Hybrid Lead/Lithium


Nick Newington
 

Fellow Amel owners,

Since my post on the possibility of adding Lithium to a lead bank I have been following others with similar thoughts, specifically S/V Temptress and his you tube videos….I think we are onto something…something superior to just Lithium…I do not like the idea of being completely dependent on an electronic BMS…think lightening strike…think electronics and out of the way places….it looks to me like a hybrid system is the way to go….some have gone for Lithium but with a small amount of lead. If the Lithium BMS decides to shut down, the alternator will still have lead to charge into and thus not fry….in my opinion this is vastly superior to just lithium….others have gone for mostly lead with a small amount of lithium….in terms of chemistry it does not matter. It's the physics that count. What I mean is the batteries are only linked by cable. So what if the chemistry differs. 

Personally I am thinking that I would like to go 20% lithium and 80% lead for starters…..still thinking about it… no hurry. There are others doing this with great results….but if the lithium BMS were to fail then I would be where I am now, if the lead were to gradually die as they do, then the lithium would prop it up until they could be replaced…

The only question is how safe is it? As I say others are experimenting…so far so good..

NIck in the UK….Omicron going nuts but hopeful that this is the beginning of the end, and not the end of the beginning.

S/V Amelia AML54-019 ashore in Leros


Scott SV Tengah
 

Nick,

I think if you were struck by lightning to the extent that the BMS is killed, the chargers would probably be gone, too. I agree that a weak point, at least in my Victron system, is that a BMS failure would render the Victron chargers useless. To solve this, I bought a backup BMS, which was only $120 USD. 

That said, if both my primary and backup BMS die, I could still use the Mastervolt alternator to charge my batteries, just without the cell level over voltage protection. Not a great situation, but as long as you don't charge above say 85% SOC, the likelihood that you'll get a cell over voltage is quite low. If I want to go higher than 85% bank SOC, I can just monitor the individual cells via bluetooth. This is really the "I am in the middle of nowhere and need to charge my batteries" situation that we must think about when we're circumnavigating.

One disadvantage of a lead-heavy hybrid system is that you lose three of the big advantages of lithium: (1) high charge acceptance and charging efficiency (2) stable voltage under heavy load (3) the ability to use all those AH between 10-100% SOC. Do not underestimate the charge acceptance and efficiency gains as it is like getting a 20-35% larger solar array on your boat.

Personally, after over 3 years on this Victron system, I think it works quite well. The BMS tells the charging sources (solar, 230v charger, alternator) to stop charging VS. some other systems which appear to disconnect the batteries from the charging sources, leaving the charging source without a place to send that current and putting that source at risk of damage.

Another thing to think about is the insurance "problem". A non-standard system may raise the eyebrows of insurers more than an integrated system from one manufacturer. I put "problem" in quotes because clearly any insurance companies that have an issue with lithium will clearly need to figure it out and allow it as many of the A50s and I believe all of the A60s have it as standard equipment. 


--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Dean Gillies
 

Nick,
I understand your desire to extract best value from your existing lead batteries, but I would strongly recommend you think about big lithium and small lead content as being the optimum longer term solution.  I'm sure you will agree when you become accustomed to the operational profile of lithium.
I would suggest that you give careful thought to the future migration path from big lead/small lithium to small lead/big lithium.   Make it easy in your system to add lithium when your lead batteries wane in a few years. 

cheers, Dean
SV Stella
A54-154


Dean Gillies
 

Nick,
On the subject of safety ... 

A couple of years ago when I started thinking about a hybrid solution, I frequently heard the risk statement "you can't mix chemistries" because apparently bad things will happen. (I have a cartoon picture in my mind of a mad professor dropping lumps Lithium into sulphuric acid in a beaker producing lots of coloured smoke lol.)

I have never seen any explanation of what that actually means.  What exactly is the worst bad thing that happens when you 'mix chemistries"?  I would love to know.

There is an electrical interaction between the battery types, and it's important to understand how that can play out in worst-case scenarios. What else?

