Domestic battery replacement..

[David Mack]

Maybe it's a Samsung thing.

[Alan de Enfield]

3 minutes ago, nicknorman said:

Arrr you going to tell us how you dunnit?

 

Type it out in Word and then cut-and-paste onto the forum.

 

A 'right faff' but if you want it, then that seems to be the only way.

[nicknorman]

3 minutes ago, Alan de Enfield said:

 

Type it out in Word and then cut-and-paste onto the forum.

 

A 'right faff' but if you want it, then that seems to be the only way.

Ok thanks. I think I’ll stick with being dimensionally incorrect!

[Rob-M]

David is making use of an Android keyboard feature I expect which means you get different options such as ² when keeping your finger on a key. 2 ⅖⅔² can be typed from the 2 key in this mode.

[Murflynn]

75mm2 is easy to write and should be clear enuff for most folks - even the super-pedants couldn't misinterpret that.

[ditchcrawler]

13 hours ago, nicknorman said:

Basic physics, if you want to drop voltage you need resistance. If you have resistance and current you have power, which becomes heat. Of course you are right in that if you choose a fairly fat cable that is very long, the same heat is dissipated in the cable but over a much longer length, and therefore the temperature rise is less. But that is not what the person in the video was doing, she was using 6mm cable. And with no fusing.

 

On my own installation I have a 500A fuse built into the Mastershunt, which is adjacent to the battery positive. There is about a couple of feet of 75mm cable that runs over the wooden battery box between battery positive and mastershunt positive. Not really any scope to develop a short. I am well aware of what 600Ah of lithium batteries could do if they are angered, and the thought of 75mm copper cable turning to vapour is not appealing.

Actually it was a bad move on my part suggesting the fusing on your boat Nick as its built to a very high standard, but I bet you will find lots of boats out there with a cable between the second alternator and the domestic battery bank with no fuse in it, lots even go to the battery side of the alternator, I also bet a lot of them drop a bit of voltage when the alternator is working hard.

[MtB]

22 minutes ago, David Mack said:

See my post above.

Curiously my superscript is smaller than Alan's!

 

Yeahbut we wanna no how Alan dunnit on a propa puter!

[nicknorman]

1 minute ago, ditchcrawler said:

Actually it was a bad move on my part suggesting the fusing on your boat Nick as its built to a very high standard, but I bet you will find lots of boats out there with a cable between the second alternator and the domestic battery bank with no fuse in it, lots even go to the battery side of the alternator, I also bet a lot of them drop a bit of voltage when the alternator is working hard.

I’m sure you are right and there is of course a case for not fusing the alternator cable as a blowing fuse could trash the alternator. In my case by having a fuse rating around 3 times the max expected current, hopefully the fuse will not “age” due to getting hot and eventually blow due to old age.

 

The BSS requires the alternator to be connected to the boat side of the battery master. But I can’t really see it making a difference in an emergency, with a major short circuit, pungent smoke and flames, one is presumably supposed to reach into the engine bay to shut off the master switch. Hmmmm, not likely!

 

And then of course having shut of the master switch, with the engine still running the alternator can still feed 100A or more into whatever fault that might be causing the problem, if the fault is boat side of the switch.

 

I think the main point of having the alternator route via the switch is so that the engine area is “dead” when working on it, rather than for some emergency situation. But I will admit to having the alternator on the battery side when we had lead acid, due to the slight voltage drop the switch created. Now we have lithium and smart alternator controller, I no longer need that as the alternator voltage is sensed at the battery.

[Rob-M]

4 minutes ago, MtB said:

 

Yeahbut we wanna no how Alan dunnit on a propa puter!

In Windows you can hold Alt and type 0178 on the number keypad.

