Do I need two batteries?

[briannh1234]

Re: Do I need two batteries?

gals -<br /><br />I can see how it can be confusing. There are lots of different ways and different opinions on how to best wire and maintain a dual battery setup. Each different setup has it's own benifits and problems.<br /><br />Now for my opinion:<br /><br />The most important thing is to fully recharge the batteries when you are done using them. The most convenient way to accomplish this is to keep the batteries isolated from each other, and invest in a dual bank smart charger. When your not using the boat - plug in the smart charger. However - even with perfect battery maintence expect to only get about 6 years out of your batteries - they just don't last.<br /><br />It's also convenient to be able to run the motor and charge both batteries either:<br />1) through an isolator.<br />2) through a combiner.<br />3) with a battery switch in the both position.<br />But with these 3 options the typical battery is not getting a full recharge - and as a result you will get less than the 6 years out of the batteries.<br /><br />IMHO the battery switch in the both position is the worst option. The reason is if you forget to turn it from the both position when you shut of the motor, you run the risk of discharing your starting battery - and then needing a tow home.<br /><br />The combiner is like an automatic switch - It comes on when the engine starts and shuts off automatically. IMHO these are best for inboards with normal (50 amp and above) alternators.<br /><br />The isolator is the last option and the cheapest. IMHO it works best with outboards with weak alternators (5 to 15 amp) where you not going to get much of a recharge anyway.

 

[mattttt25]

Re: Do I need two batteries?

use the search feature. there have been plenty of detailed posts from members that fully explain the different setups and operation.<br /><br />not the best method, but here's mine- two dual purpose batteries, one switch (1,2,both). select 1, start engine, run out, run electronics, etc. go home on 1 as well. next trip, do the same but on battery 2. in my thinking, i always have that spare battery, but only if i need it. i don't think your electronics really require a deep cycle, but just my opinion.

 

[Boatist]

Re: Do I need two batteries?

Tengals<br />Lets start with a few thing I thing all will agree with. <br />1: To get the best life out of your battery or batteries then they must be fully recharged. Never leave them discharged as it will shorten there life. This means you need some way to fully charge them at the end of your trip, from dock power and a onboard charger or on a home charger. If you have two batteries then you need a two bank charger or a battery isolator so can charge both but keep isolated. In my opinion your charger should be fully automatic so will fully charge without over charging. I would not get less than a 10 amp charger.<br /><br />2: If you run bateries in parallel then both batteries need to be same size, type and age. This will increase the time you can run on batteries, but will only be as good as your weakest battery.<br /><br />The iteams you have listed can draw a lot of power but when sitting for 8 hours I supect your are not running Bilge Blower or Pump and gagues are turned off. LCD type color sounder is a low draw, also CD Player. CB radio a low draw except while transmiting. Navigation lights required while drifting at night or foggy but at anchore just need the anchore light. Deck light and High watt Radio can be a big draw.<br /><br />If you go with two batteries I suggest you wire everything needed to run the boat on your starting battery. Bilge blower, pump, gauges, Navigation lights, compass, Horn.<br /><br />Wire everything else to the second battery. Color Sounder, GPS, CD Player, Radio, CB, Deck Lights, VHF radio.<br /><br />This is the way I have my boat wired and it works great. I charge both batteries thru a battery isolator and have never had a battery that did not last 6 years. Good thing about an isolator is even if you install a battery switch and forget and turn the switch thru off with the motor running it still will not blow your alternator because your alternator will always see the load of both batteries.<br /><br />I trailer my boat but when I get home Hook up battery charger to a plug on the front of my boat and thru the same battery isolator charge both batteries. If out camping or going down the road can also hook up a 12 volt line from my truck to the same plug on the boat.

 

[tengals123]

Re: Do I need two batteries?

thanks for the replies. I think im going to go with two seperate batteries. At the end of every trip Im going to charge the secondary battery with a home charger. The starting battery will be charged using the motor. Now, with the switch. Can I use 1 volt gauge wired afetr the switch, so that if im on batt. 1, I can get the volts reading from batt.1. and if i flick to batt. 2, I can get the volts from that battery?<br /><br />can this be done?<br /><br />cheers

 

[Dunaruna]

Re: Do I need two batteries?

