An Affordable Lithium Boat Battery

[geem]

You're almost making me homesick
I was in the same position as you, I couldn't afford to put in Trojan 105 batteries, it would have cost me £790 delivered to address. My cells and BMS were £407. It's a big saving, for batteries that should have a far longer lifespan, without monthly maintenance, etc. A no brainer really.

Can we put to bed the idea that lithium is the expensive option?

I don't disagree. The point of my post is that many people are not up to the job of converting to lithium. You only have to read some of the posts on the lithium forums to realise how many numpties there are out there dabbling with stuff they know little about. No wonder insurance companies are twitchy about lithium. Its not the cells that is the issue but the way many are installed.
There are people like you and me and Migs who can do it. There are many that can't.
Interestingly, I asked on the DIY solar forum how many cycles people had done with their lithium battery installs. Nobody had done thousands and only a very small number had done hundreds. Most were still below 100 cycles. I wonder how many lithium batteries will make several thousand cycles in their lifetime? I am up to 27 cycles in 98 days.
I know of 3 installations where they are on their second set of batteries in under 10 years. I think misuse killed one set. Heat killed another. Not sure about the third set

 

[Neeves]

It is a pity, easy to say in hindsight, that there was not a separate part of the forum for lithium installations. Currently the background is largely in PBO but requires some patience to read and abstract from those who have generously taken time to post - and in detail. The amount of detail is quite extraordinary (unlike most other threads where you are lucky to know a yacht size, location nor enough background on the OP's thread opening to make a sensible comment - certainly no pics - it makes me weep. ).

On the various threads we have had named suppliers, product to avoid, copious notes on fuses, or a fuse - some educational discussion on different 'types' of installation - and warnings ......

On cost - not based on a lithium installation but the major cost of installing electrics on a yacht is the time taken simply to feed cable through a conduit. It might be difficult to train a monkey but its is not difficult - and takes time and patience, which if your sparky does it - costs money.

If we have a question - there are enough people here who have done it - Geem's numpties take note

Jonathan

 

[rogerthebodger]

Can we put to bed the idea that lithium is the expensive option?

I am in a simular ass neeves with LA batteries that ae getting towards end of life and thinking about Lithium but frightened by the cost.

Some indication of where the cost-effective lithium can be obtained from and the various protective circuits

 

[B27]

One thing I've noticed is that compared to 20 years ago when I had my previous yacht, people 'need' an awful lot of power now, despite all the lights changing to LED.
So people are talking about several hundreds of pounds worth of lead-acid batteries.
Yet people seem to use their engines more.

People seem to size their batteries around the idea of being at anchor for many days, whereas in reality few of us often do that.

 

[noelex]

Surely if you were to install Winston cells with 3C rating it would be a total waste of time with your set up. You aren't doing anything with your lithium that others aren't doing with lead.

Lead and lithium batteries are fundementaly very different. One advantage of lead is that it can deliver very high current for a short period of time without any damage. As well as differences in the battery chemistry with lead there is no limitations from the BMS (as these are not fitted).

Even deep cycle lead acid batteries can typically deliver well over 5C for thirty seconds without damage, although they will suffer significant voltage sag.

This means that for very high draw devices you need to be careful simply switching lead acid for lithium without doing some homework. This is the primary reason why lithium batteries are not commonly used for engine starting in marine situations. Bow thruster operation driven by lithium is feasible, but some care is needed to make to make sure the current delivery is adequate, especially when the limited capabilities of some BMSs are considered.

 

[geem]

Lead and lithium batteries are fundementaly very different. One advantage of lead is that it can deliver very high current for a short period of time without any damage. As well as differences in the battery chemistry with lead there is no limitations from the BMS (as these are not fitted).

Even deep cycle lead acid batteries can typically deliver well over 5C for thirty seconds without damage, although they will suffer significant voltage sag.

This means that for very high draw devices you need to be careful simply switching lead acid for lithium without doing some homework. This is the primary reason why lithium batteries are not commonly used for engine starting in marine situations. Bow thruster operation driven by lithium is feasible, but some care is needed to make to make sure the current delivery is adequate, especially when the limited capabilities of some BMSs are considered.

