Lifepo4 and led acid hybrid system

[Pecco 10]

I came across this video which refers to a couple of websites as well.

Does anybody have any experience or thoughts about it?

It would apear to be pretty simple....is it???

[CarpeDiem 430]

There's nothing unsafe with doing this (unless your BMS karks it).

There's a few gotchas:

You need a programable BMS that will switch off the Lithium-ion battery or it will overcharge... Usually one would program it for 3.55v/cell but you could be more conservative. 

This means that you won't get full capacity.

Because you are switching off at 3.55v, never getting into the CV phase of the charge cycle and not immediately putting load on the battery, you will create a memory effect in the Li and the addional capacity will eventually be locked out.

Once you start taking capacity out of the LA, which realistically will happen once you have used 40% capacity of the Li-ion  you need to fully charge the LA.  Yes there's some argument here for lead carbon and it's better psoc resistance to sulphation. 

Unicorn benefits of LC aside, to keep your LA in good shape it needs to go though the full charging cycle so now you are not benefitting from the advantage of fast charging which comes with Li.

If you just want to add capacity to your existing LA bank and live with the normal LA charging and battery life constraints of LA then this is a OK solution to achieve that. 

The "experts" will tell you "no way". The standards say don't do it. But there are plenty of people doing it... 

There's really no right or wrong way to do Li-ion.  There's just safe or unsafe... And so long as you choose safe, then it's just pros and cons of the magnitude of options... 

I think if I did this, I would want a redundant BMS to ensure I could shut off the charge bus. Cause if it doesn't shut it off you run the risk of a thermal runaway. And straight away I have blown the $$ I was going to save...

 

[K4309 258]

I investigated LiFePo recently. Ended up going with Lead Carbon. The benefits of Lead Carbon match all of the positive attributes of LiFePo, are 1/4 to 1/2 the cost and avoid all the risk of uncontrolled load dumps blowing your alternator (as well as other aspects of a simplified like-for-like install).

This guy talks with his hands a lot, has lots and lots to say but no actual detail. I don't understand how his proposed system works. It comes down to the charging and discharging voltages, which he didn't mention. He just showed a picture of Batman and Robin. Apparently they are complimentary?!? I felt more like I was watching a lifestyle coach than a techo guy (maybe just my perception, meaning, I felt he was trying to convince me of his idea, without giving any facts or details)

In general, if no-one else is doing it, there is a reason. He was making a big deal about not needing a DC-DC charger, but then needed to install a new AGM to make it work. Both are components that are required to safely charge a LiFePo from an alternator. I'm not sure how using one over the other gets you any further ahead, you still need to spend $$$ on another item so you can charge a LiFePo.

Did anyone get the actual details on how this is supposed to work? I may have missed it.

[CarpeDiem 430]

1 hour ago, K4309 said:

Did anyone get the actual details on how this is supposed to work? I may have missed it.

I didn't watch the video.  The principle is relatively straight forward but requires an understanding of charge discharge profiles... 

1. Lead acid rests at ~12.8v and floats at ~13.2v

2. LFP rests at 13.32v (there is no float for lfp) 

So when in parallel, without any load, the LFP is float charging the LA. 

As the load comes on the LFP will provide the power to the load.

Once the lfp goes below the LA float voltage, power will be taken from the LA, but the amount of energy between 12.8v and 13.2v is insignificant and just surface charge. So the lfp will still provide the bulk of the power. But now the LA is no longer floating. 

Once the lfp reaches around 12.8v more power will be drawn from the LA but it still won't be as much as what's being provided by the lfp.   But now the LA is starting to work. 

When the system reaches 12.2v the lfp has supplied ~90% of its capacity and LA has supplied 30% of its.

Nows probably time to stop, but if you kept going, eventually the LFP would cut out due to low voltage, and you could keep taking the LA all the way down to 9.6v... (if you dared). 

Now comes the recharge... 

Your charging system starts throwing power at both batteries. The voltage will rise gradually and the Li will be held back from accepting charge by the internal resistance of the LA. 

