charles_reed
Well-Known Member
I'm sorry to have offended your sense of propriety - however I'll not rise to your nit-picking.
I do happen to know what I'm talking about, even if you can't accept it.
Solar panel ....Do I really need a smart charger?
- Thread starter ctroutz
- Start date
I'm sorry to have offended your sense of propriety - however I'll not rise to your nit-picking.
I do happen to know what I'm talking about, even if you can't accept it.
charles_reed
Well-Known Member
How come the meter in the video is showing over 15v with a 12w panel connected to 220Ah?
Started with fully charged batteries in an area of high insolation.
Those who place implicit faith in sales videos on YouTube deserves the derision they'll get.
GHA
Well-Known Member
I know it started to its a fully charged battery, and what sales video are you talking about?
The point was regarding a statement that a small panel could never get terminal voltage above 15v, which obviously it can.
And why direct insults at someone you have never met and know nothing about? Get out of the wrong side of bed or are you just a nasty human being deserving no better than derision.
sailinglegend420
Well-Known Member
Thanks for your support.
I do know Mr Charles Reed having spent some uncomfortable time on a 10 day Cruising Association rally with this over-opinionated man. That's is why I try to correct some of his ill-conceived postings.
sailinglegend420
Well-Known Member
If you know what you're talking about then you haven't explained what you actually mean by your statement ...."there are no such things as a "smart" charger for solar panels..."? I thought I was agreeing with you, in part, but was trying to avoid confusion by your ill-conceived statement.
This is NOT a You Tube sales video but comes from Maine Sail's excellent site @ http://www.marinehowto.com
He is a marine electrical engineer who really does not what he is talking about!
sailinglegend420
Well-Known Member
I think you have totally missed the point.
If you have fully charged your batteries with shore power and then leave the boat for 6 months with a small solar panel on a large battery with no regulator then it will get up to 15+ volts each day and eventually kill the battery. Leaving a small load on overnight is an excellent idea.
Overcharging may also happen with so-called "smart" solar controllers that get up to absorption voltage each day but have a set time of say 3 hours at 14.4v before dropping to float. Staying too long at only 14.4v when the battery is fully charged will also cause excess gassing and kill the battery, especially in sunny climates like the Med in winter, or worse leaving a boat for 6 months in the summer when the batteries may get to 40C when they will start gassing at 14.0v.
ctroutz
Well-Known Member
Well...I only asked, didn't think I'd start an international incident! Seriously though, thanks to all who chipped in. I'll try my new batteries first to see if they lose their charge as before and spend an hour on board with a beer, listening for pump noises as well. The 'drain' shouldn't screw up the new batts. short term should it?
The boat's been sat with flat batteries for a week now and it's pretty dry so hopefully no more serious issues apply.
Seems my regulator will be enough (when I get around to the solar panel) unless we get access to shore power when, I suppose, a smart charger might be valuable if left on for long periods?
The boat's been sat with flat batteries for a week now and it's pretty dry so hopefully no more serious issues apply.
Seems my regulator will be enough (when I get around to the solar panel) unless we get access to shore power when, I suppose, a smart charger might be valuable if left on for long periods?
Stemar
Well-Known Member
Leaving the declarations of war aside for a moment, and going back to the point of the thread...
If your boat isn't half full of water after a week with flat batteries, the bilge pump isn't an issue! That does suggest that the batteries are unwell, to say the least, so replacement sounds like a plan.
Your original question was whether a 50w solar panel and regulator would be better than a smart charger. I'm a fan of solar panels. They work independantly of shore power and have no running costs. I'd expect your planned 50w panel to keep your batteries topped up through the winter and keep up with bilge pumps & the like until a leak becomes so serious the boat's in danger. In the summer, fridges apart, it'll go a long way, perhaps all the way to keeping up with electricity use at anchor or under sail. If you go down this road, remember that a rope's shadow over a panel can reduce the whole panel's output significantly. Unless you can guarantee a clear view of the sun, you're likely to be better off with a couple of smaller jobs, arranged so if one is shaded, the other is in clear sun.