[nicknorman]

Just looking at the spec on my cells, internal resistance 0.2 to 0.3 milliohms. 4 cells in series gives around 1 milliohm. So in a dead short, 13v across 1 milliohm gives 13,000A. I have 3 such strings in parallel, giving 39,000A. That would make a bit of a mess of 70mm cable I suspect. Ok one is not actually going to get that much current in practice, but it is still going to be “A LOT!”.

[Murflynn]

22 hours ago, nicknorman said:

 

 

The BSS requires the alternator to be connected to the boat side of the battery master. But I can’t really see it making a difference in an emergency, with a major short circuit, pungent smoke and flames, one is presumably supposed to reach into the engine bay to shut off the master switch. Hmmmm, not likely!

 

 

 

I would presume that a good installation would have the battery master switch (emergency isolation switch) in a readily accessible location which would not require lifting the engine bay cover.

[nicknorman]

41 minutes ago, Murflynn said:

 

I would presume that a good installation would have the battery master switch (emergency isolation switch) in a readily accessible location which would not require lifting the engine bay cover.

But that’s not what the BSS requires. It’s OK to have the switch under boards provided it’s label is in clear view.

[Alan de Enfield]

42 minutes ago, Murflynn said:

 

I would presume that a good installation would have the battery master switch (emergency isolation switch) in a readily accessible location which would not require lifting the engine bay cover.

 

You would have hoped so, but there was a recent thread regarding moving 'his' master switches to mount on the bulkhead above & alongside the batteries, citing "master switches must be as close as possible to the batteries'. Now, not only must he access the engine space, but must also lean over, potentially fizzing, about to explode, batteries.

 

Not my idea of a good installation.

[MtB]

1 minute ago, Alan de Enfield said:

 

You would have hoped so, but there was a recent thread regarding moving 'his' master switches to mount on the bulkhead above & alongside the batteries, citing "master switches must be as close as possible to the batteries'. Now, not only must he access the engine space, but must also lean over, potentially fizzing, about to explode, batteries.

 

Not my idea of a good installation.

 

Tricky innit.

 

Why would the batteries need emergency isolating? If the problem is a fire 'boat side' of the isolator then leaning over the batts doesn't matter. If the batts are fizzing from an internal short circuit turning them OFF won't make any difference....

 

 

[Alan de Enfield]

1 minute ago, MtB said:

 

Tricky innit.

 

Why would the batteries need emergency isolating? If the problem is a fire 'boat side' of the isolator then leaning over the batts doesn't matter. If the batts are fizzing from an internal short circuit turning them OFF won't make any difference....

 

 

 

But, just one example, - the supply lead to the Inverter has chafed and now shorting onto the Hull / engine (whatever), "1000s" of amps rushing to escape the battery you need to disconnect the supply.

[MtB]

3 minutes ago, Alan de Enfield said:

 

But, just one example, - the supply lead to the Inverter has chafed and now shorting onto the Hull / engine (whatever), "1000s" of amps rushing to escape the battery you need to disconnect the supply.

 

Nah, the fuse does that for you. Just get of the boat!!

[nicknorman]

15 minutes ago, Alan de Enfield said:

 

But, just one example, - the supply lead to the Inverter has chafed and now shorting onto the Hull / engine (whatever), "1000s" of amps rushing to escape the battery you need to disconnect the supply.

I think toxic smoke from burning insulation might determine human behaviour! But anyway, the inverter should be fused.
The other thing to bear in mind is that a battery isolator is probably rated for 2 or 3 hundred amps max. With 2 or 3 thousand amps, chances are the contacts are already welded closed and opening the switch will do nothing.

And anyway, what happens if this fault occurs when you are not on the boat, asleep etc? The safety of the boat’s electrical system can’t depend on human intervention.

Edited February 5, 2022 by nicknorman

[MtB]

2 minutes ago, nicknorman said:

I think toxic smoke from burning insulation might determine human behaviour! But anyway, the inverter should be fused.
The other thing to bear in mind is that a battery isolator is probably rated for 2 or 3 hundred amps max. With 2 or 3 thousand amps, chances are the contacts are already welded closed and opening the switch will do nothing.

