Hypothetical lithium question

[lustyd]

Not the usual Lithium will make us all burn to the waterline thread (I hope!). It just occurred to me that if lead is unable to continuously supply enormous amps when compared to lithium, might there be situations where additional devices have been added without uprating wiring but where the lack of amps in the lead bank has prevented fire? In which case, could we go from mildly warm wiring with slightly annoyed electronics, to a fire when the battery is upgraded and effectively unlimited amps are available?

TLDR - is a wiring size review quite important when upgrading?

 

[[167227]]

All well designed electrical systems will have correctly sized fuses to protect wiring. If you're relying on wiring size to protect your boat from fire, it's only a matter of time before you have one.

Your question doesn't really make sense, a battery will only provide the power its asked for by a load. If you're adding equipment then look over your wire sizes and more importantly your fusing.

 

[lustyd]

All well designed electrical systems will have correctly sized fuses

That may well be the case, but the Jeanneau I have didn't have any fuses from the factory as far as I can tell so I think it's more common than you're imagining. Add in 20 years of owner upgrades too.

A battery will supply power up to it's capability for what is asked of it. A Lithium battery may well be able to supply considerably more than the outgoing lead one.

 

[[167227]]

That may well be the case, but the Jeanneau I have didn't have any fuses from the factory

Is there not a breaker panel?

Lead acids can give a massive amount of current, that's why we use them for start batteries and windlass batteries. Usually lithium is restricted by the BMS. Off the top of my head the lead acids I had before could push just as much current as the lithium I have now.

I still stand by the fusing comments, that's number one in any electrical installation, and I would 100% review that first

 

[lustyd]

Is there not a breaker panel?

There's a switch panel. Don't assume that because there are switches that there is circuit protection. No fuses anywhere near the battery, none near the main isolator switches, and as far as I can tell none in the over-complex switch panel which is based on latching relays and LEDs. No fuses and no thermal breakers that I could see anywhere, and they're not on the original wiring diagram either.

 

[Buck Turgidson]

There's a switch panel. Don't assume that because there are switches that there is circuit protection. No fuses anywhere near the battery, none near the main isolator switches, and as far as I can tell none in the over-complex switch panel which is based on latching relays and LEDs. No fuses and no thermal breakers that I could see anywhere, and they're not on the original wiring diagram either.

when was the boat built and is it CE marked?

 

[geem]

There's a switch panel. Don't assume that because there are switches that there is circuit protection. No fuses anywhere near the battery, none near the main isolator switches, and as far as I can tell none in the over-complex switch panel which is based on latching relays and LEDs. No fuses and no thermal breakers that I could see anywhere, and they're not on the original wiring diagram either.

Cost saving by the manufacturer?
Our 1980 boat has fusing for windlass, engine and domestic circuits in its original set up. Each circuit on the main panel has a circuit breaker

 

[lustyd]

when was the boat built and is it CE marked?

1999 and yes, it's a Jeanneau so obviously CE marked

 

[Buck Turgidson]

1999 and yes, it's a Jeanneau so obviously CE marked

page 60

You're fine mate!

 

[lustyd]

page 60

You're fine mate!

Yes I have a copy of that, thanks . No protection on main battery cables, and those "thermal breakers" are relays with apparently extremely high ratings. I've certainly run more Amps than I'd expect to work through one with no bother at all (I added Starlink to the nav switch without thinking, then moved it when I realised). The fridge one actually needs the off button holding for 3 seconds to disengage the circuit. They certainly aren't sized to the load, being all identical, nor do I believe they are all sized to the wiring.

 

[penfold]

The breakers carry several times their rated current for short periods to allow for starting motors, they wouldn't be much use if they didn't. The diagram indicates the cable size changing according to load, I would be very surprised if the breakers don't change also although the diagram is illegible.

 

[lustyd]

The breakers carry several times their rated current for short periods to allow for starting motors, they wouldn't be much use if they didn't. The diagram indicates the cable size changing according to load, I would be very surprised if the breakers don't change also although the diagram is illegible.

OK here is the switch board:
Scheiber Switch Panel PCB with Relays and LED Indicators | 36.16205.00
There are no components on the reverse side
Here is the relay:
PCD-112D2MH Datasheet Tyco, Download PDF
The other components are switches, one normally open to switch on the relay latch, the other normally closed to switch it off.

The relay is rated to 10A. That doesn't make it a breaker, it just means it might catch fire if you pass 100A through it as far as I can tell.

Not that any of this is relevant to the thread

 

[penfold]

OK here is the switch board:
Scheiber Switch Panel PCB with Relays and LED Indicators | 36.16205.00
There are no components on the reverse side
Here is the relay:
PCD-112D2MH Datasheet Tyco, Download PDF
The other components are switches, one normally open to switch on the relay latch, the other normally closed to switch it off.

The relay is rated to 10A. That doesn't make it a breaker, it just means it might catch fire if you pass 100A through it as far as I can tell.

