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pandion

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"So, I have a few questions fo

"So, I have a few questions for the experts out there. I need to re-wire my battery supply & add some gauges. I've got a pretty good idea as to what needs be done, but a few detailed questions:
1. I have two Crusader 250's; is there any reason I can't use one alternator for the starting bank & the other for the house bank?
2. Is one Group 27 w/750 cca adequate to use to start both engines?
3. Any idea what the output is on the stock alternators & if I use the stock one for the engine bank, can I get by using the default regulator using a wet cell starting battery?
4. Any recomendations as to where I can find an aftermarket high output alternator that will bolt on my engine?

Thanks guys, I love this site."
 
"I too have twin engines, alon

"I too have twin engines, along with 5 batteries (since we have an inverter). THe boat came with a battery paralleling solenoid that allows both engines' alternator outputs to charge all 5 batteries (that are all identical, deep cycle type). This system has worked well over the years and is simple in concept. I know there are all kinds of fancy, electronic devices out there for charging this but not that battery, but this setup works for us.

Your alternators are probably 60 to 70 amps--the usual. You can get them rebuilt at a good alternator shop to put out more juice. At the same time they can be converted to one wire designs to eliminate external regulators, if you want to.

Jeff

PS: A local shop accepts alternators by mail and does good work cheap (if you're interested)."
 
"Jeff's idea of the soleno

"Jeff's idea of the solenoid is a good one - they usually have the moniker ACR - automatic charging relay. I'd suggest that to permit sharing the alternator with the house bank.

Do NOT mix battery types (gell, AGM, wet, etc) with the ACR.

The regulator's and alternator's characteristics should match the batteries' needs as well as your usage - until you do the math you may find that your stock alternator/regulator is ok.

Before you make any changes, make a drawing to show the physical layout of things and a schematic to show the elctrical interconnects.

Also, be sure that you have a good ground connection between both engines' systems and the batteries share this, too. I've seen many 'upgrades' where things didn't work due to grounding issues"
 
"Answers to questions:

1. N

"Answers to questions:

1. No

2. No

3. 60-70 amps / Yes

4. Lots of websites for marine alternators:
http://www.alternatorparts.com/marine_alternators.htm
http://www.go2marine.com/category.do?no=13604
http://www.ebasicpower.com/charge/

Changing alternators is complicated. Adding bigger batteries just means your existing alternators will take longer to charge the batteries back up.
Your existing alternators will charge your (Group 27) 100 amp hours (aH) battery back up to full charge in 1 hour if you have discharged it to 70% (70 aH) (12.32V).
http://www.solar-electric.com/deep_cycle_batteries/deep_cycle_battery_faq.htm"
 
"I had planned on using the AC

"I had planned on using the ACR to combine the banks, so it's good to get confirmation. I've gone through rough estimates to calculate charging times. Given that when I motor, it usually for several hours at a time, I think I'm probably fine with the 60-70 amps output of my alternators.

I'm still a little fuzzy on the alternator outputs: 1)Can they both be run through an external regulator simultaneously? 2)Do I need to have the alternators modified to accomplish this? Given the charging characteristics for wet cells, I think I want the safety of the external smart chargeers. Thanks again."
 
"1. No (Each alternator ha

"1. No (Each alternator has its' own external regulator.)

2. Yes (Need new alternators)

Here is a link to a word document about external regulators: http://209.85.173.104/search?q=cache:UaVWxR7cBWEJ:[url]www.marineelectrics.ie/documen ts/BatteryCharging_000.doc+external+regulator+marine&hl=en&ct=clnk&cd=12&gl=us&c lient=firefox-a[/url]

Here is a link about different ways to combine battery banks: http://www.electromaax.ca/InstallationManual.pdf
Scroll half way down to section titled "Multiple Bank Charging Options"."
 
"make sure your engine running

"make sure your engine running style (rpm) is factored intothe alternator's output value...Very few will produce their rated outputs until spinning real fast 5000-6000.

i'd also do a min-max-avg calculation vs a rough calculation as it is easy to spend lots of $$ here - knowing your areas of need vs want enables making good trade-offs, when necessary"
 
"Battery isolators are the sim

"Battery isolators are the simplest and best solution. You can allow both alternators to charge both banks, yet keep them separated from draining each other.

I can't get the link to work but go to www.arcomarine.com. Follow the link to catalog, then isolators. There are several diagrams of different options available for meting your needs, without replacing alternators or massive rewiring projects."
 
"On the isolators, just be awa

"On the isolators, just be aware that unless you relocate the sensing lead on the regulator, you'll never put full charging voltage on your battery. Usually not an issue with flooded batteries but can inhibit full charge in 'newer' technology batteries. The multi-in/multi-out versions have more drop than the single-in isolators due to the additional diode(s)."
 
"Mark, This is true but it is

"Mark, This is true but it is never an issue unless your alternator only puts out 12 volts. Most put out 14-15, the voltage drop from an isolator is only .5 volts. This actually works fine with the newer AGM batteries as they charge at .5 volts less than flooded lead. This is the reason for the "flooded/AGM" switch on most newer chargers. Charles actually makes a .5 volt resistor which allows you to charge your lead and agm batteries from the same charger. They will also tell you that with an isolator, there is no need for the resistor if mixing batteries."
 
