[aquaknot]

Just finished a ride on the snow trails and recieved a message from my Marina saying they dropped one of my new triton batteries (the boat came with two triton deep cells, which I just replaced) and they have replaced it with a mercruiser starting battery. They say I should have one starting battery and one deap cell. Any thoughts, are they correct, and why have I had no problems running two deep cells. 1999 Z222 7.4L................thanx

[ShabahZ280]

I wouldn't think it'd be necessary to have a starting and a deep cycle battery, almost every boat I've seen with dual batteries have dual deep cycles. As long as your cold cranking amps on the starting battery are equivalent (or greater than) your deep cycle, you should be set. Just don't rely on your starting battery if you're going to be anchoring and listening to your radio or something that could potentially drain it. Deep cycles are meant for multiple charges and drains, starting's aren't. Just remember to flip that battery switch!

[WetWilly]

Hi aquaknot,

The simple answer – Yes, they are correct if the “Starting” battery is used only for starting and the “Deep Cycle” battery runs everything else on your boat and is the backup battery for starting. Plus they save some money as Starting batteries are typically cheaper than Deep Cycles.

So it really depends on your wiring setup. Simply put, Starting batteries are designed to discharge at very high rates (amps) for a short periods of time (i.e. starting the engine) and Deep Cycle batteries are designed for constant discharge at lowers rates for long periods like running the music and lights. You can use a Deep Cycle batteries if they are rated for your starting needs and if you rotate them they should last without any problems. This is what I do.

Now a quick Google search produced the following from an expert at Interstate Batteries;

Can I use a deep cycle battery as my starting battery?

Yes – if the battery meets the CCA specifications for your vehicle’s engine starting requirements. However, a marine/RV deep cycle battery typically will not offer the total number of starts you’ll get from a starting battery. If your customer has the space available, the best alternative may be a multiple-battery or an isolated-battery system, where you add a marine/RV deep cycle battery to power accessories and leave the starting battery to do the job it does best – start the engine. Remember, to maintain multiple batteries, a larger alternator may be needed.

When should I choose a marine/RV battery over a starting battery?

If you are going to discharge (cycle) your starting battery only once or twice per month to no more than a 30% depth of discharge (70% state of charge), a heavy-duty commercial starting battery may be adequate. Just make sure that your starting battery has a reserve capacity and CCA rating equal to or greater than the OE battery ratings. If the customer’s original starting battery is being repetitively discharged to more than a 30% depth of discharge, choose a marine/RV deep cycle battery.

How many cycles should I be able to get from a deep cycle battery?

Numerous variables determine the actual “cycle life” you may get from a marine/RV deep cycle battery including:

• maintenance and care,
• battery discharge levels,
• battery operating temper- ature,
• recharging,
• proper battery size and capacity.

One customer may get 150 cycles or less while another gets more than 500. If batteries are properly maintained and recharged to 100% state of charge, the customer should get approximately 200-plus cycles with normal use. However, the depth of battery discharge per cycle has a tremendous effect on the total number of cycles. For example, (with all other variables equal) a marine/RV deep cycle battery that is consistently discharged to only 50%, versus 100%, more than doubles the number of cycles.

Hope this wasn’t information overload!
WetWilly

[mikeyt]

damm.....Willy's good!

[dudders]

Originally Posted by mikeyt

damm.....Willy's good!

You got that right Mike, I thought batteries were batteries. Used to start the boat, run the radio and lights and thats it. Didnt imagine they could drain in just a day of running my Village People Cd's

[aquaknot]

WOW. Wasn't expecting that kind of a reply. Thanx Wetwilly. I wasn't very comfortable with the Marina replacing one of my deep cycles with a starting battery(not installed yet-in storage), but I feel a lot better after reading your in depth response. Do you think they will have to reconfigure any of the original wiring..............thanx again

[indykoch]

Yeah, that "Super Moderator" title wasn't just handed to WetWilly, was it?!?! Great info!

However, I think the necessary change in wiring and/or manual switching isn't worth it. I'm pretty sure all boat manufacturers provide one (or two) deep cycle batteries, approved by MerCruiser/Volvo, to start the engines. If the manufacturers think its okay, I'm staying that route. I have two batteries on a switch, and just leave it in the "both" position. I've had issues with low voltage, mostly due to late nights rocking out and never fully charging them again, but I think two deep cycle batteries are more than adequate for starting and giving me peace of mind knowing there's enough power to return home (and if not, oh darn - another night under the stars!!!).

