8 x 200ah batteries die after 18 months

[Hurricane]

I would think that 600w would be easily achievable, shading should not be a significant issue, cloud cover might slightly diminish output but there should be no other shading, orientation too in the position Mike suggests would not be a significant issue, so a good quality panel should achieve maximum design output for most of the day in the Med. A typical roof mounted PV panel should be capable of 250w and he has good area over which they can be employed.

So 600w/24v gives an optimum 25A an hour - most useful. Even at 50% efficiency over 10 hours would give a potential 125A available. I reckon he will come up with a couple of CT's and a Raspberry Pi program to monitor energy use and to switch the array on/off as needed it will probably even talk to you ' the amount of energy consumed over the last hour is 300w the PV array has been energised and will terminate in 30 minutes......'

Yep John
Those were my calcs as well.
I've not given up on this idea yet but the Raspberry Pi idea doesn't work when there are so many really good controllers out there.

 

[MedMilo]

Thanks for all these really helpful responses, all very interesting and much appreciated as I try to navigate through this conundrum!

Just to clear up a couple of points in terms of how we use the boat. We actually have 2 x 100 amp chargers - so not quite the 300 amps of charging jfm's suggesting but still sufficient I would have thought.

Our daily routine is not that dissimilar to Portofino's description in that we typically spend two or three days at anchor and put the generator on once or twice during the day when cooking or boiling kettles etc. We generally have quite a few people on board which gets pretty warm in the Med so we tend to run the generator all night virtually every night we're at anchor in order to run the aircon throughout all five cabins (we always try to anchor a decent distance away from other boats so as not to p*ss others off!!!). So in answer to Hurricane I'm pretty sure we fully charge the batteries at least once in every 24 /36 hour cycle - I certainly keep a close eye on the charge amps going into the batteries and by the morning the chargers are very much in the Float stage and only putting a couple of amps of charge into the bank.

Furthermore, the boat has fin stabilisers so we tend to cruise everywhere at 10 knots - when we move to a new anchorage (which we do most days) we'll spend two or three hours underway during which time the 100 amp alternator is also trickle charging the battery bank too. And every third or fourth night we'd likely be on shore power so again the charge would be full.

So I'm reasonably confident the battery management isn't too bad and during the handover Fairline confirmed they'd set the discharge cut off at the correct level for the installation so the system cuts off before the bank becomes overly discharged I think.

Runningman's comments about the battery voltage sensing wires is very interesting and I've no idea whether or not Fairline wired these up properly - I'll check this over the next day or two. Also, the domestic bank is in the engine room so the temperature question is a consideration too and I need to check whether or not the temperature sensors have been correctly fitted. And that the micro switches have been set to gel - this was discussed during the build but I've never actually checked them myself! I definitely like the idea of the solar panels trickle charging the batteries and obviously this could work well in the Med but without a hard top over the fb it's hard to know where one could install enough panels!

I will try to post a few pictures of the instal tomorrow - Fairline built custom battery boxes to accommodate the extra batteries so it might be interesting to share pics and see whether this sheds any further light on the problem.

 

[BartW]

.....during the handover Fairline confirmed they'd set the discharge cut off at the correct level for the installation so the system cuts off before the bank becomes overly discharged I think.
.....

can you explain this discharge cut off,
what does the system fysically shut off ?

I'm not familiar with modern installations, but the few systems I know off, keep on draining the battery's much deeper than 50% of their capacity,
mostly they switch off only when battery voltage becomes much too low, and at that stage you have severy damaged the battery and compromised its lifetime
Only after installing the battery monitor with a alarm we realised how quickly we drained the battery's during day time, especially when using 'heating" appliances via the invertor. ( kettle, dishwasher, boiler)
We also run finstabs from Battery's in daytime.

we have a quite similar modus operandi like you except that we mostly don't run the generator at night, it switches on automatically in the morning somewhere between 5...8 am (depending on how long the UWL'w have been used the night before ;-)

regarding charge current;
we have alway's used the guideline from Victron, and that is a charge current of 10% to 20% of battery capacity,
our Bank is 600Ah, and the 5Kw quattro charges 120Amps (when in Bulk stage) so thats a good setting imo

Your 2 x 100A is OK, but do you use both 100A chargers on the domestic batt's ?
I have a second 120A charger, but that is connected to the Other battery bank. (engine's)

 

[MedMilo]

can you explain this discharge cut off,
what does the system fysically shut off ?

