there a big difference between brands of LiFePO4?

 

https://www.bimblesolar.com/batteries/lithium-batteries?sort=p.price&order=ASC&limit=100

Edited by ivan&alice
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7 hours ago, ivan&alice said:

What model of batteries do you use? The cheapest I could find on Bimble Solar are 706 GBP + VAT for 500Ah? Is there a big difference between brands of LiFePO4?

 

https://www.bimblesolar.com/batteries/lithium-batteries?sort=p.price&order=ASC&limit=100

But have you spotted that you would need 4 of them as they are only 3.2v? It also seems to say that you have to order a minimum of 8 of them. 

Edited by MHS
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9 hours ago, ivan&alice said:

Very interesting concept! I am soon planning on installing a proper bank and strongly considering Lithiums. Would you need 440Ah+ to make this "bottom tank" or could I get some of the benefits of the hybrid system by simply keeping my single 110Ah LA (and single starter battery) as somewhere for the power to be dumped?

 

I'd also taken it for granted that I'd get rid of the LA (especially as it has been hammered quite hard in its 9 months life). But if it could be beneficial to keep...?

My system uses a single 110Ah LA as both starter battery and load-dump.

 

MP.

 

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On 21/05/2019 at 14:21, Dr Bob said:
9 hours ago, ivan&alice said:

Very interesting concept! I am soon planning on installing a proper bank and strongly considering Lithiums. Would you need 440Ah+ to make this "bottom tank" or could I get some of the benefits of the hybrid system by simply keeping my single 110Ah LA (and single starter battery) as somewhere for the power to be dumped?

 

I'd also taken it for granted that I'd get rid of the LA (especially as it has been hammered quite hard in its 9 months life). But if it could be beneficial to keep...?

 Option 1 is to go to Victron and get them to put in their commercial system. £6K. Ouch! No way. Never going to pay back. Too much to go wrong. Option 2 is a DIY system like T&B or Moominpapa put in. They chose a hybrid system retaining the start lead acid battery so when the batteries are full, the charging sources have something to 'dump' into. Very important that!

Option 3 is sort of similar to that, which is what I did, but my hybrid system retained the whole 660Ahr of lead acid and just added the 480Ahr of LiFePo4 in parallel. My system is described in

https://www.canalworld.net/forums/index.php?/topic/99667-another-lithium-battery-thread/page/9/

…....its all good info with Peter, T&B and Moominpapa all putting in their designs. Look at post 212 on page 9 for what I ended up with.

 

 

I & A,

The single 110Ahr LA is option 2.

That is what MP and T&B use. Yes it is fine and works well with the single LA acting as a dump for the alternator etc.

The problem here is that then your main battery capacity is Lithiums which cost money.

 

9 hours ago, ivan&alice said:

What model of batteries do you use? The cheapest I could find on Bimble Solar are 706 GBP + VAT for 500Ah? Is there a big difference between brands of LiFePO4?

 

https://www.bimblesolar.com/batteries/lithium-batteries?sort=p.price&order=ASC&limit=100

If you buy new, you are talking almost £2K for a 160Ahr 12 V battery. I think you can find them down to £1200 if you look.

All the Li users on here seem to have bought 2nd hand ones....ie used on EV's. Look in the previous thread  as in the link above for the source. T&B, MP and I, all got ours from Jeremy for around £330 per 160Ahr @12V.

As MHS says, your prices must be based on a 500Ahr 3.2V Battery.

 

The whole point of this thread was to alert peeps to the fact that you could buy one 2nd hand 160Ahr 12V for £300 ish and get the major benefit of a full Li system, ie no low tail current charging.

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On 22/05/2019 at 16:50, Dr Bob said:

So a day without a response. Other than Blackrose who argues to use lower power, can anyone see any flaws in my thinking on the affordable route to lithium's?

How do you ensure your LAs are properly charged and hence don’t get sulphated? Obviously I “get” the benefits of Li, but by keeping a large bank of LAs you seem to be retaining their undesirable features. In the scenario you described in OP you have used most of the Li and a fair bit of the LA. Of course the Li are easy to charge quickly. But you are still left with having to charge for hours in order to fully charge the LAs. Either that or they will sulphate from being left for long periods only partially charged. The way you describe it as a “top tank” doesn’t seem quite right. On discharge the Lis discharge first, then towards the end of the Li delivery the LAs start to contribute. But on recharge the Lis recharge quickly and hence first, the LAs lag way behind in becoming fully charged. So it is not a reversible system. (I am looking for a word that describes a system that runs in a mirrored way when it runs backwards, to the way it runs when going forwards. Does “palindromic system” exist as a descriptive phrase?)

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2 minutes ago, nicknorman said:

How do you ensure your LAs are properly charged and hence don’t get sulphated? 

