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16-03-2009, 16:29
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#1
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Registered User
Join Date: Aug 2007
Location: Southbound
Boat: Pearson 31-2
Posts: 303
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Iota 45 Cable Sizing
My charger arrived with very little documentation. What size wires to the battery have you other Iota guys used?
I'm no expert but it seems 45amp wire is overkill since it spends so little time at full power. The run is going to be very short(2-3ft).
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16-03-2009, 17:01
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#2
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Registered User
Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
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How long do you think it would take to overheat undersized wires?
Don't forget the fuses!
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16-03-2009, 17:09
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#3
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Eternal Member
Join Date: Jul 2006
Posts: 4,046
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I'd use AWG4 wire. That would give you a voltage drop of about 0.1v with a run of 8' (4' each way).
By the way, unlike most chargers, the Iota is capable of putting out full power for quite awhile if your batteries need it. It will hang in there above 40A output if needed. Depends on the state-of-charge of your batteries.
Bill
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16-03-2009, 17:23
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#5
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Registered User
Join Date: Mar 2006
Location: Nevada City. CA
Boat: Sceptre 41
Posts: 3,857
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I believe that #4 wire is the biggest that will fit in the Iota chargers. The charger that I purchased two years ago did not meet ABYC standards b/c it only had a compresion screw to hold the #4 wire and not a plate. I don't know if they are still manufactured that way.
I don't know if this was the best idea but I added a little solder to the end of the wire which made it so that it wouldn't splay the wires as much. I tried to compress this while it was still warm so that the shape of the screw would be held in the wire. Great chargers.
__________________
Fair Winds,
Charlie
Between us there was, as I have already said somewhere, the bond of the sea. Besides holding our hearts together through long periods of separation, it had the effect of making us tolerant of each other's yarns -- and even convictions. Heart of Darkness
Joseph Conrad
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17-03-2009, 06:57
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#6
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Registered User
Join Date: Aug 2007
Location: Southbound
Boat: Pearson 31-2
Posts: 303
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Quote:
Originally Posted by DeepFrz
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That is exactly what came with the unit. My guess is that they are packaged for professionals that don't need instructions.
I was hoping to use some #6 battery cable that I have already. Trips to the store are a PITA these days but I guess I'll suck it up. Thanks for the info.
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17-03-2009, 09:39
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#7
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Registered User
Join Date: Mar 2006
Location: Nevada City. CA
Boat: Sceptre 41
Posts: 3,857
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Aquaholic:
Looking thru the tables for 50 amps using SAE wire if you have a #6 wire a run of less than 15' is fine . If you are using AWG wire there is an even bigger safety margin. No reason to run to the store the #6 cable should be fine.
Source:
Table 3-5 conductor size for 3% drop in voltage.
Boatwoners Mechanical and Electrical Manual
Nigel Calder
__________________
Fair Winds,
Charlie
Between us there was, as I have already said somewhere, the bond of the sea. Besides holding our hearts together through long periods of separation, it had the effect of making us tolerant of each other's yarns -- and even convictions. Heart of Darkness
Joseph Conrad
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17-03-2009, 13:55
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#8
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,082
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Use a minimum#14 AWG wire on the (12A) 120VAC input, and minimum #10 AWG wire on the (45A) 12VDC output.
Your #6 cable should good for at least a 20' run (10' separtion = 10' pos + 10' neg = 20' cable).
The Iota 45 draws 12 A at 120VAC input, for which #14 is adequate. The (nom.) 12VDC output of 45 Amps requires a minimum current-carrying capacity of 45 Amps (#10AWG). #10AWG wire is suitable (per ABYC, but not per NEC, which would require #8) for an ampacity of 45 Amps, and over a round-trip distance of 6 feet (2 x 3') 270 Amp/Feet A, also requires #10AWG (good to 300 A/Ft) wire to limit Voltage Drop to under 3%. Should the cable run turn out to be longer than6.66 Feet (3.33' pos + 3.33' neg), you will require larger (#8) cable.
See (print & save) the Wire Size Charts:
http://www.cruisersforum.com/gallery...r&imageuser=79
and
http://www.cruisersforum.com/gallery...r&imageuser=79
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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17-03-2009, 15:49
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#9
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Registered User
Join Date: Aug 2007
Location: Southbound
Boat: Pearson 31-2
Posts: 303
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I finished the job earlier with the #6 and the cables didn't get warm at all after charging at 35-45 amps for 2 hours. The charger came with its own input cable/plug.
The old charger had 2 hot wires. One for each battery. I only have one now. If I leave the switch in the 'both' position, its the same as having the bats connected in parallel, right? Does the other battery take longer to charge?
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17-03-2009, 16:37
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#10
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Registered User
Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 8,462
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Quote:
Does the other battery take longer to charge?
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No, as long as there is no appreciable voltage drop across the switch.
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