Tuesday, 3 February 2015

Electricity, inverters and a Smartgauge explanation, but not toilets.

Most boaters will tell you when a couple get together they invariably talk and sometime argue on the merits of how to hold and dispose of your bodily waste - toilets. Not this boater, I have a real electricity fixation.

Now I need to add a squirt of clarification to that.... as this boater (me) is off grid - fully. Lots will live in marinas for the winter when power is most demanded and most pressed and have a 'hook up' as well as a galvanic isolator to  stop their boat fizzing away to nothing.  Power to these boys and girls is limited to their wallet thickness in the main.

One thing living afloat for the winter has taught me is how much you are aware of the drain different bits of kit have on your bundles of liquid electricity storage - or batteries. I have gone from 170a/h to 220a/h to currently (sorry) 330a/h.

Now while like the sound of Percy's Lister CS2 I prefer to listen to it while on the back steering through this green and pleasant land, so I resist starting it up as much as I can whilst stationary. Also I am bound to self lubricate after each generation session as the 'donk' is a 1929 design and does not have such delights as oil pressure and much more than a simple 'splash' lubrication system for those bits inside I cannot see.

So I don't like to have to top up basically.

Now the inverter is a no name 1000 watt jobbie. It'll start and run the Dyson as well as the 700w microwave. After that all other devices are TV 22w, and charges for laptops and phones/Ipads etc.

Now the Smartgauge explanation - trust me I'll be back to inverters soon....

I nicked this from Mr Delting from this canalforum thread - the thread is interesting reading but Mr Delting's explanation is the best I have seen for owning a Smartgauge  - I am a devotee, it was the first thing I fitted to Percy.....

As I understand it Smartgauge is not meant to be read like a 'Bible' and mine certainly doesn't work as one. If I run some equipment for a known time I know I have used X percent of the 550 Amphours my batteries theoretically can hold. Smartgauge does not drop by X percent straight away but wait a while and it will be very close.

When we get back to the marina after a good run and SG states C100, when I connect shorepower the Victron goes Bulk, Adsorption to float in about 5 minutes so the batteries are pretty full.

What I do know is that if it says C60 in the morning I need a good charge period today, if it says C78 then in summer the solar will probably be enough. It is also useful when you look at 5:00pm and realize that all is not well when it reads C65 so you had better run the engine for an hour or so to survive the night. It doesn't matter if C65 is actually 65 percent or not, it indicates that your batteries are below 70 percent and that may be important at 5:00pm otherwise Murphy states that by 8:30 your inverter will beep and turn off in the middle of that film / match. and it is too late to charge your battery!

So if you were thinking of getting one what is stopping you?

Back to inverters....

I left mine on the other night by accident and came back the next morning to find it had robbed about 8% from my batteries as told by the SG. So I then realised the old inverter was using a good chunk of watts just waiting to be used. We only turn it on when needing 240v but I have realised that its standby and its no doubt poor efficiency in 'inverting 12v to 240v means it is an electrical luxury I had not thought about. 

So my dilemma and advice if you have got this far....

I have a small 150w inverter I could wire into the battery bank and use when I only need the tv or a charger or two.... I am not sure what this devices's standby or efficiency is but I am understanding that the closer to the maximum you run the inverters at the more efficient they are and this is a newer device it might be/should be more efficient even at standby.

My other option is to get a 180w Victron for about £100 of which I know its standby use is 2.6w (0.16 amps) and 87% efficient so my 22w tv will be in effect consuming about 25w? This option means on the times I want to run the vaccum or microwave I'll have to swap over the plug to the respective inverter, a simple system. 

My final option is to blow the budget and get a 1200 Victron that has a standby of 6 watts and is 92% efficient but can be put in search mode - sleep that consumes 2 watts but needs devices with enough draw to wake it up - a problem I have read about elsewhere.

I may well investigate the old inverter to see if I can find out more about it. I may well try the 150 watt one I have for now and see how that works, progressing to the 180w Victron until the old inverter dies one time when the vacuum is being used etc..... good typing that all up has given me a plan/strategy/approach.

Always welcome thoughts on what I have posted especially of you think  am wrong or you have a Victron to give me ;-)


Amy said...

We are totally off grid all year round as well and this (using a smaller inverter for smaller devices) is exactly what we do. In fact we have 3: a tiny 75W which I got for £3 from Asda, a 300W one in the living room and a 2000W in the engine room. We hardly ever use the 2000W one, tending to run things that need higher wattage only when the Honda EU20 is on. Having the little inverters to hand means it's easy to turn them off when not required so the standby draw isn't an issue.
Amy NB Willow

Nev Wells said...

Amy, a really helpful and encouraging reply thank you. We also have a suitcase genny and if we are going to give the boat a deep clean (or saw wood or mow the lawns) use the genny. I have tried the 300w (I thought it was a 150w) Belkin tonight and after about 2 hours tv the SG has not moved from 73%.... so far so good.