How to deal with the alternator?!

[Statistical]

Originally Posted by s/v Jedi

Okay, that boostcap has some merit but you need to understand that this is in fact six capacitors connected in series, which means the capacitance is only 1/6 of the capacitance of the individual capacitors.

Elon Musk sold Maxwell after deciding he was not gonna power Tesla’s with these, but that doesn’t mean anything for this application.

I guess it would be used as follows: installed just by itself, instead of a start battery and charged by a dc-dc converter from the house battery.

Questions:

- would the dc-dc converter be switched off when the engine isn’t needed?

- what would the recharge time be?

- how many starts on one charge?

- how much energy is required to start (larger) marine diesels?

- modern diesels need electric power to power their electronics to be able to start, so it’s not just about cranking the engine. They have a minimum voltage requirement during cranking. Can the boostcap provide that minimum voltage?

- what is the actual lifespan in our engine rooms and how does that translate to cost per year in comparison to top of the line AGM options. And LTO?

I don’t see any possibility for it to outperform an Odyssey battery.

Cost is the big killer. There are ultracapacitor banks designed for starting even large semi-trucks. One advantage which isn't a huge one for more boaters is they don't lose max amps in cold conditions.

Starting an engine takes negligible amount of energy but a huge amount of power which means in a cost is no object analysis ultracapacitors are the ideal system especially in a scenario like on a boat where you have a house bank.

The problem is cost does matter and AGM starter batteries are just dirt cheap and will last 5-7 years.

If ultracapacitor were 80% cheaper yeah it would be a no brainer and LFP for house bank and ultra cap for starter likely would be pretty common.

[Fuss]

Originally Posted by noelex 77

I understand what you have done and I don’t see any reason why it would not work. People prepared to experiment with alternative systems deserve our praise for testing the viability of these and working out the kinks.

However, I still don’t see the advantages. You are replacing a simple, small and cheap AGM battery with a larger, more expensive and complex combination of lithium batteries and an ultracapacitor. At the same time, you are ignoring one of the chief goals required of a starting battery, which is to provide a system that is totally independent from the house bank.

I’m not sure I’m going to get the point across, but here goes…
In the old days, the battery needed to be independant as if it was not at a full state of charge due to other parasitic loads, then there was a good chance it would not start. With lead, dedicated is the only way.
These days it’s not so important as lifepo4 can start from a much lower doc than lead. So you can make your start battery an extension of the house bank…if it also has a large capacity like 280ah.
This gives redundancy as all cells can be the same.
But you still need a backup starting method, something I never had with the 2 lead batteries.
So to create my backup start method I installed the boostcap…out of necessity mainly and of course a bit of experimentation.

[nfbr]

My “last resort” start is a Supercap Jump Starter that uses and boost charges itself from a nearly flat battery, USB or near anything.
It wont crank for long but has plenty to start my 45hp diesel.

https://youtu.be/bMXyoIBJyJA?si=l65zpQwOtFvdqGM8

Means I dont need to worry about lithium batts or keeping it charged.

No dedicated start battery required. Just House (48) and Boat (12)

[Fuss]

Originally Posted by s/v Jedi

Okay, that boostcap has some merit but you need to understand that this is in fact six capacitors connected in series, which means the capacitance is only 1/6 of the capacitance of the individual capacitors.

Elon Musk sold Maxwell after deciding he was not gonna power Tesla’s with these, but that doesn’t mean anything for this application.

I guess it would be used as follows: installed just by itself, instead of a start battery and charged by a dc-dc converter from the house battery.

Questions:

- would the dc-dc converter be switched off when the engine isn’t needed?

- what would the recharge time be?

- how many starts on one charge?

- how much energy is required to start (larger) marine diesels?

- modern diesels need electric power to power their electronics to be able to start, so it’s not just about cranking the engine. They have a minimum voltage requirement during cranking. Can the boostcap provide that minimum voltage?

- what is the actual lifespan in our engine rooms and how does that translate to cost per year in comparison to top of the line AGM options. And LTO?

I don’t see any possibility for it to outperform an Odyssey battery.

I did this as I had no start redundancy, I’ll try to answer the questions in order without repeating myself from earlier posts.

It’s not installed by itself ,its paralleled to the eve280 and thus charged by the eve280.

