1996 MKII, hull 1530
I'm finally going to replace my 15 year old Promariner flyback 20-3 charger. Batteries (two 4Ds) just aren't lasting that long any more, and I've got a feeling I'm over cooking them with this older style charger (noisy too).
While on-line purusing the instruction manuals for some of the potential replacements, I noticed that most manufacturers call for a fuse in the DC charging cable within 7" of the battery terminal. However, I don't seem to have this fuse in the DC charging line with the existing flyback 20-3 setup. Why would this be? Is the fuse absolutely necessary? (I bet so!). If the fuse is necessary, any suggestions on an easy way to implement. I've seen some neat fuses on the Internet that sit directly on the battery terminals, but I doubt I can find them locally.
I was thinking about replacing the flyback with either a Xantrex or Mastervolt unit (both available at West). Any opinions on those 2 manufacturers? I'd love to get by with the 20 Amp Xantrex, as it's the cheapest, but am also considering going up to 40 Amp. Is the only difference between a 20 and 40 Amp charger the time to charge (we rarely burn through more than 1 battery before being back at the dock), or am I really buying an undersized charger?
Thanks for any insight.
Joe Welna
There would be no fuse because the standards didn't require them back then. Things get constantly upgraded. I don't think it has to be a fuse, it has to be a circuit protector, so you could use a circuit breaker like a Blue Sea surface mount of the appropriate capacity. You can surface mount one of them in the battery storage box fairly easily. You should have them on your positive leads from the batteries to the switch as well, you probably don't have them now. The ABYC standards for electrical wiring are available on the web if you google it you'll find them.
IMHO, 20 amp isn't enough, you need 40 minimum. A 20 amp charger may not be able to raise the voltage enough to keep the batteries in top condition. Consider an IOTA DLS charger. Widely considered to be among the best and relatively inexpensive compared to most others. We have a 55 amp IOTA with a smart 3 stage regulator that does a mini-equalization cycle automatically every 7 days to keep the batteries happy. Best unit I've ever had.
When you say you "burn through" a battery, how low are you drawing it down? Drawing it way down regularly is going to severely shorten the life of a flooded lead acid battery.
The fuse near the battery is a good idea. Remember that a fuse or circuit breaker is there to protect the wire; even though the wire from the charger is normally supplying voltage from the charger, if the charger were to develop a short, that wire attached to the battery most likely would catch fire; the wire becomes the fuse. A fuse as close to the battery as possible, protects the wire in case of a short circuit or other overload. The size of the fuse is based on the gauge of the wire, and what current it can safely handle.
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
On the C375, there are in-line fuse on the positive wire close to the battery post connection. The battery charger is 30A and the fuses are 40Amps.
Francois Desrochers - C375 Tech Editor
S/V Alizes #15
Lake Ontario
2009 C375
I was informed by a local boat electrician just last week that according to code I need to have a switch installed to turn off my inverter/charger. Apparently newer boats have this safety precaution onboard.
Glenn Druhot
Carpe Diem
New Bern, NC
35* 6' 10" N / 77* 2' 30" W
2001 C36, Hull #1965
Std Rig; Wing Keel; M35B
Thank you all for the sage advice. I was able to find the Blue Sea surface mounts bstreet mentions at West. I was just surprised as I had never seen them before. I'm only putting them on the charger lines, but maybe I'll add them to the switch positives before too long. They do seem like a good idea, abeit expensive.
When I say burn through a battery, I meant leave it on the charger too long. I guess even float-mode induces some plate sulfation. Batteries are 4 years old, so maybe that's not too bad given that I can't remove them (can only disconnect) for the winter.
Paineolde, my understanding (from the instruction manual) is that the chargers are fused internally at DC output, hence protecting the DC wire from a malfunction of the charger itself. I would assume that means that the battery end fuse (circuit breaker) is designed to protect the wire from a short in the battery. Does that make sense based on your understanding.
ProfDruhot, would not the circuit breaker in the AC to the charger suffice as a switch? I guess it would be easy enough to put one in line on the AC feed.
Well I've pulled the old charger and purchased a Xantrex 40A. I know the Iolta is highly regarded, but I have tomorrow off and am anxious to get things repaired and go for a sail next week. Now all I need to do is find a #4 crimper and determine what to do with the ground on the charger. But I guess that merits a separate post ...
Thanks again.
Joe Welna
Ouch. I just typo'd plaineolde as paineolde. Sincerest apoloigies and nothing insinuated. (I can just hear the jokes starting now).
Joe, that's where the IOTAs with the IQ4 regulator are so good, the equalization it does every 7 days raises the voltage into the upper 15 volt range for a bit, that gets the electrolyte moving and knocks the sulfation off the plates. Based on past experience with other chargers that don't do that, it makes a huge difference.
Also for winter storage, I left my 220 watt solar panel on all winter (which up here is October until May, 7 months) and left the batteries in place. The solar panel has a 3 stage MPPT controller and it too will raise the voltage as high as it can on a set schedule, again to keep sulfation off the plates. But for that to work you need a pretty good sized panel or it can't raise the voltage enough to do any good.
Take a look at the Fire Protection Standard for Pleasure and Commercial Motor Craft section 9.9.3.3. It seems to indicate you need overcurrent protection on the charger wires to the battery.
I also looked up the requirement for a switch on the Inverter feed circuit as mentionned by ProfDruot. Section 9.10.2.1 states that you need a switch whenever the cold cranking capacity is above 800Amps. Looks like feeding the inverter after the main switch with fuse/breaker would be fine. Otherwise, it would need it's own switch and fuse/breaker when fed directly from battery.
The whole section 9.9 on overcurrent protection is interesting especially when looking at an older boat. Requirements have changed a fair bit over the years.
I found a pdf copy at: [url]www.minhbao.com.vn/userfiles/file/A_NFPA30.pdf[/url]
Francois Desrochers - C375 Tech Editor
S/V Alizes #15
Lake Ontario
2009 C375
[QUOTE=JBWelna;9800]Ouch. I just typo'd plaineolde as paineolde. Sincerest apoloigies and nothing insinuated. (I can just hear the jokes starting now).[/QUOTE]
I've been called far, far worse; on purpose..!:D
As to your question about the fuses protecting the wires from a battery short: that would not be my understanding. The way I see it, those wires are connected directly to the battery posts. So they could potentially carry the entire battery capacity in the event of a short. Lets say the 2 wires pass through a hole on their way from the charger to the battery, and vibration causes the insulation to chafe through. Dead short and potentially a couple hundred amps passing through those wires. With a properly sized fuse, the wires are protected from overload. Without a fuse, the WIRE becomes the fuse, heating up and possibly burning/melting. So having the fuse as close to the power source, in this case the battery, protects the wire against this occurrence.
Hope that makes sense.
Gary and Cathy Price
1997 C36 Mk II Tall Rig/Wing Keel Imagine...
Hull # 1617
Worton Creek, Md.
Northern Chesapeake Bay
I understand. Thanks for the clarification.
[url]www.amplepower.com[/url]
Tech tab for the Primer, other tabs for the wiring diagrams.
Have fun! :)
Stu Jackson, C34IA Secretary, C34 #224, 1986, SR/FK, M25 engine, Rocna 10 (22#)