Not that any of this is relevant to the thread

I think it's a pretty rum do that the circuit diagram of your AWB shows breakers but there are no breakers; the links you provide demonstrate that well enough. Having no circuit protection at all aside from no volt release is bizarre and quite unsafe, I'd be planning to remove the panel and replace it with one that has protection, but that's no quick or cheap job. It is relevant as you are asking about electrical safety and yours is lacking through french perfidy, unless there are overcurrent detection circuits hiding on the board and I'm not seeing them.

 

[dankilb]

On our Jen Scheiber panel each ‘switch’ is actually also a magnetic (I think) circuit breaker.

 

[dankilb]

Re: the original question, wires don’t draw high currents down themselves (so to speak) without either a load or a short circuit at the other end. So having lithium or lead makes no difference. Short any wire on the boat with your lead bank and it’ll burn/melt - same with lithium. Similarly connecting the biggest load on your boat (say windlass) to a small wire will melt/burn it whether or not there’s a lead or lithium bank on the other end (both can provide more than enough current). Otherwise wires don’t sit there drawing current - so having a battery capable of larger loads doesn’t matter in that sense. But I’m no electrician - that’s just my lay understanding.

 

[lustyd]

wires don’t draw high currents down themselves

Yes I know this, but if a lot of things had been added to a single circuit, all drawing current then the wire is at risk. Lead is not able to continually supply high current, hence the C20 ratings. My question was that if the lead had been struggling to keep up, and old lead may well have, then potentially the lithium which will absolutely not struggle to supply all it's Ah in very short timeframe could provide sufficient juice to start a fire. Obviously the fire risk would always have been there, but the ability to deliver more amps more consistently may heighten that risk.

 

[geem]

.......

Yes I know this, but if a lot of things had been added to a single circuit, all drawing current then the wire is at risk. Lead is not able to continually supply high current, hence the C20 ratings. My question was that if the lead had been struggling to keep up, and old lead may well have, then potentially the lithium which will absolutely not struggle to supply all it's Ah in very short timeframe could provide sufficient juice to start a fire. Obviously the fire risk would always have been there, but the ability to deliver more amps more consistently may heighten that risk.

If lead couldn't keep up, then you would have a lower voltage. If an item such as a motor was running at lower voltage it would still pull the same Watts but at higher current. I don't think you have any worry that lithium will be more of a risk since voltages tend not to dip with lithium. The biggest risk is not having adequate cable fusing regardless of battery type

 

[sgodseafarer]

Not the usual Lithium will make us all burn to the waterline thread (I hope!). It just occurred to me that if lead is unable to continuously supply enormous amps when compared to lithium, might there be situations where additional devices have been added without uprating wiring but where the lack of amps in the lead bank has prevented fire? In which case, could we go from mildly warm wiring with slightly annoyed electronics, to a fire when the battery is upgraded and effectively unlimited amps are available?

TLDR - is a wiring size review quite important when upgrading?

Your point about lead batteries supplying fewer amps compared to lithium is intriguing. It's definitely possible that adding more devices without upgrading the wiring could lead to issues. Safety is paramount, so considering the potential risk of fire due to inadequate amp supply is a wise perspective.

When you're upgrading batteries, especially to higher-capacity options like lithium that can provide a lot more amps, reviewing your wiring size is indeed important. Ensuring that your wiring can handle the increased current is crucial to prevent overheating and potential hazards. Taking this step could save you from troubles down the line.

In essence, your thought process is spot on. It's always a good idea to think holistically about your electrical setup and not just focus on the battery itself. Safety and functionality go hand in hand.

 

[dankilb]

Okay. Sorry for the confusion, I see what you mean now - adding more loads because the lithium allows you to draw/use more current.

But the wiring should be sized and circuit protected adequately for the loads anyway. It would be that way from the factory and additions since should have followed the appropriate spec (often in the instructions for marine-type devices or using a wire spec calculator or ohms law).

Fair enough that many boats end up with rats nests of layer upon layer of wiring and the thought of every load attached drawing its max current at the same time thanks to the affordances of a higher current/capacity battery bank is worrying. But it shouldn’t be that way! Spec the wiring correctly to begin with and/or check and replace any that isn’t.

I can’t imagine your Jen didn’t have some sort of individual circuit protection from factory. Our 1989 has what I’d describe as ‘good’ wiring for its time (decent quality generously spec’d wires properly terminated and those expensive mag breakers on every circuit - with a full diagram that corresponds to the numbered tags still on each end of every wire). My rewiring additions inc 50mm/1awg to a post next to the panel (as it also goes on to the windlass) and I just checked and that claims 345amps - so no worries there.

So I’m still not sure I understand the theoretical problem?!

 

[lustyd]

Our 1989 has what I’d describe as ‘good’ wiring for its time (decent quality generously spec’d wires properly terminated and those expensive mag breakers on every circuit

I think we went though something of a switch fetish in the '90s which led to the overcomplicated setups like I have which look good and ensure the owner pressed lots of buttons every time they arrive so they can pretend it's important like a space ship. No protection though that I can see, and even if there is, those boards are completely standard so the protection doesn't relate to the wire size. The original incoming wire is no bigger than 6mm either, which is absurd these days to cover everything. I've changed quite a bit to improve things so not overly worried it was just an idle thought