There is no dc to dc charger as the paralleled Eve keeps it full

Recharge time is instant after a start… it loses 1v per start roughly

On its own , 2 starts, (you normally would never run it in this mode) but paralleled with the eve280 , which is normal mode, I’m not sure, much more than 30.

To start my 3500w starter diesel, needs 2 800cca batteries so no redundancy when on fails… and talking of failure at 6+ years, it was nearly immediate, one minute all ok and then I guess it got a plate short and that was it.

Boostcap is not designed to run on its own, it needs the eve280 in the background. The engine needs no power once running, it needs 12v for the stop solenoid and the engine instruments used to run off the start batteries which gave me safety problems so now the run off a 24 12 dc dc converter from the house bank. So the safety problem was that the flyback diode failed behind the engine instruments and switched the engine off. It has this diode due to the spike problem than exists with all sensitive things connected to start batteries.

I don’t install any batteries in the engine room

Odyssey battery … probably true when you have a start backup that is another odyssey. If you have no backup and your big diesel needs 2 batteries to start then my solution works very well.
But, you could remove your 2 Odyssey batteries and make another house bank and have even more redundancy with a parallel supercap.

Remember the house bank and paralleled supercap will provide engine starting power probably 10 times more than the Odyssey solution as the Odyssey does not have 280ah behind it.

Redundancy is everything.
I hope my iPad question answering is ok and without too many spelling mistakes.

[s/v Jedi]

Alright, let me figure this out… the supercap is installed parallel to the house battery. This is the use case for the boost cap as presented by Maxwell and of course works to handle peak loads in a system with enough storage capacity but not enough high power handling capacity.

I don’t think it was designed to be paralleled with LFP batteries though. The reason is that you have no control over the charge current from battery to capacitor, which for LFP with it’s low internal resistance means it doesn’t take care of the peaks by itself and the battery still gets these peaks with high probability to go beyond the BMS maximum current limit with the BMS intervening en disconnecting the battery.

This installation setup as boost cap is meant for batteries that self limit their output current due to internal resistance. Like regular LA batteries or “slow” deep cycle batteries used for “quick” applications like engine starting.

Also used for storing energy from regeneration like when a car needs to slow down.

To find out, you need to measure peak current output from the LFP battery. My guess is that somehow your battery can start the engine by itself without the boostcap so can can just as well remove it.

Also, this means it does not provide redundancy. The setup I described, with a dc-dc converter (stupid one as power supply is enough) does provide that function and does limit the battery output current to safe levels. But it’s still just an extension of the house battery and I don’t think it will keep its charge long enough to be labeled a redundant source for starting the engine. But when one has multiple house batteries, like I recommend, then it seems just fine from a technical standpoint.

That leaves comparison with something like an Odyssey battery which isn’t just compatible in this application (a smart dc-dc converter with AGM charge profile would be better) but also retains its charge for years without help and can start an engine a hundred times or more. And that’s before comparing price.

Note that an Odyssey isn’t a regular LA start battery. It doesn’t require multiple ones in parallel. It has a 6kA Isc so it’s internal resistance is more like LFP than traditional start batteries. I would compare it closer to an LTO battery than a typical LA start battery.

[rslifkin]

Those thin plate Odysseys do make great starting batteries, only downside is the price compared to other AGMs.

In my mind, regardless of what your primary starting power source is, there should be a switch-selectable second source just in case of a failure. In my case, I have 2 engines and a generator, so 2 start batteries. Each engine and the gen has a switch to select which start battery it's using. Or I could pull out the jumper cables to start from the house bank in a real pinch. On a single engine boat, the house bank would likely be the selectable backup starting power source.

[Fuss]

Originally Posted by s/v Jedi

I don’t think it was designed to be paralleled with LFP batteries though. The reason is that you have no control over the charge current from battery to capacitor, which for LFP with it’s low internal resistance means it doesn’t take care of the peaks by itself and the battery still gets these peaks with high probability to go beyond the BMS maximum current limit with the BMS intervening en disconnecting the battery.

This installation setup as boost cap is meant for batteries that self limit their output current due to internal resistance. Like regular LA batteries or “slow” deep cycle batteries used for “quick” applications like engine starting.

Also used for storing energy from regeneration like when a car needs to slow down.

To find out, you need to measure peak current output from the LFP battery. My guess is that somehow your battery can start the engine by itself without the boostcap so can can just as well remove it.