My safety assessment was focussed on risks which are peculiar to lithium and an interconnected hybrid architecture. There are plenty of risks with lead batteries which are also extant in lithium batteries. These are important, but are not reasons to discount LFP. 

Dean
SV STELLA
A54-154

 

 


James Alton
 

I am using the Victron Super Pak Lithium batteries with the internal BMS along with a high quality German made Sonnenschien gel battery on my Amel.  I like the internal BMS in each individual battery concept better than the external because I feel it is a safer way to go.  The external BMS systems are very appealing and allow a lot more monitoring but it seems to me that there are still possible scenarios that could be dangerous that the  internal BMS option would protect against.  One scenario that comes to mind would be the batteries being charged by a temporary charging source that was not connected so that the external BMS could talk to it.  In such a scenario,  the internal BMS should disconnect the battery if any charging source exceeds a preset voltage.  Overcharging Lithium cells the main thing that you need to worry about with Lithium.  The gel battery is in parallel with the Lithiums and could handle house loads if for instance lightning destroyed the BMS's in the Lithiums or if the Lithiums we're somehow overcharged and disconnected. The gel is also a nice filter for the Lithiums and doesn't care about alternator electrical noise etc.   I personally would be leery of connecting Lithium with a common low quality lead acid battery.  What happens if you get a short in your lead acid battery and it is connected to a big bank of Lithiums?   I installed the high quality Sonnenschien batteries in boats for decades and have never had one fail in a bad way regardless of the abuse. One battery that is a similar vintage had a 1/4" hope drilled right through the case by the customer and it was caulked over, nothing came out.  The life expectancy is so long that I would often build these maintenance free batteries into the cabinetry of the boat.  These gels have virtually no self discharge and can be left without charging for up to two years so if they are healthy they will not pull down the Lithiums. They do have lower energy density than other lead acid batteries which is one downside and the cost is high.  Because the Lithiums hold about 13.2 volts during discharge the Gel doesn't really do much work unless the bow thruster is used or the Lithiums we're to ever be depleted or fail.  I look at the batteries on my boat as a critical system so I like having the gel.battery backup. One could lose their boat if power failed at the wrong time after all.  By the way, the Sonnenschien gel that is installed on my boat was purchased from a customer who wanted his 8 hear old Sonnenechien batteries changed ahead of a circumnavigation. (which he completed.)  That battery is now well over 20 years old and still seems healthy though given the age I want to replace it with a new battery.  So those are my thoughts and current solution. This is of course an evolving technology.   James Alton SV Sueno

On Thu, Dec 16, 2021 at 5:40 AM, Dean Gillies
<stella@...> wrote:

Nick,
On the subject of safety ... 

A couple of years ago when I started thinking about a hybrid solution, I frequently heard the risk statement "you can't mix chemistries" because apparently bad things will happen. (I have a cartoon picture in my mind of a mad professor dropping lumps Lithium into sulphuric acid in a beaker producing lots of coloured smoke lol.)

I have never seen any explanation of what that actually means.  What exactly is the worst bad thing that happens when you 'mix chemistries"?  I would love to know.

There is an electrical interaction between the battery types, and it's important to understand how that can play out in worst-case scenarios. What else?

My safety assessment was focussed on risks which are peculiar to lithium and an interconnected hybrid architecture. There are plenty of risks with lead batteries which are also extant in lithium batteries. These are important, but are not reasons to discount LFP. 

Dean
SV STELLA
A54-154

 

 


Dean Gillies
 

Hi James,
Those are very sensible considerations. I am also a big fan of Gel's, except for their cost and energy density as you point out. I have happily used them in many military projects over the years where safety and ruggedness were paramount.

I cannot speak for every external BMS system, but my REC BMS and I'm sure the vast majority of others, do provide over-voltage protection against charge sources regardless of whether they are controlled and/or monitored by the BMS.  The BMS will disconnect the LFP battery when an over voltage is detected. 

With regard to the other safety issue you mention, where a short occurs in the lead battery of a directly-connected hybrid system, is mitigated by means of the series fusing provided on both the LFP and Lead batteries. In my system for example, 400A class T fuses protect both batteries.
I don't know what the fusing arrangement is on LFP batteries with internal BMS.

