Question? NEW BATTERIES ????

MATTANZA · Jul-24-2008, 05:14 PM

after 5 years my batteries finally took a dump. i have rigged plenty of boats in the past, but we didn't have all of the "toys" like we do today. i have a merc 225hp optimax outboard. the vhf,radar, gps, fisffinder, 1100 gph bait pump, stereo and 3 auto bilge pumps 500, 1500 & 2000 gph rules, all are always on [these items may , or may not be running all at the same time]. i'm going to put in 3 trojan scs200 group 27 deep cycle batteries. here's the specs...200mins @ 25 amps, 52 mins @ 75 amps, cca@0=620 amps, ca@32 = 760 amps, ah@5hr 95 amps, ah@ 20hr 115amp, weight 60lbs & cost is $95.00. i'm thinking this should be more than enough power to run everything. i was thinking of keeping 1 just for starting [battery postion 1] and keeping 2 for house batteries [battery postition2]. is there any advantage, or disadvantages to tieing batteries together, or keeping them seperate? i think 760 ca is ok. any suggestions, or comments appreciated. by the way, i don't want 6v golf cart batteries and the batteries being replaced are trojans.

scuba e · Jul-24-2008, 05:31 PM

sounds like your on track.
The point of starting batteries is to dump large amps quickly to crank over the engine starting motor. Those engines spin pretty easy and sont really require the cranking amps of say a diesel.
The deep cycle also allows you to abuse it more times (drain it down or forget to charge it).
The biggest issue will be the cables and contacts. Use quality switchgear and go overkill on the cables. You can have all the amperage in the world but your resistance is in the cables and contacts.

Cartero · Jul-24-2008, 05:32 PM

Rick,

I think I remember the mfg calling for 1000 cranking amps for the Optimax starting battery but I know it'll run on less. Good luck.

sickcat · Jul-24-2008, 06:56 PM

I have seen an Opti do strange things such as alarms and cutting RPM with the size battery your installing (760CA) that went away with a 1000CA battery. Just sayin - YMMV

As far as separating the starting battery and house bank? Absolutely! I would do the 3 way switch like your saying. Starting on 1, house on 2 and run the engine from the 1 position other than in an emergency. Run trim tabs, windlass and of course all engine gauges from that switch also. Run the all other loads from a separate feed (fused of course) with an on/off switch from the house bank. Use a combiner like a Yandina c100 to keep the house bank charged.

MATTANZA · Jul-24-2008, 09:27 PM

if i started on all that would cure the ca's right? 3 X 750 = 2250 ca's right? maybe a group 30 deep cycle for starting and 2 27's for house.

sickcat · Jul-25-2008, 07:32 AM

Quote:

Originally Posted by MATTANZA

if i started on all that would cure the ca's right? 3 X 750 = 2250 ca's right? maybe a group 30 deep cycle for starting and 2 27's for house.

You could start on all fine but then you have mess with the switch. A 30 for the engine along with a combiner to keep the house charged and you have to touch the switch twice. When the boat goes in the water and when it comes out.

furniture 4 me · Jul-25-2008, 07:54 AM

my suggestion is not to tie two batteries in together on the number 2 side of your switch. its hard on the charging system. you should run 2 switches and then you can regulate and control you batteries much better. with out putting a huge load on your outboards charging system.

2na · Jul-25-2008, 09:19 AM

I use 4 6V Trojans for my house bank...does well but it's a bummer having
to replace all 4 at a time.

MATTANZA · Jul-25-2008, 09:33 AM

Quote:

Originally Posted by 2na

I use 4 6V Trojans for my house bank...does well but it's a bummer having
to replace all 4 at a time.

just went through that. too expensive.

2na · Jul-25-2008, 09:48 AM

Quote:

Originally Posted by MATTANZA

just went through that. too expensive.

I know what you mean. Fortunately, I have a business friend that makes
products for Trojan.

I do have a 12v Trojan in my side yard. It was new and never used,
but I have not maintain it since my friend gave it to me a year ago.
I am not sure what group it is; most like a 27.

I am in S. OC, you can have it if you are interested.

Moleculo · Jul-25-2008, 09:53 AM

Look at how they do this in RV's...it's the same application (and there's a lot more of them around to find out what DOESN'T work). Seperate the starter from the house bank with a switch that will let you start from the house when in a pinch with a combiner to keep the second bank charged.

I STRONGLY disagree with the recommendation of not tying the house batteries together. Running them in parallel (if they're 12v) will give obviously give you much longer useage for electronics and such, which is why you should do it. It may be harder on the charging system but electronics like radios & fishfinders (especially those two) don't like it when the supplied voltage drops much less than 12 volts. And that is exactly what happens when the battery start to lose it's charge. It's VERY hard on those electronics. Now ask yourself, which is more expensive to fix/replace...your electronics or your charging system?

gecsr1 · Jul-25-2008, 09:54 AM

If your present battery set up lasted "FIVE" years...That's great battery life,,STICK WITH WHAT YOU HAVE,,,,,and call it Good..... if it an't broke don't fix it.....

sickcat · Jul-25-2008, 06:23 PM

Quote:

Originally Posted by Moleculo

Look at how they do this in RV's...it's the same application (and there's a lot more of them around to find out what DOESN'T work). Seperate the starter from the house bank with a switch that will let you start from the house when in a pinch with a combiner to keep the second bank charged.

I STRONGLY disagree with the recommendation of not tying the house batteries together. Running them in parallel (if they're 12v) will give obviously give you much longer useage for electronics and such, which is why you should do it. It may be harder on the charging system but electronics like radios & fishfinders (especially those two) don't like it when the supplied voltage drops much less than 12 volts. And that is exactly what happens when the battery start to lose it's charge. It's VERY hard on those electronics. Now ask yourself, which is more expensive to fix/replace...your electronics or your charging system?

+1

The reality is whatever power you take out of the batteries you have to put back. There is little advantage to keeping the house bank batteries separate. Tied together the draw down will be over both batteries so the voltage drop will be less. The alternator will run longer to bring both batteries back up but at less output than if you ran a single battery down twice as much. Granted you could draw down both batteries the same and then recharge them one at a time with a period of rest for the alt between but that is really way overkill. The alt will still have to do the same amount of work either way.