I've heard some people say you can go with automotive batteries. I see 680 CCA on Amazon for an AGM battery for $123 . any thoughts? that's about 20% of the price for a marine battery of the same type on west marine .Thanks
Thoughts on new batteries for yanmar 3YM 30.
- Thread starter Ted10028
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A battery like that will be just fine for starting the engine. The problem is that starting the engine isn’t what you need most of the battery capacity for on a boat. The house bank is needed to run all of your electronics, fans, lights, radio, and everything else for hours on end. In the process the house bank often gets deeply discharged, having many tens of amp hours taken out of each battery. A car starting battery, on the other hand, is never really subjected to those prolonged loads and deep discharges, and isn’t designed for it. True deep cycle batteries have much thicker plates than start batteries and are able to handle those deep discharges. Start batteries lose an inordinate amount of their health when deeply discharged.
The downside of deep cycle batteries, (other than the cost driven by having more lead) is that they can’t provide the sudden big rush of current that’s needed for starting big engines. But for our small diesels that’s not an issue - any deep cycle that we’d use for house banks provides plenty of starting current.
The downside of deep cycle batteries, (other than the cost driven by having more lead) is that they can’t provide the sudden big rush of current that’s needed for starting big engines. But for our small diesels that’s not an issue - any deep cycle that we’d use for house banks provides plenty of starting current.
Ideally you want a starting battery for engine use only and at least one house battery on a separate circuit. Many boats have an isolator that allows both batteries to be charged off the alternator while allowing you to choose which battery you want to be using for starting or house usage.
I used a Group 24 FLA battery from Autozone for years to start my Yanmar 3JH2E.
The big difference between a "Marine" cranking battery and an Auto cranking battery is the label on the battery.
Here's a good article on Deep Cycle batteries.
The big difference between a "Marine" cranking battery and an Auto cranking battery is the label on the battery.
Here's a good article on Deep Cycle batteries.
What is a Deep Cycle Battery? - Marine How To
Light Cycle vs. Deeper Cycle NOTE: This article deals with FLOODED marine batteries, not AGM or GEL batteries. The Problem: The problem, as I see it, is one of dishonest marketing where multiple battery types wear the same clothes (sticker) and will perform differently when
marinehowto.com
I don't really see the specifications for a deep cycle. How can I be sure I am getting a deep cycle battery? thanks
Features of AGM Batteries
Low internal resistance.
The AGM battery charges faster than a gel or flooded battery.
Offers an 80% Depth of Discharge (DoD).
Excellent recovery performance.
Low-temperature startup capabilities.
Leak-proof, and low-maintenance.
according to this AGM battery is always going to have deep cycle capability? what do you think?
AGM for Boats
Changing batteries
AGM technology is the worst for boaters ever invented.
Why? Read Maine Sail's reasons:
AGM Batteries - Making The Choice (from Maine Sail)
AGM Batteries - Making The Choice
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries
Additional Observations on the Limits of AGMs Electrical Systems 101 - Page 3
Comment: The main disadvantage of AGM is if they are overcharged they will vent and then your battery is toast.
Reply: While possibly true, the only thing that can overcharge a battery is too high a voltage, and modern marine chargers are pretty capable units.
The main and CRITICAL disadvantage of AGMs on a boat is their inability to cope with PSOC - Partial State of Charge. They require recharge to full regularly.
Unless you plug in whenever you stop sailing, or you have a huge solar array (rare for monohull sailboats) it doesn't happen for cruisers. Many cruisers deal with this, but if you don't AGMs are the wrong choice.
And for most people who do plug in after weekend sailing, AGMs are a waste of money because for the way you use your boat, wet cells would be just fine (unless you have batteries in hard to reach spots; and then you just have the wrong boat
).
Changing batteries
AGM technology is the worst for boaters ever invented.
Why? Read Maine Sail's reasons:
AGM Batteries - Making The Choice (from Maine Sail)
AGM Batteries - Making The Choice
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
Darn AGM Batteries
Additional Observations on the Limits of AGMs Electrical Systems 101 - Page 3
Comment: The main disadvantage of AGM is if they are overcharged they will vent and then your battery is toast.
Reply: While possibly true, the only thing that can overcharge a battery is too high a voltage, and modern marine chargers are pretty capable units.
The main and CRITICAL disadvantage of AGMs on a boat is their inability to cope with PSOC - Partial State of Charge. They require recharge to full regularly.
