Electrical Dilemma

[thataway]

First batteries we will assume a high quality "Dual Purpose" battery 20 hour rating; Most c Dory come with group 24 batteries (amp hrs: 65) often a good compromise is a group 27 (amp hrs: 80), or best a group 31,( amp hrs 105) The group number only means case size. Generally a heavier battery will be better.--more lead. You only want to take 50% out of a battery, so you don't want to discharge it to less than 12.2 volts. (Since it was running the CPAP, the battery voltage would have seen lower than the "resting state". But best to stop at 12.2 volts, to avoid damage to the battery, "Deep cycle" group 24 batteries, as sort of a crock...real deep cycle batteries are going to be like Trojan T105, 6 volt Golf cart (2 in series to = 12 volt) Better yet, Rolls Surgett which are much heavier, or L 16 floor sweeper cells.

Next "Charging batteries" If you just run the batteries on the engine--most likely you will never fully charge them. The only way to know will be an amp in and out meter. Can do a fairly cheap, or go with the Victron. If you have a volt meter--use it! Learn what it means. You might say what about our cars? Well, most of us run a cars almost every day--and run them a lot more than the boats. On the boat, either top them off with solar, a generator, or shore power, at least every few days.

Again--if you don't top off the batteries, you are harming them. They will not last as long, or give as good service. If away from mains power--get a small solar charge. I stored the boat and a van out west, and it would be 6 months between visits. Batteries were always topped of--solar panels!

Every battery off the engine usually comes to the last 20% of capacity--20% is a lot! you have to go thru the Bulk and Absorption phases, and be at the start of the float stage. Different batteries have different profiles, you have to take into account the temperature of the battery, if charging heavily.

The 3.75 amps at 24 volts = 7.5 amps at 12volts (plus some loss in the converter) . If it is using that much, then you are going thru the battery overnight! (This is why it is necessary to get a good meter to measure just what you are using.) Casey's way works OK also. This 3.5 amps@ 24 volts is the max power consumption and output--not what is being used all of the time. Wiring and fuses should be speced to this. Inverters have some inefficiency--some where in the 90% + efficient. The inverter sized for the load is best.

Back to Jazzmanic: Still want to have manual way to connect start and house battery. Can be a simple switch for an emergency assume you stay with 2 batteries.

AGM--yes, if inside--where are you going to put it? But if only once a year, there are other options, such as solar, plug into power, etc.
I believe that the below 9.5 is true--but that battery is now damaged--and has been be being left at a partially discharged rate. Might be brought back with pulse tech. But I would tend to replace it. (3 years old--I get 4 to 5, sometimes more).

Parasitic drains. Many boats are wired, so that GPS, radio, stereo etc all have small current draw. Same with volt meters which plug into a socket. same with what Marco is considering. For that there is 23 milli amp per hour. That is almost 3/4 amp in a 24 hour day. Not a problem on a daily basis. But over a month--battery is dead. So when not using radios etc, be sure they are completely off no memory! reset the FM channels, etc. Marco, you put 4 of these around the boat, and now you are using almost 100 Milli amps an hour! Sure seems picky, but it all adds up. Even for these little volt meters, I think they are best used with a push button switch, to get a voltage. If your not looking at it--why have it on?

As for the Ryobi. Save your money up for a good Honda or Yamaha, if you want a generator. Even the EU 1000 will do almost everything you want on a small boat. It will run a 5,000 BTU air conditioner, charge @50 amps for 12V batteries, run a induction burner (at a medium setting). Read the reviews on people who have issues with the Ryobi. Look at getting engine parts. A Honda is good for years-thousands of hours. I have one which is 30 years old --550 watts steady--800 surge. It has charged batteries and run lights for many hours. Still runs fine. I have some Ryobi tools, I like their batteries (Li Ion), but I know that these are not long lasting tools. I have good tools for the shop at home, the Ryobi are "traveling"--and if damaged or lost, I don't worry.

Casey good numbers. What I was suggesting to Casey that if there as an issue to put a second battery in the truck, run it off a VSR, so no chance of damage to the truck battery or getting stranded. This is what we do in our truck, with the refer/freezer.

[hardee]

Hi Peter, and all,

(NOTE: You posted your post as I was writing mine so there is some new info there. I will address that here in Italics and then my response to your original post will be below that.

Mostly regarding the battery state prior to your trip. I was probably down, and though I would have thought it would have charged on you run over to the anchorage, due to the connected regulator, it may not have. That would mean you stared on an already somewhat discharged battery. Your proposed fixes look expensive. Another possibility could be to either, pull the battery to take home and put on a BatteryMINDer, or similar device or put in a charging system to charge the boat batteries while towing. I might go with a larger battery set, (Group 27 or 29 Deep cycle) rather than adding a third battery and all that it entails.

I think it is "curious" why you had GPS and VHF on starting and then 5 minutes into the trip, those went south. Seems to me like the outboard should have been providing charge power to that battery if the switches were in the right places. (ACR or 1-2-all). As a usual practice, I do a battery level check prior to starting the OB's. Once they are started, then the electronics are switched on, in a specific order, with the plotter being the last in line so it does not get fluctuations from the other devices coming on line, and by then the OBs are on long enough to have stabilized their alternator output.

