CAN YOU JUST SWAP YOUR LEAD ACID BATTERY FOR LITHIUM?

[Jim]

This thread is for the general discussion of the Article CAN YOU JUST SWAP YOUR LEAD ACID BATTERY FOR LITHIUM?.

 

[Wissel]

Really good article I thought

 

[Steve and Denise]

Yes and no, just depends on how efficient you want the battery to be,
I am sure there will be some experts along shortly
I myself have changed the mains charger to Victron with lithium profile, solar with lithium profile, and installed a b2b with the same total cost of 300ah lithium with all relevant equipment less than 2k
Don’t be over charged by the experts with all the hype.
With a little research and a bit of savy it is not a difficult task.

 

[Carpmart]

I think this raises the issue of optimal installation of lithium to replace lead vs can you just replace lead with lithium, in a potential less than perfectly optimised way. The answer is you absolutely can drop in some makes of lithium batteries without too much worry or any changes to your current setup. However, you do need to consider what you are doing in terms of the best value from your battery investment if your infrastructure supporting the batteries isn’t optimal.

I’ve replaced 400A of lead with 400A of lithium. My mains charger doesn’t have a lithium profile, but is a decent one and capable of 40A per charging connection. It has three concurrent 40A connections possible, so theoretically I could run additional cable and double or indeed triple the charging speed. I haven’t yet.

The alternator kicks in up to 60A to the lithium’s when running, again I’ve not changed anything from when the lead was in.

New MPPT (with lithium profile) being installed as my solar was dated.

BMS’s should be ‘smart’ enough on reasonably well built quality lithium’s to protect the battery from damage by what you have connected to it.

As above, optimising what is going into the batteries from your infrastructure is a complete other question, but absolutely shouldn’t mean that you can’t just ‘drop in’ a decent quality lithium battery.

 

[andy63]

This thread is for the general discussion of the Article CAN YOU JUST SWAP YOUR LEAD ACID BATTERY FOR LITHIUM?.

Ill add my thoughts..

The points made are all valid...but the real elephant in the room so to speak when we talk about replacing lead acid with lithium is that all the charging sources whilst claiming to use a lithium profile continue to hold the batteries at the upper end of their state of charge...if we are to believe what we read then this isn't ideal either but it's claimed its a low enough level to not cause harm... that to me is still a throwback to a lead acid charging regime ...ideally the charging sources should just stop charging When the batteries are full..and the batteries then loaded and used ...the charging sources switching back on again at a predetermined lower state of charge ..that would be a correct charging regime for lithium imo..
In other words you may have the batteries back up to a fully charged state after one hours drive...but you may be on the road for hours..holding the batteries at that high level..
Same with mains or solar charging... the batteries are brought to fully charged and held there while the charger often then continues to supply loads up to its max current capacity..the batteries only making up a shortfalls.. my thoughts have always been that the charging source should be removed when the batteries are fully charged..
Just like you use the other lithium chemistry batteries in say your phones..ie charge it and use it..not keep it on charge once its charged..
So to me until you install chargers that are capable of switching off and on at defined limits of charge and discharge you do not really have a correct lithium charging set up just another compromise..
Andy...

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[Carpmart]

Ill add my thoughts..

The points made are all valid...but the real elephant in the room so to speak when we talk about replacing lead acid with lithium is that all the charging sources whilst claiming to use a lithium profile continue to hold the batteries at the upper end of their state of charge...if we are to believe what we read then this isn't ideal either but it's claimed its a low enough level to not cause harm... that to me is still a throwback to a lead acid charging regime ...ideally the charging sources should just stop charging When the batteries are full..and the batteries then loaded and used ...the charging sources switching back on again at a predetermined lower state of charge ..that would be a correct charging regime for lithium imo..
In other words you may have the batteries back up to a fully charged state after one hours drive...but you may be on the road for hours..holding the batteries at that high level..
Same with mains or solar charging... the batteries are brought to fully charged and held there while the charger often then continues to supply loads up to its max current capacity..the batteries only making up a shortfalls.. my thoughts have always been that the charging source should be removed when the batteries are fully charged..
Just like you use the other lithium chemistry batteries in say your phones..ie charge it and use it..not keep it on charge once its charged..
So to me until you install chargers that are capable of switching off and on at defined limits of charge and discharge you do not really have a correct lithium charging set up just another compromise..
Andy...