I'm not familiar with modern installations, but the few systems I know off, keep on draining the battery's much deeper than 50% of their capacity,
mostly they switch off only when battery voltage becomes much too low, and at that stage you have severy damaged the battery and compromised its lifetime
Only after installing the battery monitor with a alarm we realised how quickly we drained the battery's during day time, especially when using 'heating" appliances via the invertor. ( kettle, dishwasher, boiler)
We also run finstabs from Battery's in daytime.

we have a quite similar modus operandi like you except that we mostly don't run the generator at night, it switches on automatically in the morning somewhere between 5...8 am (depending on how long the UWL'w have been used the night before ;-)

regarding charge current;
we have alway's used the guideline from Victron, and that is a charge current of 10% to 20% of battery capacity,
our Bank is 600Ah, and the 5Kw quattro charges 120Amps (when in Bulk stage) so thats a good setting imo

Your 2 x 100A is OK, but do you use both 100A chargers on the domestic batt's ?
I have a second 120A charger, but that is connected to the Other battery bank. (engine's)

TBH I'm not exactly sure what I mean! All I know is that during the handover Fairline told me that the system had been set up so that it would trip / cut-out before damage could be done to the batteries, so at about 50% of capacity. I've rarely allowed them to discharge this far, partly because I don't want to overwork the batteries and partly because, stupidly in view, on the S65 there's no crossover rocker that allows the engine start bank that's attached to the port engine to start the starboard one if the domestic bank is flat. So you end up having to start the genny and start charging in order to start the starboard engine. And the genny only starts off the domestic bank anyway!!! So a dead boat is a real risk…, but that's another story! (this winter I'm fitting a dedicated generator start battery to mitigate the risk of a dead boat!).

And yes, AFAIK, both chargers charge the whole domestic bank and, I assume, the four starter batteries. But I'm not 100% sure! BUK are looking at the system configuration now and I'm hoping they'll shed some light on the circuitry over the next day or two. Who knows, Fairline might take some responsibility too

 

[MapisM]

before Jfm beats me to it

Yup, of course mainstream is what I meant. :encouragement:

 

[MapisM]

two or three hours underway during which time the 100 amp alternator is also trickle charging the battery bank too.

Are you sure it's ONLY trickle charging?
I mean, in my experience most alternators are nowhere near as "clever" as modern battery chargers are - the setup jfm previously mentioned being rather an exception than the norm.
In other words, let's assume that you are docked for a while, with batteries fully charged and the battery charger running on float. You should see a DC voltage around 26.5.
Now, what happens the moment you leave the dock?
My bet is that the alternator isn't clever enough to sense that the batteries only needs to stay on float charge, and immediately throws around 28+ volts at them.
And afaik, overcharging is also very bad for battery life.

 

[BartW]

....... I've rarely allowed them to discharge this far, partly because I don't want to overwork the batteries and partly because,.....:

could you find out how the system "knows" the charge status of the battery's ?
there should be some monitoring / controlling device ?

perhaps Jfm can explain or highlight the standard fit in a Fairline ?

 

[jrudge]

How is a dead boat likely?

The engine batteries just start the engines and that is it. You can turn the engine electrics off if you wish ( i leave them on all the time) which would possibly save a tiny current, but i cant really see in the absence of any fault that you can possibly drain the engine batteries.

Are you not over complicating this? Adding more batteries for gen start must just complicate the whole charging regime, and i am not really sure for what end.

We have ( had) the gen running probably 6 hours a day. 2 hours say in the morning. Breakfast, air con and battery charging and water making. If you leave the front hatch open and all the cabin doors i have never found a need for AC overnight.

Then maybe 30 mins in the middle of the day to run the bbq grill.

Then say 4 hours in the night. AC, batteries, water maker, dinner.

The gen uses i think 4 lph, so a total of 25 or so litres. Given the boat uses some 350 ph at cruise this is rather lost in the rounding.

The solution you have is expensive and i am not sure that there is any ROI to it given the low cost of running the gen and the need to do so anyway to charge batteries and make water.

I cannot see adding another gen does anything as it will cost money, take space, need servicing , all to save .... maybe 15 lt of diesel a night with i dont know 20 nights on the hook a year. Cant see it is worth it!

Jeremy

 

[MapisM]

AFAIK, both chargers charge the whole domestic bank and, I assume, the four starter batteries

I would be EXTREMELY surprised if that would really be the case.

Btw, I can't for the life of me understand why some builders still think that it makes sense to have separate starting batteries for each engine...

