Quote:
|
As for the ignition SW being in the accessory position ... I read a thread that said the charger had another set of wires to the main, boat battery and that when the ignition was on, it would parallel all the batts so as to charge them up off the engine's alternator. I'm not sure how well this would work but it sounds like the charger is breaking the series connection btw the batts and paralleling them when the ignition sw is in the accessory position.
|
This is right. The manual says the charger is connected to the ignition switch so that it is "on" when the ignition switch is on. It says this allows the batteries to charge while the boat is running.
Quote:
|
Now as to why you get zero volts ... at first glance it seems there's only 2 possibilities : the charger is broken (not making the series connection) or the terminals are mislabeled.
|
I wonder if this connection to the ignition also may answer why I get 0V when the ignition switch is off. Since the jumper connection is only made inside the charger, the charger has to be on or I have an open circuit between the two 12v batteries. It seems to make sense to me that with the charger off I should get 0v at both locations. What I don't understand is why I get 12v when the ignition switch is on. Maybe the charger is wired internally so the 24v terminal is looking only at one 12v battery, but does it make sense to you that measured across batteries 1 and 2 with no jumper I should get 12v?
Quote:
|
Thus I agree it sounds like the charger isn't making the serial connection when it should. But if this is the case, then with only 2 wires going to the TM from the batts/charger, then there would be no voltage due the missing serial connection. Again at some point both TMs ran, if only at some lesser voltage perhaps. So I'm beginning to think you have a wiring issue and a maybe a half working charger. Did you notice how it was wired when it came from Expo North ? I'll guess (again) perhaps they had it wired somehow for 12V operation only.
|
Actually, there are 4 wires going from the charger to the TM. This is just how it was wired originally and how it is hooked up now. The only difference now is that I have installed #8 wires and 60a fuses. Two wires come from the 12v terminals and 2 wires come from the 24v terminals. The only time it was wired with only 2 wires was when I connected the 24v directly to the TM directly. I never have understood why those 12v wires are there. I thought maybe the motor that runs the positioning ran at 12v, but I see in the manual that this motor should run with only a single 24v connection, if I understand the drawing. The motors apparently both still work at 12v only more slowly.
I agree that #14 wire is insufficient to run any TM off of, so the wires burning up (at 60A) isn't a surprise ... though ... if the charger is supposed to make the series connection btw the batts, then the wires (2 of the 4 to be exact) connecting the charger to the batts would be carrying the full current through them. AWG12 might just work for a small run but I wouldn't trust it so I doubt the charger designer would have either (at 60A). The rule I read is 1A for each lb of thrust at 12V, half that at 24V. But let's take your TM's book at face value and say it's supposed to draw 60A. Hence the smoked wires. The AWG8 should have been OK but the melted connector is troubling. Unless it was corroded and making a "high" loss connection, then the melting at 60A would be understandable. I get the gut feeling there's something I'm missing here ...
Quote:
|
The way the old systems worked was to deliver 24V to the TM. If you wanted less than full speed, the TM controller added resistance in series with the motor, thus decreasing the current draw and also reducing the voltage seen by the actual motor itself. If you kept reducing the speed, increasing the resistance, at some point the motor would have less than 12V across it. So the old 12/24 systems would switch out the series resistance and 24V, and connect 12V, perhaps through a lesser series resistance, to the motor. It saved the battery this way and allowed a finer low speed control. The question for you is where this switching is taking place, if indeed it is at all. Newer TMs come with pulse width modulation (PWM) speed control and don't have any voltage switching. I do worry that your old charger might not be rated to handle the newer motors current. May I assume it came with 30A fuse ? That the new(er) TM came with the 60A fuse but that it wasn't installed when you brought it to Expo North ?
|
The Minn Kota manual talks about pulse width modulation to extend battery life. Neirther the Minn Kota or the Dual Phase II manuals discuss amperage. The Minn Kota motors now all are sold with a warning to protect them with a 60A reseatable safety. I think this is where I got the 60A number.
Quote:
What other wires come out of the charger to ... well, any place ? What are the labels on the wires ... or terminals on the charger ?
How many wires run to the TM controller; 2, 3 or 4 ? What gauge would you guess they are ? What MK TM do you have ?
|
There are 4 output wires going to the TM control (2 at 12v and 2 at 24v), a power cord, a red wire to the ignition switch, three sets of leads to the 3 batteries (main, aux 1 & aux 2) and a "sense wire" that goes to the pos terminal on Aux 2 battery. The wires going to the TM control now are #8 with 60a fuses. The trolling motor is a Minn Kota Bowmount Powerdrive Autopilot with a 60" shaft and 64ib thrust for operation at 24v.
Quote:
|
Lastly I'd think the series/parallel connection internal to the charger would be made by a fairly hefty relay or solenoid. Can you hear a good click or clunk when the ignition switch is turned from off to accessory (or on) ? Or going back the other way, accessory to off ?
|
Yes, I could never figure out what it was before, but when I put the switch into the accessory position there is a windup and a click sound. I must have the engine compartment open and it has to be quiet, but I heard it this morning. It is definitely coming from the area of the charger.
Quote:
|
If you feel inclined and have some electrical saavy, take the charger inside. It sounds like you have a complete manual for it. I'm not sure how well trouble shooting over the forum will work but you've got my curiousity aroused now.
|
I'll try it.
Quote:
|
Here's my guess at how the system should work. When AC power is off and the ignition is off, the relay switch goes to it's unpowered state and the batts are connected in series (internal to the charger) and you should see 24V across the proper terminals (assuming the right connections to the batts). This voltage should go to the TM on 2 hefty wires (AWG6 or 8). The TM then works off the 24V as it's designed to. When the AC is on or when the ignition is on (really shouldn't be accessory but ...) the relay switch is energized, the series connection is broken and the parallel conenction is made. I'm assuming there's another pair of wires to another battery (the main boat batt) that you haven't mentioned. The TM batts are then charged off the AC/DC converter or from the engines alternator. The voltage at the 24V output would then also be 12V, same as across all the + to - battery terminals. The charger should have 2 current "ratings"; one at which the batts are charged (perhaps 5 - 10 amps) and a max current when the TM is being run. Ideally the TM connections are made to the batteries themselves and not to the charger terminals. If it's done at the charger then all the wires from the charger to the TM batts need to be "hefty".
|
I'll have to think about this some more. I can't get past the thought that the voltage at the 24v taps on the charger were 0v until I put the ignition switch into the accessory position. Then I got 12v...?
Here's a simplified diagram of the wiring paths in each mode; when trolling or when charging. Note the fat lines indicating where the max current is
supposed to flow.