I would recommend having a portable handheld VHF on board, no matter what else you come up with.

Now back to the original answer:


Ahhhh, CPAP on the boat. Well it should be CPAP every night; so CPAP on the boat should not be a question, right? Want a good night’s sleep, (if you have Sleep Apnea) then you need to use your CPAP. Sleep…. One of my favorite subjects. Rates right up there with C-Dorys.

Some Disclosure: I have Obstructive Sleep Apnea, and to get a good night’s sleep, and wake up refreshed and without a headache, I use a CPAP set at 17cm H2O, or an Auto CPAP set at 6-17cmH2O. I am also a Registered Polysomnographic Technologist. In plainer English and most of my friends, that’s “Sleep Guy”. Working in that field allowed me to fine tune my treatment very accurately, and have access to a pretty wide variety of equipment. In looking at my pressure record for a night I found I needed the 17 very rarely, usually only once a night. At 15cm about 40% of the times I needed pressure, the4 15 was the maximum so I settled on using a pretty old, fixed pressure machine set at 15cm H2O. It is an old Respironics REM Star Pro and like the other older Respironics, it runs on a 12VDC Cig Plug, straight from the plug to the CPAP and by doing that I avoid the “power brick” transformer or using an Invertor, both of which cause a power loss of some value. I have used this system on SleepyC for going on 9 years. Never a problem and no dead batteries.

To be sure, I use a very cheap, battery level monitor that just plugs into the same Cig Plug and gives me a digital voltage reading. I can check either battery or the combined voltage by switching my “1-2-Both-Off” switch, which I do and log every morning and night. Running my CPAP for about 7 hours uses about 0.3 volts off my two group 29 marine deep cycle batteries that have 95 amp hours each. If my evening volt check shows less than 12.6VDC I will run my twin 40 Yamahas at about 1800RPM for long enough to bring the VDC up to 12.7 at least. Generally, If I run the engines for an hour or so, at even my preferred slow cruising speed I have plenty of battery reserve. If I hang at anchor for more than one night, there are times I have been able to do two nights without running the OB’s to charge up. (Again, I watch my monitor and use very little electrical accessories. If at anchor, I do use my Garmin GPSMAP640 for anchor watch, and maybe charge my phone.)

So Peter, Looking at your battery down situation, I would be tempted to not change a whole lot. If it were me, I would: #1. Be absolutely sure the heater and humidity settings are off. You can still put some water into the system but in some newer machines that will trigger the humidity (heater) to come on, depending on the settings. #2. Watch the battery voltage in some way. In your case, the house system for sure, since it is isolated from the start. #3. Care a jump start device of some sort. And #4. Don’t give up on the CPAP. Sleep apnea, untreated, has a HUGE adverse effect on our health and well-being. Props to you for using it and working on a system to make it reliable.

I would not recommend carrying a generator just to run a CPAP device off of for all night. To use one to charge the battery system via the onboard charger, or shore power system is fine, but I have real compunctions about running any Carbon Monoxide generating system overnight while sleeping onboard.

Solar power is often used successfully for charging the house or combined systems. Some are more effective than others due to system design and/or environmental conditions. Some CPAP systems are designed to be charged by solar energy, and can be effective adjuncts. There are small(er), portable batteries that can charge on 12VDC while you are running during the day, or charge off of shore power when plugged in there. Again, running an inverter to charge a battery is not the most efficient use of your 12VDC power but if the OB’s are running there is most likely sufficient voltage for that purpose too.

Spoiler alert: I am working on a “CPAP on D-Dory” thread posting to come up in the near future, so #1, I welcome questions, and #2, I recommend “Use it if you need it”.. which means that if you are supposed to be using it at home, you are also supposed to be using it in the boat or RV (or motorcycle) when traveling.

To all, A good Night,

Harvey
SleepyC (Get it?)

[Aurelia]

Peter, It sounds like there is one key element to your story and Bob mentioned some of the impacts. You store the boat indoors/racked at twin bridges with no shore power available for charging and no light for solar. That means your batteries sit for long periods, slowly discharging and becoming generally weaker while also not being peaked when you go to use the boat. If you are currently using regular batteries (not AGM) then you should consider switching to AGM before you do anything else.

Deep cycle AGM offers deeper safe discharge levels so you end up having greater power available overall without damaging the batteries or going up in size.

AGMs self discharge around 3% per month instead of 10% per month so they can sit and still be healthier and more ready for use.

With your storage situation, I would switch to AGMs (bigger only if you can fit them) and consider any possible periodic charging options you could pursue at twin bridges even if that means de-racking the boat and topping up the batteries with a shore connection for half a day every other month of the year while you do some cleaning or just have a couple of beers and tinker. This would also help recover from any small parasitic draws you might have on that boat that are making your storage discharge problems worse.

