Batteries and electrickery

[Mac26Mpaul]

Go easy on me fellas, I'm a bit of an electrical dunce..

I'v been running two 70ah deep cycle batteries in parallel for everything, including starting. I knew that deep cycle batteries were not designed to handle starting, but since my boat came with it set up this way and it seemed to work, I left it that way, and all up I think those batteries were in there for maybe 3 years like that so when I replaced them about a year and a half back, I decided to save the extra expense of a VSR and separate starter battery and do it the same, Well these batteries now appear to be stuffed after about a year and a half so I figure the time has come to do it right.... Will go House and Starter and get one of these gizmos
http://www.ebay.com.au/itm/121321158259 ... EBIDX%3AIT

One concern of mine is weight, as it is very hard to keep the boat below the legal road trailering weight here and insurance means nothing if in an accident with an overweight boat.. So really, I want to keep the weight down as much as possible. Secondly, I want to try and keep all batteries in the battery compartment. The boats not here to take measurements of that, but I'm leaning towards something like this for house duties
http://www.australiandirect.com.au/buy/ ... ry/KA12150

My power use consists of a 47L fridge/freezer (couple of amps) which I normally turn to economy mode after the sun goes down (and 120 watt panel not charging) and then turn it off at bed time, also we have a 16 inch LED TV, which often gets a couple hours running at night, a stereo, chartplotter, electric pump, LED lighting, and that's about it, so not huge power demands. Still the more a/h the merrier and this would be nice if it fit in the compartment
http://www.australiandirect.com.au/buy/ ... ry/KA12230
but the weight is really getting up with this and a starter battery....

To cut a long story short, the questions:

What sort of start battery should I be using with the 50hp ETEC - Can I get away with just a motorcycle battery? I really want to keep size and weight down if possible and try and fit it all in the battery compartment?

Can some of you give me an idea of some of your setups, as in, house capacity and how it works out for you, and where you are putting your batteries in the M. Do they all fit in the battery compartment and if not, where are you putting them?

[Tomfoolery]

I knew that deep cycle batteries were not designed to handle starting . . .

While DC batts aren't designed for engine starting per se, they are perfectly capable of starting an engine if the current demand isn't too high. OB's are pretty puny engines, and just don't draw that much while cranking. Starting batts have more plates which are thinner than DC batts, which have fewer plates that are thicker. Starting batts can convert chemical potential energy to electric energy faster than DC batteries which results in high current output, but they don't like having as much energy drawn out of them as DC batteries. You're supposed to limit draw down to something like 90% of full charge, compared to DC batteries at 60% or lower, depending on type.

My last boat had a 27 hp Yanmar diesel, and would start easily on a single DC battery, though I normally used two of them in parallel for starting and house duty, with one more (starting) for backup in case I ran the house batts down too far. But I never, ever needed the third battery, even after running a lot of things all day long sailing (12+ hours), like cold plate fridge, autohelm, navigation, VHF and FM radios, and the two still spun the diesel up without the spare battery.

One concern of mine is weight, as it is very hard to keep the boat below the legal road trailering weight here and insurance means nothing if in an accident with an overweight boat.. So really, I want to keep the weight down as much as possible. Secondly, I want to try and keep all batteries in the battery compartment.

You might want to consider staying with two house batteries, on an A/B/Both/Off switch, charged from the OB and/or shore charger, with a charge relay between them for the OB, and use an emergency start unit for starting backup. That way you get the most DC capacity you can fit (maybe squeeze Group 30's at 130 AH each in there?), and still have emergency starting capability. Those little units are getting real popular these days, as the size goes down and the CCA goes up.

Or probably better yet, look into two 6V golf cart type DC batteries in series to make your house bank, and have the emergency unit stowed as in the above. No charge relay required, though you lose the ability to work off of one battery while keeping the other (identical) battery in reserve via the A/B/both/off switch.

I just use two DC batts with selector switch and shore power charger with dual outputs, making me the energy monitoring and management system. About the only improvement I would add to mine is a charging relay so the OB can charge both batteries without switching to 'both', which I don't like to do since the two batteries are different age, with one nearing the end of its useful life.

