With lithium do we actually need a dedicated starter battery?

[s/v Jedi]

Originally Posted by CaptainRivet

Sure you have an AGM buffer battery where you can run your nav equipement independently from the house, you wrote it, showed the wiring schematic and even showed picture of the buffer AGM. Also part of your lighting strike prevention. Cannot find the thread right now but i remember i change some cabling on the buffer due to the thread as you had a better solution then mine was before.

Your buffer is a small AGM so you cannot use it as backup starter like i do with the Toshiba 20AH LTO SCIB. But you don't need that as you have 2 AGMs as 12Vstarter which also runs other 12V loads and also needed for the DC2DC for the alternators if i remember right, correct?

My alternator only charges an AGM start battery. There are dc-dc converters charging the house battery when I enable them and they detect a higher charge voltage from the alternator. But that is strict isolation and nothing is connected in parallel of my lfp house batteries, other than several lfp house batteries.

I have mentioned that one could add a small, “sacrificial” AGM battery to the alternator output to protect it’s diodes during HVC events. Incorrect charge parameters will reduce it’s lifespan significantly and using an isolator to charge both the start and house batteries from the alternator is a much better solution because you can add a small dc-dc charger to finish charging the start battery and keep it in float.

There are multiple ways something can be achieved but that doesn’t mean they are all equally good. The whole charging from alternator is flawed apart from when the engine is used for propulsion. And even that is questionable for a sailboat where the engine is supposed to be auxiliary!

[CaptainRivet]

Originally Posted by s/v Jedi

My alternator only charges an AGM start battery. There are dc-dc converters charging the house battery when I enable them and they detect a higher charge voltage from the alternator. But that is strict isolation and nothing is connected in parallel of my lfp house batteries, other than several lfp house batteries.

I have mentioned that one could add a small, “sacrificial” AGM battery to the alternator output to protect it’s diodes during HVC events. Incorrect charge parameters will reduce it’s lifespan significantly and using an isolator to charge both the start and house batteries from the alternator is a much better solution because you can add a small dc-dc charger to finish charging the start battery and keep it in float.

There are multiple ways something can be achieved but that doesn’t mean they are all equally good. The whole charging from alternator is flawed apart from when the engine is used for propulsion. And even that is questionable for a sailboat where the engine is supposed to be auxiliary!

Yes i know your starter setup, have that schematic saved. The small AGM as dump load with argofets was discussed here as well. I actually have still exactly that setup with argofet with an FLA starter for the BB engine which also works as dump load for the STB one. FLA where new as replace by boatyard and because they screwed them and didn’t wanna give me money, so keep them till they die. Buffer is 40AH LTO now as i added the LTOs ment as starter for BB till the lead dies to the buffer..

But we are talking/discussing here about a buffer battery at the navstation eg powering all nav electronics independently from house. I remember that i even mentioned to you that i don't wanna have an AGM in the salon that could gas out and suggested to use LTO and you said that an AGM is perfect as buffer because it like to be floated.
You also explained that you disconnect mast instruments in a lightening and can run them from the buffer independently from house.

[newhaul]

Originally Posted by CaptainRivet

Yes i know your starter setup, have that schematic saved. The small AGM as dump load with argofets was discussed here as well. I actually have still exactly that setup with argofet with an FLA starter for the BB engine which also works as dump load for the STB one. FLA where new as replace by boatyard and because they screwed them and didn’t wanna give me money, so keep them till they die. Buffer is 40AH LTO now as i added the LTOs ment as starter for BB till the lead dies to the buffer..

But we are talking/discussing here about a buffer battery at the navstation eg powering all nav electronics independently from house. I remember that i even mentioned to you that i don't wanna have an AGM in the salon that could gas out and suggested to use LTO and you said that an AGM is perfect as buffer because it like to be floated.
You also explained that you disconnect mast instruments in a lightening and can run them from the buffer independently from house.

Except I thought it was a discussion about keeping lead based start battery with Lifepo4 house or not .

[CaptainRivet]

Originally Posted by newhaul

Except I thought it was a discussion about keeping lead based start battery with Lifepo4 house or not .

I answered the question what a buffer is and what it does when you Kuss said that wrong and dangerous and non of you both answer my question why...buffer on boats is 20 years old and many circumnavigating boats have them due to the advantages i described above.
And nothing is dangerous here beside having an AGM in ths salon that can get a thermal runaway and thats why i exchanged it to LTO which cannot get a thermal runaway and is the safest battery chemistry worldwide avaliable to endconsumer.
So please tell me fact based whats wrong and dangerous here with a buffer???

