Flat battery

petem

petem

Well-Known Member
Joined
16 May 2001
Messages
19,106
Location
Cotswolds / Altea
www.fairlineownersclub.com
Our port side battery has been flat the last couple of times that we have gone to start the boat. As people may be aware the standard Fairline architecture is not to charge this battery from the battery charger.

Is a battery that discharges itself normal once they get to a certain age (I think it's 4 or 5 years old). Or do I have another issue?
 
You could try linking it to the house batteries for a day.

At least you can gtee a decent charge.

If you do short runs it may never be full. Add in a few marina starts over winter and it is only part charged all the time
 
Best thing I ever did in terms of batteries was fit a 30W solar panel to the radar arch to starter battery and a 200W 2mm thick flexi panel to the top deck where the lounger cushions go to service house batteries. Never had anything less that fully charged batteries at all times and am completely free from the need of shore power (which I dont have anyway). With the exception of hot water for which I have to do a short run I am completely self sufficient. All for less that 800 quid.
 
petem said:
standard Fairline architecture is not to charge this battery from the battery charger.
Click to expand...
P, not much to add to what has already been said for checking if/what is wrong, aside from suggesting that a multimeter is enough to check if at least the port alternator does charge the battery, when the engine is running.

Anyway, regardless of whether the battery or the alternator is the culprit, I would change the above silly arrangement.
The easier route is to get a small charger dedicated to that battery, connect it to the same AC line which feeds the existing charger, and leave it attached to the port battery. This way, whenever the main charger takes care of the other banks, also the port engine battery is kept topped up.

A nice bit of kit which I keep onboard as an emergency backup and I can recommend is the Noco Genius.
Small and light, available in a wide range of power, good for all sort of batteries (6/12/24V, lead acid, AGM, lythium, you name it), spark-proof, protected from overcharge and reverse polarity, and with status LEDs. :encouragement:
 
Have you been maintaining it?
Cleaning the contacts and (assuming it is a standard wet lead acid) checking the fluid levels regularly.
I have found that I get through batteries in the Med far quicker than I used to in the UK.
Probably because it is hotter.
If it is 5 years old, just replace it and then give all the batteries some TLC
I don't think any of my wet lead acid batteries have lasted that long.
I would probably fit a trickle charger to it to keep it fully charged - thats what I have done for our generator battery (I isolate it from the rest of the boat when charging though) - I then leave it on charge whilst we are away.

However since switching the house bank over to AGM and fitting solar panels, my house bank has been working well.

But earlier this year, I went to start the engines - all the engine batteries were dead - one rogue battery in the bank of 4 took the lot out.
They would have been 4 or 5 years old. - reasonably good ones as well.
 
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Hurricane said:
all the engine batteries were dead - one rogue battery in the bank of 4 took the lot out
Click to expand...
M, what sort of FLA batteries are you using, for the engine bank?
I'm asking because I use FLAs also for domestic, but the relatively expensive 6V Trojan, hence needing 4 of them to get 24V (for each of the two banks connected in parallel, but that's just a matter of reaching the desired total power).
Otoh, for the engines bank I've always used cheapish 12V starting batteries, akin to those used in trucks, so needing just 2 of them for the 24V bank.
Imho, for engines any more sophisticated setup is just wasted.

PS: btw, waddumean "isolate it from the rest of the boat when charging" with reference to the genset?
Ain't the genset starter 12V, hence with its own battery+charger and isolated from the rest of 24V system anyway?
 
Last edited:
MapisM said:
M, what sort of FLA batteries are you using, for the engine bank?
I'm asking because I use FLAs also for domestic, but the relatively expensive 6V Trojan, hence needing 4 of them to get 24V (for each of the two banks connected in parallel, but that's just a matter of reaching the desired total power).
Otoh, for the engines bank I've always used cheapish 12V starting batteries, akin to those used in trucks, so needing just 2 of them for the 24V bank.
Imho, for engines any more sophisticated setup is just wasted.

PS: btw, waddumean "isolate it from the rest of the boat when charging" with reference to the genset?
Ain't the genset starter 12V, hence with its own battery+charger and isolated from the rest of 24V system anyway?
Click to expand...

