Power Consumption Calculator

[haddock]

All

I have developed a spread sheet to calculate the power consumption of my Jeanneau 39i whilst cruising the med underway and at anchor. I built it to estimate how often I would need to run my generator. Fairly rough guide but might be useful.

If anyone wants a copy please send me a message with you email address and I will forward.

H

 

[hoppy]

Maybe you should not include the windlass in the total figures as it is a separate battery and I guess you are running the engine when you use it.

BTW why no hours for the watermaker or is that there for the spreadsheet and you don't have one?

[so36idavid]

Haddock,

Thanks for doing this and offering to share it. It's very useful to know what loads on your boat are consuming power. However I don't suggest that you run your generator based on a spreadsheet. All kinds of things can affect the state of charge of your batteries. There's no substitute for an Ah meter to tell you what's actually going on. 

P.S. If you change your anchor light bulb to an LED you'll knock 7 Ah/day off.
P.P.S. I'd also like to have a fridge that consumes 1 A for 12h/day. If you've patented that you're going to be a wealthy man!

[Mistroma]

+1 for LED anchor light. I did something similar several years ago before setting off for the med. but also included estimates of when kit would run. It was therefore able to allow for effect of Peukert's law (as peaks and troughs could be seen) but was a bit OTT as I also built in allowance for charging inefficiency. It was a useful tool initially and convinced me not to bother with a built-in generator and also type of battery to use.

If you have flooded batteries, the following thoughts might help. I think that you have already considered some points already wrt solar.

1) Don't assume you can simply replace usage with an equivalent amount generated.
Flooded batteries need a lot more put back in than you've taken out (if you want them to last).

2) Fridge duty cycle will increase hugely in July/August if it is standard (i.e. No keel cooler)
If it runs 20% of the time in UK then expect 25%-30% in med. and 50%-70% when temp. gets to 40C. Extra insulation will pay huge dividends (though I haven't managed to improve mine yet).

3) Don't assume that a couple of hours on engine will fully charge the batteries
It's common for alternator output to be 60-80A initially and then fall rapidly to 20A and then even lower. Depends on battery type, regulator, battery type and size etc. It's worth measuring if you were thinking of a larger alternator as better regulation might help instead. Of course that loads up the alternator so that it overheats and you end up changing it anyway.

4) Generator is a terrible way to charge batteries if that's the only charge source.
It runs at very low load if that's all it is doing and isn't run long enough to get to full charge. The load is higher if used to heat water but waste heat from generator cooling system is actually more efficient than using it to generate electricity for heating. However, it is useful to push in the initial charge early in the day if you don't have a huge solar array.

5) Fit as much solar as you can manage
I have rigid 3 panels in front of the sprayhood and a flexible on the bimini. The rigid panels are shaded but can be moved out board at anchor. However, they are cheap and I found it worthwhile buying 3 (65W + 40W + 40W). I dislike flexible panels as I've seen many fail after 2 years and said I wouldn't have one. However, I ran out of deck space and then found a 100W semi-flexible fibreglass model as a reasonable price. So I fitted that on the bimini and it's working well (might still die or course).

6) Measure the battery state and monitor regularly
I use a German made SG gauge and also a SmartGauge. I've measured alternator and 240V charger output with a clamp meter at different battery states. I'm now pretty confident that I do know battery state via SmartGauge and only take SG readings every 4-6 weeks. Jeanneau's standard Amp meter doesn't catch everything as some items near the stern don't run through the shunt in the saloon.


I hope that these ramblings are of some use. You've already done more than most people by trying to estimate power usage and that's a great start.

You won't get a perfect system as every change affects lots of things but you will develop an understanding of where priorities lie.

I can let you have actual figures from my boat for daily wind and solar power generation for 2012-2015 from UK to med. Spain if that would help.

[haddock]

Thanks for the feedback. The numbers in the spread sheet are for playing around with and are only representative. Agreed on the windlass. This battery is isolated. The water maker draws 16 amps and I would tend to only run it while on engine or with the generator running. I have also installed a smartgauge so can keep a close watch on available power. I have also installed a flexible 60w solar panel in front of the sprayhood and have a 150w panel mounted on two poles attached to the push pit. The main reason I did the spread sheet was to try and establish what the boats power requirement was and if the boat could run on solar panels alone...not possible with available space. I have also installed air conditioning 700w standalone unit which, again I will plan to run when the 2.8kw generator is running. I have installed a 1500 pure sign inverter so could also run for short periods on battery. I have put the remote start generator in the liferaft locker and insulated so the noise will be bearable for my neighbours when at anchor (I hope). Yet to fire her up so time will tell.

What I am trying to do is make the boat as independent as possible for longer passages. However, my initial cruising is going to be around the western med islands so will always have access to fuel pontoons to fill the water tanks.

I have 3 domestic 110amp batteries so another option is to install more but space is limited.

I bought the boat with very little on board and had a limited budget of £10K to upgrade her. Managed all the above fitted and a lot more (have list if interested) with change!

She is now a well sorted boat with all options ticked and requires nothing else. Been an interesting project.

Planning first adventure sailing from Sant Carles to the Balearics for 5 weeks at the end of the month with wife, two daughters and a friend. Going to be cosy!

Haddock

[haddock]

Also, Mistoma, would love to see your numbers.

Thanks

Mike

[Mistroma]

OK, I'm actually heading for San Carles and will probably be there soon, around 15th June. I might stay a few days before heading to Badalona but had only planned to anchor. I'll keep an eye open for your boat, let me know if you will be in the marina. It would be good to meet up if you are in the area.

I'll dig out the figures and also some information about a solar output model which gives excellent estimates for daily output based on panel size and cruising area.

We spent much of last summer at anchor in the Balearics and no need to stay in a marina or on a mooring. It does get worse each year. I was told that San Antoni got wall to wall moorings just after we left.

[haddock]

Hi Mistoma,

I will be leaving Sant Carles on the 29th of June then heading south to the Columbretes and on to Ibiza so unlikely to hook up.

Great anchorage in the bay if you have not been there before, very protected.

Look forward to receiving the numbers.

Enjoy your sail!

Haddock

[Mistroma]

Sorry for the slight delay. We had Wifi problems yesterday and busy with sewing machine today.

Download the data at www.mistroma.com/BalearicSolar2015.xlsx

I realised that the raw data was probably not much use and added some extra information. I tended to aggregate days in a marina but usually kept a log for each day when at anchor. Batteries were always on mains charger in a marina and so I wasn't bothered much with the detail.

Filter by "Anchorage" in first column to get off-grid readings
Last 4 columns are Net Total, Net, Solar and Wind Gen

Net Total is output from panels and wind gen going into batteries
Net is simply solar and wind added together

Net total to batteries will be lower that Net figure as the regulator throws away power whenever batteries are well charged.

I also have data for 2012-2014 from France, Spain & Portugal but will need to tidy it up.

[haddock]

Thanks for the insight and data. Have purchased an LED anchor light to hang of the rigging which draws 100ma! Big saving.

Ta

Mike

[david100]

Haddock,

I'd love a copy of your spreadsheet as I am working on upgrades as well, and this is an excellent place to start.  Please send to DPSAIA "at" COMCAST.NET.

THANK YOU!!!!!