Flat Batteries

[Dolphin]

Some of these turbines in wind mode can be quite noisy so be careful and listen to one before you buy.
They sound like a good idea, but they are towed 30m behind the boat!

Aaron, I found that when I renewed the oil sopper in the bilge to soak up the oil, the smell in the boat was quite noticeably reduced. I could smell diesel even in the sleeping bags. Its fresh now and I haven't washed the bags.

[storm petrel]

The Duogen looks like a better system, but it is very costly. What about some of the other water generators on the market. I think water generators are the best way to generate current while cruising and I would certainly look at them more closely if I did not have a diesel.

[Tales]

If you are into DIY have a look at this.


http://www.tradeaboat.co.nz/View/Articl ... 4294967263

Cheers,

Tom

[RodM]

Those little Honda/Alternator systems look good, however the website brochure says the 55Amp system is only recommended for 70AH batteries. From memory it said using it on larger batteries 'could cause the alternator to overheat or the engine to stall'. They do make larger units as well - but they're considerably heavier & no doubt more expensive. Given most marine batteries are 85 or 100AH, it'd be worthwhile checking how well such a setup would work charging a couple of larger batteries...

Rod

[rob.lovelace]

I believe it said N70 size battery not 70ah. N70 batteries can be in various amp hr capacities.
here's some interweb blurb on it
It IS important to make sure you have the right type and size of charger for your particular battery and application, because..."The Laws of Physics will always trump the Laws of Wishful Thinking".

The following rule-of-thumb formulas are used by engineers and technicans to calculate the approximate size of a battery charger needed to fully recharge batteries (to 100%) within a minimum available time period:

8 hours charging time available equals the Amphours to be replaced divided by 4
10 hours charging time available equals the Amphours to be replaced divided by 5
12 hours charging time available equals the Amphours to be replaced divided by 5.5

Say for example you had a 100 Amphour (Ah) battery from which you regularly took 80Ah, and you needed to replace those 80Ah in 8 hours, then 80 divided by 4 equals approximately a 20 Amp charger for charging to 100% full in 8 hours.

If you had 10 hours available, this would work out at 80 Amphours divided by 5, which equals about a 16 Amp charger.

12 hours available to replace 80Ah would need about a 14 Amp charger.

source

http://www.macfarlanegenerators.com.au/ ... da-engines

http://haze-n70-gel.com/

[Swift]

Hi
The long charge times quoted at http://haze-n70-gel.com/ are for GEL batteries which of the three lead acid batteries-(Floooded, Gel & AGM) have the highest internal resistance and therefore the longest charging times. A DC generator such as the Christie's 40 amp unit will charge a dead flat 100-amp AGM in less than 3 hours. In actual use you would never totally flatten your battery so re-charging times would be much shorter.

That said, the reducing prices of AC inverter generators is making DC generators less attractive. A 1000w Honda used to cost well over $2000, they now cost around $1200. Cheaper brands such as Kipor and Ryobi can be had from Bunnings for as little as $400. The problem with these cheap generators used to be that a lot of them had modified sine wave outputs which would not work with some battery chargers and you were forced to use a basic old style heavy and expensive transformer type battery charger. In fact in some ways the cheap AC inverter generators were worse than the old two stroke $100 GMC (non inverter) generators. The two stroke generators produced a rough sort of sine wave but had poor voltage regulation as the generator speed up and slowed down. The inverter generators had a steady voltage output but a horrible wave output. That all seems to be fixed and cheap generators (except the $100 two strokes) now advertise clean 100% sine wave outputs.

The other thing that has changed since I looked at this years ago is that switched mode battery chargers have come down in price. 20 amp and 40 amp chargers range in price from $100 - $350. So at the low end you could put a 20 amp battery charger together with a 700 watt inverter generator for a total cost of $500. If 40 amp charging is required a bigger generator would also be required.

For people who don't like 240 volts on boats, DC generators are the way to go. But for others, AC generators with a battery charger offer some advantages: You have 240v available to run tools without having to buy a DC to AC inverter, you have a wide choice of battery chargers including sophisticated multi-stage battery chargers which are kinder to batteries than the bulk charge from DC generators, when staying at a marina you don't have to fire up the generator because you already have your battery charger available for use with 240v shore power, the noise level of inverter generators is much lower than DC generators- A Honda AC is 53 dB compared to the Christie's DC generator which is 73 dB, (sound doubles for each additional 3 dB) Other brands of inverter generators are in between these extremes. I have read that it's hard to hear any difference in sound levels between a Ryobi and Honda.

Cheers
Keith