[WetWilly]

Originally Posted by aquaknot

WOW. Wasn't expecting that kind of a reply. Thanx Wetwilly. I wasn't very comfortable with the Marina replacing one of my deep cycles with a starting battery(not installed yet-in storage), but I feel a lot better after reading your in depth response. Do you think they will have to reconfigure any of the original wiring..............thanx again

Hi aquaknot,

Now personally, I would have them put back the same type and rated Deep Cycle battery as the one they dropped. As you said, you have had no problems before so in your case dual deep cycles were OK. I like to think- if it ain’t broke, don’t fixit, so I would put it back the way it was and it will give you back peace of mind!

FYI - I’m too am using two Deep Cycle batteries through a Blue Sea Dual Switch and ACR system on our Z240. This system combines both batteries should the starter battery becomes too low. The ACR unit automatically charges both batteries when the motor is running and isolates both when the motor is off independent of the Switches position. Pretty neat setup….

Indykoch is lucky, I have to remember after using the switch, to set it back to position #1 when the motor is running or I end up really discharging both batteries. Now I don’t mind a night under the stars myself but unfortunately, some of our friends are real “landlubber city folk”, camping under the stars ain’t their thing…..

I knew there was a reason I carry long jumper cables onboard…..

WetWilly

[ShabahZ280]

Originally Posted by indykoch

I've had issues with low voltage, mostly due to late nights rocking out and never fully charging them again...

I'm guilty too! I didn't realize the complicated part of how the switch worked until earlier this year. I had no idea when the switch was on Battery 1 with motor running, it was only charging battery 1. I don't have an Automatic Charge Relay unit, but might add one this year just to be on the safe side! Either that, or keep a jump box onboard!

I also found out that the built in 110v Battery Charger was only connected to one battery, and is only rated for one bank, so I'll probably be upgrading that as well.

[MariahMan]

Hey guys, i guess i'll chime in here on the batteries and a good setup to ensure no deads out on the lake. Both my dad and i are of the opinion that everything on a boat should be simple, easy to use, reliable, and when possible, redundant for safety.

When we got our boat it had 1 battery with simple on/off switch. Well it was very easy to end up w/ an almost dead battery when we'd go to fire her up at the launch ramp. So we replaced the batteries, re-examined the way the electrical components in the boat were wired, and came up with a system that that meets all of our criteria.

We essentially have divided the boat's electrical systems into 2 categories; house and starting. Mariah included two fuse buses under the helm. 1 was full, the other had maybe 2 items hooked up to it and both wires feeding each bus ran to the battery. First step is i figured out the components we wanted on the house circuit, which in our case only being a bow rider, was the stereo and interior lighting. So everything else was put on 1 fuse bus, the stereo and interior lights on their own. The bus with the majority of the items on it, which were all the power leads for gauges, ignition switch, etc. became the starting circuit, and the other bus became the house circuit, or the circuit for accessories. So now, no matter what items we add to the boat, we have two separate circuits depending on the type of item.

Now, to the engine compartment. Here we added this switch panel. These switches act as an interrupter for the two circuits we set up. We hooked up a Optima Blue Top deep cycle/starting battery to the starting switch and a normal deep cycle to the house switch. The two leads we discussed earlier coming from the helm then attached to their appropriate switch. The bilge was connected straight to the deep cycle battery so no matter what it gets power, the starter connected to the starting switch and the engine wires to the starting switch as well. So now the two circuits are independent of each other and no matter what, if i run the stereo all day and completely kill the battery, engine will start just fine off the starting battery.

To charge the batteries, we installed an ACR to connect the batteries when the engine is running and alternator is charging and disconnect when the engine is off so that the two banks are isolated.

As you can see, this is a very reliable system and its easy to understand. You don't have to think "oh, wait, is 1 the house or is 2 the house or should i just put it on both...." You can just flip the switch you need. Usually we just flip both on and use the boat all day. But if i go out in the evening to relax and just listen to the stereo at the dock, probably just flip on the house circuit.

Now with that switch panel we got, it has an interconnect switch so lets say the starting battery goes bad or something and i want to start the engine off the house deep cycle. Well, flip the switch, both banks are joined, and the boat starts right up, simple as that.

It's a good system and i think is the best way to wire your boat. I will eventually do a long detailed writeup on the process, but not tonight...