I am in the process of spec'ing out the charging system for the voyaging sailboat I am constructing and am looking for recommendations on fitting a second high-capacity alternator. First, a few facts--the boat is 41', 22,500 lb. and is fitted with a new Betamarine BV2203. I order the engine with the PTO stub-shaft, and the standard 65 amp alternator. The intent is to dedicate the 65 amp alternator to the starting battery and mount a separate high-capacity alternator for the house bank, controlling both with a smart regulator. I have the space for a very large battery bank--up to six L16s--but will start with 4, for a capacity of around 820 amp/hours.
I am a big fan of the simplicity, reliability and engineering of the Electodyne brushless alternators [http://www.electrodyne.com/models.html ]. They have models ranging from 80 to 350 amp output. Their 200 amp model has a charging curve that seems to pair well with the RPM range of the BV2203 and the size of my battery bank.
My initial question is if the BV2203 can handle the HP draw imposed by an alternator of this size, given the characteristics of my vessel? Also, is the PTO stub-shaft up to the side-loads it might impose?
One potential problem is that I only have room to mount the big alternator on the port side of the engine, which is the same side as the factory alternator. As the factory alternator is powered by a serpentine belt, it is unclear to how significant a side-load component it contributes, and, thus, whether this is an unworkable situation. Any thoughts would be greatly appreciated.
Thanks, Collin
-- Edited by collinharty on Saturday 20th of June 2009 02:30:32 PM
__________________
____
Building Galene
Facts & reflections on building a 41' voyaging sailboat from a bare hull
Collin: My experience is limited on your topic but I have done my electrical differently. I put in two new house batteries. Trojan SCS225 that rate at 225 amp hours, but in real terms are 130 amp hours. The Start Battery is the Interstate 27HD series that rates at 1000 cranking amps but in real terms is about 850. I have purchased the Xantrex 40 Amp Shore Power Charge (good for 110 and 240V) and also the Xantrex Smart Charger. I also got the Xantrex Echo Charger. I then put in the Link Lite to monitor the batteries. I only power the House Bank (in parrallel) and let the Start Battery draw the power from them. Although this sounds a little hard on the House Bank, it actually works very well. The Start Battery only takes power when it senses a charge is present so anchoring out is still safe. As all of the units charge in the typical 3 stage manner, I get my batteries to the desired 100% level as they need time to absorb the last 20%. The Xantrex items do this for me nicely. All this is operating in conjuction with my old and tired MD2 (the reason for joing this forum) I had my 55 Amp Alternator tested and it actually puts out 42 Amps. A tech. told me my old engine may have trouble with a 90Amp Alternator. Keep in mind, that with the Xantrex equipment, and possibly the Smart Charger you mentioned, can get your old Alternator cranking like it never has before. This is why they are telling me that even my old Alternator may be too much for the power of the engine. (25 HP when new) I only mention this as I am not sure of the HP of your Engine and with two Alternators, you may find it a little hard to drive them. Again, I am only repeating what the Techs. are telling me so I would suggest you get some facts from your own people. I am thinking of replacing with the 20 HP, 3 cyl unit. I wonder if any viewers have experience with putting one in where a Volvo MD2 was used. My sailboat is 35', Full Keel, and is about 14000 lbs with gear. Regards Ron
I have heard nothing bad about the Electrodyne alternators. My suggestion would be to use the Electrodyne as your only alternator. The best way to charge your start battery is with an Echocharge. All charge outputs go to the main bank, whether they be alternator, shorepower charger, wind or solar. The Echocharge echos the charge regimen of these methods (ie-3 stage) and siphons a charge for the start battery up to 15 amps when it senses a charge is present - easy to hook up (3 wires) and foolproof. The start battery does not need a 65 amp alternator if you only use it for starting the engine. If say your starter uses , lets say 120 amps (probably high) and you use it for 30 seconds you have used 1 amp/hour. This is a simple bulletproof system if done the following way: Battery switches control use only, not charge. All charge outputs go to the big house bank. The start battery is reserved for starting only. The switches needed are two - one for house and one for start. This eliminates the possibility of anyone frying alternator diodes by turning