If you have access to shore power, a smart charger will be useful, especially if you plan on using the boat a lot in winter, when solar power's at its lowest but, personally, I wouldn't want to leave it on while the boat's unattended. My solution would be to go for a couple of rigid panels installed permanently and a Halfrauds or similar portable smart charger (can't remeber if mine came from Lidl or ALdi) that you can plug in if the voltage starts to get a bit low. I'd also install a couple of eBay voltmeters so keep an eye on starter and domestic voltage, 'cos I like to see a the figures that tell me in good time if I need to plug the charger in or turn the fridge off!
ctroutz
Well-Known Member
Hi Steve, thanks for getting back to basics. I'm just about to change those batteries anyway so one way or the other it should become clearer. I've also just got a copy of the '12v Bible' to help track the 'charge leak' if it still happens. I'll go one step at a time but build in the expectation of fitting a second solar panel... I'm a bit short of space on deck (26' Colvic Watson with aft cabin) and my existing panel will have to go on wheelhouse roof obviously affected by the boom. I'll have another look and I may just 'bite the bullet and invest in two smaller panels as you suggest. It's all about engine starting, particularly as I haven't yet got the facility to hang an outboard on the canoe stern and I haven't yet got the hang of those 'things that flap around on top of the boat'. I also can't get 240v on my mooring so I think I'll blank thoughts of a smart charger until I get this lot sorted out.
Thanks to all again,Graham.
charles_reed
Well-Known Member
Unfortunately know him well, he had a row with the marina we both occupied, probably both parties @ fault, but caused considerable problems for others.
We spent 3 days on a CA cruise in company until he cried off going into Kolpos Messianikos due to possible wind.
Both of probably have opinions - to which we're no doubt entitled.
I do wish he wouldn't try to falsify what actually happened.
Stemar
Well-Known Member
You're in the same situation as me. I'm on a swinging mooring. I can get shore power provided I get to the club pontoon before the tide goes too far out, but I don't do marinas, so I really need to be independant. I wouldn't spend out on replacing a perfectly good panel until you've got it set up properly. My panels are rigid, so I made up a frame from angle ally and pop rivets & it's working well, 2 years on.
My setup is pretty simple. The domestic battery that runs everything except engine electrics, through its own master switch. This is connected to position 2 of a 0-1-2-both switch. The starter battery is connected to position 1. All the engine stuff - starter, "ignition" circuit and alternator output is connected to the Common. There's a simple car headlamp relay between Common and 2, energised from the field coil of the alternator, so it's on whenever the alternator's producing power. That takes care of starting the engine and charging from the alternator. The solar panel goes through one of these controllers http://www.sunstore.co.uk/EP-Solar-Duo-Battery-Solar-Charge-Controller-12-24v-10A.html which is connected to Positions 1 & 2 of my switch, concentrating on the starter battery until it's fully charged then turning its attention to the domestic one. This ensures that my starter battery is always ready to go at the theoretical expense of the domestic, though in practice, that's never been a problem.
William_H
Well-Known Member
"There is a simple car headlamp relay operated from the field coil of the alternator." I wonder what this means? It is obviously doing the job of a Voltage Sensing Relay.
It is the connection to the alternator which worries me. Generally the current for an alternator field is supplied in the first instance before engine start via the "ignition" light and ignition" switch key for the engine electrics. This supply is supeceded or made redundant by the supply generated from the laternator when it starts charging.
A simple connection of a relay to the field coil would either have the relay operating when the ignition is turned on giving parallel batteries for engine start or more likely the relay would soak up the meagre current flowing via the light so laternator would not get that kick to sart charging.