Unless you plug in whenever you stop sailing, or you have a huge solar array (rare for monohull sailboats) it doesn't happen for cruisers. Many cruisers deal with this, but if you don't AGMs are the wrong choice.
And for most people who do plug in after weekend sailing, AGMs are a waste of money because for the way you use your boat, wet cells would be just fine (unless you have batteries in hard to reach spots; and then you just have the wrong boat
).
According to others on this website weight is a useful metric to compare batteries to tell true deep cycle vs. "Dual" or starting batteries.
I am seeing lithium lifepo4 batteries on Amazon for $287. That is very tempting. Who knows the quality but I wouldn't be surprised if China is doing a fairly good job with these .
No. As a rule, AGMs are should not be discharged below 50%.
As @Stu Jackson said, AGMs are not a good idea for boats, except for use as a starting battery. A battery used solely of starting a small diesel is never discharged very deeply so it can be recharged very quickly. AGMs used as house batteries is a poor idea because of the time required to recharge the batteries.
Don't you like your boat? Almost all the LFP cells are made in China. The really cheap LFP batteries are really cheap for a reason, they use cheap BMSs, they use low quality cells, and they are poorly assembled. Do some research on LFP battery assemblies and LFP battery teardowns.
There's a lot of very good info on Lifepo4 batteries in these forums. Do some research and you'll learn a lot including which ones are good deals and which are poor quality regardless the price.
China, like other countries with manufacturing capabilities, can build to a quality point or to a price point. High quality rarely goes hand in hand with lowest price.
China, like other countries with manufacturing capabilities, can build to a quality point or to a price point. High quality rarely goes hand in hand with lowest price.
seems like China electric cars are going to be about 40% less and Tesla. I don't think I have the time to try to figure out which Chinese Amazon lithium batteries are good deals and which are not.
The YouTube channel "Emily and Clark's Adventures" has some really good info on lithium batteries and how to use them and why ya can't just drop them into an existing lead-acid system. his many other videos are good to watch and he has a spreadsheet of tests on the more inexpensive batteries that he disassembles and tests against the claimed specifications..
2 Ways Lithium KILLS Your Alternator (and how to prevent it) (youtube.com)
2 Ways Lithium KILLS Your Alternator (and how to prevent it) (youtube.com)
Well, golly, by Jove and gee wizzikers!!! Isn't it the internet age? You think somebody hasn't done that already just for you?!? And if you don't know Maine Sail already, you should get to read everything he writes.
Drop-In LiFePo4- Be an Educated Consumer
Lead is Dead (almost) Warning: This article is long and detailed. It may require two reads so the nuances and detail are not missed. You may be wondering why I am saying lead is dead ?The answer to that is simple; lead acid battery makers dug their own graves
marinehowto.com
that was great. Convinced me I don't want to mess with lithium batteries. I think I'll just go to AutoZone and get a regular battery. I trust them more than Amazon for something like a battery. What do you think? west marine I would trust but they seem very expensive.
There are only a couple of major battery manufacturers in the country, but there are many many brands. All the batteries from one manufacturer are the same, just dressed up differently with varying prices. West Marine batteries are made by East Penn and have pretty labels and high prices. The easiest way to tell the manufacturer is to look at the battery caps.
I think you can stumble along picking up stones to see if there is one that is golden. You can spend a little time reading knowledgable sources to gain wisdom to make decisions based on critical thinking. Or you can search the internet for what ever suits your fancy and sounds like an idea that fits your historical data base (i.e AutoZone knows cars, cars have batteries. They must work on boats.)
Deep cycle batteries are different (night and day) from car starter batteries. The links that @Stu Jackson shared were prepared by knowledgeable individuals with years of electrical and marine experience. Like a trusted guide to follow to the top of Mt Everest or at least as high as you might choose to climb.
It is often assumed that West Marine will have the worst price but...earlier this week I purchased a marine rated battery from WM. I had first looked at AutoZone and Walmart. WM was a better price, better rated battery and came with an 18 mo. automatic warranty.
West Marine was in some serious financial difficulties last year. Since they entered an out of court agreement to restructure their debt (read stay out of bankruptcy court) they have been more aggressive with their pricing, enough so that I now check their pricing on many items before purchasing. I've found their prices to still be a little higher than other sources, but not as much and their more frequent sales are helping to keep costs down for boaters.
However, even their "Pro" pricing is often higher than Defender's regular pricing.