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Kelpies boatman

Power drain

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Hi all. So- new batteries, new inverter, added 2x100w solar panels and STILL off grid power seems to drain. Take last night. Had to run engine for 2 hours to get to 12.6v. Bed time 12.3v. This morning 11.3!! Only thing running is the fridge at 35w and the inverter on power save mode at 0.2w. Any thoughts?? Would be welcomed.?

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First of all was that 12.6 volts while the engine was still running, almost a soon as you turned it off or after about an hour during which time the water pump or fridge had run a bit? If the latter then it should more or less indicate a little over half charged batteries. If one of the first two absolutely nothing can be deduced from the reading. In fact if you alternator is working as it should and the engine revving fast enough (you do charge at about 1200 to 1500 rpm, don't you) we can see the batteries were far from well charged. The alternator's regulator had not yet started working indicating a high charging current and that in turn indicates well discharged or faulty batteries.

 

You probably need well in excess of 12 hours running to get well discharged batteries any where near fully charged.

 

Unless you monitor the solar output and the alternator output (Amps) you will have no idea how well charged the batteries are at any one time.  In my experience some cheaper solar controllers seem to drop to float voltage long before the batteries are anything like fully charged. Also from the weather forecast it seems that you may have had a lot of cloud and rain yesterday.

 

Without more data it is hard to know what is going on but based on a lot of experience, especially with posters with low post counts, the likelihood is that you have never fully charged you batteries and have over discharged them regularly. The over discharge will have dramatically  reduced their cyclic life while being left permanently well discharged has probably lead to major sulphation that ha snow reduced the battery capacity to a fraction of their stated capacity. People new to living aboard regularly destroy batteries within a very few weeks until they grasp how long they take to recharge and how to look after the.

 

I would suggest two things.

 

1. Get some battery monitoring equipment. You seem to have a voltmeter so add an accurate ammeter to it. Then lean how to interpret both.

2. Read, mark and learn the content of Wotever's Battery Charging Primer that you will find pinned to the Maintenance section of this forum.

 

Do not go buying new batteries until you get your charging  regime sorted or you will destroy them.

 

  • Greenie 1

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2 hours ago, Kelpies boatman said:

Hi all. So- new batteries, new inverter, added 2x100w solar panels and STILL off grid power seems to drain.

 

Ok so taking these points one at a time:

 

1) New batteries. Batteries simply store the power you generate. If they are emptying out too soon, you are prolly not filling them properly in the first place. You can only burn the electricity you previously generated and stored in them.

 

2) New inverter. This is a power consumer, not a power creator or storer.

 

3) 2 x 100w panels. Good. Should be enough to run the fridge in summer months so yes, 'something' is wrong. My gut feeling is your new panels are not actually working.

 

 

We here can only guide you to find out for yourself. Firstly, you will need some instruments to measure the current in your conductors as well as voltage. DO you have a DC clamp meter? How are you meassuring the voltages you mentioned?

 

 

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"fridge 35w" might be the problem. Is it 240v running through the inverter or a 12v 35w cool box running off the batteries direct. If its one of those that will be the problem. They flatten batteries. 

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2 hours ago, Sir Nibble said:

This may seem an odd question. How does the alternator warning light behave? Particularly, does it light with ignition off?

I did consider an alternator problem but on balance I decided this problem was more likely to be a lack of charge problem (or the cool box thing Jim mentioned).  However as it may be an alternator fault I did point out charging amp readings are an important diagnostic tool.

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Thanks Tony.

And Bod

I reckon it's down to not fully charging the batteries while off grid. After shore power the batteries hold power for much longer. Thanks for your suggestions. I will action both. Clearly don't have to worry about my brain collapsing into a state of retirement with new skills to learn. As I have already purchased new batteries and scrapped the old ones, that's a learning curve cost!

 

Thanks also Mike.

1&2 noted and 3 would be good if it wasn't so cloudy perhaps. When the the sun is out the solar panels seem to throw out around 20volts although I think the controller limits the charging ability same as the alternator charging issue mentioned by Tony. More personal education needed methinks!

 

Thanks Sir Nibble. Alternator seems to run fine at around 13.7v (however not long enough issue)

 

Hi Jim. The fridge is a multi function 240/12v/lpg switched and wired direct to 12v. Just checked again and it's not 35w but 110w power consumption. Starting to think this is the power drain issue. Will have to work out the amount of power relative to time/volts this uses.