If you want to run high current with lithium, one option to go the route of a BMS controlled relay where none of the load goes through the BMS.
The alternative is to to use multiple smaller paralleled batteries with their own BMS each such that the load and inrush current is shared by several batteries. I know of several yachties doing just that. One guy installed 6x100Ah lithium drop in batteries as his domestic bank. He runs the windlass and thruster with no issues. There is a cost to this approach, but benefits of redundancy and resilience.
You still need to be careful that the BMS is capable of handling the loads. There are many cheap drop in lithium batteries totally unsuitable for use such as this where they have tiny BMS load handling

 

[Kelpie]

I am in a simular ass neeves with LA batteries that ae getting towards end of life and thinking about Lithium but frightened by the cost.

Some indication of where the cost-effective lithium can be obtained from and the various protective circuits

The cheapest option (and the one I took) is Alibaba. I'd never used it before. Selected a seller who had every sort of accreditation possible, and then browsed forums and Facebook groups to get real world experience from actual buyers in Europe and the US. When I was satisfied that my seller was legit, I went ahead. I'll admit I was a bit nervous about it, and the £350 I forked out on the cells would have been a lot to lose. But it all went perfectly.
In my case the seller was called Shenzhen Basen. But that was two years ago and I would suggest checking that people are still getting good experiences, because these things can change. The DIYSolar forum is great for this kind of thing.

I could have bought the BMS the same way, but following a suggestion on the DIYSolar forum I went straight to the seller's own website- lithiumbayyerypcb.com- and bought a 120A BMS for £57 inc delivery.
A year or so later I bought from them again, upgrading to the newly introduced 200A BMS. Again a pretty flawless procedure, other than the marina I had it sent to refusing to accept it. But that's not the seller's fault!

I've actually just bought another set of 4 cells and BMS, this time directly with a seller. An acquaintance was making a huge order (8x24v batteries) and I've piggybacked on that. With the 200A BMS and 280Ah cells, it came to about £420 but I'm going to have to wait and see what happens with the extra costs for shipping, taxes, and customs, here in Grenada.

One downside of dealing with a Chinese company directly is the shipping takes about two months. They speak perfect English and everything is done through email or WhatsApp. And the seller is always an attractive young lady. I suspect it might actually be a fat bloke hiding behind a stock profile picture

If you don't want to deal directly with a Chinese company, and/or you don't want to build your own battery, then there's lots of other options out there.

Long winded, but you did ask...

 

[migs]

'Interestingly, I asked on the DIY solar forum how many cycles people had done with their lithium battery installs. Nobody had done thousands and only a very small number had done hundreds. Most were still below 100 cycles.'

This from Rod Collins on the Facebook group:

'Happy Belated 14th birthday to my LiFePo4 bank. it turned 14 on May 9th and I missed it. It was built by me years before ”drop-in batteries even existed and is still going strong.

* It has well in excess of 2300 cycles (got sick of counting)
* It was almost always discharged to 80% DOD or deeper
* Has had at least 80+ cycles to 0%
* It has had Three different BMS’s over the years
* most charge cycles were at .4C via high performance alternator
* It ’s a 400Ah bank and as of Feb It could still delivering excess of 400AH.
* It has never been charged in excess of 13.8V
* It has never been floated
* when not being used it is left at 50% or less

Stick a fork in it, LEAD IS DEAD!'

My feeling is that people are killing their batteries (especially drop-ins) with elevated charge and 'float' voltages. From the article:

'For example, if a lithium battery is held at any voltage above its charged rest voltage of ~13.4V it will continue to charge, yet some well-known ‘lithium chargers’ float batteries at 13.8V indefinitely. This is definitely not a good idea as long term the battery could be overcharged and damaged.'

 

[Kelpie]

According to my BMS I've done 78 cycles, in two years of full time use.
Rod Collins's experience is remarkable. It looks like LFP is practically immortal unless you do something bad to them. Which is great news given that they are now fitted to nearly half of new EVs.

Of course, even if my LFP doesn't last longer than lead, it was still half the price to buy so I'm ahead from day one.

 

[migs]

'In my case the seller was called Shenzhen Basen'

Coincidentally, my cells came from Basen as well.

 

[Neeves]

I am in a simular ass neeves with LA batteries that ae getting towards end of life and thinking about Lithium but frightened by the cost.

Some indication of where the cost-effective lithium can be obtained from and the various protective circuits

Its a whole new ball game.