 

[BartW]

......Now, what happens the moment you leave the dock?
My bet is that the alternator isn't clever enough to sense that the batteries only needs to stay on float charge, and immediately throws around 28+ volts at them.
And afaik, overcharging is also very bad for battery life.

thats the way it works on 99% of most pleasure boats i think, (Jfm has the 1% exception )
but the system will regulate itself, more or less; because as soon the battery's are more charged, there will be less current going in to them (internal resistance increases in that direction)
at least that's how I think it works.
this is afcause much less accurate than a fully regulated system

 

[MapisM]

Yep B, all agreed.
I just have a funny feeling that in this specific situation (batteries already fully charged), a very powerful alternator can actually damage the batteries - unless managed by some clever multi-stage regulator, like the Mastervolt one that jfm mentioned (and which I wasn't aware of, the only similar bit of kit I came across in the past being the so called "Max Charge" supplied by Balmar together with their alternators).
But I'm not positive about that.

 

[Deleted User YDKXO]

I cannot see adding another gen does anything as it will cost money, take space, need servicing , all to save .... maybe 15 lt of diesel a night with i dont know 20 nights on the hook a year. Cant see it is worth it!

Agreed. TBH I dont understand why you'd want to run large AC loads from an inverter/battery system anyway. Even though we have 2 inverters on board, whenever we need to boil the kettle or run a hairdryer we turn the genny on and when we've finished turn it off again. Its not difficult and it certainly saves hammering your batteries. As for a 2nd genny, in my experience, small gennies have clattery/vibey single cylinder engines which are actually more intrusive than larger gennies which have smoother 3 or 4 cylinder engines and as you say the fuel saving would be negligible. If the root of the problem forcing owners to use inverter power for AC loads is an intrusive generator, I would have thought money and effort on reducing noise and vibration from the generator would be money better spent than on fancy inverters and replacement batteries every year at £650 a pop. All IMHO of course

 

[Hardmy]

I also cooked my 2 x 200Ah batteries last year.

To avoid a similar scenario, I did the following:
- installed new gels. I have now 600Ah (12V) for hotel alone.
- installed a new 60A charger (the old one was to weak and did not work properly anyway)
- fitted 3x100W/12V solar panels on my cockpit overhang (can only be seen, when one stays above them). They give me together up to 15 Amperes in the Greek sun.

We anchor quite a lot, and even if the genny is well insulated, we hate to start it in a calm anchorage. So we run it as few as possible and only to cook/bake/run the dishwasher (we don't use the boat in July-August so no aircon running). Anyway, this episodic usage of genny combined with solar seems to work now, but it is true that we never manage to recharge the batteries to 100%. This works only when we spend a night with landpower.

And now, a question for the panel: I am considering installing a Sterling "Alternator to Battery Charger", which will help to top up my batteries when running the main engines. Is it a good idea or not?

 

[Portofino]

Yep B, all agreed.
I just have a funny feeling that in this specific situation (batteries already fully charged), a very powerful alternator can actually damage the batteries - unless managed by some clever multi-stage regulator, like the Mastervolt one that jfm mentioned (and which I wasn't aware of, the only similar bit of kit I came across in the past being the so called "Max Charge" supplied by Balmar together with their alternators).
But I'm not positive about that.

I think you under estimate modern alternators ,and the way they are set up -think about it with today's stop/start tech in cars ,they do not cook the bats do they ? as you imply by throwing all in @ every start up .
So me too. Not too sure what JfM , got that to regulate over charging that A N Other alternator hasn,t ? .
I think as said these days with a "all singing /dancing " charger correctly set up and specced re bat cap size ,the whole thing should give many years service .
Back to the Op -1 1/2 years., knackered bats -defo summit wrong with the set up !
They should not be able to over charge ,ether by alternator on a extended cruise or long Geny run eg AC on all night .
Charger should be smart enough ( if correctly set up ) + temp monitoring to care of it all for you .

 

[BartW]

I am considering installing a Sterling "Alternator to Battery Charger", which will help to top up my batteries when running the main engines. Is it a good idea or not?

V, I don't understand why you need such a unit, pls explain,

on our installation:
the alternator on our P engine charges the engine battery's
the alternator on the SB engine charges the domestic batt's
each alternator can deliver 140A

I'm also considering to add solar panels to the installation, for topping up at anker...
we also love the silence and no exhaust gasses
but other priority's first

 

[Hardmy]

I am not an engineer, you should explain me

The alternators of my old CAT 3208TA's do not deliver a nice loading curve as do smart chargers. I understand that the regulators just stop charging as soon as certain amount of Volts have been reached on the battery bank. Because of this, I will never fill my batteries to 100% when running the main engines. You could argue, that my charger hooked on the genny will do the job, or the smart solar charger. But, my aim is to fully exploit the loading potential underway (without firing up the genny), which is not the case today. Does it make sense?