It's worth noting that most (if not all) external BMS units are fail-safe. The LFP is dis-connected by default and is only connected when all parameters are within spec.  In the event of a failure of the BMS, the LFP is disconnected. (Another reason that it's nice to have the lead component in the circuit to keep the lights on). 


cheers,
Dean
SV STELLA
A54-154

 

 


Juan de Zulueta
 

Dear Amel fellow,
On the subject of Safety, a few years ago in St Raphael, the boat moored next to my Super was badly hit by a strike, some of its cockpit instruments went outside boat and all wires burned 🥵.
On my boat all electronics were totally destroyed at once even the regulator of the alternator… all this happened in the harbour … I don t think this is a Pb of Lithium or Lead…
I am planning to install two new lithium batteries Victron and indeed i will buy an extra BMS for safety. I am planning to interface them with Mastervolt via the Masterbus digital input device (connected to the Ve Bus BMS)which will to stop charge or stop load of the mastervolt devices including the alternator.

Envoyé de mon iPhone

Juan de Zulueta
SM 32
Ophelie X
Guadeloupe

Le 16 déc. 2021 à 07:08, Dean Gillies <stella@...> a écrit :



Hi James,
Those are very sensible considerations. I am also a big fan of Gel's, except for their cost and energy density as you point out. I have happily used them in many military projects over the years where safety and ruggedness were paramount.

I cannot speak for every external BMS system, but my REC BMS and I'm sure the vast majority of others, do provide over-voltage protection against charge sources regardless of whether they are controlled and/or monitored by the BMS.  The BMS will disconnect the LFP battery when an over voltage is detected. 

With regard to the other safety issue you mention, where a short occurs in the lead battery of a directly-connected hybrid system, is mitigated by means of the series fusing provided on both the LFP and Lead batteries. In my system for example, 400A class T fuses protect both batteries.
I don't know what the fusing arrangement is on LFP batteries with internal BMS.

It's worth noting that most (if not all) external BMS units are fail-safe. The LFP is dis-connected by default and is only connected when all parameters are within spec.  In the event of a failure of the BMS, the LFP is disconnected. (Another reason that it's nice to have the lead component in the circuit to keep the lights on). 


cheers,
Dean
SV STELLA
A54-154

 

 


--
Juan de Zulueta
OPHELIE X
Super Maramu #32


Scott SV Tengah
 

Juan,

I have a full victron system except for the mastervolt 110 alternator.

You can interface the charge disconnect from the victron BMS with the brown reg-on wire of the master volt alpha pro 2 or 3 regulator. This allows the victron BMS to tell the alternator to shut off charging current in the event of a cell overvoltage situation.  It just requires a solid state relay and two regular automotive relays.

I wrote some posts a while back about how I implemented that. Hope that saves you some work.

On Thu, Dec 16, 2021, 06:55 Juan de Zulueta via groups.io <jdezulueta=icloud.com@groups.io> wrote:
Dear Amel fellow,
On the subject of Safety, a few years ago in St Raphael, the boat moored next to my Super was badly hit by a strike, some of its cockpit instruments went outside boat and all wires burned 🥵.
On my boat all electronics were totally destroyed at once even the regulator of the alternator… all this happened in the harbour … I don t think this is a Pb of Lithium or Lead…
I am planning to install two new lithium batteries Victron and indeed i will buy an extra BMS for safety. I am planning to interface them with Mastervolt via the Masterbus digital input device (connected to the Ve Bus BMS)which will to stop charge or stop load of the mastervolt devices including the alternator.

Envoyé de mon iPhone

Juan de Zulueta
SM 32
Ophelie X
Guadeloupe

Le 16 déc. 2021 à 07:08, Dean Gillies <stella@...> a écrit :



Hi James,
Those are very sensible considerations. I am also a big fan of Gel's, except for their cost and energy density as you point out. I have happily used them in many military projects over the years where safety and ruggedness were paramount.