And because the LTO can do 10C and 20C peak and the windlass cable runs past it i taped into it with a selection switch and can start the engine and use windlass with it too, just because the LTO can and another backup is always good. And like this you have the redundancy with a 2nd battery as emergency starter that has a lifespan of min 20 years. Its your personal risk assessment if you need a 3rd battery as pure starter or not...

[Fuss]

if I answer Rivet with what is wrong with your buffer battery post you will then argue with me with another huge complicated post or posts and then start parroting the new information in your future posts.

[CaptainRivet]

Originally Posted by Fuss

if I answer Rivet with what is wrong with your buffer battery post you will then argue with me with another huge complicated post or posts and then start parroting the new information in your future posts.

What exactly is wrong with a buffer? What exactly is dangerous????
A buffer battery is the same then a starter battery, just instead connected to starter its connect to your switchboard..only difference. And the same then a bowtruster battery but instead bowtruster its connected directly to switchboard...again only difference. A bowtruster battery is nothing else then buffer for the house or starter due to the long cable runs and its power needs...

FACTs not blabla!

[newhaul]

Originally Posted by CaptainRivet

What exactly is wrong with a buffer? What exactly is dangerous????
A buffer battery is the same then a starter battery, just instead connected to starter its connect to your switchboard..only difference. And the same then a bowtruster battery but instead bowtruster its connected directly to switchboard...again only difference. A bowtruster battery is nothing else then buffer for the house or starter due to the long cable runs and its power needs...

FACTs not blabla!

Honest question .
Are there any boat manufacturers that don't have a dedicated start battery for the iron wind as a default for the electrical system?

[CaptainRivet]

Originally Posted by newhaul

Honest question .
Are there any boat manufacturers that don't have a dedicated start battery for the iron wind as a default for the electrical system?

Thats not the question here...the question is a buffer wrong and dangerous.

Another question why then a lot and increasing number of battery companies start to offer hybrid lithium starter and house batteries?

And to your manufacturer question: short answer its a money and warranty game...if you look at the glued together yogurt cups with CE cat A they give a f... about security.

Manufacturers still have lead as standard and if an lithium option the cheapest way via DC2DC so they need a starter not only as starter. Its a money game. Even regulated alternator are 99% retrofit and not avaliable as options as the engine manufacturer not offering them. And if not offered from engine manufacturer the boat manufacturer doesn't touch it as the waranty is on the engine and engine manufacturer responsible for it.
And the 1 or maybe 2% are the semi and custom build higher end cats where they outsource the whole electric system to a subcontractor installing the whole electrics and responaible for warranty claims and they stick what people know and make more money by selling starters, DC2DCs....2nd they all install drop ins and a lot dropins exclude starter application because the manufacturer of the battery uses mosfet BMS that from the BMS manufacturer are not allowed to be used as starter.
And battery companies wanna sell a house and a starter, best a lithium starter as huge marigins on them.

Exception are the hybrid cats but here again its costs as the hybrids still have a standard alternator and therefor also a 12V or 24V starter and also 12/24V ECU when eg commonrail. Again cheapest to use lead.
If done right they would have 48V starter and ecu starting from the propulsion bank but sales are too small and the lead way much cheaper.

[thinwater]

Google "dump load" and "dark ship".


If the BMS disconnects, the alternator power has nowhere to go. You will get a major voltage spike that can damamge electronics and the alternator.


If the BMS disconnects you will have no power. No lights, no nav, and in most cases, no engine. Kind of like the Dali.


A simple, proven solution is to use one LA battery. But I'm sure you can engineer around this.

[newhaul]

Originally Posted by CaptainRivet

Thats not the question here...the question is a buffer wrong and dangerous.

Another question why then a lot and increasing number of battery companies start to offer hybrid lithium starter and house batteries?

And to your manufacturer question: short answer its a money and warranty game...if you look at the glued together yogurt cups with CE cat A they give a f... about security.

Manufacturers still have lead as standard and if an lithium option the cheapest way via DC2DC so they need a starter not only as starter. Its a money game. Even regulated alternator are 99% retrofit and not avaliable as options as the engine manufacturer not offering them. And if not offered from engine manufacturer the boat manufacturer doesn't touch it as the waranty is on the engine and engine manufacturer responsible for it.
And the 1 or maybe 2% are the semi and custom build higher end cats where they outsource the whole electric system to a subcontractor installing the whole electrics and responaible for warranty claims and they stick what people know and make more money by selling starters, DC2DCs....2nd they all install drop ins and a lot dropins exclude starter application because the manufacturer of the battery uses mosfet BMS that from the BMS manufacturer are not allowed to be used as starter.
And battery companies wanna sell a house and a starter, best a lithium starter as huge marigins on them.

