question

underwater-rob avatar image
underwater-rob asked

2 motor 3 battery dc to dc charger requirement question

Hi everyone I am in the middle or drawing up plans to re wire my boat. Its a 7.8 mtr Rib with twin outboard motors. I'm running 2 FLA start battery's and an AGM house battery.. My intention is to run motors to start battery's and then through a

Orion-Tr Smart 12/12-30A Dc-Dc Charger Isolated to the AGM house battery. My question is do I need to run a charger for each start battery ? I would not imagine I would but there does not seem to be enough room for 2 10 AWG wires running into the charger


I've attached a rough plan for ease of understanding Electronics_plan.pdf


Many thanks Rob

charger
electronics-plan.pdf (5.5 MiB)
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3 Answers
JohnC avatar image
JohnC answered ·

Hi @Underwater_Rob

One should do it, providing 30A is suitable for the size of the house bank (and loads from it).

No need to run two sets of wires to it, as you already have a combiner switch for the start batteries. One alternator alone might be pushed keeping up, and you may need that.

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underwater-rob avatar image
underwater-rob answered ·

Hi John, Thanks for your reply :-) My understanding is that the starter cables run from the alternators to the switch, through to the start battery's and then from the battery terminals through to the smart charger ? Is that incorrect /


Thanks Again Rob

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JohnC avatar image
JohnC answered ·

@Underwater_Rob

Please don't take wires from both batteries to the Orion. You really don't want to join the batteries there, as the potential exists then for a massive current flow between batts through those terminals. We don't want you back here complaining of a faulty battery (the cause) and the terminals burnt out of your Orion. Just run one pair of wires to it from either one batt or one side of the selector switch (whatever's more convenient). Then use the selector to join the batts.

You mentioned in your question 10AWG wire. Your Orion terminals are specced at 16mm2 AWG6. Pretty big wires. Best keep your AWG 10 well away from this job..

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