Alternators often have an auxiliary output being a kind of AC from the centre point of the star connection of pick up coils. This point is the one often used to drive tacho. It can be rectified to operate a relay as described. Or a relay can be connected to the oil pressure light circuit to operate when oil pressure is built up. However most commonly and simply a circuit is made that senses when the alternator has raised the voltage of the engine battery up to about 13volts this operates the relay to connect in the service battery for charging. No tricky connections to engine or alternator wiring.
I only make these comments in case anyone thinks from your words (perhaps not carefully chosen) which imply that you can simply connect a relay to the field coil of the alternator. good luck olewill
BabaYaga
Well-Known Member
If Stemars setup is what I think, a relay operated from the D+/61 terminal on the alternator, then I have the same on my boat and I can assure you that it has worked just fine for the last nine years. In fact I think it is quite common to use a "simple" relay instead of a VSR for splitting the charge, although perhaps a "car headlamp relay" may not always cope with the alternator output. I use a heavy duty 70 A relay as I have a 70 A alternator.
You outline two possible drawbacks, either the relay operating (closing) too early, triggered by the current running from the ignition switch via the warning lamp to the D+ terminal (in my understanding connected to the field coil/rotor, could be wrong there). AND/OR the relay soaking up this current, so that the alternator does not get excited and therefore does not start to generate.
None of these two happen. The alternator does start to generate after a few seconds and only then does the relay close, paralleling the batteries. Why this works so well I can not explain, but would be very interested if someone could.
VicS
Well-Known Member
I suspect Stemar has wired his relay to the output from the field diode. Not the field coil, which is the rotating coil to which current, controlled by the regulator, is fed via the slip rings
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BabaYaga
Well-Known Member
I'm not quite sure what the field diode is.
Is it one of the three output diodes from the stator windings that does not supply the B+ terminal? In that case = D+. (On my alternator, that is. I suppose they are not all the same).
Is it one of the three output diodes from the stator windings that does not supply the B+ terminal? In that case = D+. (On my alternator, that is. I suppose they are not all the same).
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JumbleDuck
Well-Known Member
How was that measured?
Volts don't go into anything. Volts go across things. Amps go into things.
The only thing volts will damage is insulation, and even then it does the damage by pushing amps through.
Gassing is a direct result of current and only of current: it's electrons moving around which turn ions into gases.
VicS
Well-Known Member
The main DC output comes out via a three phase ( 6 diodes) rectifier and B+
There are two ways in which the field current can be obtained. The most common, AFAIK, is via a rectifier consisting of three diodes. That was what I meant when I said field diode... I should have pluralised it!
FWIW this diagram show the two types. In the first the main diodes supply the field current but there then has to be a blocking diode in the main output to B+
BabaYaga
Well-Known Member
Thanks Vic, looking at the second diagram (which is similar to my alternator, perhaps also Stemar's) I think I can conclude that connecting a relay to the field diodes (FD) is electrically the same thing as connecting it to 61 or D+. Just a matter of where it is done, inside or outside.
Stemar
Well-Known Member
The terminal I referred to is the one to which the charge warning light is connected.
As I understand it, when I turn the "ignition" on, +12v is supplied to the charge warning light and earthed through this terminal, providing a small current through the field coil. As the resistance of the coil is a lot less than that of the bulb, everything downstream of the light is at near enough 0v, so the relay stays asleep. When the engine starts and the alternator spins up, this small current provides a magnetic field to start the alternator generating current, at which point it's fed by the output from the alternator. The terminal is then at +12v, so the spilt charge relay wakes up and the warning light has +12v on both sides, so it goes out.
My relay is rated at 50amps and the alternator at 55amps. It isn't overloaded because the voltage builds up over a (short) period of time as the alternator spins up and it switches at, probably, something like 10v, long before the possible output, even to a flat battery, gets anywhere near maximum. Relays can carry a lot more current once switched than they can safely switch, so in the unlikely event that the domestics take the full output, I'll be fine
JumbleDuck
Well-Known Member
That's precisely how the starter cutout (prevents the starter motor from being energised when the engine is running) works on my DS.