[Azzarac]

As usual, Tom pretty much nailed it except for me personally I would stay away from the 6V's exactly because of what Tom said. If one goes bad the other does you absolutely no good. I like having a reserve 12V available if needed. I would add though that 3 years of usage for deep cycles is about average. 1 1/2 years is a short life for a quality battery but may not be bad for a "value" batt. Maintenance of these batts is as important or perhaps more important than the quality of construction. When I installed my solar panel which is left connected year round, I discovered it brought new life back into a battery that I was going to replace 3 years ago. That questionable battery is now 7 years old and tests perfectly now. My other "good" battery was replaced 5 years ago and also tests fine. I thought the claims of chargers being able to de-sulfate battery plates were sketchy at best but now I'm a believer.

[Russ]

What Tom said.



For emergencies, I have this.
http://www.amazon.com/PowerAll-PBJS1200 ... mp+starter

[Gazmn]

To cut a long story short, the questions:

What sort of start battery should I be using with the 50hp ETEC - Can I get away with just a motorcycle battery? I really want to keep size and weight down if possible and try and fit it all in the battery compartment?

Can some of you give me an idea of some of your setups, as in, house capacity and how it works out for you, and where you are putting your batteries in the M. Do they all fit in the battery compartment and if not, where are you putting them?

1. Check or double check battery requirements on the Evinrude site or a BBS like this.

My E-90 needed 850CC Amps, if I remember correctly. I think that it's not that another level battery won't work - but it might not when you really need it to. I don't think a motorcycle battery is big enough. & I wouldn't want to risk burning out my emm

& while I have an my PO made a battery compartment under the rear of the fee berth. My understanding is, adding more weight to front is good - or at least up to a point. I currently have 2 size 29's or 27's in parallel in there.

[mastreb]

I'm going to keep on about just using a single battery. I'm on four years with the single factory stock setup, and still no issues. I do carry a $50 wall-mart jump-starter, and I've used it twice to good effect. Leave it plugged in for 30 minutes after starting and its topped off and ready to be put away. Also, the ETEC-50 can be pull started, although it's a pain in the butt to have to do it, it does work.

If you're worried about weight and you want simplicity, these boats work just fine with a single battery and a disconnected jumpstarter as the emergency backup.

Complicated installations with inverters and fixed shore power circuits for AC are overkill on these boats IMHO, when you can get every appliance needed in a 12VDC version, including refrigerators, television/dvd players, AC units, and even Microwaves.

If you need AC to run a billy-box A/C, get a Honda EU2000 and call that your AC circuit. Inverters won't power it for long anyway. If you decide to do refrigeration, make sure you get a 12VDC fridge and don't bother with AC aboard at all.

Even on my big boat, we don't use the AC that came with it. The only thing it powers stock is an anemic 700 watt microwave, which I'm about to replace with a 600 watt 12VDC microwave rather than install an inverter to power the silly thing.

I do wish I could find a 12VDC induction cooktop because those are the most efficient and safest way to cook aboard a boat. I've gone over the circuit diagram for them and determined that the AC is rectified to DC before being re-inverted to high-speed AC to setup the induction field, so it should be possible to dig into one and convert it to 12VDC operation with just a 1:10 step-up transformer.

[sunshinecoasting]

Gday Paul, I pondered the issue of 2 batteries and gadgetry for ages before I realised I was wasting my time and potential money and simply bought a $300 generator, I have two batteries, the first is dedicated to starting the motor and is recharged by the motor of course, the other I fully charge before a trip, I run the fridge and TV from it and run the genny about twice a day for about 30 minutes each time, seems to cope well, I have no solar. The genny sits nicely under the captains seat and runs there as well, as it is 240v I also run the fridge and anything else I need (charge phones, tablet etc) from mains while the battery charges, no need to worry about economy mode. In short, I guess you could have two batteries and lots of expensive trickery to make it all come together but a couple of times a day I start the generator, run it for 20-30 mins and thats that, yes its a bit noisy, yes it needs a little extra fuel (not much though) but it is easy and most important, always there. I have also considered putting the genny in the inflatable, towing it behind the boat and run the extension lead out with the tow line so you can charge and run the fridge longer without fumes and noise, I am yet to test this theory. You can always put the genny on shore when you are camping and use a 30 metre extension lead as I do so the noise and fumes arent an issue, remember it only needs to be run about an hour a day, a little longer if you want your fridge below 6 degrees.

Food for thought, Dennis.