Eventually the charge voltage will reach 14.2v (or 14.1v depending on how conservative you want to be) this will be achieved only when enough Watts have been jammed back into the LA... Once this voltage is reached the lithium will sense High Voltage and the high voltage disconnect will kick in.

The lithium is now disconnected.  And the charging source can continue to push the LA battery to absorbtion voltage (14.4v or 14.7v).  Once the charger finishes it goes into float mode @13.2v and the Li detects that the high voltage condition is gone and reconnects

The cycle starts all over again... 

 

 

[Frank 157]

Our land yacht has LA for the start battery and 330 AH LifePo for the house battery, Its a fantastic but expensive set up with the beating heart of it being the battery which cost north of 6K.  Battery quality  like most things is variable but if you go for a quality product it makes sense to protect the asset by following the OEM's advice on equipping and configuring the system. I will watch the video later but i suspect it does not follow accepted practice and that could have expensive consequences.

 

 

 

[K4309 258]

1 hour ago, Frank said:

Our land yacht has LA for the start battery and 330 AH LifePo for the house battery, Its a fantastic but expensive set up with the beating heart of it being the battery which cost north of 6K.  Battery quality  like most things is variable but if you go for a quality product it makes sense to protect the asset by following the OEM's advice on equipping and configuring the system. I will watch the video later but i suspect it does not follow accepted practice and that could have expensive consequences.

 

 

 

The video most definitely does not follow accepted practice. Whilst I skipped through it looking for the techo / charging detail, it did not provide any.

CD's summary far exceeds any info in the video.

In engineering (or almost anything) there is the old saying of what happens in theory and what happens in reality. The theory sounds great, but the reality of having two different batteries with completely different chemicals and charging profiles, both aging and deteriating at different rates... There are just waaayyyy too many variables to make this work safely in reality. That, and I think you loose many of the advantages of LiFePo by parallelling it with LA.

It doesn't even touch on other charging sources (solar, wind) and doesn't discuss what happens at partial states of charge, or current draw while charging. He did make a big deal that you need the AGM in good condition. I can see if the AGM was in 'used' condition, this system would not work at all, the AGM would flatten the LiFePo, and you'd be back to candle light...

Fast charging is one, but even the video said you need to monitor alternator temp. Was talking about using a handheld infrared thermometer. That sort of hap-hazard system is going to cause major problems.

[Psyche 633]

Heres a good article on lithium drop in's https://marinehowto.com/drop-in-lifepo4-be-an-educated-consumer/

[waikiore 399]

As a detached observer still with LA that work -I see a terrible amount of money being spent on Lipo batteries without anyone upgrading their charging setup, this seems to defeat the purpose as they are not getting:

1 Full Charge

2 Rapid recharging 

3 Long life

4 Real safety

At the price difference of traditional LA or even quality AGM batteries -I have yet to be convinced -also the issues with solar voltage etc etc.

I think starting with a quality alternator and charge controller may be a better investment for those wishing to upgrade......

[K4309 258]

2 hours ago, Guest said:

It seems a symbiotic relationship with little downside but not ABYC endorsed so I did not employ.

I Went 4s2p with two bms’s (4cells in series x2, paralleled) the same capacity as LA’s.(460Ahr) alternator to splitter . Set 55%, ~80A in the flat of charge curve, never goes over 60C.

Advantages experienced to date:

*With the type of sailing I’m doing ( every couple of weeks, the motor to hoist is enough to keep in 20/80% zone for supposed longevity. I often use my field kill switch to stop charging while extended motoring depending on cruising plans.

*Fridge stays on at dock (no shore power) to provide discharge in case soc is too high on returning. Also I sometimes leave another load on if it’s >80.Means beer is always cold.

*Every few months before a longer trip I charge from dock to at least 3.6V per cell into the knee .( Top balance each bank to tail current of~ 0.2A) Its a bit tedious currently but I am about to fit an active balancer spec’d 5A to cut in at 3.4V/cell.

*Was pretty much the same cost as same capacity AGMs. 2k$  Flatten Cu pipe for bus bars etc, cost conscious build.