.

It works fine paralled with lifepo4, even better than lead but there are rules.

A very good question about self limiting, it works like this as we don’t want the complexity of a dc dc charger.

Firstly under no circumstances is a 0v supercap allowed to be paralleled with anything. It needs to be precharged if it has not been paralled for a while. You don’t have to do this, it does it itself as it is connected to a red high wattage light that precharges. When the light is red then no paralleling. When the light is out or dim, then the supercap can be paralled, takes 15 mins. Anything over 10v on the supercap and paralleling is ok.
From this point on, there is nothing to do and it is self managing.
If you manually unparalleled , then the red light would come on as a warning.

Yes the lifepo4 can start the engine, 1st level redundancy

Yes, the supercap can start the engine and very importantly also from a 10v flat source battery, so in a way 2 more levels of redundancy.

Originally Posted by s/v Jedi

Also, this means it does not provide redundancy. The setup I described, with a dc-dc converter (stupid one as power supply is enough) does provide that function and does limit the battery output current to safe levels. But it’s still just an extension of the house battery and I don’t think it will keep its charge long enough to be labeled a redundant source for starting the engine. But when one has multiple house batteries, like I recommend, then it seems just fine from a technical standpoint.
.

I hope I understood this part correctly and my explanation above answers the question of redundancy and self regulating…anything over 10v and it can be paralled to the Eve lf280.

Furthermore, when starting the Maxwell does all the work and the Eve none. The clamp meter read 50a peak between the two. At one stage I had just thin cables connecting the supercap to the Eve and this was ok for starting but of course it would not support paralleling if the supercap was only at 10v.

I’m not sure the Odyssey can engine start more than the Eve lf280 and supercap as it only has 100ah behind it.

I see that the Odyssey 100ah has nearly 1200cca. Ok, I am pretty sure that this would have solved my 2 battery problem had I gone down this route and then I would not have needed the supercap solution.
But the advantage for me that I now have a 3rd house bank and I sort of like that idea as 1 house bank and another that also starts the engine seems a bit low on redundancy to me.

[s/v Jedi]

Originally Posted by Fuss

It works fine paralled with lifepo4, even better than lead but there are rules.

A very good question about self limiting, it works like this as we don’t want the complexity of a dc dc charger.

Firstly under no circumstances is a 0v supercap allowed to be paralleled with anything. It needs to be precharged if it has not been paralled for a while. You don’t have to do this, it does it itself as it is connected to a red high wattage light that precharges. When the light is red then no paralleling. When the light is out or dim, then the supercap can be paralled, takes 15 mins. Anything over 10v on the supercap and paralleling is ok.
From this point on, there is nothing to do and it is self managing.
If you manually unparalleled , then the red light would come on as a warning.

Yes the lifepo4 can start the engine, 1st level redundancy

Yes, the supercap can start the engine and very importantly also from a 10v flat source battery, so in a way 2 more levels of redundancy.



I hope I understood this part correctly and my explanation above answers the question of redundancy and self regulating…anything over 10v and it can be paralled to the Eve lf280.

Furthermore, when starting the Maxwell does all the work and the Eve none. The clamp meter read 50a peak between the two. At one stage I had just thin cables connecting the supercap to the Eve and this was ok for starting but of course it would not support paralleling if the supercap was only at 10v.

I’m not sure the Odyssey can engine start more than the Eve lf280 and supercap as it only has 100ah behind it.

I see that the Odyssey 100ah has nearly 1200cca. Ok, I am pretty sure that this would have solved my 2 battery problem had I gone down this route and then I would not have needed the supercap solution.
But the advantage for me that I now have a 3rd house bank and I sort of like that idea as 1 house bank and another that also starts the engine seems a bit low on redundancy to me.

No, I think you don’t understand me: when the boostcap can start the engine then that doesn’t mean you have redundancy. It only means you have redundancy if your LFP fails and you still have another source to start your battery. When you connect the boostcap in parallel to the battery, you lose that redundancy because the cap will discharge into the failed battery. You could regain redundancy by putting something like ArgoFET in between.

Also, this only works in your specific case for two reasons:

1. Your house battery is 12V. Most of the lithium based systems will be (often now but much more even in the future) a different voltage, like 24V or 48V. I even think we will see 96V and 144V as people start using electric propulsion more.

