The Gravy Boater

Well the alternator is 95 amp, the last diode was rated at 100 amp, it was fused at 150 amp (which I don't understand)... and one output melted on it after 2.5 years. Is there a rule of thumb for the ampage rating of stuff you should connect to an alternator? i.e. how much higher should it be?

£160 odd for a three way 120 amp.

Ha! Yes no relays out of a Christmas Cracker please... sounds like they were bigging up risk for sales purposes.

Found a moment to look for it... I was reading the blurb at the bottom of this page about the various charging options from alternator: https://sterling-power.com/products/split-charge-diodes-70-200a-2-3-outputs Probably unrelated to what you are discussing or sales blurb... I've just been injesting this stuff all day. "2) Split charge relay. This system is both dated and extremely dangerous, unless understood and the correct relay used for the correct job, ie current limiting relays may be required for safety reasons. The good side is, that it is easy to fit and requires no alterations to the standard engine system, but, it merely connects the domestic battery bank to the engine battery via a relay, which is energised when the engine starts. The bad side (and the very dangerous side) is that a relay is prone to over loading. Say, for example, you have a 70A relay on your system and a 55A alternator, all seems great, but if you fit a 1500W inverter which can draw 150A and one morning the domestic battery is flat. So, you start the engine to charge the domestic batteries, the 70A split charger relay will come online to enable the alternator to charge the domestic battery bank. Then you load your inverter to 150A, the 150A will not be drawn from the domestic battery because it is flat but can be drawn from the engine battery (which is full). That means you will draw 150A up the split charge cable and through the 70A relay. If you are lucky you will destroy the relay, if you are not so lucky then you will set fire to the cross over cables, hence the dangerous aspect, A Sterling Currint limiting relay prevents this problem. (see later) The system must be suitable for the purpose for which it is installed and this is clearly not. "

Will do upon the morrow but got to shoot off for now. Thanks for the replies.

I've read a couple of things in passing about 'battery feedback' when using relays and that this is potentially hazardous? Is this the bullshit? For reference... my domestic battery bank is 3x180ah sealed lead acid... starter is 90ah... bowthruster was 110ah as far as I can remember.

Thanks. How does that work with the domestics also having input from a solar array? And also voltage drop from draw on the domestics?

A-ha... now I get it. The alternator just feeds the domestics... when they are full the domestics feed the Starter... when the Starter is full it feeds the Bowthruster? That's also a solar dump, right? Because the solar (connected to the domestics) wouldn't normally feed anything to the other batteries.

Well, that's two votes for that I guess... also, that's some messed up Camberwick Green 🙂

I'll goggle it. Not yet seen that is an option for a three way battery setup with one alternator. Sounds like witchcraft. Burn the witch 🤨. Still trying to read up on this stuff but I just need a simple, affordable and safe bulletproof replacement.

My boat has a three way Split Charge Diode to service my Starter, Domestic and Bowthruster batteries. Apparently the output that was going to my starter battery is now dead, so as a temporary measure this has been switched to the bowthruster while I source a replacement. I've checked and the other batteries are still getting good charge. My domestics are also serviced by a large solar array and I also have a genny so I have no immediate power concerns. The alternator is an original 90 or 95 amp (depending on who you talk to) Vetus brand. The diode is unmarked but RCR think it is a 100 amp Stirling. There is also a Stirling Alternator Regulator. The alternator is fused at 150 amps, which seemed odd to me... but maybe someone can explain if this is usual. RCR have suggested I replace the three way Split Charge Diode with a 150 or 200amp version and mount it directly to the steel for better heat transfer (the original was on wood). This setup ran without issue for 2.5 years, so what are the most likely causes of the burnout? Throughout that time I have used my 2.1kw Stirling Inverter/Charger while the engine has been on with varying loads... certainly much higher loads in the past than I have done lately. So I can't think of a specific event that might have put stress on the setup. Regarding a replacement... everyone says Victron or Mastervolt but what is adequate and above all safe in this instance? I know there is a voltage drop associated with diodes. Are the type that claim to overcome this legit? https://sterling-power.com/collections/relays/products/volt-drop-alternator-splitting-system-pro-split-r?variant=882764291 Thanks for reading and all advice welcome.

My Bluetti isn't directly plugged into an alternator but I have been charging it via my boat's inverter all year, because I have some solar going to my LA and some directly to the unit. If I'm getting enough solar off my main array it will run the 500w a/c brick, but sometimes I also run the engine to keep the LA battery voltage up. As far as my inverter is concerned, it's just another 500w appliance. I'm aware of the issues with alternators and lithium installs which was yet another reason why I didn't go that route.

Unless you're an electrician, buy the cells, build the battery yourself and already have an inverter etc I don't think it makes any sense to do a lithium battery installation on a boat now. You're better off leveraging the economies of scale offered by the off-grid market in the States and buying a Lithium Power Station which has everything... battery, BMS, solar controller, inverter and all the connectivity. Portable and with a four year warranty now (for Bluetti, at least). If you want Lithium it's a no brainer. Others will disagree, of course. 🤷‍♂️

That will be because they are just offering the RCR retainer as part of the deal. £65 quid/year, bascially. https://www.rivercanalrescue.co.uk/breakdown-cover/help-me-decide/

So what you're saying is, because you ain't gonna be moving the fuel... you need...

Craftinsure +1 Not had to claim off them so far but certainly the cheapest I've found and minimal questioning.

When I got my boat I also had three domestic batteries that the surveyor had pronounced dead... or moribund, at least. One thing to remember about surveyors is that they have to come up with something to justify their fee and batteries are low hanging fruit. As others have said... you only really know their condition when tested properly or over time. Mine were fine for another six months but only really because I was charging across country and running the engine half the day... they were not retaining charge but it didn't affect me because I was otherwise occupied. As for battery types... others will disagree but I really don't think the various species of mid range LA are worth the money. You are better off spending that premium on larger bog standard LA and solar to maintain it. At the end of the day if it ain't lithium you are still dealing with the same limitations of lead acid to some degree. As was mentioned the physical space available for batteries is a major factor. I had three 110ah batteries in suspiciously large steel trays that an engineer mentioned were 'truck battery sized'... I eventually replaced these with three 180ah LA that fitted them perfectly and that they were clearly intended for. A decent solar array takes away most of the anxiety of maintaining LA. As for lithium... if you simply don't need it, no reason to get it, but if your decision was cost related it is no longer necessary to pay someone to do a murderously expensive lithium boat install. If you're not an electrician it is more sensible nowadays to get a Portable Power Station such as those offered by Bluetti, Jackery et al... they are relatively cheap due to the size of the offgrid market, portable (you can take it with you, including if you change boats) and you can plug a variety of panels into them depending on the spec. The warranty on mine is now four years and if it hasn't broke by then it's rated to have 80% capacity 10 years from now. I run both battery types. But you pays your money and makes your choice.

Just go down to Three Locks... the best water pressure I've encountered anywhere... could strip your paint with it.

The knees are always the first thing to go...

La la la I'm not listening...