*My system: 8 CALB 230Ahr cells and two JBD 200Ahr. Plus Victron bmv 712 for over/under V audibles pre hvd/lvd.

*I have all requisite fuses, T, anl etc.

*Open to critique as I would like to add low cost additions improvement/safety features.

*’Have just received a dcdc 18A iso Victron Li to SFA starter on Black Friday special to look after my 14yro start battery! $150. As there it was getting a bit neglected at Li charging spec.

*cold 🍺24/7 .

 

 

 

 

 

Just to clarify Guest, how do you manage the load dump from the BMS onto the alternator?

Are your Li parallel with your AGM start?

[K4309 258]

39 minutes ago, waikiore said:

As a detached observer still with LA that work -I see a terrible amount of money being spent on Lipo batteries without anyone upgrading their charging setup, this seems to defeat the purpose as they are not getting:

1 Full Charge

2 Rapid recharging 

3 Long life

4 Real safety

At the price difference of traditional LA or even quality AGM batteries -I have yet to be convinced -also the issues with solar voltage etc etc.

I think starting with a quality alternator and charge controller may be a better investment for those wishing to upgrade......

I agree with this. 

A safe Li install is expensive. You can get almost all the benefits of Li with lead-carbon at between 1/4 and 1/2 the cost, and with a like for like swap out of your existing AGM's, zero risk and zero new system hardware.

Lead-carbon tolerate Partial state of charge (no sulphation) can be charged fast (up to 30%of C), can give big discharge load if you want to run coffee makers or microwaves. They are heavier than Li, but most of these installs are going into floating caravans, I don't see weight as a factor. Depending on your brand and repeated DoD, Lead-carbon have a huge cycle life, and in many situations will match Li for cycle life.

Sure, Li are great, but as soon as you apply $$$/Amphr, they are shithouse. If you look at the $$$/Amphr for Lead-Carbon, all the Lithium talk just looks like a marketing / PR blitz.

[K4309 258]

12 minutes ago, Guest said:

Yep, but through an argofet isolator. (Splitter). So same benefit of there always being a load.  Also as 4s2p they don’t charge at the same rate. In theory they should but inherent variables of individual cells and then parallel banks make it unlikely. Victron alarm can be set to a level to warn you when approaching once you get to know their behaviour .  If you want “hands off” idiot proof, you will pay dearly.

Not saying my choice is the ideal budget setup, but I am comfortable with it’s requirements and it’s a vast improvement over the FLA’s especially in the amount of power useable and replenishable quickly.

Do those argofets have diodes in them? Is the much of a voltage drop over them? And do you need to adjust your alternator output voltage to account for the voltage drop? (assume that is easy if you have a smart regulator).

I was looking at argofets but was told they were a bit old tech and the voltage drop was sub-optimal. Noting that old tech is normally bomb-proof tech in my view. Nothing wrong with it if you understand it.

[CarpeDiem 430]

3 minutes ago, K4309 said:

Do those argofets have diodes in them? Is the much of a voltage drop over them? And do you need to adjust your alternator output voltage to account for the voltage drop? (assume that is easy if you have a smart regulator).

I was looking at argofets but was told they were a bit old tech and the voltage drop was sub-optimal. Noting that old tech is normally bomb-proof tech in my view. Nothing wrong with it if you understand it.

Argofet is a Victron brand name - they use MOSFETs internally, all MOSFETs, like all electronics induce a voltage drop.  These units suffer between 0.03v and 0.01v drop depending on the current and the units rated capacity.

If you consider that something invented in 1959 makes it old-tech then I guess that they are old-tech - but you will find them in the power supply of pretty much every modern day piece of electronics...

[CarpeDiem 430]

30 minutes ago, Guest said:

Yep, but through an argofet isolator. (Splitter). So same benefit of there always being a load.  Also as 4s2p they don’t charge at the same rate. In theory they should but inherent variables of individual cells and then parallel banks make it unlikely. Victron alarm can be set to a level to warn you when approaching once you get to know their behaviour .  If you want “hands off” idiot proof, you will pay dearly.

