Adding an extra battery?

[Ship Wreck]

Re: Adding an extra battery?

I think I have it, I used the Mini VSR that Drew linked to and added a second battery for back up. That way if I am correct my second battery will charge evertime engine is running to use as a spare....
It's all coming together, thanks for the help....

 

[SIR]

Re: Adding an extra battery?

I have a question about the setup that Bonus diagramed so well with the switch and Blue Sea isolator/combiner. Assuming a welded aluminum boat with a floating ground (ground cable from outboard connected to negative battery post, then bow mounted grounding block connected to battery, and all devices islolated from hull with plastic mounting plates/washers) how would one do the ground connections when adding a second battery as per Bonus's diagram. Would the ground from the outboard go to the starting battery then daisy chain to the second battery? Or would this screw up the isolator/combiner? Would you have to ensure that the feed to the house grounding block came off the house battery and the ignition ground went to the starting battery or would it not matter as they are daisy chained?

Also I'm trying to do this with a 115 Merc Opti with a 60 amp alernator. I see the Deep Blue isolator/combiner is rated for 120 amps so can handle the load but I never saw any responses about the issue of putting a switch between an EFI outboard and the starting battery..... is this a problem or not?

Who ever thought adding a second battery was going to require a electrical engineering degree

 

[Newbie518]

Re: Adding an extra battery?

How much is this switch at west marine??
thanks

 

[flargin]

Re: Adding an extra battery?

Dual circuit plus are about $50 at west marine.

 

[plmskier]

Re: Adding an extra battery?

Shipwreck, Sorry for the delay. The main ground point in your system is the engine. The ACR you use should recommend the proper place to ground it in its instructions. This would normally be at the negative buss bar you mentioned or possibly at the batteries depending on where you mount the ACR.
The red wire shown in the diagram is a charging wire that supplies charging voltage to the batteries. I cannot say exactly how you should connect it without knowing your engine's charging system. It is important to become familiar with how your outboard supplies power back to the batteries and how the charging system works. Especially if you are completely isolating house and start loads. I recommend buying an engine manual for your engine.
The idea is to completely isolate the starting circuits from everything else and connect the charging wire in such a way to supply charging to either battery independently or to both through the ACR or the parallel switch. This provides redundancy in the event of battery failure or ACR failure, or both. (like fire or dead battery cell) NOTE: NEVER switch the batteries to OFF while the engine is running! This will damage the charging system. (I prominently labeled the face of the switch panel to remind me never to switch to off, I suggest you do the same)
The diagram shows interrupt protection in its cables to protect the cables in the event they become overheated. The rating of the fuses or breakers depend on the amp rating of the ACR, the size (gauge) of the cables, and the length of total circuit run. My ACR has an option built into it that allows the ACR to be manually closed. This means I can use the switch on the ACR to temporarily combine the batteries in the event of a dead start battery. This makes the ACR a part of the STARTING circuit and hundreds of amps can pass through it while starting the engine. Therefore I do not use fuses or breakers in its cables. I can do this safely because I am using large battery sized cables to connect it, and the ACR itself is rated to carry the load of starting the engine. It is also placed very close to the batteries so I do not have long cables.
Some ACR are not rated for starting currents and are used for CHARGING only. These types do not normally have the 'manual override' feature. If they do, and they are not rated for at least 150 amps, they should not be used to start an engine with a dead battery. They should be used for charging only. Fuses should be used to protect the cables and the ACR at each battery for this type ACR. The ACR should come with instructions on the proper gauge cables and fuses to use. Some ACR's come with the cabling already attached with the fuses installed. (if you need more help on this, give me some more info on your setup)

I added the Blue Sea add a battery system. 2 new batteries...Everything is set up correctly as far as I can tell...been having problem with the terminal fuses used on each pos terminal leading to the ACR. West marine suggested to use 30 amp...well I blew one, replaced with a 60 amp and then blew the other 30 amp. Now the blue sea directions state: "with 80 charging amps, 4 gage wire, use 110amp." I checked with my boat mech and he thinks my engine is putting out about 65 charging amps. So my question is, do I put in the 100 amp fuse box for each 4 gage wire I have from pos term to pos term or use a lower amp? 100 seems kinda high, but what do I know.

Please help...fuses are $15 a piece...lol

 

[plmskier]

Re: Adding an extra battery?

I have a question about the setup that Bonus diagramed so well with the switch and Blue Sea isolator/combiner. Assuming a welded aluminum boat with a floating ground (ground cable from outboard connected to negative battery post, then bow mounted grounding block connected to battery, and all devices islolated from hull with plastic mounting plates/washers) how would one do the ground connections when adding a second battery as per Bonus's diagram. Would the ground from the outboard go to the starting battery then daisy chain to the second battery? Or would this screw up the isolator/combiner? Would you have to ensure that the feed to the house grounding block came off the house battery and the ignition ground went to the starting battery or would it not matter as they are daisy chained?

Also I'm trying to do this with a 115 Merc Opti with a 60 amp alernator. I see the Deep Blue isolator/combiner is rated for 120 amps so can handle the load but I never saw any responses about the issue of putting a switch between an EFI outboard and the starting battery..... is this a problem or not?

Who ever thought adding a second battery was going to require a electrical engineering degree

I would also like to know about this. I have a merc 225 hp EFI no carb, is it ok or not ok to have the switch prior to starting battery?