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New battery Charger


embis

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I have a bank of three leisure batteries with a total output of 400Ah. At the moment they are charged by a 20A charger and I have been advised to upgrade this to a 40A charger. It has been suggested that this might cost me about £400 for the charger and the same again for fitting. Searching online I have found a "Sterling Pro Charge Ultra " that seems to fit the bill and costing £300. I don't want to make any false economies but If I can source this more cheaply than my fitter then I will.

from the website:

Quote

The latest in battery chargers with plenty of well thought out useful features. The units have 2 clear digital displays on the front which show information about the voltage and current supplies and a series of 32 LEDs also give plenty of information about your charging system. Easy to install & wire up thanks to their simple output screw terminals.
Standard features include:
• 11 pre-programmed battery charging curves - easy to select
• 1 custom set, can be set from charger, no need for computer
• 2 digital meters for current and voltage measurement
• 1 power meter to show what reserve power left on the unit
• Synchronised rectification output
• High voltage de-sulphation cycle
• Low activity, standby mode to increase battery life
• Battery health program
• Multi speed fan control to reduce unnecessary fan noise
• Primary (processor digitally controlled) & an emergency backup secondary (analogue controlled) high voltage trip
• 32 LED information panel
• Internal scan and systems check
• Includes battery temperature sensor

Anyone have any views on this unit?

..apart from output I am not really sure what features are, essential, useful or spurious. 

..What difference does the output of the charger really make anyway? the 20A unit seems to have given us good service so far, is it worth me spending up to £800 on this upgrade?

Edited by embis
Changing A's and W's
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Firstly, some units...

You have (nominally) 400Ah battery capacity. After the abuse they’ve suffered my guess is they’re probably something like half that capacity now. 

You currently have a 20A (Amp) charger.

You’ve been advised to purchase a 40A charger. 

Yes, the Sterling charger would do well, especially as the ‘Custom’ setting would allow you to program more appropriate voltages for both Absorption and Float stages. 

Yes, I’d say it’s worth fitting if only because of the custom settings. 

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You were advised wrong.  As long as you have a multistage (bulk/asorbtion/float) marine charger that can be set for your battery type and you on average don’t use more than 20w on the boat (so not taking more out of the batteries than the charger can put in), then the 20 watt is fine.   If you use a genny to power the charger then that’s different tho.

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Just now, Robbo said:

You were advised wrong.  As long as you have a multistage (bulk/asorbtion/float) marine charger that can be set for your battery type and you on average don’t use more than 20w on the boat (so not taking more out of the batteries than the charger can put in), then the 20 watt is fine.   If you use a genny to power the charger then that’s different tho.

20A!  AMPS!!!

A 20W 12V charger will give about 1.6A!

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3 minutes ago, Robbo said:

You were advised wrong.  As long as you have a multistage (bulk/asorbtion/float) marine charger that can be set for your battery type and you on average don’t use more than 20w on the boat (so not taking more out of the batteries than the charger can put in), then the 20 watt is fine.   If you use a genny to power the charger then that’s different tho.

Thank you, I will do the sums and see what we need.

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Your and,  I'm assuming, is 400Ah rather than 400w. Your 20a charger should charge this quite happily (if a little slowly) if you're using your batteries sensibly. My inverter charger just failed on me and my little Ctek mxs 5.0, a 5 amp charger, is coping with a similar sized bank, although it's insufficient to allow me to run the fridge. I'm replacing the inverter charger with separate units and have just taken receipt of a 30a Victron smart charger which cost well under 200 quid and will be perfectly adequate.  

It depends on your usage profile of course, but do remember that your batteries are likely to be pretty close to fully charged after you've cruised back to your berth. Once there, your shore powered charger only needs to top them up and maintain them whilst coping with your 12v dc load, which is unlikely to be huge. Should you ever find yourself I the infrequent situation of needing to ram heavy amps into your batteries, you already have that capability in your domestic alternator by running your engine - mine's 175a, yours may be lower but is probably still quite beefy.

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Just now, Robbo said:

Cheers was looking for that link to post.  Although I did say as long as you don’t take out more than the charger can supply.  Which is what the link basically says.

But one also has to take into account bulk charging time. OP has a habit of taking his batteries down to flat and they could do with a decent stirring after that, which a 5% charger isn’t really going to do. A 10% charger will also halve his bulk charge time which, with such deep discharges, won’t be a small fraction of his overall charge time. 

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Also note Gibbo’s summing up on that page:

Users with chargers of around 25% to 30% of the battery capacity tend to seem reasonably happy with the compromise they have of battery life versus recharge time.

Other users (myself included) tend to go slightly higher than this and generally run a charger between 35% to 50% of the battery capacity, enjoy the slightly shorter recharge times, but accept the (again) slightly shorter battery life.

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2 minutes ago, WotEver said:

But one also has to take into account bulk charging time. OP has a habit of taking his batteries down to flat and they could do with a decent stirring after that, which a 5% charger isn’t really going to do. A 10% charger will also halve his bulk charge time which, with such deep discharges, won’t be a small fraction of his overall charge time. 

Isn’t “stirring” voltage related tho?

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3 minutes ago, WotEver said:

Indeed. 

Please lets not mix this up with my posting in a previous thread, lets assume I have a new bank of batteries and they have not been maltreated.

Edited by embis
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13 minutes ago, embis said:

Please lets not mix this up with my posting in a previous thread, lets assume I have a new bank of batteries and they have not been maltreated.

But whatever happened to your old batteries could easily happen to your new ones :

Example :

Is your existing battery charger an 'ok size' but is boiling the batteries by putting out 16 volts ?

Is your consumption going to continue to exceed your input ?

 

Simply changing the batteries for new ones (that you have killed without knowing why), and replacing the battery charger without knowing why may not solve the problem & just be an expensive short term fix until you manage to kill the new batteries.

You really need to undertake a review of all of your electrical equipment that both 'consumes' and 'generates' power to ensure that it is balanced.

 

You also need to put in 'systems' to monitor and control both your charging and discharging cycles - a battery which is not fully charged (every day) will start to sulphate and reduce its capacity - after (as little as a few weeks) this can kill the battery. How do you (will you) monitor your charging levels ?

Ideally you should charge until the tail current is 1% (some say 2%) of your battery bank, so, with a 400 Ah bank when your charger is outputting 4 amps, and has done that without change for an hour, it is safe to consider the battery fully charged. 

Edited by Alan de Enfield
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