Batteries - Charging Regime

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Ian_Rob

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I have just had to replace my domestic batteries ( 2 x 95 Ah). The old ones were 5 years old. I have been on a swinging mooring for the last 2 seasons and had just relied on recharging with the engine when using the boat every three weeks or so , though there were one or two longer periods when the boat wasn't used during the awful weather of last year.

I really need to buy some solar panels but until I do so, how long is it going to be safe to leave them? I would like to keep this set as healthy as possible.

They are ER450 sealed batteries.

Ian
 
I am not an expert on these issues (you'll find some more informed answers I am sure) but it may be worth checking the output voltage of your alternator just to make sure it is charging the batteries. They should be charging at over 14 Volts.

I have had a few problems in the past with batteries but I now pay close attention to a keeping them in good health, topping them up with water, checking they are actually being fully charged and making sure they are isolated.

If you fail to do any one of the above it could considerably shorten the battery life.

Having said all this I also think from time to time I have bought 'bad' batteries which have simply not lasted as long as I think they should have...would be interesting to hear what others think on this particular issue too.
 
paella said:
Having said all this I also think from time to time I have bought 'bad' batteries which have simply not lasted as long as I think they should have..
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Not sure about 'bad batteries' ...... but I certainly think there are 'bad vendors' whose can't even be bothered to rotate their stock properly, let alone actively maintain their batteries in top condition.
 
Basically you are doing all that you can for your batteries. If you can't get to the boat more often and the engine charging is all you have then you can do no more. If the batteries have a shorter life because of your use then so be it.

You could spend a lot of money and effort to fit a smart regulator which will put more charge into the batteries for a given finite engine run time. I think however that some solar charging would be best for the batteries. Fortunately the cost of solar is going down so cost of solar versus possible additional life of the batteries might look attractive. The plus being also that you will not worry so much about the batteries.

You won't get much charge from a small panel in UK and especially on a swing mooring where panel can not be tilted toward the sun so 20 watts might be a good size. You can just use 2 diodes to feed 2 batteries with no need for a regulator. Or buy 2 10w panels. Actual mounting the panels is a difficulty. I prefer a temporary mount so panel is removed before sailing. I mount mine with bungee on the top of the mainsail cover. Others feel this might lead to theft. Mounting on the deck can lead to damage from big feet. good luck olewill
 
batteries have a finite life and the lower you discharge them, the shorter that life. the whole problem is made worse if they arent fully re-charged and since this takes maybe 5 hours of engine use with batteries 50% discharged, it will never happen on a swinging mooring with a sailboat.

I've used a 35 watt solar panel and this has worked well to keep the batteries fully charged between visits to the boat. Its even worked well over the winter on the hard. But it hasnt a hope of keeping up with domestic use when on board so this year I am adding a windmill. I am not confident. I think it might yet end up on ebay. The only two real answers I know of are a generator or a pontoon berth.

P.S. I have tried a Sterling digi regulator but this makes the alternator work harder and with poor engine box ventilation the result has been alternator failures rather than battery ones.

P.P.S. When fully charged I find my batteries are fine for several weeks with everything shut down.
 
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Firstly THANKS for all replies and for Nigel's link to the informative Victron article.

I am thinking along the lines of a Solbian 40w flexible panel, stuck down to the deck ( for security reasons), immediately in-front of the companionway. Inevitably the sprayhood and boom will cast shadows at times but, on the basis that every little helps, it seems a reasonable starting point at least. I am not sure how these particular panels are affected by partial shadow but if this is an issue, I suppose I can always add more (when I can afford them!). Positioned here, they are not really going to be walked on that much - though supposedly they can take it.
 
Ian_Rob said:
Firstly THANKS for all replies and for Nigel's link to the informative Victron article.

I am thinking along the lines of a Solbian 40w flexible panel, stuck down to the deck ( for security reasons), immediately in-front of the companionway. Inevitably the sprayhood and boom will cast shadows at times but, on the basis that every little helps, it seems a reasonable starting point at least. I am not sure how these particular panels are affected by partial shadow but if this is an issue, I suppose I can always add more (when I can afford them!). Positioned here, they are not really going to be walked on that much - though supposedly they can take it.
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This will certainly improve your battery charging although 2 x 20w might be better from a shading point of view. Also a MPPT controller would squeeze more charge out of the panel (s) are available for a tenner from Sunstore. You'll then return to your boat to see a re-assuring green LED which tells you the batteries are fully charged. I don't know anything about Solbian panels but the Sunstore semi-flexible ones are good and cheaper.
 
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ghostlymoron said:
This will certainly improve your battery charging although 2 x 20w might be better from a shading point of view. Also a MPPT controller would squeeze more charge out of the panel (s) are available for a tenner from Sunstore. You'll then return to your boat to see a re-assuring green LED which tells you the batteries are fully charged. I don't know anything about Solbian panels but the Sunstore semi-flexible ones are good and cheaper.
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Sorry, I don't think you'll find these are MPPT - just ordinary controllers. MPPT seem to start c£50 for 10A.

Anybody know where I can get a reliable 20A MPPT controller at a good price?
 
Ian_Rob said:
I have just had to replace my domestic batteries ( 2 x 95 Ah). The old ones were 5 years old.
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I don't think you've done too badly with the old batteries. In my experience leisure batteries (the ER450's are leisure batteries?) generally last about 5 years....sometimes I can get a little more out of them, sometimes a little less. If I had true deep cycle batteries I would expect longer life but I'm not convinced that the substantial extra cost is justified for my use.

A solar panel will help, but if you can't fit it for a few weeks it won't be the end of the world. Just make sure you get to the boat and charge them up every few weeks.
 
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Tradewinds said:
Sorry, I don't think you'll find these are MPPT - just ordinary controllers. MPPT seem to start c£50 for 10A.

Anybody know where I can get a reliable 20A MPPT controller at a good price?
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Sorry, I was thinking of the 'very efficient PWM charging system' for a tenner. These are more efficient than the simple on/off controllers. I'm not convinced that the MPPT are worth the extra money.
 
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