John,
This is a bit later in getting out.
A complete discussion of batteries takes a long time and a lot of electrons. If you go to the INA site, in the maintenance section, you can find an presentation entitled Batteries 101. It was written for an oral presentation so does not read the same as an essay. It does contain a fair amount of info.
The regulator that comes with the alternator on the Beta engines is basically a standard car style regulator. It is not a smart regulator.
I don’t know who said it first but I heard it from Jeff Cote, a marine electrician specialist in B.C. and owner of Pacific Yacht Systems Inc. He said “Most batteries don’t die of natural causes, they are murdered by their owners.” Some of us don’t understand the care and feeding requirements of the type of battery we have and in some instances we have the wrong battery type for the job at hand.
Batteries are often classified by chemistry and purpose. For marine use the most common chemistries are lead acid and lithium. Lead acid batteries are broken down into subcategories - wet cells, gels, absorbed glass mat (AGM) and carbon foam. Wet cells can be standard batteries, low maintenance or no maintenance (sealed). Standard wet cell batteries have removable caps that allow you to add distilled water to the battery. When the batteries are charged the acid will boil and release hydrogen gas. Water is lost in the process. If the batteries lose enough water that the top of the lead plates are exposed they can be damaged when electricity flows in or out. Sealed batteries are no maintenance and water can’t be added. If too high of charge voltage is applied the battery will lose water. The only option is to replace the battery. Gel, AGM and carbon foam batteries are seal so water can’t be added. Gel batteries should be charged at about 14.1-14.2 volts. Standard alternators charge at 14.4 volts. Many gel batteries have been destroyed by standard alternators and therefore have ceased to be used by many people. The most common lithium battery chemistry used in boats is lithium iron phosphate (LiFePO4). In terms of purpose there are starting batteries, deep cycle and dual purpose batteries. These categories apply more to wet cell batteries than to the other types. AGMs, carbon foam and Lithium all produce plenty of power for high demand loads and provide decent cycle life for house bank loads. Golf cart batteries usually are 6Volt wet cell lead acid batteries. They are robust, available and cheap. They do not require any special charging system but they do require topping up with distilled water periodically. Generally they are taller than most 12v batteries so depending on where they are installed the height could be an issue. They must be installed standing up. Taken care of they are still one of the cheapest batteries for amp hours delivered;
AGMs are now the most commonly installed batteries for boats - they are probably the most expensive battery per amp hr given back, however they can be charged using a standard wet volt charging system, they can be installed on their side and they don’t require topping up with water so are lower maintenance than wet cells. They accept a charge faster than a golf cart battery but the difference is not great (Lifeline suggests 20% faster). Most AGMs will not tolerate an equalization or condition charge. If wet cell batteries or AGMs are left in a partial state of discharge they will lose capacity. Over time the capacity keeps dropping and in a few short years the batteries are finished. Some may be saved by reconditioning charges. It takes a long time to charge wet cell or AGMs much beyond 80% of charge with just an alternator so if you are out cruising and anchoring out a lot, the batteries may suffer. If you discharge wet cells or AGMs below 40 of 50% you will significantly shorten their life. It varies from battery to battery but going down to 20% of state of charge might reduce the number of cycles they will deliver to 150-300 cycles. Discharged to 50% they might give 700-1000 cycles. Cruising without going to docks or having alternate charging sources generally means you can only realistically use 30% of your banks rated capacity if you want to achieve reasonable battery life. When I bought La Reina she needed new batteries. I considered golf cart batteries but they were too tall to fit under the quarter berth so I went with Lifeline group 31 AGMs rated at 105 amp hrs each. They were about 2x the cost of golf cart batteries at the time. I installed them in March of 2005. I am in the process of replacing them this week. so I think they were worth the extra purchase price. Most people do not get that many years out of batteries.
Today Firefly carbon foam and lithium batteries are picking up in popularity. Firefly batteries are a specific type of lead acid battery first developed to a practical form by Caterpillar. The rights have been sold to a company in India. When the India company first took over they had some quality control issues. I don’t know if those have been fully worked out. The Firefly have more charging cycles, they can be charged with a standard wet cell charging regime but they work better with a custom set up. They are more tolerant of deep discharges and being left in partial state of discharge than other lead acid battery types. Conditioning charges will recover lost capacity. If memory serves me correctly they are rated at 3000 charge cycles if discharged to 50% and 1000 if discharged to 20%. They also have a high acceptance rate so can be charged closer to 100% capacity faster than wet cell or AGMs. Availability is still limited. In my neck of the woods retail price for a 100 amp hr group 31 Firefly and a 125 amp hr group 31 Lifeline are about the same (about $900 Cdn).
Lithium batteries come in different chemistries but for marine use LiFO4 is the standard. They cost more money than lead acid. Battleborn batteries have a pretty good reputation and price. A 100 amp hr group 31 sells for $1322.00 Canadian in Canada (SolaCity Inc in Ontario). Other high quality ones sell for over $2500. You can find cheaper ones but they are built to the price and do not have good battery management systems (BMS). A good BMS is essential with lithium batteries. Lithium batteries have specific charging requirements. With the exception of Trojan’s new Trilium they can’t be charged at temperatures below freezing. They do not tolerate a float charge. They have a high acceptance rate and will burn out a standard alternator unless you take steps to protect it. Battleborn sells a device taht will shut the alternator off after 20 minutes to let it cool down.Lithium maintain constant voltage until they are deeply discharged which is good for electronic instruments. They will die if they are discharged much below 10% so the BMS system will shut them off when they reach 10%. They do not really like being charged to 100%. Some manufactures rate the battery based on full potential capacity others do it based on usable capacity so direct comparisons can be difficult. They do not like high temperatures. More of a problem in the tropics than Ontario.
The cost per amp hr is interesting. A 100 amp hr group 31 Battleborn will have about 90 usable amp hours. It takes 2 - 125 amp hour group 31 Lifeline AGMs to give similar usable amp hours if they are discharged to 40%. The retail price for the 2 Lifelines would be about $1800 or $500 more than the Battleborn. My shore power charger can cope with the lithium but I would need to protect the alternator so the price becomes about the same after the alternator protection is purchased, however I have access to the Lifeline batteries at a discount and 2 will run me about $1160 so about $400 less than one Battleborn with alternator protection. The numbers get more interesting because the charge cycles for the Battleborn using 90 amp hrs will be about 1000 to 1200. For the lifeline discharging to 40% will give about 500 to 750 cycles. It gets more complicated because I won’t always discharge either battery that deeply. Assume I deeply discharge the batteries 50 times a year (deep discharge almost every day on 8 weeks of cruising) that works out to about 10 years for the LIfeline and over 20 years for the Battleborn. I decided to go with another set of LIfelines in part because they are immediately available and it is a straight switch to install the new ones.
Mark Powers
La Reina 26C
Vancouver, B.C.