 

I’m inclined to say it doesn’t matter. (I’m not convinced received wisdom properly describes sulphation behaviour anyway. Batteries in my experience seem to degrade in noticeable steps. Fine for a while then suddenly not.). 

 

The Li batts in practice rarely discharge to  the point the LA start contributing so they get used far less anyway, they still get recharged slowly and continuously when they do contribute and so what if they Do get sulphated? They will still perform their fuction as an alternator load dump.

 

 

 

 

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3 hours ago, MHS said:

But have you spotted that you would need 4 of them as they are only 3.2v? It also seems to say that you have to order a minimum of 8 of them

Ah, I did not spot this! They do also do a 3.2V 100Ah version at 150 GBP. So I guess you could buy the minimum 8 and connect half in parallel to give you 200Ah at 12V for 1200 GBP.

 

54 minutes ago, MoominPapa said:

My system uses a single 110Ah LA as both starter battery and load-dump.

 

27 minutes ago, Dr Bob said:

The single 110Ahr LA is option 2.

That is what MP and T&B use. Yes it is fine and works well with the single LA acting as a dump for the alternator etc. 

The problem here is that then your main battery capacity is Lithiums which cost money. 

We have two LA batteries though - 1x starter and 1x domestic - so I presume the "load dump" circuit would still keep the split charge relay and dump the load into the batteries alternately?

 

I'm OK with spending money for a decent system. This thread just piqued my interest as I imagined Li to be a lot more expensive. 

 

29 minutes ago, Dr Bob said:

If you buy new, you are talking almost £2K for a 160Ahr 12 V battery. I think you can find them down to £1200 if you look.

All the Li users on here seem to have bought 2nd hand ones....ie used on EV's. Look in the previous thread  as in the link above for the source. T&B, MP and I, all got ours from Jeremy for around £330 per 160Ahr @12V. 

Great, I'll have a look into that. Is there any complication with using EV batteries, do you need any special battery management system or do the units come with a BMS?

 

9 minutes ago, nicknorman said:

How do you ensure your LAs are properly charged and hence don’t get sulphated? Obviously I “get” the benefits of Li, but by keeping a large bank of LAs you seem to be retaining their undesirable features. In the scenario you described in OP you have used most of the Li and a fair bit of the LA. Of course the Li are easy to charge quickly. But you are still left with having to charge for hours in order to fully charge the LAs. Either that or they will sulphate from being left for long periods only partially charged. The way you describe it as a “top tank” doesn’t seem quite right. On discharge the Lis discharge first, then towards the end of the Li delivery the LAs start to contribute. But on recharge the Lis recharge quickly and hence first, the LAs lag way behind in becoming fully charged. So it is not a reversible system. (I am looking for a word that describes a system that runs in a mirrored way when it runs backwards, to the way it runs when going forwards. Does “palindromic system” exist as a descriptive phrase?)

This sounds like a very fair objection to the hybrid system... interested to hear @Dr Bob's thoughts.

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4 minutes ago, Mike the Boilerman said:

so what if they Do get sulphated? They will still perform their fuction as an alternator load dump

How essential is it to have a load dump? Are pure Li systems deficient in this regard - why can't they simply have systems that cut the charge from the alternator at the right point?

 

Or is it about squeezing efficiency by increasing your capacity, but still keeping your LAs for that bit of extra capacity to store excess alternator juice? Because if so, sulphation would matter, wouldn't it?

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1 hour ago, nicknorman said:

But you are still left with having to charge for hours in order to fully charge the LAs. Either that or they will sulphate from being left for long periods only partially charged.

I understand the idea to be that the LAs get the tail current from the full LFP battery, so you fast charge the lithium and bulk charge the LAs for an hour or 2.

 

When you stop the engine, the lithium discharges into the lead acid bank for the next few hours, taking them up to fully charged.

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3 hours ago, ivan&alice said:

How essential is it to have a load dump? Are pure Li systems deficient in this regard - why can't they simply have systems that cut the charge from the alternator at the right point?

 

Or is it about squeezing efficiency by increasing your capacity, but still keeping your LAs for that bit of extra capacity to store excess alternator juice? Because if so, sulphation would matter, wouldn't it?

 

It is essential for long Li battery life that you don't overcharge them (or discharge them to far).

 

To prevent the alternator from over charging Li batteries you disconnect the Li battery from it. Suddenly dropping the load from the alternator will destroy it.

 

To prevent this from happening you put a lead acid battery in parallel with the Li battery, so that when the Li battery is switched off the alternator still has some load to feed.

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On an all singing and dancing properly integrated system, when the lithiums are full, the battery management system shuts down the alternator by switching off the field current, thus safely turning the alternator off and there is no need for an LA dump battery, but for this you need an alternator with external field control and wiring.

 

Most pragmatic lithium installs just isolate the lithium batteries from the alternator instantaneously risking a voltage spike, the LA dump battery avoids this.

Edited by PeterF
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