Understand your points, however in real world application, the BMS handles this. Effectively it doesn’t matter what your charging infrastructure (mains, engine and solar) presents to the batteries, the BMS will only use the power it needs.

 

[Helen Ariel]

A very informative article Jim and thanks eddievanbitz for taking the time to put it together.

Am I right in reading that any Euro6 engine will have a B2B system fitted?

”because of regenerative breaking alternator issues brought in because of emission controls on Euro6 chassis (another side issue for another day) that a suitable B2B system will be fitted by the converter”

Is there a simple way to look under the bonnet and spot if it is fitted? We have a Euro6b Ducato engine in our Dethleffs and are interested in lithium as we spend most of our time off-grid, plus the extra payload is a bonus, but I’d like to check to see if there’s a B2B fitted.

Thanks again, Paul

 

[andy63]

Understand your points, however in real world application, the BMS handles this. Effectively it doesn’t matter what your charging infrastructure (mains, engine and solar) presents to the batteries, the BMS will only use the power it needs.

But my point is that whatever way you wrap it up... the point made is that lithium do not need or by all accounts want to be held at the upper end of their soc...they are because we have adapted a regime that was used for a different technology... it wasn't designed from the ground up to deal with lithium..the industry added a lithium profile to chargers but in an ideal world that profile would provide for a cessation of charging...
I think that anyway...

If you are referring to the cell balancing aspect that may be present in some bms systems..be it at the upper or lower end of the charging cycle....thats not the same issue..and would be achieved even if the chargers were designed to cease the charging When the batteries are fully charged..
In an ideal installation that would still be my take on what would be ideal...
Andy.

 

[Lenny HB]

Am I right in reading that any Euro6 engine will have a B2B system fitted?

If it is Euro 6D it should have one but manufacturers tend to only fit a 30amp B2B. So for serious off grid use you will probably need to upgrade it to a more powerful one.

 

[Helen Ariel]

If it is Euro 6D it should have one but manufacturers tend to only fit a 30amp B2B. So for serious off grid use you will probably need to upgrade it to a more powerful one.

It‘s Euro6b. Does that make a difference? The article refers to Euro6 only.

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[Lenny HB]

It‘s Euro6b. Does that make a difference? The article refers to Euro6 only.

Fiat vans had smart alternators on all Euro 6 versions but they were supplied to the Motorhome manufacturers with standard alternators until 2019 when the Euro 6D came out. I think only on 2020 year models they have smart alternators so from around September 2019. Mercs have had smart alternators on Motorhomes since around 2014/2015.

 

[Raul]

You couldn’t be more wrong, without knowing the spec of hardware that’s built in, you can’t take a decision in assuming it’s ok the bms will take care of it, and a drop in is ok without upgrades. There are bmses with single relay and two relays. Many up market Li packs come with single relay. Imagine you drive on a sunny day for 6-8hrs on a full battery since morning. You have charging sources without comms to bms. Repeat that several times with the peace of mind that bms will take care of it.

Understand your points, however in real world application, the BMS handles this. Effectively it doesn’t matter what your charging infrastructure (mains, engine and solar) presents to the batteries, the BMS will only use the power it needs.

 

[Helen Ariel]

Fiat vans had smart alternators on all Euro 6 versions but they were supplied to the Motorhome manufacturers with standard alternators until 2019 when the Euro 6D came out. I think only on 2020 year models they have smart alternators so from around September 2019. Mercs have had smart alternators on Motorhomes since around 2014/2015.

Typically ours is a 2019 Euro6b…

 

[Raul]

It‘s Euro6b. Does that make a difference? The article refers to Euro6 only.

