Domestic batteries *only* lasted 14 years (engine start battery a *mere* 12 years)

[Babylon]

I wasn't a happy bunny when I got to the boat yesterday to run the engine etc, to discover that I'd foolishly forgotten to the isolate the domestic and engine circuits when last down in the Autumn, with the result that both banks were utterly dead (i.e. sub 3v). This is despite always leaving the Rutland wind-generator on when she's on her mooring. Also I didn't realise that with the engine key off and out and the domestic panel master switch also off that there'd be any residual drain?

But what is astonishing is the two Numax CVX27MF 95Ah sealed lead-acids which made up the domestic bank were fitted in Spring 2009, and the Varta D59 60Ah engine battery in Spring 2011! That the whole lot now needs replacing at a cost of about 300 nicker is annoying, but I don't think I can complain about their longevity!

The other factor that kept them in good shape, apart from the wind-generator and a VSR, is the fact that my boat has a very low electrical demand relative to the max 95Ah available (half the total) : few electronics (usually off), an extremely efficient fridge, incandescent cabin bulbs all replaced with LEDs, no telly, etc.

 

[Sunny265]

My boat is currently off shore power after delivery and I am concerned about the state of the 3 batteries onboard.?

 

[Tranona]

If you have a long time horizon worth considering AGMs as price premium has dropped to around 30% for at least 50% longer life. I bought 2*95Ah Exides for £230 last year, but note they are now ££290 a pair!


The start battery is an Odyssey because there was not room for a "normal" 60Ah. That cost £150", but current price for an Exide 60Ah is £97. So £390 rather than £300 for Leisure batteries.

Just a suggestion.

 

[Boater Sam]

I would not give in so easily. Get them on a charger, you never know.
If they have not been flat for too long a long slow charge may bring them back.

 

[Stemar]

I would not give in so easily. Get them on a charger, you never know.
If they have not been flat for too long a long slow charge may bring them back.

+1.
A faulty alternator energised my split charging relay and ran both batteries down to around 3v, but a long trickle charge brought them back to life and I got a couple more years out of the domestic battery and several more out of the starter battery.

 

[vas]

+1 a ctek or victron charger with a "conditioning" option may do the trick - however 11yrs is v.good going even for minimal consumption loads

 

[Minerva]

Batteries seem to be getting cheaper; Amazon have been spamming me with adverts for Renology Lithium batteries - 170ah for £699. At that price it’s getting quite tempting to switch!

 

[Refueler]

I would not give in so easily. Get them on a charger, you never know.
If they have not been flat for too long a long slow charge may bring them back.

Doubt it - but worth a try. Usually what happens is the voltage seems OK until you put a load on ... then it drops like a brick.

I have recovered a small 30A/hr Lawn Tractor battery with a Desulfator connected across the charge leads ..... but that battery will not start a Lawn Tractor (13hp B&S) .... but can power a GPS for days !!

 

[Babylon]

Thanks for the suggestions to try to rehabilitate the batts. However I agree with Refueler - from past experience of lead-acids, once they're knackered (even just down to 10v) they'll never be able to handle any real load.

Perhaps then the answer is to first just replace the engine start battery, which is the cheapest anyway, and which is the only one that needs to provide serious CCA's (fat plates) Then see how the domestic pair (thin plates) recover under charge.

I don't have a trickle charger, just the CTEK 7amp on board, which requires a min battery voltage of 2v. The multimeter showed the domestics at 3v, so this might work. (The eng start was history at 1v.)

 

[Refueler]

mmmmm just a correction ....

Starter CCA batterys use THIN HARD plates to get maximum area contact for electrolyte.

Leisure non CCA batterys use THICK SOFT plates to allow the 'slightly' deeper discharge at lower rates .... and that they don't need the increased contact area for high power demands.

Pages 30 - 31 of Alastair Garrods excellent book : "Electrics Afloat" describes well.

Its one of the reasons that TRUE leisure batterys cannot be used for starting engines .... that the usual 'Leisure' battery seen is actually a compromise battery True Deep Cycle suffer buckled plates as soon as high starter demand is applied.