Actually, I needed replacement batteries quickly this year.
I needed to get the boat over to the boatyard.
We did have a look round our part of Spain for the correct orientation and size to replace the dud ones,
But I was then convinced by the local chandler to buy 4 of his Vetus sealed batteries.
They are slightly smaller in capacity as the ones that I would have liked to install and I had to put some spacers in the bottom of the battery box.
I would usually have used ones that I can top up.
I was feeling lazy at the time - these ones are maintenance free - still need to keep them clean though.

Generator battery charger.
Over the years, I have bought several of those cheap motorcycle battery chargers that I leave on whilst we are away.
Currently, one keeps the generator battery charged and another keeps the RIB's battery charged.
I was worried that (being cheap chargers) they might affect the boat's galvanic system.
The generator battery has an isolator on its positive wire.
So, right back when the boat was new, I fitted an extra battery isolator to the negative of the generator battery as well.
The battery charger is permanently wired to the battery side of the isolators
When I leave the boat, I make sure that both isolators are off and the cheap battery charger is on.
This is probably completely unnecessary but it was easy to do and easy to switch whenever needed.
And the last thing I wanted is my props fizzing.
 
MapisM said:
P
I would change the above silly arrangement.
The easier route is to get a small charger dedicated to that battery, connect it to the same AC line which feeds the existing charger, and leave it attached to the port battery. This way, whenever the main charger takes care of the other banks, also the port engine battery is kept topped up.
Click to expand...

+1
fe a Victron Blue smart charger
 
Pete, i expect you have a knackered battery. It is not holding charge. As others have said, it is not very clever to have a charger that only charges part of your set up.
 
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Personally I think it needs investigating properly as swapping a battery for another one is an exercise in futility if the issue is elsewhere, you replace the battery and still have the same problem and spent money for nothing.

Begin at the beginning and remove the battery terminals overnight and measure the charge immediately after removing the terminals and then again in the morning and this will give an indicator of whether or not it is the battery or something else drawing power, then try and start the engine/s, if the battery seems fine then begin isolating circuits until you find the one discharging the battery and if you have a modern multimeter you can run up to 10amps through the meter to help find the offending circuit. Isolate that circuit overnight and try and start your engine/s and if they are fine then you have cracket it and you can innvestigate everything on that circuit.

Had one recently and once the circuit was isolated I found a leak on a relay and when it was stripped the air gap between the contacts was clogged and a tiny current passed through it constantly and over a couple of days it discharged the battery sufficiently to prevent the engine from starting, cost? £2.48 for a new relay from a specialist supplier.
 
A quick check - measure the voltage.
If it is below 11v its is dead - end of discussion.
I have a load tester that puts a load on the battery - if it can't hold its voltage over about 8 to 10 seconds - it is dead.
Don't muck about - just change it.
 
The guys have gone to replace the duff battery and have realised that the flat port side battery is the one that is connected to the charger (that I leave on) and the stand-alone battery (not connected to charger) is the one that still has charge.

Seems like it could be a duff charger. If that's the case then what would be the best charger to replace it with?

Also, do I really need a 50 amp charger to charge 2 x 135AH batteries?
 
I gave my opinion earlier. You have the sun? Use it. Personally I think a modern MPPT controller is going to be the equivalent of anything else you are going to be recommended.
 
I agree with Bruce, although getting a solar panel that matches the style and shape of a boat is always a challenge...
my 4 6V Trojan T105RE (225Ah) are charged throughout the year by my 30A Victron MPPT controller that with 600W solar panels rarely pumps more than 20A in them. They are absolutely fine. So doubt you really need more than 30-40A charger other than the first 20mins or so with depleted batteries where a larger charger would probably be capable of pumping more juice in them (and that's debatable)
For the record, the mains charger is a 60A Victron, used once in 2019 (last week!) to check something with my batteries...

my 2eurocent

V.
 
petem said:
Seems like it could be a duff charger. If that's the case then what would be the best charger to replace it with?

Also, do I really need a 50 amp charger to charge 2 x 135AH batteries?
Click to expand...

depends on your mode of operation,
we stay a lot on anker, and avoid running the genny for long periods,
so powefull chargers are very important to us
curently we charge our 2 x 620Ah banks with 2 x 200A (bulk) chargers (2 x Victron Quattro8000)

for you, its the right moment to invest in a intelligent Charger / invertor combi,
fe Victron Multiplus 1200, 1600 or 2000W

is it 12V ?
 
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