Look at the starter negative battery post. If the cable is directly bolted to the battery, then you have a conventional alternator. If the cable is attached to a shunt resistor, that’s attached to the battery post, then you have a smart alternator. The ecu uses the shunt data to control the alternator.

 

[Lenny HB]

Typically ours is a 2019 Euro6b…

Look on the bright side if it doesn't have a B2B you won't be throwing away a working B2B to replace it with a better one.

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[Wissel]

My own personal view is very similar to eddievanbitz. I just can't see the point of paying a larger amount of money for a better product, if you're not going to get the advantages it can deliver?

Besides, the correct chargers for LiFePO4 don't just protect your battery investment. They can also protect your van.

I was quite an early adopter of lithium batteries, buying them in January 2018 to upgrade our van ready to go fulltime. Back then, there was very little mainstream information about the technology, so I spent a very long time learning everything I could before purchasing. This I had a lot of help with, especially from Gromett who would dig out industry articles for me, then we would discuss every aspect - often over weeks before drawing conclusions.

The bottom line is LiFePO4 is a very different technology to Lead Acid, therefore it needs charging in a different way.

With Lead Acid, what we try to do is fill the batteries to the max as quickly as we can. These batteries last longer if kept almost full but will fight against being fully charged. They become more resistive as they are filled. A smart charger can completely fill a Lead Acid battery over time, far better than a split charger, as it uses different stages of charging. So with Lead Acid, a smart charger is used to keep the battery full. Adding a larger smart charger won't necessarily charge a Lead Acid battery faster. The battery decides how much current to take, not the charger how much to provide.

With LiFePO4, it's the other way around. These batteries have next to no resistance to charging, making them very efficient at filling quickly. They are greedy and will take as much charge as they can, but to keep them in prime condition, should not be full all the time.

A smart chargers purpose with LiFePO4 isn't just to charge, it's to protect the battery from itself.

Most LiFePO4 batteries can be charged at a much higher rate than Lead Acid batteries. For instance, my battery can safely be charged at 200A per hour and will try to pull far more. Without a smart B2B to LIMIT the charge while driving, my battery could be overcharged. Also, I don't think my alternator would last very long.

I fitted what I believed to be the best charging system available at the time, along with 400Ah of Winston cells and a very smart BMS, which all worked very well - but not perfect.

The issue was that my chargers, although all set with the correct lithium profiles would trip my BMS sometimes. My BMS will stop charge going into the battery once the cells balance at 3.4v each (13.6v total). It's wasn't a major issue as that's what my BMS should do and cutting the charge doesn't stop the battery being discharged (my BMS uses separate relays for charging and loads). Charging would automatically start again when the battery state hit 95%. The trouble was, this kept the batteries fairly full, which wasn't ideal.

My chargers had set profiles that couldn't be altered, and I have my battery set quite conservatively, to prolong it's life. So I swapped all but my B2B to Victron last year, where the settings could be tweaked. I set my MPPT and EHU charger to deliver a slightly lower voltage so they never quite fill the battery. This is especially useful in the Winter while we are using EHU as my batteries are always in their sweet spot. Looking at the app now, my cells are 78% full, I'm using 6.4A and I'm charging at 5.8A. If I were upgrading today, I'd swap the B2B to Victron as well.

So now I have a system that is as close to ideal (for me) as I can get it. My batteries are well protected, my alternator is well protected, my BMS shuts down and auto restarts as an insurance policy and my battery is always in its happy place. I couldn't do this with most chargers.

I know that I now do this for a living and some of you might think me biased, but all of the above I bought and upgraded way before I started installing others systems. It's what I did spend my money on and would again if I were buying now.

Another point made in this thread was cost. I've just done a quick search on products I am happy with and would recommend, to see what the parts could be bought for.

