Adding second battery using Blue Sea Systems

badrano

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Aug 7, 2018
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I'm looking at the Add A Battery kit from Blue Sea and it includes the battery switch that will keep the house circuit separated from the engine circuit and the ACR.

The install instructions state that the wiring from the ACR to the batteries has to be sized accordingly based on charging amps.

How do you determine charging amps? Is it based on the amp rating of the alternator?
 

alldodge

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Depends on the output of your alternator and the distance between start bat, to ACR, to house bat. If you have a standard Merc, VP, OMC then it should be close to 55 amps (don't know which motor or alt you have). For 12V a 10 AWG wire is good for 5 feet and 70 amps. If you go 10 ft then 8 AWG for 50 amps, and 6 AWG for 70 amps
 

badrano

Petty Officer 1st Class
Joined
Aug 7, 2018
Messages
331
Depends on the output of your alternator and the distance between start bat, to ACR, to house bat. If you have a standard Merc, VP, OMC then it should be close to 55 amps (don't know which motor or alt you have). For 12V a 10 AWG wire is good for 5 feet and 70 amps. If you go 10 ft then 8 AWG for 50 amps, and 6 AWG for 70 amps

Thanks. I just wasn't sure. I have a Merc 5.0L TKS with a 65A alt.
This gives me the info to price out and lay out the ACR and wire paths.
 

badrano

Petty Officer 1st Class
Joined
Aug 7, 2018
Messages
331
Additional question. I thought I saw some posts about the topic, but I can't seem to find them.

With the Blue Sea Systems Add-A-Battery kit (keeps starting batt isolated from house batt along with an ACR), can you mix battery types? The start batt is a starting battery and the house is a deep cycle battery?
 
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