 

Is there a simple equation for this? (Homework reading of (Wotever's Battery Charging Primer )

 

IF the fridge power consumptiom is the issue. How else do you keep food cool apart from canal storage.

 

As my wonderful wife tells me - life afloat isn't easy or glamorous, just a great life (if you have funds to B O A T)!

 

 

 

 

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Fridge is only suitable for use on gas or shoreline. 12v should only be used when the engine is running. 

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Those multi function fridges are very inefficient on 12V.  It may be running 50% or more of the time,  which at 110W is between 100~200Ah per day.  Which is a massive amount

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12 minutes ago, Kelpies boatman said:

Hi Jim. The fridge is a multi function 240/12v/lpg switched and wired direct to 12v. Just checked again and it's not 35w but 110w power consumption. Starting to think this is the power drain issue. Will have to work out the amount of power relative to time/volts this uses.

If this is the standard Electrolux 3-way fridge - DO NOT USE ON 12V

 

These fridges are designed for car / caravan use.

The ide is that you get it cold overnight before you leave, using the 240v, then whilst towing the caravan it runs of the 12v (and the manual says "do not leave the fridge switched on if you stop the engine as it will flatten your car battery) then run it on gas at the campsite.

 

The 110 watts will be continuously drawing about 10 amps from your battery as on 12v setting they do not have any thermostat so run continuously.

 

This will flatten your batteries in a matter of hours - only use it on 230v or gas.

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2 minutes ago, Kelpies boatman said:

Thanks Stegra. So no one uses fridges afloat?

Most use fridges afloat, but not that kind on 12V.  

Edited by Chewbacka

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If you want to run off batteries you need a compressor fridge, either 12v (expensive) or 240v using the inverter. 

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2 minutes ago, Kelpies boatman said:

Thanks Stegra. So no one uses fridges afloat?

Yes - proper fridges, with thermostats. 

Cost £600+

Edited by Alan de Enfield

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Yes it"s the fridge. I bought a dometic compressor cool box for our boat. It uses 1.5ah ish. Not cheap though. £400 ish. We keep milk etc in there and veg etc in a cupboard down on the bilge, lined with insulation. 

Edited by Jim Riley

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Just now, Alan de Enfield said:

Yes - proper fridges, with thermostats. 

Cost £600+

or a good  240V A+++ rated fridge powered by an efficient inverter with a low 'standby' load.

A good 240V fridge is considerably less than £600

  • Greenie 1

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1 minute ago, Chewbacka said:

or a good  240V A+++ rated fridge powered by an efficient inverter with a low 'standby' load.

A good 240V fridge is considerably less than £600

This ^^^^^

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3 minutes ago, Chewbacka said:

or a good  240V A+++ rated fridge powered by an efficient inverter with a low 'standby' load.

A good 240V fridge is considerably less than £600

Very true.

Depending on what inverter he has just purchased it may be the way to go.

If he needs to spend £100's on a good inverter then it could, financially, be a toss up between 12v & 230v

Edited by Alan de Enfield

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Just now, Alan de Enfield said:

Very true.

Depending on what inverter he has just purchased it may be the way to go.

If he needs to spend £100's on a good inverter than it could, financially, be a toss up between 12v & 230v

Agreed, just letting him know there are options.  Oh and last time I looked a good flexible for the future inverter say 2kW for power tools etc is over a grand, but just for a fridge 1kW would do.

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59 minutes ago, Chewbacka said:

Those multi function fridges are very inefficient on 12V.  It may be running 50% or more of the time,  which at 110W is between 100~200Ah per day.  Which is a massive amount

It will run 100% of the time

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Just a question of coming to terms with how poorly lead acid batteries perform - the ever slowing crawl to recharge. 

Is the o/p going to be on the cut all the time? Winter? I'd be inclined to whack a load more solar on for a start. Unless you cruise every day of course.

Maybe fit a smart gauge too?

And a shoreline fridge!

Edited by Johny London

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2 hours ago, stegra said:

Fridge is only suitable for use on gas or shoreline. 12v should only be used when the engine is running. 

 

and no way is it 35 Watts on 12V. More like 96 watts or 8 amps all the time it is on and in all likelihood has no 12V thermostat so on 24/7

 

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1 hour ago, Tony Brooks said:

 

and no way is it 35 Watts on 12V. More like 96 watts or 8 amps all the time it is on and in all likelihood has no 12V thermostat so on 24/7

 

You estimate is a bit low, the op revised the figure to 110Watts in post 8.

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