I chose the following:
Roamer 300Ah battery - £1305
Victron 100/30 MPPT - £192
Victron 12/12/30 B2B - £194
Victron SmartShunt - £108
Victron IP22 30A EHU Charger - £170

So without upgrading wiring, the parts come to just under £2000. Thats for all great parts, all Bluetooth and all tweakable. Considering the battery is almost 2/3rd's of the total cost, is it really worth risking not having great charging?

Anyway, that's my opinion

 

[Raul]

I know few mates off grid with winston, synopoly and early callb ally case. The oldest Calb is well over 10 years in service with a 8kva. Quattro. They are still serving the house ok, some capacity gone of course.
The winston ythrium came in later, and I chikened out on a group buy in 2015. I’m kicking myself now as I was hunting for a used EV pack, but they all gone up.
Wissel, the LFP it’s been used in off grid for over 12 years now with good results. Ppl are happy with the low degradation by keeping out of the edges. I do agree that made it very late into leisure market, but even for grid storage was used for quite some years by BYD, sonnen, Pylontech, Growatt etc.

 

[mitzimad]

Real world example in the last discounted battery compertion i was lucky enough to get one
Nothing was added and we switched charger and solar to the gel settings
We have 180 Watts of solar
Were not heavy users just lights ,mostly led ,pump and charging phones
Weve been out since Thursday morningweather has been mostly overcast and a fair bit of rain so I doubt solar has put much in
I've just checked voltage and its sitting at 12.7 with a couple of lights on and the heating running
Obviously only time will tell about the longevity but at present I'm very happy with the performence

 

[bigtwin]

I've just checked voltage and its sitting at 12.7

Unlike LA (where the voltage reduces as you use the battery) Lithiums maintain the same voltage level over much of its capacity range. Consequently, you cannot infer much (in terms of state of charge) from a reading of 12.7V.

Ian

 

[cmcardle75]

My own personal view is very similar to eddievanbitz. I just can't see the point of paying a larger amount of money for a better product, if you're not going to get the advantages it can deliver?

Besides, the correct chargers for LiFePO4 don't just protect your battery investment. They can also protect your van.

I was quite an early adopter of lithium batteries, buying them in January 2018 to upgrade our van ready to go fulltime. Back then, there was very little mainstream information about the technology, so I spent a very long time learning everything I could before purchasing. This I had a lot of help with, especially from Gromett who would dig out industry articles for me, then we would discuss every aspect - often over weeks before drawing conclusions.

The bottom line is LiFePO4 is a very different technology to Lead Acid, therefore it needs charging in a different way.

With Lead Acid, what we try to do is fill the batteries to the max as quickly as we can. These batteries last longer if kept almost full but will fight against being fully charged. They become more resistive as they are filled. A smart charger can completely fill a Lead Acid battery over time, far better than a split charger, as it uses different stages of charging. So with Lead Acid, a smart charger is used to keep the battery full. Adding a larger smart charger won't necessarily charge a Lead Acid battery faster. The battery decides how much current to take, not the charger how much to provide.

With LiFePO4, it's the other way around. These batteries have next to no resistance to charging, making them very efficient at filling quickly. They are greedy and will take as much charge as they can, but to keep them in prime condition, should not be full all the time.

A smart chargers purpose with LiFePO4 isn't just to charge, it's to protect the battery from itself.

Most LiFePO4 batteries can be charged at a much higher rate than Lead Acid batteries. For instance, my battery can safely be charged at 200A per hour and will try to pull far more. Without a smart B2B to LIMIT the charge while driving, my battery could be overcharged. Also, I don't think my alternator would last very long.

I fitted what I believed to be the best charging system available at the time, along with 400Ah of Winston cells and a very smart BMS, which all worked very well - but not perfect.

The issue was that my chargers, although all set with the correct lithium profiles would trip my BMS sometimes. My BMS will stop charge going into the battery once the cells balance at 3.4v each (13.6v total). It's wasn't a major issue as that's what my BMS should do and cutting the charge doesn't stop the battery being discharged (my BMS uses separate relays for charging and loads). Charging would automatically start again when the battery state hit 95%. The trouble was, this kept the batteries fairly full, which wasn't ideal.

