sjc

There's a new product coming out soon called DumbGauge, it is an iphone App, costs under a fiver, requires no connection to the batteries, accurate to within +/-0.001% at all times. All you do is point your phone at any boat and it tells you the SoC of every battery on board, the level in the fuel, water and waste tanks, the state of the anodes, and whether blacking is required...

Yes I did edit my post to correct my arithmetic, basically 1W for 2 hours is 2 Watt hours, at an average of 1Watt per hour ( I erroneously said 0.5Watts per hour ). I was not suggesting the Watts per hour as a new SI unit, it was just to demonstrate the difference between Watt-hours ( Watts x time ) and Watts per hour ( Watts divided by time ). I am sure we are all bored with this now and are posting over semantics, time to move on I feel, this isn't helping MtB !

I never said you didn't get energy, simply stating the units, which I did mean to be watts x time, what you describe is watts per hour, which is different. 1 Watt for 2 hours is 2 Watt-hours, but only 0.5Watts per hour. The confusion is that Watts sounds like it should be a power, but has an intrinsic " per second" within it, so multiplying by seconds gives Watts x seconds, or Joules, indeed the unit of energy. So there is no disagreement ? I did make a schoolboy arithmetic error, it should read 1 Watt per hour, not 0.5. This is in effect an average. A Watt hour is watts x time, not watts divided by time ( ie an average )

The resultant units for V x I are Watts, multiply that by time and you must get Watt-hours ?

Power generation is given by current and voltage, whereas power consumption does depend on resistance - As Loafer demonstrated in post#85, manipulation of Ohm's law can make it a factor of whichever you prefer : ( I2R, or V2/R, or VI ( where V = voltage drop across the resistor ) ).

As seems to be the case recently, most posts are just contributors arguing between themselves, leaving the OP to seek an answer elsewhere as the wide variety of answers tells them nothing ! As mentioned earlier in this thread there is no perfect method of measuring SoC, so how on earth can anyone claim 1% accuracy ? Unless you have accurate, calibrated equipment to compare against you cannot possibly claim anything ! That said, I considered buying a smartgauge but never did, it seems to me to be a very simple tool for the non technical boater. If you want more this equipment isn't for you, live with ( without ) it ! I have no problems with the smartgauge principle, I can only assume the algorithm measures the rate of change of terminal voltage, very simplistic, but probably gives a good enough indicator without getting down and dirty every few days. A very ingenius idea but probably mis-understood by people expecting too much for very little. As with any equipment, it is impossible to fit and forget, the user has to apply common sense in all situations and whenever any gauge alerts you, the first thing to do is to suspect the gauge and do a sanity check. Those of you talking about fault finding on your degree courses take note ! The un-calibrated smartgauges out there, do they really need their voltage reading calibrated, in this day and age, a voltage reading is the easiest thing in the world, no calibration required, smells like BS to me... Personally I would like to know my remaining Ah capacity, rather than just having 60% of some unknown capacity, but that's just me. If it was truly for the non technical boater that be the icing on the cake. If at any time you want to know your true battery capacity try the following, I have no connection with them, and cannot claim to know any accuracy levels :- http://www.actmeters.co.uk/battery-testing/chrome-ibt That should stoke the fire somewhat...

I suffer from asthma, in my case damp / musty conditions are an absolute no no. I can tolerate it during the day ( although I don't like to ) but overnight I have no chance. I suspect the stove is innocent and the damp is the cause, especially as you close ALL windows, I always insist on cracking a couple open whatever the temperature. Last year we bought a Meaco dehumidifier ( 240v ) which helps a lot as it keeps the atmosphere dry overnight ( almost zero condensation ) - you may not be able to do this without a shoreline, in which case ventilation is your best bet. However, for me, once the damp has taken hold it is a big job to clear it to keep my lungs happy, you may need a good dry summer to do that, in my case even that didn't work !

Sorry SirN, but it certainly does, it has inductance and resistance, therefore impedance. It may not be relevant in this case, but it is there.

Here's a thought before you take the plunge ... Replacing the bulbs will save you 1Ah per bulb for every 3 hours use. So if you use 2 lights for 3 hours each per evening that's 2Ahs saved, assuming 440Ah capacity, on a 50 % SoC basis, that's 2/220, or less than 1% of your useable capacity. Is it really worth the cost and hassle ? Merry Christmas.

More to the point, any safety recommendations should be followed no matter who builds it or uses it. They have evolved over many years to keep people safe. Also, if anything did happen to a guest / visitor I doubt you would be in a good position having ignored the standards...