Exception are the hybrid cats but here again its costs as the hybrids still have a standard alternator and therefor also a 12V or 24V starter and also 12/24V ECU when eg commonrail. Again cheapest to use lead.
If done right they would have 48V starter and ecu starting from the propulsion bank but sales are too small and the lead way much cheaper.

Great word salad .
My interpretation of it is even when the manufacturer installs lifepo4 house banks they st8ll use lead based start banks and DC2DC .
I say let's do what the manufacturer does. They have done the reserch and decided that this is the appropriate decision.

That is the end result of 18+ pages of debate.
Use a lead based start bank a DC2DC to charge the lifepo4 house bank .

[dave777]

Originally Posted by newhaul

...
Use a lead based start bank a DC2DC to charge the lifepo4 house bank .

What DC2DC charger(s) do you recommend?


We can set our Solar and shore power chargers for LifePO4, just leave alternators on the Lead Acid starters?

[CaptainRivet]

Originally Posted by thinwater

Google "dump load" and "dark ship".


If the BMS disconnects, the alternator power has nowhere to go. You will get a major voltage spike that can damamge electronics and the alternator.


If the BMS disconnects you will have no power. No lights, no nav, and in most cases, no engine. Kind of like the Dali.


A simple, proven solution is to use one LA battery. But I'm sure you can engineer around this.

1) the starter and windlass is connected via a breaker directly to shunt of BMS but before cutoff relay. So the BMS can take the usage into acount for eg SOC etc but even if BMS cuts off i can still use the house for starting and windlass. Nothing can happen, if a defect the breaker or the main battery bank fuse disconnects. If LCV thats at 12V or 3.0V per cell means i still have more power to start in the house then in a 100% full lead and thanks to LTO buffer plotter and ap still working. Even if at LCV 2.5V i prefer to ruin the house before running aground if having no time to switch to backup/buffer. Insured and conform with iso like this.

2) i have an LTO buffer as backup starter which has no BMS, no LCV, HCV at 20V, can be charged /discharged -30
to 80 degrees celcius, you can drill into it while you use it, it looses 0.3V in a year of no use doesn't matter at which SOC, no floating needed but you can at any SOC for years as LTO don't care at any voltage a 12V regulator (even a slightly damaged one) of any chemistry can deliver. Which means also there won't be a cutoff from the alternator as LTO stays connected all the time as lead does. LTO starts both engines even at 9V when all is dark already (tested that) and in 2 min one alternator brought it up to >12V, 5 min one alternator brought it back to 40% SOC and another 10min its at 85% SoC where i normally keep it.
Means also any lead is long dead, useless and/or empty before the LTO is. In every possible use case the LTO is still there and start the engine when the lead is long gone.

[newhaul]

Originally Posted by dave777

What DC2DC charger(s) do you recommend?


We can set our Solar and shore power chargers for LifePO4, just leave alternators on the Lead Acid starters?

That is entirely subjective myself I use a 40 amp DC2DC from renogy. ( got a great deal)
My alternator is a 75 amp 12v internally regulated stock chevy. My bank is only 250ah lifepo4.
Alternator is a third level backup charging source . Mainly only used entering or leaving a marina or Anchorage.

[CaptainRivet]

Originally Posted by dave777

What DC2DC charger(s) do you recommend?


We can set our Solar and shore power chargers for LifePO4, just leave alternators on the Lead Acid starters?

Renogy 12V 50A , no need to pay victron premiums for the same. And compared to victron all renogy DC2DC have a switch where you can reduce ouput by 50%, great for eg motorsailing long distances.

[CaptainRivet]

Originally Posted by newhaul

Great word salad .
My interpretation of it is even when the manufacturer installs lifepo4 house banks they st8ll use lead based start banks and DC2DC .
I say let's do what the manufacturer does. They have done the reserch and decided that this is the appropriate decision.

That is the end result of 18+ pages of debate.
Use a lead based start bank a DC2DC to charge the lifepo4 house bank .

I would believe a Henry Amel to really test and make an appropriate decision..and he put an seperate externally regulated big alternator as stock config on maramu and super maramu already 20 years ago and engine manufactured bailed out of warranty as said to much load on crankshaft bearing and Amel simply took over the warranty for the engine...non had a problem with the bearings...

At any french mass production boat the controller would sell his mother to safe 1 Cent more per boat...test, whats that?

And by the way my FP Lavezzi was delivered from factory with 300AH hybrid starter/house in STB and 100AH starter in the BB hull. Simple and cheap and i kept it like this, just replaced lead with lithium.