And anyway, what happens if this fault occurs when you are not on the boat, asleep etc? The safety of the boat’s electrical system can’t depend on human intervention.

 

All this whataboutery is good fun, innit! 

 

I do find the BSS a bit of a farce, particularly the need for labelling. Can you really imagine someone stopping to read all the labels to identify the locations of the battery and gas isolators under emergency conditions, instead of just ripping up the engine bay floors/just going straight for the battery wires and gas bottle valves, if not just running away and calling the fire brigade? 

 

 

 

 

[nicknorman]

4 minutes ago, MtB said:

 

All this whataboutery is good fun, innit! 

 

I do find the BSS a bit of a farce, particularly the need for labelling. Can you really imagine someone stopping to read all the labels to identify the locations of the battery and gas isolators under emergency conditions, instead of just ripping up the engine bay floors/just going straight for the battery wires and gas bottle valves, if not just running away and calling the fire brigade? 

 

You get the same thing on buses “fuel shut off under this hatch” - ideal for stopping a runaway bus!

But I think in part it is for third parties (rescue/emergency) to be able to find and isolate sources of energy following some serious incident, rather than for the boat owner to do so in the immediate event of fire/short circuit.

Edited February 5, 2022 by nicknorman

[Tony1]

On 01/02/2022 at 19:28, Barry Orton said:

Want to replace 2x SLA with 2x lithium.  Don't want to go hybrid.  Can they just be connected in the same way as the SLA's were or do any extra gizmos need to be added?

 

40A alternator to starter and 100A to domestic.

 

TIA

 

That thread mentioned is the length of a book, but it does have some critical information in there, and lots of tips from experienced users like Nick and Peter etc. 

 

I spent nearly £1400 on 400Ah of lithiums a year ago, and I very nearly destroyed them the very first time I tried to charge them using the alternator and A2B charger setup that I had. To be fair I am a numpty with electrics, but I would advise proceeding with caution. 

 

You probably know this already, but just in case- your 100 amp alternator is designed to be used with lead acids, and it will probably only give out about 50 amps at most if it runs on a continuous basis (which is what the lithiums will do) before it starts to overheat. Mine gets to over 100 degrees if I take more than 45 amps from it continuously.

Some people are ok with the alternators getting to 120 degrees, but when you think their normal temp is around 55-60 degrees, 120 degrees feels like pushing it a bit. 

 

The best solution is available from Ed Shiers as Nick mentioned, which is an alternator controller that will monitor the temp and dial the output down if it gets too hot, as well as lots of other clever things, but they do a cost a fair bit.

 

The way I ended up going was to use B2Bs, which I wouldn't really recommend, but will work in a basic way, if you cant afford the controller. 

If you do go the B2B route, be sure to test and check first to find out how much current your alternator can put out (at tickover) without getting too hot, and then get a B2B that puts out that level of current. 

Test at tickover because thats when the alternator runs slower, and is more likely to get hot- which is what will happen when you are going past a line of moored boats, or waiting in a lock, etc. Tickover is the 'worst case', so test it that way, as well at higher revs.  

There are Sterling units (BB1260 or BB1230) which have the option to switch to half power output, but most dont have that, so be sure not to buy a B2B that puts out more current than is safe for your alternator. 

 

I considered the thin wire route but I wasnt confident about being able to manage the voltage during charging, so I went B2B. 

But the other thing to mention is that if you decide to put in extra battery management features like BMV712 monitors or disconnect systems, that will quickly add up to a lot of money, so before jumping in, plan out your system, and discuss it here so that you can get an idea how safe it will be in terms of protecting the batteries. You may come away thinking you need a BMV712 or other stuff. 

 

ETA- when testing how much current your alternator can put out with out overheating, bear in mind you'll be running it in summer as well, so maybe allow a 10-15 degree margin for the temp. 

