Dual Battery Question

[Boilers2000]

I have a 92 Sea Ray 200 BR with a single battery. Want to add an additional battery to prevent accidnetally drain the battery with radio. Wanted to get thoughts on if a standard switch will suffice or investing in the dual circuit system is worth it. Not having to worry about switching seems nice, but dont want to overkill on a boat I am hopefully upgrading from in the next couple of years. Let me know. Thanks in advance!

 

[ahicks]

What price is "affordable" when it comes to peace of mind? Will it be enough to afford a dual battery setup? Could be as simple as a battery, and some cables to set up a LEFT-BOTH-RIGHT switch.

 

[Boilers2000]

Going to do s dual setup regardless just trying to decide if I do the $35 switch or the 120 dual circuit system. I'm probably good with switching to the house battery while floating and then back to both to start/charge both batteries when under way and cruising.

 

[KD4UPL]

I've had 2 boats with dual batteries and switches. I do pretty good at remembering to throw the switch. But, it is kind of a pain. I'm also cheap and haven't convinced myself to spend the extra money on an ACR. Some day I will, probably right after I forget about the battery switch and strand myself somewhere.

 

[alldodge]

Another option is the isolator

 

[Boilers2000]

For the 1 + both + 2 switch am I correct in understanding that if you are in both and one battery is full and the other has lost some voltage due to usage the lower voltage battery wont charge because the alternator can see a full charge on the other battery on the circuit?

 

[Bondo]

For the 1 + both + 2 switch am I correct in understanding that if you are in both and one battery is full and the other has lost some voltage due to usage the lower voltage battery wont charge because the alternator can see a full charge on the other battery on the circuit?

Ayuh,..... The 1st thing that happens when you turn the switch to both is, the charged battery trys to charge the dead battery,.... they'll in essence equalize,....

When the motor is started, the alternator charges the system to 13.6 volts,..... so both batteries,....

 

[ahicks]

Agree with Bondo, but would add that on "both" and assuming properly sized cables, you would have twice the amperage available for your load.

So a low battery, say at something like 11.5v, and a fully charged battery at 13.6, when placed in parallel (both), on paper you would have a single battery with 12.5v available, with twice the available amperage. That should turn over your engine pretty easily.....

 

[legalfee]

[No message]

 

[Boilers2000]

Got it...so next question is and apologize if I use a made up term but what batteries do I want...1. Deep Cycle and 1 starter, 2 multipurpose or some other combination.

Then on the mismatched voltage question...if the total charge is 12.5 volts does the alternator keep charging until the total fully charged voltage is reached?

TIA

 

[alldodge]

Either will work for what your wanting, deep cycle can be discharged further without harm prior to recharge

With motor running, ALT will try to fully charge bat(s) at around 14.5V. When motor is shut OFF bat will settle to around 12.6