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 Post subject: Re: Batteries
PostPosted: 14 Sep 2020 19:28 
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Skipper

Joined: 29 Dec 2006 09:38
Posts: 656
jfalsone wrote:
Sorry to dig up an old thread but this one interested me, especially the comments made by Velera concerning the matching of capacity to intended use. I plan on 1-2 week cruising moving forward, mostly local Chesapeake Bay but also New England in the future. Currently, my house bank are two Group 31 Deka deep cycle batteries with about 200 AH capacity. I just installed a new Dometic Cold Machine and replaced almost all lights with LED. Dometic recommends 300 AH capacity. Don't know what assumptions they made but I am under capacity on paper. Current bank and starting battery are in the usual location under the quarter berth / nav seat. Original WB50 with original alternator. I have a Xantrex Link 10 battery monitor that I am just becoming familiar with. Can anyone with a similar setup and cruising requirement give me some advice? I'd say I'd be on anchor for 2-3 days tops in most cases, then using the engine to go somewhere. Wondering if I should consider a third battery for the house bank. Thanks.


Ok. I agree with the Dometic folks that you probably need about 300 Ah--because you are likely to use about half that in a 24 hour period. I have 440 in my banks of 6v golf cart batteries and it is really too much--my "smart regulator" senses when the batteries are getting close to full charge and cuts back on the alternator output and it takes forever to get a full charge on them. So I have too much capacity for what I use and it is not healthy for my system. I have no starter battery and have never needed one in 27 years of cruising.
In looking at your situation, another consideration is your ice box: the Tartan came with a relatively good ice box, but how you use it can mean a BIG difference in how long it runs and how much battery you use. Here are some tips: seal the covers with some refrigerator door seal and make sure both doors have insulation on the back (some Tartans did and some didi not). Put some drain plugs in the holes in the bottom of the box so that your cold does not run down into the bilge. I was able to cut my running time by about 20% by putting a very small computer fan (wired to the compressor fan power) in the botttom of my box to keep the air circulating so that everything in the bottom did not freeze while stuff at the top was warmer. These things will make 10 times the reduction of energy usage than installing LEDs in a Tartan 37.
You probably do not need to buy a huge new alternator. I am not sure what yours puts out (let us know but 80 amps is probably enough) and you do not tell us whether you have an external regulator. As I said in my original response--it is important, as you are doing--to think of your battery, charging systems vs usage as a system and assess it in its whole rather than looking at one thing. If you were doing only a day or two, I would think what you have is fine. But describing your usage, I think an upgrade is probably in order. You do need to have two banks so that you can isolate a bank if one develops a bad cell. Not common, but devastating if it happens at the wrong time. You do not need a starting battery if you have two banks as I have noted before. Even Nigel agrees with me these days.
Ray Durkee
T37 #373


 
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 Post subject: Re: Batteries
PostPosted: 19 Sep 2020 19:31 
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Skipper

Joined: 14 Jul 2012 20:36
Posts: 495
Location: Norfolk, Va
I used two 12V Golf Cart battery by US Batteries. They are 155Ah ea for the house, works very well for us. Others make a similar battery, same footprint as the Group 31 just a little taller. We have 200w solar, but can go a few days with no sun. Have a AB fridge and LED everything. Adding insulation to the top of the fridge does helps big time.

_________________
Hull #208, Puff Card
Southern Chesapeake Bay


 
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 Post subject: Re: Batteries
PostPosted: 28 Sep 2020 09:39 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 142
After over a week cruising the Ches Bay I've learned a lot about the T37 and my requirements. On the electrical side, clearly 200 AH were not enough as emphasized by Dometic. I could only achieve a full charge off shore power and this seems adequate for perhaps 2 days of use at anchor but will bring the batteries down to 50% / 12.2V. I'll qualify this by saying that my first two days were colder that normal so that reduced frig consumption some. While we were blessed with some great sailing weather (sailed a ton!), we still had to motor some through creeks and it is clear that my charging system is not capable of giving the batteries a full charge. Whereas my shore power charger will put about 14V and 10-30+ amps in, I found that my alternator/regulator system will only allow about 13.3 and the amps quickly draws down to well under 10 amps. In fact, while running the engine there are times where I'm negative on amps when the frig kicks on. I find this very frustrating! I don't have the particulars on the regulator but will find out but I'd be surprised is it was anything other than what came with the boat.

On the frig, I have some 1" insulation on the lids but will upgrade to 2" and add some seals. Not sure what people use for seals because the lids barely close flush as they are now without them. Suggestions welcome! I had added rubber drain plugs. I will look into the fan. Copy @Velera on the two banks. Need to check this but I think I can isolate the batteries now. Looking for the most sensible solution that doesn't break the bank.


 
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 Post subject: Re: Batteries
PostPosted: 28 Sep 2020 11:55 
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Skipper

Joined: 16 May 2009 08:06
Posts: 236
I would imagine with a more "modern" regulator, your stock alternator would put out enough power to keep your batteries charged on a reasonable engine running schedule. I put a 400AH system in a T-37 some 15 - 20 years ago. That boat has a high output alternator and a "smart" regulator. I think he has replaced the regulator a time or two and the batteries 2-3 times (he is not getting quite 10 years) and the system has worked pretty well. He has electric refrigeration (Adler Barber and original to the boat). We all keep our boats in a marina on the Chesapeake and over the years have cruised the bay and north to New England. I think a bank of 4 6VDC golf cart batteries and a relatively modern engine charging system, you should be fine. Maybe you will not get the absolute optimum life span from your batteries but at the same time, your beer should always be cold and you should always have juice left in the bank in the morning. Rather than redundant house batteries (a really smart idea for living aboard and imperative if you are away from civilization) I would opt for a starting battery as a back up. With a Sea Frost refrigeration system (came with the boat I bought), I still get by just fine with 2 group 31 marine batteries in the original battery boxes. If I were starting over, I would put on the extra batteries and the electric refrigeration.