[Mac26Mpaul]

Thanks, a lot to think about there and I will go through it all again.

Dennis, I have a genny, in fact, that''s the only way I have been able to start the boat the last three times including this morning when I finally retrieved it (its been out there on the hook for about a month). I'v only got a CTEK 7amp charger though and I'd have to run it for hours to top up my depleted 150ah of batteries. The motor does a much better job of charging the batteries in a much shorter time. You only need stick a $60 VSR in-between your starter and house battery, and if you do any motoring at all, you will probably find you don't have to flash that genny up much any more.

I definitely want(need) at least 150ah wether I do it in one big one or two in parallel.
A boat builder fella I know reckons that using my deep cycles to start would be the cause of early failure, but perhaps it was more likely my poor maintenance...

Anyway, to save the VSR, I'm thinking about using one of these, or maybe two in parallel. They seem to have a pretty good name here and a decent warranty.
http://www.superstart.com.au/tabid/95/v ... ttery.aspx
Not sure what type yet, but would really like to move to AGM I reckon.

I keep the genny onboard so that with my CTEK charger is my backup starting.

[Retcoastie]

We use two large AGMs as A and B batteries. Usually just leave them in parallel. Just for funs, one time, I used a lawn mower battery to start the engine for maintenance in the barn. It did the job and started the Honda 50 no problem. A lawn mower battery could be a useable choice between a motorcycle battery and a full size battery for weight and size considerations.

Ken

[Dragos Filimon]

I did the same thing, being in parallel they can both charge from the solar panel. Then one battery died, instantly discharged the second one, middle of the lake, no wind, was not so pleasant.

[81venture]

I use a combination of a house deep cell and a starting battery with an A/B/Both switch...

The house battery has a larger solar panel hooked up to it, found it on another boat I scrapped, about the size of a small pizza

The Starter battery has another smaller solar panel from another junk boat, its more of a "tender" panel

While motoring all day I usually stay on the starting battery...the house soaks in the sun... Switch over at night and in the morning the starter is ready to go

Dave

[Russ]

I did the same thing, being in parallel they can both charge from the solar panel. Then one battery died, instantly discharged the second one, middle of the lake, no wind, was not so pleasant.

I have 2 batteries totally separate with a combiner. They only combine when voltage is 13v on one side (charging). The combiner has a safety so that it won't combine if the low battery is too low (10.5v). This could be the case if the low battery is faulty, dead cell etc.

1) house - Connected to solar panel
2) Starting - Charges from motor

Whatever battery is getting charged, it combines to charge both.
This has worked perfectly.

In a pinch, I have the jumper pack or I could switch starting for the house. As mentioned, some of these motors will even pull start. I've never tried (or needed to).

--Russ

[ris]

After rewiring the boat we plan to have four 6 volt batteries wired as one bank house/start battery. Plan is to use 4 Trojan 105's wired parallel/series. Which would make them two 12 volt with 450 amp hours. This is for extended stays away from shore power.

[Sumner]

After rewiring the boat we plan to have four 6 volt batteries wired as one bank house/start battery. Plan is to use 4 Trojan 105's wired parallel/series. Which would make them two 12 volt with 450 amp hours. This is for extended stays away from shore power.

...and of course you know I approve Two 6 volt or four 6 volt all as one bank is the way to go if you want to have the most efficient system in use and in charging and then tuck a battery start pack away somewhere as has been mentioned for a worst case situation,

Sumner

============================
1300 miles to the Bahamas and back -- 2015

The MacGregor 26-S

The Endeavour 37

Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

[RobertB]

I have close to the same power requirements you have. My biggest issue was maintaining power to the refrigerator. With the battery monitoring circuit in the Dometic refrigerator, I found one battery would not work and I also needed to reduce the length of the wire run to reduce wiring voltage drops (until I addressed these issues, the fridge would cycle on and off every several seconds late at night and drive me crazy). What is working well now is two house batteries side by side under the ladder (as installed by Mac Factory Sales) size 24 I believe. I also have a third battery I keep separate for starting. I used a battery from a car I junked but in the future will likely replace it with a smaller battery closer to a motorcycle battery. I have a quality battery charger that maintains all three batteries and use two Perko type switches. One feeds the motor starting/charging to either the starting or the house. The second house switch feeds the breaker panel from either or both house batteries.