 

[Boater Sam]

I have a big diode stack connected to an arc welder. I use it to frighten supposedly duff LA batteries. It is surprising how many will pick up and prove at least useful but not as good as new of course.

 

[Refueler]

Years ago - you could buy a fluid that you added to the cells ... it was supposed to cause the 'deposits' on the plates to dissolve away and let plates function better .. as well as sorting the gunge that sits in case bottom.

Did it work >>>>>> no idea !!

 

[garymalmgren]

Also I didn't realise that with the engine key off and out and the domestic panel master switch also off that there'd be any residual drain?

What would that residual drain be, that is was more than the occasionaly boost from the wind genny?

 

[Babylon]

Also I didn't realise that with the engine key off and out and the domestic panel master switch also off that there'd be any residual drain?

What would that residual drain be, that is was more than the occasional boost from the wind genny?

You're not wrong! I'm beginning to wonder whether, having forgotten to isolate the batteries, I might also have knocked the fridge switch back on when stuffing bits into the quarter-berth (where the fridge controls are) before locking up? I'll check the rocker-switch when I'm next down. If not then something must have caused the near-total drain, but I can't imagine what.

 

[Babylon]

Went back to the boat yesterday. Aside from the two main battery isolator switches (separate ones for each of the engine-start and domestic banks) I found that nothing else had been originally left on since the autumn, except the wind-generator as usual to top up etc. So mystery remains as to what cased the total drain except old age and leaving the isolator switches on?!

Then fitted identical lead-acids as before, everything worked a treat, went for an afternoon sail (glorious), spent the night aboard with shore-power (a bit parky in the small hours as I'd turned the heating off before bed), now back on her mooring with fully-charged new batts, isolators off and wind-genny on.

 

[Poey50]

Went back to the boat yesterday. Aside from the two main battery isolator switches (separate ones for each of the engine-start and domestic banks) I found that nothing else had been originally left on since the autumn, except the wind-generator as usual to top up etc. So mystery remains as to what cased the total drain except old age and leaving the isolator switches on?!

Then fitted identical lead-acids as before, everything worked a treat, went for an afternoon sail (glorious), spent the night aboard with shore-power (a bit parky in the small hours as I'd turned the heating off before bed), now back on her mooring with fully-charged new batts, isolators off and wind-genny on.

I suspect it was simply the result of self-discharge which increases with the age / number of cycles of battery. High temperature would be an issue too but less likely in this case..

 

[Boater Sam]

Is there a gas alarm? Any USB sockets? Bilge pump been on auto? WiFi modem?

 

[Boater Sam]

Is there a gas alarm? Any USB sockets? Bilge pump been on auto? WiFi modem?

I think to get them both down to 3v that either there is something connected between them like a VSR that is taking power or you had something taking a tiny amount. Why did your wind charger keep at least one up?

 

[Babylon]

I simply don't know Sam. While the isolator switches were both left on by mistaske, the master domestic and nav-light switch panel switches were all off, plus she's a very old-fashioned manual boat (i.e. no electric pumps, no telly or modem, etc). Yes there's a VSR wired in to always prioritise charging the engine battery first whatever the input (alternator, shore-power or wind-gen).

All I know is that I'd left both isolator switches on several months ago, which somehow allowed a gradual drain on batteries which were all more than a decade old and despite my habitual care just pretty tired?! Then in December and January we had extended periods of very cold and windless weather (high pressure obvs), so there was no wind-gen input then at all, then by the time we had normal breezier conditions again it was simply too late?

Perhaps one of the domestic batteries simply failed and dragged its mate down? But that wouldn't explain the engine start battery failing as well - as I thought the VSR was a one-way street? So perhaps it was the engine batt that failed and the VSR then allowed it to start sucking all the juice out off the domestic pair? But the VSR doesn't actually work this way either, as it just prioritises one bank over the other when there's an input charge from one of the three outside sources. So perhaps the VSR failed? - although I find this highly unlikely!

None of this matters any more: I've simply replaced three pretty old batteries (2009/2011) with three brand new ones, and as long as I remember to always SWITCH OFF the isolator switches before leaving the boat then they should be good for the next ten years etc.