Battery and Charging Question

On my boat I have a perko switch hooked up to 3 batteries. I believe on switch #1, 2 batteries are dedicated to the stereo equipment (not really sure cause I bought the boat used last year) and switch #2 is hooked up to the starting battery. In between switch #1 and #2 there is the All switch. Last week I had a stereo dealer install some new tower speakers and while working on the install he said that my starting battery was dead, but the stereo batteries were not as he had the perko set to postition #1. Yesterdy I was messing around with the boat (spring cleaning) and wanted to hear the speakers (since I had yet to her them outside). I set the switch to #1 and the stereo turned on, but nothing came out of the speakers (in boat and tower). Next, I turned it to switch #2 thinking maybe I had it backwards and it basically turned nothing on at all. My last resort was to switch to the All position and finally stereo and speakers were working. If switch #1 is hooked to both batteries should everything turn on? Also, I'm not familiar battery chargers and am wondering if I can hook up a battery charger to one of the batteries and have the perko switch turned to the All postion? Will this charge all batteries? Basically I would like to get some suggestions on the type of battery charger I should purchase. Any help or suggestions would be appreciated.

Thanks,

Moon

If you are running the Perko on 'ALL', then you really should make sure that all three batteries are the same make/model. Charging them all on one charger is not a good idea if they are different batteries.

My first guess is that all of the batteries are so low that switching to either 1 or 2 positions didn't provide enough juice. Putting it on 'all' provided enough juice to power everything up.

That would be an assumption based on everything wired properly. If things are wired funny (some amps hooked to one battery with the stereo to another bank), then you may have a mess to untangle.

My reccomendation is to keep it simple. Put two starter batteries (same exact batteries) in a parrallel bank to run everything (start the boat, run the stero and amps, and other accessories). Leave your Perko switched to that dual battery bank most of the the time. Keep the third battery hooked up as a backup in case you drain the main bank. As long as you have a good alternator with decent output, this will work for most all situations. I don't sit on the sandbar and play music much though, so that could drain the batteries more often.

If you incorporate deep cycle batteries into your system, keep in mind that deep cycle's are intended to be drained/charged frequently - but they are designed to recieve a trickle charge, not necessarily the higher output charge coming off an alternator. In other words, it is best to have a home charger to charge deep cycles overnight. Starter batteries, on the other hand, are not designed to be drained/charged frequently. They are designed to take a higher charge from your alternator, which keeps them regularly maintained without letting them drain. So, the sandbar type boater may want to run a stereo on deep cycles and charge them at home. You can hook them to your alternator, but I don't recommend it. You may recall a recent post showing an Earmark Marine stereo installation on a big 'ole Nauty - they basically are doing their big installations this way and not upgrading to a big alternator to charge the deep cycle banks, but putting an onboard charger in place to plug in/charge up at home.

All that being said, i run a lot of stuff in my little boat. I have 3 blue top starters hooked to a perko switch like i described above. I basically keep the switch on '1', which is hooked to my dual bank. The third sits there as a backup for my own mental security (and added weight to the boat. ;) ). I've lost the alternaor belt without knowing it, kept riding the rest of the afternoon, blasting the stereo AND made it back to the dock before realizing what happened. Never even had to switch to the backup third. I've tried isolators (drained the batteries when the boat was off), capacitors (to help the amps) and this is the setup that has worked the best with zero issues.

Moon,

Your stereo source unit and amplifiers must reference the same battery regardless of the selection position.

The common method when using a multi-battery switch is to move the amplifiers, helm buss and alternator to the output post of the battery switch. Nothing is wired directly to the batteries except the switch.

There are alternate schemes that don't apply to your system as it is presently equipped.

I would use two independent chargers of different capacity. This way your two stereo batteries can remain permanently paralleled. For the stereo bank with two identical batteries use a larger capacity charger that can restore overnight. The reserve starting battery should never be in a state of discharge where it would require anything more than the smallest of maintenance chargers.

After lounging for several hours you may run your two stereo batteries all the way down. For preservation of your alternator its not a good idea to bring these two depleted batteries on-line suddenly, especially when its in conjunction with your stereo playing. Ultimately, you may want to look into a combiner/separator scheme. For now, you should exercise restrictions manually. With three batteries you definitely need to be dependent on a shore power charger.