$.02

Chip Seltzer
Esprit #324


 
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 Post subject: Re: Batteries
PostPosted: 29 Sep 2020 08:19 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 142
cseltzjr wrote:
I would imagine with a more "modern" regulator, your stock alternator would put out enough power to keep your batteries charged on a reasonable engine running schedule. I put a 400AH system in a T-37 some 15 - 20 years ago. That boat has a high output alternator and a "smart" regulator. I think he has replaced the regulator a time or two and the batteries 2-3 times (he is not getting quite 10 years) and the system has worked pretty well. He has electric refrigeration (Adler Barber and original to the boat). We all keep our boats in a marina on the Chesapeake and over the years have cruised the bay and north to New England. I think a bank of 4 6VDC golf cart batteries and a relatively modern engine charging system, you should be fine. Maybe you will not get the absolute optimum life span from your batteries but at the same time, your beer should always be cold and you should always have juice left in the bank in the morning. Rather than redundant house batteries (a really smart idea for living aboard and imperative if you are away from civilization) I would opt for a starting battery as a back up. With a Sea Frost refrigeration system (came with the boat I bought), I still get by just fine with 2 group 31 marine batteries in the original battery boxes. If I were starting over, I would put on the extra batteries and the electric refrigeration.

$.02

Chip Seltzer
Esprit #324


Thanks Chip. So, in your estimation (and others on this thread), is a new regulator and one additional Group 31 battery (for 315 AH total) a reasonable solution in my case? Can someone suggest a regulator that will pair well with my stock 55 amp alternator? I'll also search the forum on this since I'm sure it has been discussed.


 
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 Post subject: Re: Batteries
PostPosted: 29 Sep 2020 09:08 
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Skipper

Joined: 16 May 2009 08:06
Posts: 236
It is my opinion that you are better with 4 golf cart batteries, representing 1 parallel connection, than you would be with 3 group 31 batteries represent 2 parallel connections. The installation is more cumbersome and you are, perhaps, going a bit overkill on your AH budget but I think in the long run you will be better off and will get longer life out of your batteries. I went through this with my dad for years (he ran multiple 12VDC batteries in parallel to achieve capacity). He was constantly waking up with dead batteries. The system I am suggesting for bay and coastal cruising should serve you well. Your connections between batteries should be really robust and tight. I am pretty sure the stock alternator on the W50 has all the connections on the back for installing a new regulator. I don't think you need anything that fancy and depending on where on the bay you are, there are folks who know how do do that sort of thing. I can generally figure it out if need be but as mentioned, everything I am running is pretty much stock and my 20 hour budget is pretty small. My suggestions are not completely in agreement with Ray's and while I have never met him, I have been reading his posts for years and he knows a lot more about this stuff than I do!


 
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 Post subject: Re: Batteries
PostPosted: 29 Sep 2020 09:34 
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Skipper

Joined: 16 May 2009 08:06
Posts: 236
To further clarify, the W50 already has a remotely mounted voltage regulator. It is not included in the alternator. I think mind is toward the back of the engine, lower down, on the starboard side.


 
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 Post subject: Re: Batteries
PostPosted: 29 Sep 2020 11:25 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 142
Thanks Chip. So, your recommendation is 4 6vDC golf cart batteries and a "modern charging system". Does this mean new alternator and regulator?

I'm in Herrington Harbor North in Deale MD BTW. There are three other T37s at the marina that I know of. Only one other seems to get used. The others seem in pretty rough shape to me.


 
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 Post subject: Re: Batteries
PostPosted: 01 Oct 2020 17:50 
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Skipper

Joined: 16 May 2009 08:06
Posts: 236
There is a guy in your neck of the woods named Peter Kennedy. He really knows his $#,+ about this stuff (starting that with a $ was not intended to imply anything!). You might try looking him up and buy some advice. Your alternator is pushing 40 years old and putting a new regulator on it that will push it much harder than the stock regulator might be the straw that breaks the camel’s back. Who knows. If you can fit a better regulator to the alternator you have, it might work just fine and you would save a few hundred bucks. I do think you are too light with 2 G31 batteries and for regular bay / coastal cruising, you should be able to get 100 ahs back into the battery bank without having to motor all day (a couple hours).

$.02


 
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 Post subject: Re: Batteries
PostPosted: 05 Oct 2020 07:39 
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Tactictian

Joined: 06 Aug 2020 09:02
Posts: 142
cseltzjr wrote:
There is a guy in your neck of the woods named Peter Kennedy. He really knows his $#,+ about this stuff (starting that with a $ was not intended to imply anything!). You might try looking him up and buy some advice. Your alternator is pushing 40 years old and putting a new regulator on it that will push it much harder than the stock regulator might be the straw that breaks the camel’s back. Who knows. If you can fit a better regulator to the alternator you have, it might work just fine and you would save a few hundred bucks. I do think you are too light with 2 G31 batteries and for regular bay / coastal cruising, you should be able to get 100 ahs back into the battery bank without having to motor all day (a couple hours).

$.02


Thanks for this advice. Any idea how to get hold of Mr. Kennedy?


 
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