2. As I suspected, you can start your engine straight from the LFP battery. This means you either have a very small engine or a very big BMS or no BMS or one that isn’t based on MOSFET’s. Most boats will have the MOSFET based BMS in their house batteries in which case engine starting is likely not supported.

I don’t mean that the peak from charging the boostcap is what triggers BMS protection. It is the engine starting that will do it because the house battery is not isolated from the starter circuit during starting.

All this is why a dc-dc converter is the superior option as it will work for every scenario.

About backup: a backup is something that should only seldomly used. A jump starter would work but only when it is fully charged and ready to go. Not many can bring up the discipline to keep it ready at all times.

Two house batteries with a dc-dc converter with a boostcap to give it enough oompf for peak loads like engine start, bow thruster, windlass, electric winch etc. is a viable option. The boostcap would be installed close to the peak load while the dc-dc converter can be anywhere in between battery and boostcap.

The thing is that the boost cap can be replaced with a small LTO or Odyssey AGM battery and you get similar performance for a better price, plus it holds much more energy than a capacitor, allowing hundreds of starts before requiring charging.

[Fuss]

Originally Posted by s/v Jedi

I did and found nothing that will start an engine. Your inability to point one out implies there is nothing.

https://www.ebay.de/itm/235618585892...Bk9SR_6i-eCLZA


Well, there it is above and even less than 150€...might even be able to get one for 120€ as they are open to offers. 120€...unbelievable!!!
Start every marine diesel regardless of size, and certainly bigger ones than my 6l 135hp.
Its smaller than every other solution.
It starts from only 10 volts input so 3 lifepo4 cells ...the ultimate in redundancy. Try that with LTO.

That means that a modern Lifepo4 boat does not need any FLA, AGM TPPL at all in any shape or form.


Can you imagine 150€ for an engine start solution that charges in the shortest time imaginable, is backed up by the lifepo4 house bank, giving it nearly indefinite amount of starts. No BMS, no DC to DC charger or converters.


The simplest most compact solution for the world cruising mono especially when the diesel is over 70hp.


You never know, with a bit of haggling, might even be cheaper than a brand new horrible flooded lead acid one...or AGM or the usual suspects that are in the marina battery pile after 4 years.

[s/v Jedi]

Originally Posted by Fuss

https://www.ebay.de/itm/235618585892...Bk9SR_6i-eCLZA


Well, there it is above and even less than 150€...might even be able to get one for 120€ as they are open to offers. 120€...unbelievable!!!
Start every marine diesel regardless of size, and certainly bigger ones than my 6l 135hp.
Its smaller than every other solution.
It starts from only 10 volts input so 3 lifepo4 cells ...the ultimate in redundancy. Try that with LTO.

That means that a modern Lifepo4 boat does not need any FLA, AGM TPPL at all in any shape or form.


Can you imagine 150€ for an engine start solution that charges in the shortest time imaginable, is backed up by the lifepo4 house bank, giving it nearly indefinite amount of starts. No BMS, no DC to DC charger or converters.


The simplest most compact solution for the world cruising mono especially when the diesel is over 70hp.


You never know, with a bit of haggling, might even be cheaper than a brand new horrible flooded lead acid one...or AGM or the usual suspects that are in the marina battery pile after 4 years.

No, a capacitor does not provide the redundancy because it doesn’t hold the charge long enough. It is dependent on the other battery to function.

Starting at 10V is crazy, this requires much more current in an already stressed setup. Your ideas become more extreme as we go.

These capacitors are great for what they are designed for: handle peak loads for a battery, with that battery taking care of storing the energy.

[Fuss]

Originally Posted by s/v Jedi

No, a capacitor does not provide the redundancy because it doesn’t hold the charge long enough. It is dependent on the other battery to function.

Starting at 10V is crazy, this requires much more current in an already stressed setup. Your ideas become more extreme as we go.

These capacitors are great for what they are designed for: handle peak loads for a battery, with that battery taking care of storing the energy.

Ok, no redundancy then ....but it recharges in minutes from any 12v charging/converter/battery device.



Between 10v and 16v it can start the engine several times.


My Boostcap was specifically designed for this purpose by Maxwell...The trucking industry have been using this technology for years and emergency starting between 10 and 16v.


It also costs less than 150€

[Fortytwo]

https://www.sterling-power-usa.com/alternatorprotectiondevice.aspx