Quote:
Originally Posted by Mee-n-Mac
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".
FWIW here's a nice chart and online calculator for what wire size is needed and how much voltage drop can be expected for a given current draw and AWG ... http://www.powerstream.com/Wire_Size.htm
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. |
OK. I have finally digested your drawing and comments on how the system should work. I agree and now understand why I registered 12v at both the 24v output lugs on charger and at the batteries after turning the ignition switch to the accessory position. The 0V readings with power off must mean some malfunction in the charger and I am preparing my mind to remove the charger from the boat for a look inside. It takes time to get my aging body into a position to remove this from the very back of a small engine compartment. Meantime I'll try to attach some drawings from my manuals. If it works, I'll attach others.