It dices it slices it juliens (whatever that means). This would solve all your problems, full automatic, no switching and no need to constantly monitor voltage - it's an isolator, a relay, a battery switch, it'll keep you batts in tip top shape, it'll even make an expresso! All for the low price of $125.00 (AUS), but wait, there's more. Order within the next ten minutes and you receive a free fishing trip to westernport * that's right! A FREE fishing trip. <br /><br />

<br /><br /> * subject to weather conditions. Each fisherman is responsible for supplying ample beer and snack foods, all fish are to be cleaned by the catcher, no fish guts are to be left on the boat - by order of the captain

 

[tengals123]

Re: Do I need two batteries?

hahhaha, that is a great post. OK, i'm getting one of these. Where do I buy it? can I keep my existing century marine 500 battery? and do I still need to charge once I get home, or will the mercury charge most of it. Westernport fishing trip is ON as soon as you can mate. I look forward to it.<br /><br />cheers

 

[Dunaruna]

Re: Do I need two batteries?

Yes you can keep the century. Marine stores carry the BEP VSR, Eildon Outboard Service has the 100amp model for $125, I assume JV marine or Boronia marine would be the same although Baronia marine are having a "May Madness Sale" at the moment. I just did a quick google, couldn't find any web based sellers.<br /><br />I think you will still need to recharge at home, old outboards don't have very good charging systems but it would depend on how much you take out of the batts compared to how much the alt puts back in - dunno. This is the only grey area in your senario.<br /><br />Quote by Boatist:<br />"I trailer my boat but when I get home Hook up battery charger to a plug on the front of my boat and thru the same battery isolator charge both batteries. If out camping or going down the road can also hook up a 12 volt line from my truck to the same plug on the boat."<br /><br />Great idea.<br /><br />Aldo

 

[Boatist]

Re: Do I need two batteries?

Thanks Aldo<br />The real reason I added the plug up front is I just got tired of getting in the boat in the winter to hook up my battery charger. Also one trip I think it was the first of the season I had started the motor at home on Muffs just make sure would pump up fuel after sitting for winter and it started fine, but some how I left the key on and when I got to the ramp after a long drive the starting battery was dead. I could have just used the other battery but I do not like to start a trip with any problems. So retreived the boat and charged from truck with jumper cables then launched on our trip. I made a cable for my battery charger that plugs into the same plug so now when I get home I plug in the Automatic battery charger to the plug then unload the boat, clean the fish and cover the boat. Long before I complete these task both batteries are fully Charged. For me a simple battery isolator works best. I have tried to mesure the voltage drop acrossed the isolator with a very good digital volt meter and really have seen no drop even though I know it whould be .7 volts.<br />From My I/O I get 14.3 volts to both batteries with all the gear turned on at adle. From My truck will be 14.2 volts to to 14.7, truck has a smart alternator and it charges at a higher voltage when cold. With the battery isolator both batteries would have to have loose battery cables to blow the alternator even if I turned the switch to off.<br /><br />That VSR I had not seen before. It looks like it says cut in voltage is 13.7 and cut out is 12.6 but very hard to read. I think that would be good for boater with low output outboards so the starting battery get charged first bufore it kicks in the trolling motor batteries. I assume it is made for the marine use and has spark supression. Do You think it would chatter with a alternator output of say 9 amps. I just wonder if when it kicks in that big dead trolling motor battery if the voltage would drop below 12.6 and cut out then cut back in, out, in. Also do you know if it is a solid state relay or an actual relay?

 

[tengals123]

Re: Do I need two batteries?

thanks Aldo, I guess my last 2 questions are. What 2nd batt should I get and secondly how should all this be rigged up? costs kept to minimums.<br /><br /> <br /><br />cheers

 

[Dunaruna]

Re: Do I need two batteries?

I'm reading the literature that came with the unit as we speak, i see no reference to what type of relay it is but when I fitted mine the wires connected to a circuit board, there was not a contact in sight, also the voltage lose is negligable (0.1 - 0.3v)<br /><br />Your eyes are good, it hits the main battery first until it reaches 13.7v, redirecting again if the the main batt falls below 12.6V. It can do this very quickly which causes a 'chattering' sound. <br />I have a 20 amp alt. I've had one fitted for about 6 months now and I have found that it may take 5 or 10 minutes to stop chattering.<br /><br />Yes it is marine certified. <br /><br />Aldo

 

[Dunaruna]

Re: Do I need two batteries?