 

 

 

Edited February 5, 2022 by Tony1

[MtB]

9 minutes ago, nicknorman said:

You get the same thing on buses “fuel shut off under this hatch” - ideal for stopping a runaway bus!

But I think in part it is for third parties (rescue/emergency) to be able to find and isolate sources of energy following some serious incident, rather than for the boat owner to do so in the immediate event of fire/short circuit.

 

Yes I know that really, but I like moaning about it... (Can you tell?)

 

And yes I can see the usefulness of such labels but do they really need to be mandated in the BSS? 

 

I think they should be advisories, like the air vents. In fact the air vents are more important than labelling stuff nicely IMO.

 

[Tony Brooks]

34 minutes ago, MtB said:

 

Yes I know that really, but I like moaning about it... (Can you tell?)

 

And yes I can see the usefulness of such labels but do they really need to be mandated in the BSS? 

 

I think they should be advisories, like the air vents. In fact the air vents are more important than labelling stuff nicely IMO.

 

 

The BSC looks to me as if it is basically the old Thames Conservancy Launch Regulations plus a few bells and whistles and the TCLRs required labeling of fillers.

[David Mack]

1 hour ago, nicknorman said:

You get the same thing on buses “fuel shut off under this hatch” - ideal for stopping a runaway bus!

But I think in part it is for third parties (rescue/emergency) to be able to find and isolate sources of energy following some serious incident, rather than for the boat owner to do so in the immediate event of fire/short circuit.

Those notices are on the outside of the bus, where the emergency services can see (and expect to see) them. My fuel and battery cutoffs are located in a traditional engine room, as are the labels. The only engine room access is via two side hatches, open when we are boating, closed and locked when the boat is unattended. What use are those labels?

[MtB]

29 minutes ago, Tony Brooks said:

 

The BSC looks to me as if it is basically the old Thames Conservancy Launch Regulations plus a few bells and whistles and the TCLRs required labeling of fillers.

 

It seems a classic case of mission creep. Things that are nice to have and make for a better quality installation (like labels) get lumped in with the genuinely important stuff like checking for gas and fuel leaks. This pulls the whole scheme into disrepute IMO. 

 

Similarly the requirement for batteries to be fixed down in case the boat turns upside down. That happens a lot I would imagine although oddly, I've yet to see it.

[Tony Brooks]

7 minutes ago, MtB said:

Similarly the requirement for batteries to be fixed down in case the boat turns upside down. That happens a lot I would imagine although oddly, I've yet to see it.

 

I don't think that is what the BSS requires although some examiners may be gold plating it. I think the BSS requires the terminals/top of the battery to be protected from short circuits and the batteries be secured so they don't move with a 45 degree list on the boat. Hence then BSS suggestion that  putting them in a fixed box that comes half way up the battery meets the regulation. I accept that to meet that requirement many builders who put batteries in stupid places (contrary to the BMEA standards) find it easier to  strap the batteries down so they can be slid out of their position. On JennyB the domestic batteries were in a lift out steel box welded into the cruiser stern. The deck board was accepted as compliant although I did fit a secondary cover secured with door bolts that I felt had advantages. The engine battery was contained in a tray with about an 8mm up stand all round with a hinged wooden lid that dropped down and was secured with a cord.  This had about a 25mm down stand with cutouts for the battery cables. The up stand met the not moving bit and the hinged lid the protection from shorts and prevented the batteries falling over. This was also accepted as fully compliant.

#Its trikes me the BSS regulations about this, as written, are entirely sensible but common word of mouth interpretations of what they require are often "gold plated". This is not helped by the lack of cntrol the BSS office seem to have on examiners and their interpretation of the regulations.

 

A wide beam can easily heel to more than 45 degrees if hung up in a lock and GRP ones even easier, before they fall off the hang up - if they do! Narrowboats are probably more difficult to heel in that situation but it can still happen, like when a pound/reach drains.