Not saying my choice is the ideal budget setup, but I am comfortable with it’s requirements and it’s a vast improvement over the FLA’s especially in the amount of power useable and replenishable quickly.

Nice setup - great to see the 2p configuration, awesome to see the insulation between the EVE cells, and great to see that you have compression!  This is a smoking good DIY build!

What BMS are you using?  What isolator are you using?  Separate charge and load busses?

[Pecco 10]

Interesting thoughts!

Thank you for that. 

With the little knowledge I have I figured it seemed overly simplified...

In the end consuming less of everything apears to be the simpliest answer to most urges.....maybe....

🙂 well, I've got a fridge, tiller pilot (also a windvane), chart plotter, ais and now a radar.....330 watts solar pannel and 130amps house battery. Hence my interest in the hybrid system.. also my LA battery is not done yet...

I suppose, I ll have tu start anew.

Cheers

[K4309 258]

6 hours ago, Guest said:

Typo- DIY solar is a forum.

should read Overkill solar who uses JBD boards and tweaks them.

https://overkillsolar.com/

Regarding lead carbon (firefly)being cheaper. Not from my perspective as I had them on order from Maine in 2019 with free freight to NZ. 
Covid delayed it so I cancelled. Fortunately, as some people were having failures and the warranty logistics made it untenable. (Free freight was a one off)

The CALB (or EVE) cells were cheaper than AGMs of same capacity. I don’t think the public perception of LiFePO4 and safety requirements are well understood. They are Li ion transfer but not Li-Ion & considerably safer. A couple of levels of safety is adequate, imo.
Also, name brand proprietary systems are 3x price of diy with exceptional hands off monitoring capability. Bells and whistles. Not my requirement.

Psyche link covers it. Off grid garage,diy solar, endless YouTube coverage , Nordkyn design.

https://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/

I've never heard of Firefly, and can't understand the economics of shipping one off battery purchases around the world.

I went Kijo lead-carbon. Couple of supplies in Auckland, Best Batteries and iVent. I went with iVent, based in East Tamaki. Ivent Solutions Limited

Got 300 A/hr for $900.

No sulphation so tolerant of Partial State of Charge. i.e. you can leave them half charged, which is very common on boats with a mix of alternator and solar.

Can charge at up to 0.3C, but recommended between 0.1C-0.2C. Compared with not being able to go over 0.1C for AGM. So for my 300 A/h I can charge at 60Amps (0.2C). I have a 75 amp alternator, de-tuned a touch via a Balmar smart regulator. I haven't seen them take more than 45-50Amps, but what this means is I can replace a days power consumption in 30mins to 1 hr of running the engine*. That covers getting the anchor up and motoring out of the bay typically.

There is a tail charge when the charge acceptance drops off like a standard LA. But because of the Partial SoC you don't actually need to fully charge them. Solar is ideal for topping up that last 5 amps or so and does it well on modest sized panel set ups.

These Kijo batteries are cheap, right. You can't get AGM's cheaper than that. There may be questions over cost / quality. So if they only last 5 years I haven't lost anything compared with going with AGM's again. Because they don't sulphate, I'd expect them to last indefinitely (given my typical cycle numbers per year, need to use the boat more).

For a budget, DIY lithium install I was looking at about $2,500 - $3,000 for the same usable amp hours (100-150 A/h Li compared with 300A/h L-C at 50% DoD).

To get better value for money the Li would need to last 17 years compared to L-C lasting 5 yrs. It is implausible than electrical or electronic items last 17yrs plus in the marine environment without something going wrong. That, and $3,000 doesn't get top shelf Li, it gets lower to mid range products. Odds on the Kijo Lead-carbons have a greater likelihood of lasting 5 years than cheap Li batteries last 17 yrs. And the deciding factor is the initial outlay. There is far less dollar risk going with the lesser outlay, that and I don't have $3k to drop on boat batteries. If I did have $3k to drop on the boat, there are many, many other shiny toys (essentials) I could spend that type of money on.