off a bank while it is being charged. Items such as bilge pumps and electronics needing memory power are connected to a buss labeled " always hot" and fed directly off house bank. I am not sure exactly how much power usage you are looking at on a daily basis. Are you planning on a lot of usage per day or do you want to go 4-5 days without charging? Regardless, the above system will quickly and efficiently get you to 80% charge fro a low of 50% charge (which you should never take a battery below if you expect it to last a while). Away from shorepower 100% is not efficiently achievable with an alternator based system as regardless of your charge controller, the last 20% will take forever. This is because batteries just will not accept many amps as they pass the 80% level. The solution to this is either solar or wind generation. These two systems, used together of separately will top up your batteries without using many engine hours. Also the best investment you can make is a battery monitor such as the Xantrex Link series or similar from other companies. These give you real time amp/hour readings either in or out of your battery bank which you cannot get easily any other way, as well as % of charge and amp/hours left at current use. They are also very helpful at finding inefficient lights or equipment as you will know instantly when you turn something on how many amp/hours it is costing you. As far as sizing the alternator goes, for example a 110 amp alternator puts out at max 110x12=1320 watts. One horsepower is 746 watts. Therefore this example would use 1320 divided by 746 = 1.77 horsepower. You have to allow for belt slippage and friction as well so lets say 3 hp. With a 3 stage regulator charging from 50% to 80% charge this alternator or any other is pretty much running at max output continually. Heat becomes a real concern as does belt tension and slippage. High output alternators of 100 amps or more require dual belts or multi groove serpentine belts both for optimal performance as well as for belt life. Good luck Brian
Beta Marine standard canal engines are all supplied with a similar setup, the BV2203 would be fitted with a high output 175A alternator with in practice would usually give an output of approx 30% higher than this @ 14.2 14.5 Volts. We can also fit a 3.5Kva belt driven generator to this engine, designed with pulley rations for giving max output at around 1,200 -1,500 rpm engine speed, this is similar power to the 300 Amp alternator mentioned.
To minimize side loads we make all pulleys fitted onto the crankshaft as light as possible when so much power is to be taken from the pto pulley, fitting a close coupled aluminium drive pulley directly on. This keeps the twist on the front crank bearing to a minimum as the drive pulley is as close to the engine as possible
From the description of your sailboat, I would look to repowering with the Beta 25 or 28 instead of the Beta 20. Whichever one you choose, it will be much lighter and smaller than the MD2.
Stanley- I am assuming from your post that you think the BV2203 can handle the loads of a 200amp alternator for a boat my size (there will be no other secondary loads on the engine)? If I replace the stock 65 amp alternator with the Electrodyne, is there a dual or multi-groove belt replacement system offered that could power it, or do you recommend engineering a separate system fed off the PTO stub shaft? [See attached picture.]
Brian- My original goal with the a dual alternator setup was simply redundancy, but I am coming to the fact that with my boats space/engineering constraints, a single large output alternator might be a simpler more reliable solution. The setup you describe makes a lot of sense. I wasnt familiar with the Echocharge, so that was also very helpful.
Galene is going to be a modern voyaging vessel, so by the standards I grew up with her power consumption will be relatively high, but compared to many cruising boats out there today her needs will be moderate. The large battery bank is aimed at extending the time between charges and to allow for inevitable growth in the system. The alternator will be supplemented by solar and, perhaps, eventually wind power. The battery bank will definitely be monitor by a system comparable to the Link Series.
Your engine will handle the boat and the large alternator without problem. We can supply the polyvee (serpentine) pulleys that we use for our high output and the Balmar alternators and this way you will have a good drive system for your alternator.
Please contact me at the office next week and let me know the Woc# of your engine. This way I will be able to check which pulleys will actually fit your engine before I ship them.
Stanley
-- Edited by Stanley on Friday 26th of June 2009 08:28:19 AM