Not having shore power or at least a solar option, is a recipe for short battery life spans and that very well could have been why you ran into trouble.

You system layout is likely just fine and ready for better batteries and maybe some periodic peak charging to maintain battery health a get 5+ years of life out of a set.

Skip the third battery and just carry one of those new tiny jumper packs to jump your house battery back above 11 volts so your ACR can kick back in and charge from your outboard again. That would give you a backup in the smallest and cheapest form. One of these packs would have likely saved you during that trip and got the house charging again for the time being.

http://www.amazon.com/PowerAll-PBJS12000R-Rosso-Portable-Starter/dp/B00D42AFS8

Greg

[Jazzmanic]

Good suggestions Greg. Forgot to mention I in fact installed a complete 30amp shore power system by the book including galvanic isolator and AC panel a couple of years ago when I had the boat at the Edmonds marina full-time. So I do have shore power capability and I charge the batteries every chance I get to plug into shore power. But you're right, it's the time that's spent stored on the racks that may be slowly discharging the batteries. In past years I've actually taken the batteries out and stored them at home for the winter, charging them regularly on the charger. I just checked on the boat for the first time in 3 months last weekend and the motors started right up. I should have run the DVM on both batteries during that time to see what charging state they're in. Next time, maybe in a couple of weeks. You see, since we almost always stay at marinas and very rarely anchor out for more than a day or so, we've never really had to worry about discharging a battery the whole time we've owned the boat (11 seasons) but as they say, it only takes one time.

I like your suggestion about using AGM's due to the slower discharge rate. I might have to suck it up and score a few. If I do, do you suggest two of the deep cycle batteries rather than a start and deep cycle? I also like the idea of the little jump pack too. Thanks!

And Bob, thanks for your clear and instructive explanation, very helpful as usual. And thanks for the advice to steer clear of the Ryobi. The advice from all has been very valuable and has made me think a little differently about batteries after all these years.

[thataway]

One comment on generators and charging batteries. I agree with Harvey, never consider running a generator for a CPAP machine.

For generator charging, I choose a larger charger than what comes with the c Dory. (usually a 5/5 Guest charger--that is 5 amps per battery). That may take 20 hours to even get to a float stage (because of the the tapering off as a battery gets close to a full charge).

I happen to use a West Marine battery charger, made for marine conditions, but not made as built in charger. Mine is older than the more recently sold 30 amp #BC30WM. The newer one make auto compensation for temp--mine manually you put in the temp. These are "only" $140.

One other beauty of AGM batteries is that they will take a more rapid charge than a flooded lead acid battery. Basically I run this charger on my group 31 battery for an hour, putting out 30 amps. Then it begins to taper, and I tend to shut the generator down at about 3 amps charge. This is not fully charged, but getting to the 90% range, and is a good compromise. A number of times we have used this system for over a month of boating, with no mains power--and it works well. I am cycling the battery about 50 to 60 amps draw and recharge twice a day.

I get my AGM's from Sam's club--for me it seems like a good compromise price vs quality. Their AGM's are made by East Penn--one of the better manufacturers. The Odyssey are a better battery. They are 11# heavier than the Sam's club, they cost twice as much.

Advantages of the AGM battery; low self discharge as Greg noted. Can be placed safely inside the cabin of the boat, can be put in any position, except up side down, will take a greater charge, although they can be discharged more deeply, more rapidly--any battery will suffer some loss of life with extreme discharge. The Odyssey company gives a 450 cycle life at 80% depth of discharge.
They give 700 cycles at 50% depth of discharge. Is this important? Probably not for the average boater. Where it will make sense, is if there is full time use. In this case, then the very high end, Surrette/Rolls would be a better battery, they claim 3000+ cycles to 50% depth of discharge, 2000+ cycles to 80% depth of discharge, with a similar battery of 115 amp hour and cost of $375 plus shipping (not cheap).

Another good choice is the Sears Platinum Die Hard marine, which can be found on sale--and can be the "best buy" (also made by Odyssey.

One other option is to put a solar charger remote from the boat. I have no idea if this is possible at your marina, but this is what I did with my van and boat stored in the West. I was able to screw the panels on wood, which had good orientation to the sun, Amazingly no one stole them!

[Aurelia]

Since you have the ACR in place already to protect your start battery position, you will not be deep cycling your starting battery, so a dual purpose or starting specific model should do great. I will say that the dual or deep cycles are generally a little heavier built and it could be argued that they should live longer but there are loads of factors involved. Deep cycle batteries do have significantly less cranking amps so they often need to be upsized for effect starting. That is counter productive in your case.

Bob's brand advice is good and I also like East Penn products. Below are a couple more visual and price examples for you.

Something like this would fit in your current position and work well for the house.

https://www.batteriesplus.com/battery/marine-and-boat/deep-cycle/bci-group-24m/sli24magmdc

Your motor needs a bit over 500 CCA for starting and this can easily be provide by a slightly smaller group 34 battery. It will fit a little easier (shorter), save about 10 lbs in weight, and cost a little less as well.

http://tinyurl.com/grvytev

Greg