My chargers had set profiles that couldn't be altered, and I have my battery set quite conservatively, to prolong it's life. So I swapped all but my B2B to Victron last year, where the settings could be tweaked. I set my MPPT and EHU charger to deliver a slightly lower voltage so they never quite fill the battery. This is especially useful in the Winter while we are using EHU as my batteries are always in their sweet spot. Looking at the app now, my cells are 78% full, I'm using 6.4A and I'm charging at 5.8A. If I were upgrading today, I'd swap the B2B to Victron as well.

So now I have a system that is as close to ideal (for me) as I can get it. My batteries are well protected, my alternator is well protected, my BMS shuts down and auto restarts as an insurance policy and my battery is always in its happy place. I couldn't do this with most chargers.

I know that I now do this for a living and some of you might think me biased, but all of the above I bought and upgraded way before I started installing others systems. It's what I did spend my money on and would again if I were buying now.

Another point made in this thread was cost. I've just done a quick search on products I am happy with and would recommend, to see what the parts could be bought for.

I chose the following:
Roamer 300Ah battery - £1305
Victron 100/30 MPPT - £192
Victron 12/12/30 B2B - £194
Victron SmartShunt - £108
Victron IP22 30A EHU Charger - £170

So without upgrading wiring, the parts come to just under £2000. Thats for all great parts, all Bluetooth and all tweakable. Considering the battery is almost 2/3rd's of the total cost, is it really worth risking not having great charging?

Anyway, that's my opinion

Wow. That's almost exactly my setup. Except I didn't bother with solar at all (I do lots of winter stuff and can't sit still for long) and I only have the 20A EHU charger, which was a mistake I made when I was still running lead acid. But it's a mistake I can live with, as if I plug into the mains, I'll be there for at least 12 hours anyway.

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[the1andonly]

Ill add my thoughts..

The points made are all valid...but the real elephant in the room so to speak when we talk about replacing lead acid with lithium is that all the charging sources whilst claiming to use a lithium profile continue to hold the batteries at the upper end of their state of charge...if we are to believe what we read then this isn't ideal either but it's claimed its a low enough level to not cause harm... that to me is still a throwback to a lead acid charging regime ...ideally the charging sources should just stop charging When the batteries are full..and the batteries then loaded and used ...the charging sources switching back on again at a predetermined lower state of charge ..that would be a correct charging regime for lithium imo..
In other words you may have the batteries back up to a fully charged state after one hours drive...but you may be on the road for hours..holding the batteries at that high level..
Same with mains or solar charging... the batteries are brought to fully charged and held there while the charger often then continues to supply loads up to its max current capacity..the batteries only making up a shortfalls.. my thoughts have always been that the charging source should be removed when the batteries are fully charged..
Just like you use the other lithium chemistry batteries in say your phones..ie charge it and use it..not keep it on charge once its charged..
So to me until you install chargers that are capable of switching off and on at defined limits of charge and discharge you do not really have a correct lithium charging set up just another compromise..
Andy...

The Resting or winter charging held by use of a Battery negative Issolator, is again a compromise, but works. so I've added an extra level of control. The control location could be tweaked (ie the charge going to the battery) but the system is proven to work. Simply I use a BMV712s ability to control a SSR based on SOC. Currently for winter i set the limmits to 65% relay off 40% on (ie allow solar charge) . For summer could reset to 90% max. I Have 2 circuits one 1 330w solar panel to SSR to Votronics MPPT. 2nd 220W to Duo MPPT Bat 1 to SSR2 to LB, Bat 2 trickle charge to SB. THe Votronics B2B currently is allowed to just do its thing. The SSR use 15mA 12V auto relays 300mA.
I personnaly don't use EHU sufficient to worry about (I have a small Lithium profile charger if really required.)
As to drop in Mine is a 2017 Ducato Euro6 so a drop in apart from resizing wiring adding a b2b ignoring the EHU then drop in.