Originally posted by tengals123:<br /> thanks Aldo, I guess my last 2 questions are. What 2nd batt should I get and secondly how should all this be rigged up? costs kept to minimums.<br /><br /> <br /><br />cheers

A small deep cycle for a second battery, something that has 'marine' in the description, they are built a little better and handle vibrations better. Brands such as century or mercury are good. <br /><br />I not familiar with your mercs electrical connections but you need to find the charging 'hot' wire and run that to the isolator 'IN', there are two connection coming 'OUT' of the isolator - one goes to your motor battery and the other goes to the second battery, both of the 'OUT' wires need to be 6mm. That's it. You can now start connecting anything you want onto the second battery without fear of draining you motor battery.<br /><br />I do have one concern, the size of your charging system. I would suggest you follow boatists suggestions and/or post in the merc section and ask those guys if your alt is up to the challenge.<br /><br />Finally (and this is tongue in cheek), I see you doing a brilliant job restoring your boat, I bet it ain't cheap. Why would you even consider trying to save some bucks when it comes to voltage?<br /><br />Aldo

 

[tengals123]

Re: Do I need two batteries?

not offence taken, you have been a super help. I just don't want to spend 800-1000 bucks on connections and wiring. I guess why im asking heaps of questions also, is because the old setup, had 1 battery and I was running a sounder, radio, lights and never had a problem. Im adding a cd player and replacing the sounder and adding gauges. I just found it hard to swallow, with a little extra draw, I needed all this extra batteries, switches, wiring etc. Don't get me wrong I have learnt heaps from you in an area where i am a little naive. Now I respect and apreciate volts ( power ) alot more.<br /><br />BTW, when you say small deep cycle, what size are you talking 60AHrs or around about?<br /><br /><br />cheers

 

[Dunaruna]

Re: Do I need two batteries?

I hear what your saying.<br /><br />1 deepcycle = $120.00. Isolator = $125.00. Circuit breaker = $80.00. Wires, terminals, battery clamp etc $40.00. and you still don't know if the alt will keep up.<br /> <br />What about (just thinking out loud) leaving everything as it is for now and just carry one of these as an emergency backup.....<br /><br /> http://www.projecta.com.au/products.../categoryserial/2/categorytitle/Jump Starters <br /><br />Then sometime down the track you can look at a more permanent solution.<br /><br />Damn handy in the car too.<br /><br />Also, if your motor pull starts o/k then you really don't have to worry about an extra batt.<br /><br />Aldo

 

[tengals123]

Re: Do I need two batteries?

now were talkin, wow, you just solved all my problems. I'll get one of these, and upgrade later on. I have plenty room in my boat for a second battery at a later date. Even a few months down the track, then I'll do it properly. Thanks heaps Aldo, your exellence in this field has been so helpful to me, and for that I owe you a 30 minute fight with a 10Kg snapper on light gear. ( as long as I can down some beers and watch). cheers mate

 

[tengals123]

Re: Do I need two batteries?

Dunaruna, I found out that the rectifier in my motor charges about 6-8 amps at WOT.<br /><br />Tell me what to do?<br /><br /> <br /><br />cheers

 

[briannh1234]

Re: Do I need two batteries?

6-8 amps is almost nothing. Do you have access to regular utility power where you keep your boat? If so, I would go with a smart charger, no matter how many batteries you decide to go with.<br /><br />Those jump-n-carry's work great. In a pinch I used mine as the main battery with no other battery connected and it started the motor just fine. I charge my jump-n-carry with my smart charger. The chargers that come with them are cheap no-smarts ones.<br /><br />We have a store around here called big-lots. They had jump-n-carry's for $40.

 

[Dunaruna]

Re: Do I need two batteries?

Originally posted by tengals123:<br />... I found out that the rectifier in my motor charges about 6-8 amps at WOT.<br /><br />cheers

And when you factor in wire length and the fact that WOT is usually only a small persentage of running time you're probably closer to 4 or 5 amp per hr. To put that into perspective - your car alternator is good for 55+ amps from around 1500rpm upwards.<br /><br />o/k, taking into account the low recharge rate and money factors this is what I would do: <br /><br />Get the 'jump & go'. Go boating for 12 months and then make a decision on whether or not extra juice is required based on how may times your batt needs a helping hand. The bottom line is how many accessories you will be using and how often.<br /><br />Definetly recharge your batt and the jump & go when you get home from an outing.<br /><br />Aldo

 

[tengals123]

Re: Do I need two batteries?

I will take you advice and do exactly that. Thanks heaps Aldo.<br /><br /><br />cheers

 

[tengals123]

Re: Do I need two batteries?

aldo, sorry to revive this thread again, but I have been given a deep cycle battery now by a friend who no longer needs it. So now, I have two batteries. 1 starting and 1 Deep cycle. I can get a smart charger no probs, should I get a battery switch or what?<br /><br />cheers