* daily power consumption on a modest 37ft with electric fridge / freezer, instruments, lights, diesel heater (draws power), wireless cellular broadband and one or two devices for the kids. 25-50Amp/hrs per day. Currently charging with a 75Amp alternator and a 90W solar (was 180w solar but one posh enertec panel died after 4 years). I use a 20w solar to float the batteries so they are always 100% at the start of a trip. I should be able to go 3 days without any battery charging at all, so I don't need to run the engine daily. Means if we get a low solar day, or stay on anchor in a bay for a day or two it's not mission critical on battery charging.

[CarpeDiem 430]

25 minutes ago, K4309 said:

For a budget, DIY lithium install I was looking at about $2,500 - $3,000 for the same usable amp hours (100-150 A/h Li compared with 300A/h L-C at 50% DoD).

According to the spec sheet on those batteries you can get 1000 cycles by taking them to 100% dod.

As a weekend warrior, assuming one is sailing every weekend, that would be 10 years... at 100% DOD... which is very impressive, on paper...

However the spec sheet does not say what the impact on DOD has on capacity.  Generally using a LA battery at 50% DoD will reduce the useable capacity, so your 50% becomes smaller and smaller over time and this happens much quicker than it does for a Li-ion battery.

28 minutes ago, K4309 said:

No sulphation so tolerant of Partial State of Charge. i.e. you can leave them half charged, which is very common on boats with a mix of alternator and solar.

What I have read on these doesn't say, no sulphation, rather it says that sulphation due to psoc is minimized.   Would be interesting to see some real world results.

[CarpeDiem 430]

7 hours ago, Guest said:

They are Li ion transfer but not Li-Ion & considerably safer.

They are Lithium-ion.  They have a Iron Phosphate cathode and a graphite anode - Li-ions move through the electrolyte from the cathode to the anode and vice versa.  That's the definition of a Li-ion battery - there's a lot of misconception that LiFePO4 are not Li-ion batteries mainly cause people don't want the chemistry associated with the less safe variants. 

They are considerably safer than other Li-ion chemistries, but they are not the safest.  This honor, (currently), goes to LTO (Lithium Titanate Oxide) - LTO isn't really suitable for boat retrofit setups because of the voltage range so we don't see it much - a lot of the audio guys, you know those ones that drive around blasting out loud music for 5 seconds at 2am are using LTO - some of those systems draw 1000amps...

Sparky, the POAL electric tug, uses LTO cells - the brand is Toshiba SCIB - some European cars now use LTO cells as the starter battery (BMW and Mercedes are two I know of) the battery will outlast the car... 

[Island Time 1,235]

I know there are some who wish to build their own battery banks. That's fine, but consideration should be given to the NZ electrical regs. Lithium - LiFePo4 (really the bets for marine, and very safe) MUST have audio and visual alarms fitted to warn of an impending disconnect, BEFORE it happens (for whatever reason). This is the stumbling block for most "drop in" solutions.

Multiple chemistry battery banks and not acceptable under the standards. That does NOT mean you can't have LiFePo4 house batts and Lead Acid start batts.

Be aware that a DIY (or any) install that does not meet the NZ regs (or those of flagged state if not NZ) very likely voids your insurance policy. Read the fine print on yours!

Alternator/Charge system protection is not difficult - an Argofet splitter (FET based not Diode) and preferably an alternator protection device (Balmar and Sterling have good ones for a few hundred) will protect an alternator.

Also note that a properly installed and configured BMS will NEVER need to do an emergency disconnect, unless something has failed. A properly installed and configured system will shut off charge sources  when  batts are full, BEFORE emergency shut off. It will also turn them back on when lower limits are reached.

The regs are like they are to try to prevent "Dark Ship" - where without warning, suddenly no electrical power, navigation gear, lights etc. 

Modification to an alternator is not expensive or difficult, but good  external regulators are reasonably expensive. The real cost is not the batts for LiFePo4, they are not really much  more than good VRSLA's. The additional cost in extras ( BMS units, remote battery relay, Argofet or DC-DC, etc) can be a couple of thousand.  It is very realistic to get a good working compliant system on a DIY build/Install for 3-4k.

Lead Carbon does not compare (IMO) . It's heavy, 30% of Capacity max charge rate is typical. LiFPo4 is light, and charges at 1c - 100% of capacity is typical.