David
Earmark Marine

keep in mind too that even though you have your amps hooked right to your stereo bank the rest of the boat may still be running off your starting battery (head unit, lights, etc) even if it is off w/ the perko

Thanks for the responses. Was looking at my battery setup yesterday and did some moving around two see what the third battery was. All three are basically under the spotters seat plus the switch and the amp. The two batteries that are the easiest to get to, and connected to each other are both Interstate Deep Cycle batteries, but one has the code SRM-24 and the other code is SRM-29. The third battery is a Optima Blue Top. I'm not quite sure which one it is since it is in a compartment to the front of the dash and I can't lift it out of the battery box (not really sure how they got it in there?) from either the spotter seat compartment or the bow seat. I plan on cutting it out of the box and placing this battery next to the other two, since there is room. What has me really confused now is that the optima, from what I can see has wires attached to it as well. If get the chance today, I'll try to get the optima out just to see what is running off it. Also, I was planning on buy 3 battery tender Plus' for the future. These should work when I get the hole thing figured out, correct?

Thanks

Moon

Moon,

The three battery tender will work if you have disconnects between all batteries.

A small tender may not be strong enough to recharge overnight (ie Saturday to Sunday) but will be fine for weekend to weekend durations.

David
Earmark Marine

David, talked to Battery Plus and that is what he said about the "Battery Tender Plus". He also said if one or all of them are really low then I can bring them in and they'll charge them and then just connect the tenders after each time out on the water. Also David, do you have a diagram on how I should set the batteries up? What should connect to what. And, do the Interstate batteries have to be the exact same or as long as they are both Deep Cycle they'll be good? I appreciate the help.

Moon

(Message edited by moon on May 04, 2009)

Moon,

A 1.25 amp charger is fine for a starting battery that is never depleted to any degree and subsequently can be recharged at low amperage in just minutes.

But with a stereo bank of two deep cycle batteries you'll be seriously running them down. A maintenance charger with very low current capacity will not excite these batteries chemically. This means that your deep cycle batteries will die a slow death like a sedentary person who develops clogged arteries. It's not a severe effect but its certainly less than optimum. For your stereo bank I would recommend a multi-phase 10 amp charger at bare minimum. 20 amp would be better.

In a dual battery stereo bank I realize its not practical to isolate the two batteries for charging. But since these stereo batteries are permanently in parallel a dual bank charger cannot read and service these batteries individually. It reads and services the two batteries as one. So a single bank charger applied to the dual batteries is equal in effectiveness to a dual bank charger. Both scenarios are common. Either application will work with an acceptable degree of error as long as these two batteries are identical. Dissimilar batteries, for any reason, create more serious problems and will shorten the life of all batteries concerned.

Wiring three batteries, one starting and two stereo with a single dual battery switch:

All grounds are common.
All positives from the boat and electronics go to the output lug of the dual battery switch including the alternator, helm buss and amplifier supplies. Only the switch is connected to the batteries. The single starting battery is connected to switch position one. The two stereo batteries are wired in parallel and are connected to switch position two.

David
Earmark Marine

Okay, so after some thorough digging and cutting I've figured out my battery setup. Forgive me for being a tool, since I have no experience in this and I was mistaken with how everything was setup. The two Deep Cycle Interstate batteries, which don't have the same numbers, that are hooked up in parallel, are the starting batteries. They are connected to bank 2 on the perko. Connected to bank 1 is a Optima Blue Top D34M that runs the accessories. I took all three batteries in to be charged and the two deep cycle batteries did not take charges. As of right now the blue top is being charged, so I'll find out after work if it will hold a charge (fingers are crossed).
Now my question is, Do I really need two batteries for starting this boat (2003 MB Sports 220V)? My guess is probably not. Also, can I run the optima as the accessories battery, as well as the starting battery and use the second battery as a backup hooked to bank 2? Or, do I start the boat on bank 2 then switch the perko to bank 1 in motion for all accessories as well as when we are just floating and listening to music?