The comment about the positive ground is correct, in large high voltage strings SolarPower cells need to be positively grounded to bleed of a surface charge that will choke there output. These are very popular cells because of there industry leading power density. Most high voltage solar converters support positive ground because of this.
But as I said in the last post, on a boat you will not have high enough voltage to worry about it. Plus the bendable panels are not grounded at all. So they should not be used in long high voltage strings regardless. If you did use them in high voltage strings with out positive grounding nothing bad would happen they would just not put out there full 19% efficiency.
Though having something on your boat with a small positive surface charge might make you boat a more interesting lighting target. :-) But I doubt there would be enough of one to make a power boat more interesting then a sailboat with an aluminum mast!
On Jun 9, 2014, at 11:33 PM, "'Dan Hennis' dhennis@centurytel.net [electricboats]" <electricboats@yahoogroups.com> wrote:
Quick comment I believe to be accurate.If memory serves, in about 1958-1960, all American companies stopped doing Positive ground. This I believe was a part of the NEC at the time. That is why you do not ever find any motor vehicles after that year with a positive ground. It is too confusing to us normal people to have to look up in a book for a direction. Also, it had to do with electrical engineering theory.Just sayin, ...Dan----- Original Message -----Sent: Monday, June 09, 2014 11:20 PMSubject: Re: [Electric Boats] Re: 1964 8 Metre Bobcat Catamaran Electric Drive
Does that Grape solar panel have a positive ground? and how does that work exactly?Looks just like the Renology panel, 100W Monocrystalline Bendable Solar Panel | Renogy Store, which I believe has a positive ground. Not sure exactly how to deal with that but would like to understand what difference it makes before I spend $2/watt for a couple of them for my dinhy. Only weights 3 pounds and looks like a good package but the positive ground thing has me concerned.Can anyone explain how this will affect a charging system? or does it matter?Captain CarterOn Monday, June 9, 2014 9:30 PM, "James Sizemore yamez4u@gmail.com [electricboats]" <electricboats@yahoogroups.com> wrote:
As long as the high and low cutoff can be user configured they would work. You would also want a contact relay so that the BMS could shut the charger down if a single cell went out of range. The 12 volt and 48 volt chargers are using the same feed in source so the limit is the watts used not the DC amps.120v 15a breaker can supply 1800 watts.1800 watts / 48 volt = 37.5 amps1800 watt / 12 volt = 150 ampsThe limit is almost always the source watts, just Ohm's law in action.The largest charger you can realistically buy is a forklift battery charger:You would need at least a 5000w generator to keep it feed.
On Jun 9, 2014, at 12:11 PM, "albert682@yahoo.com [electricboats]" <electricboats@yahoogroups.com> wrote:Hi Group,
I'm kicking myself for even shipping the 48v Lester chargers up to Canada but done is done. Can they even be used for charging Lithium Batteries? If not I'll use them for the coach RV batteries.
Otherwise I've been reviewing inverter/chargers and have found that 12v inverter/chargers output more amps than 48v inverter/chargers. Why is that? Also if that is the case should I be looking at a 12v high output charger?
Each of my motors produces 80amps for a combined output of 160amps full throttle. It would be nice to source out the components so that I can always return the same 160amps back to the bank. So if I'm thinking correctly then I get a large stand alone inverter and run multiple 48v chargers back into the system.
Everyone seems to go for the elcon 1500 charger but at the outset I don't know for sure if it charges at more than 20amps which would take forever to charge a large bank.
The safe limp home speed well it's more like the never going home speed I'm after. I do concurr though the DC generator is the way to go but prohibitively expensive. So AC generator(s) and a large output charger is what I'm after.
Arden
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Dan Hennis
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