Hopefully Geem will answer but I recall he, maybe one of the other gurus - my memory fails me an embarrassing number of times, has mentioned - I think in his long thread on his battery installation (I think it is this thread My lithium build ), buying the cells from a young lady in HK - and describing her as honest, and/or reliable. I'm not sure how you ship cells and whether there are restrictions in some countries.

He underlines his dislike of 'off the shelf' batteries with integrated management systems - so in addition to the cells you will need the BMS (and don't forget the 'T' Class fuse, something else Geem underlines).


I am one of Geem's numpties. I'm not discouraged by the costs as the Lithium can be discharged to a higher degree which means you are able to use more of your Lithium amp/hrs than those of lead - so you have a bigger reserve for the same capacity or a smaller reserve if you replace like for like - for which there are quantifiable cost benefits offsetting the costs. A whole new management system IS a real issue.

I understand that if you have an exisiting lead battery bank then simply replacing the lead with Lithium is a non starter - the requirements are different for the different batteries (lithium can be charged with a much higher charge etc). But I also understand you can recharge from a Lead battery using a battery to battery charger (B2B ?). If my understanding is correct then you could refresh your old battery bank with a new lead battery and then charge you Lithium bank from the lead battery - and use all the old lead battery charging management system.....? or some of it.....? I'm not sure its the most effective option but might allow the costs to be scheduled.

Jonathan

 

[geem]

Its a whole new ball game.

Hopefully Geem will answer but I recall he, maybe one of the other gurus - my memory fails me an embarrassing number of times, has mentioned - I think in his long thread on his battery installation (I think it is this thread My lithium build ), buying the cells from a young lady in HK - and describing her as honest, and/or reliable. I'm not sure how you ship cells and whether there are restrictions in some countries.

He underlines his dislike of 'off the shelf' batteries with integrated management systems - so in addition to the cells you will need the BMS (and don't forget the 'T' Class fuse, something else Geem underlines).


I am one of Geem's numpties. I'm not discouraged by the costs as the Lithium can be discharged to a higher degree which means you are able to use more of your Lithium amp/hrs than those of lead - so you have a bigger reserve for the same capacity or a smaller reserve if you replace like for like - for which there are quantifiable cost benefits offsetting the costs. A whole new management system IS a real issue.

I understand that if you have an exisiting lead battery bank then simply replacing the lead with Lithium is a non starter - the requirements are different for the different batteries (lithium can be charged with a much higher charge etc). But I also understand you can recharge from a Lead battery using a battery to battery charger (B2B ?). If my understanding is correct then you could refresh your old battery bank with a new lead battery and then charge you Lithium bank from the lead battery - and use all the old lead battery charging management system.....? or some of it.....? I'm not sure its the most effective option but might allow the costs to be scheduled.

Jonathan

My cells came from Docan in Huston, USA. They are B grade CATL cells.
The most effective way to charge lithium is directly by solar. It has a better charge acceptance rate than lead (about 15-20% better). Since you don't need to get to 100% charged with lithium ( and it not good for them to do so) the MPPT charge controller should spend 99% of its life in bulk charge mode.
Other lead acid batteries on your boat can be kept in float mode 24/7 using a battery to battery charger such as a Victron orion. These take about 3w typically, to hold say, a thruster battery in a 100% fully charged state, on float.
If you were spending a lot of time on anchor, you could also use the same sort of B2B charger to keep your engine batteries fully charged. There are lots of option.we use one on the generator battery as well

 

[geem]

'Interestingly, I asked on the DIY solar forum how many cycles people had done with their lithium battery installs. Nobody had done thousands and only a very small number had done hundreds. Most were still below 100 cycles.'

This from Rod Collins on the Facebook group:

'Happy Belated 14th birthday to my LiFePo4 bank. it turned 14 on May 9th and I missed it. It was built by me years before ”drop-in batteries even existed and is still going strong.

* It has well in excess of 2300 cycles (got sick of counting)
* It was almost always discharged to 80% DOD or deeper
* Has had at least 80+ cycles to 0%
* It has had Three different BMS’s over the years
* most charge cycles were at .4C via high performance alternator
* It ’s a 400Ah bank and as of Feb It could still delivering excess of 400AH.
* It has never been charged in excess of 13.8V
* It has never been floated
* when not being used it is left at 50% or less

Stick a fork in it, LEAD IS DEAD!'