Re solar panels. The problems on mobo's is to find a place where to mount them, without defigurating your nice boat...

 

[BartW]

The alternators of my old CAT 3208TA's do not deliver a nice loading curve as do smart chargers. I understand that the regulators just stop charging as soon as certain amount of Volts have been reached on the battery bank. Because of this, I will never fill my batteries to 100% when running the main engines. ...

OK, now I got it,
perhaps it has todo with the fact that you mostly run at displacement speed IIRC, ?
and that the alternators only gives max voltage at higher rpm

I haven't looked to the unit in detail yet, will do later, not today,
you can not increase "power" from the alternator with such a unit,
but yes you might be able to charge the battery's slowly to 100%

 

[Hardmy]

To get my alternators working, I need to increase RPMs to 1600, an then I can decrease to 1300RPM and it will continue loading. But the regulator (if I understand well) is a on/off thing. As soon as it thinks that there is enough juice in the batteries, it stops (or reduces) loading.

The Sterling bit of kit, gives a "wrong" voltage feedback from the batteries to the regulator, in order to avoid its shutdown. It keeps loading the batteries with a proper curve, as would do my 220V charger.

 

[Hurricane]

I'm also considering to add solar panels to the installation, for topping up at anker...
we also love the silence and no exhaust gasses
but other priority's first

Please keep us posted on anything you find, Bart.

 

[MedMilo]

How is a dead boat likely?

The engine batteries just start the engines and that is it. You can turn the engine electrics off if you wish ( i leave them on all the time) which would possibly save a tiny current, but i cant really see in the absence of any fault that you can possibly drain the engine batteries.

Are you not over complicating this? Adding more batteries for gen start must just complicate the whole charging regime, and i am not really sure for what end.

We have ( had) the gen running probably 6 hours a day. 2 hours say in the morning. Breakfast, air con and battery charging and water making. If you leave the front hatch open and all the cabin doors i have never found a need for AC overnight.

Then maybe 30 mins in the middle of the day to run the bbq grill.

Then say 4 hours in the night. AC, batteries, water maker, dinner.

The gen uses i think 4 lph, so a total of 25 or so litres. Given the boat uses some 350 ph at cruise this is rather lost in the rounding.

The solution you have is expensive and i am not sure that there is any ROI to it given the low cost of running the gen and the need to do so anyway to charge batteries and make water.

I cannot see adding another gen does anything as it will cost money, take space, need servicing , all to save .... maybe 15 lt of diesel a night with i dont know 20 nights on the hook a year. Cant see it is worth it!

Jeremy

Hi Jeremy

Thanks for this.

A few responses…

I'm not sure that the starter battery bank 'starts the engines', I'm pretty sure it's only hooked up to one engine, the starboard one. On quite a few occasions this summer the domestic battery bank has tripped out (admittedly, I think, because of the reduced capacity due to the faulty batteries) and I've been unable to start the port engine or the generator. So have found myself just praying that when I go to crank the starboard engine it would start…, thankfully each time it did! I've then had to rev the starboard engine up to c1500rpm in order for the alternator to start to get some charge into the domestic bank. My point is that if the starter bank had died for some reason whilst at anchor we'd have been a bit stuffed! So am just wondering whether to have an independent battery to start the genny then at al times the boat can get power….

My logic for the expanded battery bank / inverter set up isn't to do the cost of the diesel, it's to do with a) striving for the apartment - like nirvana of permanent 240v so guests can just charge stuff / watch tv etc without needing the genny to be started; b) to not run the genny with low loads (which is obviously bad) and c) to have as much time as possible during the day without the genny thumping away.

We spend around 14 weeks a year on board, often with 8 - 10 people 'in residence', and often it doesn't work to have all the cabin doors open all night from a privacy point of view. So in 25-30 deg heat the cabins get pretty stuffy unless the aircon's on hence why we run the generator most nights in July/August - the only people to hear the genny inside are my wife and I in the master cabin!

I agree with your point about the negatives around installing a second generator and I'm far from convinced that this is the way forward. I really just want my 8 x 200ah gel battery bank to provide daytime 'background' 240v power for low consumption applications as worked very successfully on my last boat. I just don't understand why all 8 of them have died so quickly!!