I would imagine the last digit is a work of fiction, not that it detracts in any way from the usefulness of the Smartgauge, just don't read too much into it !

Surely the point has been missed here ? Solar panels convert solar energy, and in the winter the levels are very low. Therefore the electrical output POWER will be low, whether you want low voltage higher current, or vice versa that is the fact of the matter. So yes increasing the voltage will work in borderline cases ( although there seems to be enough headroom ere anyway ) but still give such a low current there will be no real benefit ?

My preference , just to give you another option would be to keep the starter and domestic circuits separate. Keep one of the 70A alternators as a spare, buy a new 140A ( or so, depends on bank capacity ) alternator for the domestics and hey presto. Ensure the pulley ratios are high for the domestics to get the most out of it. One thing to consider when fully loading your starter alternator is that the belt also drives the water pump ( usually ), high currents mean more tension in the belt, and more wear on the bearings, which is why I suggest leaving the starter system alone - I am sure Tony can advise whether this is a genuine concern ?

I can only assume it depends on the voltage levels they apply / experience. The first charger ( shoreline ) would be working normally then when the sun comes out the solar fires up and tries to establish the battery SoC via the voltage level (?), then chooses the appropriate charging stage to apply, although maybe in some cases they default to bulk for some period to see what happens. So if they both work on the same voltage levels ( as in this thread, 2 identical MPPTS ) it would be part guesswork as to what happens next. They may both stay in bulk for a while or one or the other go to absorption / float, dependent on actual SoC I guess ? We need a volunteer to buy a dual system, then sit up until sunrise measuring the current and voltage levels every 60 secs - maybe with a light meter on the roof as well - merry Christmas !

I would never expect an over voltage, but I would expect the following, since one would always start before the other :- The first controller would start up, sense the battery voltage and go into bulk mode ( say ). The second controller would start up and sense the bulk voltage from the first controller, assuming this was 14.4v the second controller would then go to float ?

OK I'll get the ball rolling on this one ... then others can come along and contradict me ! IMHO :- 1) You should not mix and match panels, so you can only : parallel panels with the same voltage rating, or series any with the same current rating. 2) You cannot parallel the outputs from "intelligent" controllers ( eg MPPTs ), because they will confuse each other. 3) You could parallel fixed voltage chargers ( say PWM controllers giving fixed 14.4v ) but then you would lose the benefits of the MPPT. Would it be possible to set the MPPT to a fixed output voltage ? Good luck with the chaos that is about to be unleashed ...

I have no idea if the H connection is usual, but it does happen. I guess it reduces your losses if only one panel is in shade ?

If you imagine an "H", it depends whether or not you connect the horizontal.

If you go for a 2x2 configuration you should really ensure the bypass diodes are rated for the max current ( in this case 2 panels, rather than just one as for a series setup ).

Well, a multi-topic thread, perhaps the moderators could spilt them up so everyone can follow the branch of their choice ! 1) Whilst wet cells are great when looked after, for many, including myself, the convenience of SLAs takes some beating, even at the cost of lifespan. 2) Knowing nothing about gas installations, I hope competence isn't judged purely on whether or not it blew up. The tightening of wirings regs ( eg Part P ) was an attempt to pre-empt such disasters, surely the idea behind "gas safe" is the same ? 3) Over the years the term "engineer" has been used and abused, the respective institutions have been trying for years to restrict the use of the title to those with chartered status ( similar to chartered accountants etc ). It doesn't guarantee anything, but is meant to be a guide and give confidence. Those without the title may not be strictly entitled to use it, but could be as good, if not better...But I guess I you had to choose an "engineer" from a list ( to carry out some work ) you'd look for anything that implies competence !

Mains fridges use single phase induction motors, which I believe have a very low starting torque. I assume this is why they require the starter circuit to over-drive it to get it to start turning. For this reason I think you can burn out the motor if the startup time is excessive ( since during this time it is being over-driven ). DC motors simply have an inrush current then produce more torque from a standstill. However, single phase induction motors are relatively cheap and reliable, hence their use.

So, the system consists of a high output alternator and an inverter, if you already have an inverter why not utilize that by adding your own high output alternator. This would be much cheaper, easier to maintain, and with no centre-tapped issues as mentioned in previous posts. What is wrong with that idea ? Keep it simple ...

It may help to know the model of aerial and amplifier. It could be the amplifier filtering out the DAB, does it claim to work for DAB, or just TV frequencies ? If you are in a reasonable signal area you could try the DAB without the amplifier.

Assuming these reside within the engine room the only other consideration is the max ambient temperature, which effectively de-rates the cables.

Alan, out of interest what make is the Radar, is it Raymarine by ay chance ?