As a professional in this area, I will not build a system for a customer that does not comply with the NZ standards.

If you are considering battery chemistries, please read the Marine How To Article already posted above https://marinehowto.com/drop-in-lifepo4-be-an-educated-consumer/ for some understanding of the topic.

Oh, and sorry to the posters above with overkill or JBD BMS's - Ive not seen one of those that complies with the regs for NZ - No external alarms etc. I'd be happy to be corrected on this if you've found one though, its a rapidly changing world...

[K4309 258]

1 hour ago, CarpeDiem said:

According to the spec sheet on those batteries you can get 1000 cycles by taking them to 100% dod.

As a weekend warrior, assuming one is sailing every weekend, that would be 10 years... at 100% DOD... which is very impressive, on paper...

However the spec sheet does not say what the impact on DOD has on capacity.  Generally using a LA battery at 50% DoD will reduce the useable capacity, so your 50% becomes smaller and smaller over time and this happens much quicker than it does for a Li-ion battery.

What I have read on these doesn't say, no sulphation, rather it says that sulphation due to psoc is minimized.   Would be interesting to see some real world results.

Yes, Agree with your points. When I say 'no sulphation' it is just a faster way of typing a post than saying 'sulphation due to psoc is minimized'. The point being they are far more resilient to sulphation at PSoC than LA / AGM

But the cost comparison shifts the decision scales markedly. $900 compared with $3,000 or more.

On IT's comments about Lead-Carbon not comparing to LiFePo, yes, I understand LiFePo are far more advanced, again they are also far more expensive.

Question @Island Time, how many people actually charge or have alternators big enough to charge LiFePo at 1C? It sounds great to be able to do that, but you must need a donkey of an alternator, with associated heavier wiring and control systems etc? A typical LiFePo install must be what? 200Ah? My understanding is that alternators start getting really tricky over 125amps?Belt loads, pulling configurations, cooling etc. Obviously unless you are some massive expedition yacht or something. I'm talking in the context of the average cruising boat.

[CarpeDiem 430]

1 hour ago, Island Time said:

That's fine, but consideration should be given to the NZ electrical regs. Lithium - LiFePo4 (really the bets for marine, and very safe) MUST have audio and visual alarms fitted to warn of an impending disconnect, BEFORE it happens (for whatever reason). This is the stumbling block for most "drop in" solutions.

Hey IT,

I have a couple of questions, which you may be able to answer regarding the standard AS/NZS 3004.2:2014. (which is where the audio and visual alarm requirement comes from)

This standard does not appear to be legislated.  The latest version of the standard that is legislated in the Electricity Act is 3004.2:2008 (ref: https://www.legislation.govt.nz/regulation/public/2010/0036/latest/DLM2763782.html?search=sw_096be8ed81c5a64a_3004_25_se&p=1&sr=3)

MBIE had a working document in mid 2021, one of the recommendation of which was to update the NZ electricity legislation to change the legislation from the 2008 reference to 2014 reference.  This has clearly not happened.

I have asked two electricians how this standard is a requirement and neither have been able to tell me - they just say "it's the latest" so it's what we use.  While I can accept that, it's not the same as it being a legal requirement.

Can you please advise what leads you to the conclusion that this standard is the requirement?

Secondly, it appears that 3004.2 is only applicable if, and only if, the installation is mains connected.  Mains connections includes self generation, not just shore power connection.

Eg, the statement on many NZ websites selling Li-ion drop-in batteries says something like:

Not suitable for boats connected to shore power and needing an Electrical Warrant of Fitness as the AUS/NZS 3004.2:2014 standard need the battery to be able to disconnect from all charging sources.

When I asked an inspector about this, he said that he thought this was because the only way that the standard can apply in the first place is if it comes through the legislation and for this to happen one has to have mains power (or hv DC) in the first place as that's the only way the Act comes into force.  And without mains power the standard doesn't become applicable to the installation.  But he didn't know for sure... and he wasn't a EWOF inspector...

Do you think that the standard would only apply if the boat has mains power?