I cannot speak for every external BMS system, but my REC BMS and I'm sure the vast majority of others, do provide over-voltage protection against charge sources regardless of whether they are controlled and/or monitored by the BMS.  The BMS will disconnect the LFP battery when an over voltage is detected. 

With regard to the other safety issue you mention, where a short occurs in the lead battery of a directly-connected hybrid system, is mitigated by means of the series fusing provided on both the LFP and Lead batteries. In my system for example, 400A class T fuses protect both batteries.
I don't know what the fusing arrangement is on LFP batteries with internal BMS.

It's worth noting that most (if not all) external BMS units are fail-safe. The LFP is dis-connected by default and is only connected when all parameters are within spec.  In the event of a failure of the BMS, the LFP is disconnected. (Another reason that it's nice to have the lead component in the circuit to keep the lights on). 


cheers,
Dean
SV STELLA
A54-154

 

 


--
Juan de Zulueta
OPHELIE X
Super Maramu #32


--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


Juan de Zulueta
 

Scott,

Many thanks

This is indeed a good solution but I have many Mastervolt devices so Mastervolt digital input device will allow to stop charge all Mastervolt devices, chargers and alternators.
; and stop charge of the convertors leveraging Masterbus.

Best regards



Juan de Zulueta
+33680895892
sent from my Ipad.

Le 16 déc. 2021 à 13:31, Scott SV Tengah <Scott.nguyen@...> a écrit :


Juan,

I have a full victron system except for the mastervolt 110 alternator.

You can interface the charge disconnect from the victron BMS with the brown reg-on wire of the master volt alpha pro 2 or 3 regulator. This allows the victron BMS to tell the alternator to shut off charging current in the event of a cell overvoltage situation.  It just requires a solid state relay and two regular automotive relays.

I wrote some posts a while back about how I implemented that. Hope that saves you some work.

On Thu, Dec 16, 2021, 06:55 Juan de Zulueta via groups.io <jdezulueta=icloud.com@groups.io> wrote:
Dear Amel fellow,
On the subject of Safety, a few years ago in St Raphael, the boat moored next to my Super was badly hit by a strike, some of its cockpit instruments went outside boat and all wires burned 🥵.
On my boat all electronics were totally destroyed at once even the regulator of the alternator… all this happened in the harbour … I don t think this is a Pb of Lithium or Lead…
I am planning to install two new lithium batteries Victron and indeed i will buy an extra BMS for safety. I am planning to interface them with Mastervolt via the Masterbus digital input device (connected to the Ve Bus BMS)which will to stop charge or stop load of the mastervolt devices including the alternator.

Envoyé de mon iPhone

Juan de Zulueta
SM 32
Ophelie X
Guadeloupe

Le 16 déc. 2021 à 07:08, Dean Gillies <stella@...> a écrit :



Hi James,
Those are very sensible considerations. I am also a big fan of Gel's, except for their cost and energy density as you point out. I have happily used them in many military projects over the years where safety and ruggedness were paramount.

I cannot speak for every external BMS system, but my REC BMS and I'm sure the vast majority of others, do provide over-voltage protection against charge sources regardless of whether they are controlled and/or monitored by the BMS.  The BMS will disconnect the LFP battery when an over voltage is detected. 

With regard to the other safety issue you mention, where a short occurs in the lead battery of a directly-connected hybrid system, is mitigated by means of the series fusing provided on both the LFP and Lead batteries. In my system for example, 400A class T fuses protect both batteries.
I don't know what the fusing arrangement is on LFP batteries with internal BMS.

It's worth noting that most (if not all) external BMS units are fail-safe. The LFP is dis-connected by default and is only connected when all parameters are within spec.  In the event of a failure of the BMS, the LFP is disconnected. (Another reason that it's nice to have the lead component in the circuit to keep the lights on). 


cheers,
Dean
SV STELLA
A54-154

 

 


--
Juan de Zulueta
OPHELIE X
Super Maramu #32


--
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com

--
Juan de Zulueta
OPHELIE X
Super Maramu #32