My feeling is that people are killing their batteries (especially drop-ins) with elevated charge and 'float' voltages. From the article:

'For example, if a lithium battery is held at any voltage above its charged rest voltage of ~13.4V it will continue to charge, yet some well-known ‘lithium chargers’ float batteries at 13.8V indefinitely. This is definitely not a good idea as long term the battery could be overcharged and damaged.'

Rob used the highest quality lithium cells on the market. He has had great experience with his battery. I hope mine do as well. Only time will tell.
We don't float our cells. I don't know anybody that does. Float is set to 3.35v per cell on my battery. We charge to 3.5v/cell and absorb for 30 mins at that voltage. It gives the active balancer time to balance. The CATL cells are very well balanced and we see little deviation between cells. Often the balancer has nothing to do.
Just checking the Victron MPPT and we have only reached 3.5v twice in the last 30 days.
The battery mainly lives in the 60 to 80% charged zone., but that's 60-80% of only 90% charged if you get my meaning. I have my smart shunt at to 100% charged at 3.5v/cell

 

[noelex]

We don't float our cells. I don't know anybody that does. Float is set to 3.35v per cell on my battery. We charge to 3.5v/cell and absorb for 30 mins at that voltage.

I presume this means you have bulk/absorption setting of 28v and a float setting of 26.8v on devices such as your solar charge controller. Is this correct?

 

[migs]

geem, I'm confused; what do you mean by 'We don't float our cells. I don't know anybody that does. Float is set to 3.35v per cell on my battery'?

As explained in our article, when our battery has charged, it is simply disconnected from the chargers and allowed to discharge to a lower soc, and at this point we restart charging. In other words we completely avoid the 'what float voltage should we set dilemma...' - something that constantly crops up in the forums.

 

[geem]

geem, I'm confused; what do you mean by 'We don't float our cells. I don't know anybody that does. Float is set to 3.35v per cell on my battery'?

As explained in our article, when our battery has charged, it is simply disconnected from the chargers and allowed to discharge to a lower soc, and at this point we restart charging. In other words we completely avoid the 'what float voltage should we set dilemma...' - something that constantly crops up in the forums.

The point I was making, is that you set the float voltage below the battery voltage. Since the charge curve of lithium is so flat, you effectively set the 'float' so it has no charging function, unlike on a lead battery where you set a float voltage above the battery at rest voltage

 

[migs]

geem; understood, we should coin a new word for use with lithium batteries instead of float - let's call it 'hold' voltage.

In fact, it's actually impossible to define a best hold voltage for Lithium as the charge going in and out of the battery varies with the load applied. If you set the hold voltage high, that's fine for powering big loads and maintaining soc, but when the loads are light e.g. you are away for a few days, the battery gets overcharged. If you set the hold voltage low, the opposite happens.

So, with a fixed hold voltage, you inevitably end up constantly charging or discharging the battery, for example as the AC cuts in and out, and after a while you end up with an indeterminate soc. For us a better approach was to ensure that charge flows in and out of the battery in a controlled fashion, and this is done by disconnecting the battery from the chargers when it has charged i.e. no bulk, absorption or float stages at all, just simple constant current charging. (A side benefit of this approach was the possibility of retaining our old chargers and saving around £800.)

Maybe we should have taken out a patent on this novel approach, but surely we can't be the first people to come up with it?

 

[Kelpie]

geem, I'm confused; what do you mean by 'We don't float our cells. I don't know anybody that does. Float is set to 3.35v per cell on my battery'?

As explained in our article, when our battery has charged, it is simply disconnected from the chargers and allowed to discharge to a lower soc, and at this point we restart charging. In other words we completely avoid the 'what float voltage should we set dilemma...' - something that constantly crops up in the forums.

General advice is to have the charge source disconnect itself, to avoid the scenario where the MPPT is connected to solar panels but not battery.

 

[migs]

We prefer to let our battery control its own charge regime rather than have multiple chargers (with multiple settings) fighting it out.

No mppt controller should ever be embarrassed by disconnecting its battery. What sort of design would that be? If they were, Victron would surely be knee-deep in returns.

 

[noelex]

No mppt controller should ever be embarrassed by disconnecting its battery. What sort of design would that be? If they were, Victron would surely be knee-deep in returns.

Generally this is not a good idea. It can damage the controller, although in practice this only happens rarely.

Of greater concern is disconnecting the battery supply while still providing power for systems via the solar input. Without the buffer of the battery, the voltage fluctuations can damage sensitive electronics.