"Mak, I know that the alternat

"Mak, I know that the alternator turns faster than the engine rpm's. Do you know what I have to compare the alternator diameter to to get a ratio of engine rpm to alternator rpm. I intended to do more actual amp calculations to determine how large to size my house bank, I just meant that with two 50-60 amp alternators, I think I should be pretty close. I'm thinking about a 200amp house bank, & pretty much whatever they put out per hour should be ample if I'm cruising 4 or more hours a day. Our energy consumption at this point is pretty mild.

Rick, I keep seeing a lot of different referances to isolators & combiners; I was planning on going with the combiner route. Are they the same thing?

Lastly, if I just pull the alternator & take it to a shop for a re-build, which given their age is just prudent, can the increase their output & prep them to be used with external regulators?"
 
"My point was to bring the iso

"My point was to bring the isolators characteristics to light. The bulk of the regulators out there have a fairly large temperature dependence; as long as you know what your stuff is doing, no harm to the batteries.

The nominal voltage drop across a high current handling silicon diode is usually 0.6V. Some of the multi-in/multi-out isolators have two diodes in series so their drop is 1.2V. If you have the gell cells (desiring 14.1V) and you regulator provides a set point of 14.5V, using one of these devices will never enable full charge to the battery.

I'd be leery of the "0.5V resistor" unless it was used with a charger expressly designed to operate with it. The drop across the resistor is driven by the current flowing thru it so, unless the charger is constant current, the battery voltage has to rise over the charging cycle.

Where this is headed is that many methods to get things right. The best way is to tailor any modifications to what you have to get the best bang for the buck."
 
"[b]"Rick, I keep seeing a

""Rick, I keep seeing a lot of different referances to isolators & combiners; I was planning on going with the combiner route. Are they the same thing?"


No, they're not the same. A combiner is essentially a closed circuit with a voltage sensitive diode in it which opens at a set voltage, maybe 13.7, to allow current to trickle from the high side to the low side. It will allow you to maintain both batteries but not under much of a load.

An isolator is a series of blocking diodes which allow current to travel in one direction only, but at much higher capacity. The full load from the alternator is sent to two independent battery banks but the current from each bank can not travel backward into the other bank, therefore allowing you to run your house bank dead, yet still start your engines.

Most new yachts incorporate isolators, some in both the engine charging systems and the onboard systems. They can configure it so that any source will charge all batteries onboard, yet the draw is still isolated.

The isolator I would use would allow you to combine both alternators to both banks. This will give you 100-120 amps, depending on your alternator size. This way you have the assurance of two alternators plus the capacity to bring the batteries back up very quickly.

It is an inexpensive, safe and proven, over the counter system that is easily installed by the average do-it-yourselfer who has some basic knowledge and some common hand tools.

That just my opinion and like most free stuff, you get what you pay for so take it for what it's worth.

Good luck,
Rick"
 
"Kevin:

the alternator pull

"Kevin:

the alternator pulley should be driven off the engine - v belt most likely. Measure the diameter of the crank pulley. divide it by the alt. pulley's dia. thst should get you a multiplier for the rpm. It may be easier to get one of the laser tachs and just read it direct.

A good shop can change your alternator's output, but only to certain limits, based on its size. Same goes for the mod to change regulators.

Before doing any mods make sure they understand this is a marine application and see if they have any references...you want to make sure what you get back has all the safety features required."
 
"I've done a lot of this o

"I've done a lot of this on my boat, here is my setup:
1) I've (still) got the original (1975) Motorola 51amp alternators' they use external, adjustable regulators.
2) I ran #6 AWG ground wire from the alt. case to engine block.
3) I've got an isolator on each engine, a (one in, two out, 70 amp model)
4) group 24, 1000cca on each engine.
5) 2 x 100ah, gel cell in parallel for the house
6) I set the alternator output to 13.8v AT the starting batteries. It is important not to exceed 14v for any gel battery.
7) an emergency, momentary, remote switch solenoid to parallel the start batteries
8) #6 and #4 AWG wire in the charge circuits
9) accurate voltmeters that can be switched between the house and either start battery.
This has served me well over many 2 to 10 day trips. If I had a higher house load (or less cruising time), i'd move to a balmar 90 amp alternator on each engine. Both alt. have had their bearings and one or two have had new diodes installed as well. Overall, quite reliable."
 
"I have recently installed Xpo

"I have recently installed Xpower xantrex inverter 1500W 12.5amp and I already done some wiring, I need to find out if its done correctly, I have installed 2 batteries deep cycle 123 AH each, total 246 AH, ran 1 foot #2 AWG to 200 Amp fuse, 48"to on/of switch, 7" to inverter's positive, negative #2AWG 48"to battery.
From inverter's output I ran 24 ft. #12 AWG to main panel to Two double 20 amp circuit breaker. From breakers to main pos. and negative bus. I also installed block slide between the shore power circuit breakers and the new 20 amp breakers. This inverter is to be used mainly to power small micro-wave oven 1030w 8.9 Amp. usage time 5 to 10 mins twice daily on weekends,
is the 200 amp fuse over size ?
What size (AWG )of cables should I use between the two bank battries? Length is 48".
For charging battries: two engines, alternators are original - motorola 1989. Wired to main bus. Battery cables to 1-2-both-off switch. From switch to main bus.
One l000 mca starting battery to start both engines on cable #1.
And on cable #2, bank of two deep cycle battries 123AH each.
No isolators been used because of the power draw..
Alternators are with built in regulators and resistor wire to ignition coil.
Please clearify and sent suggestions if not done right! Thanks"
 
"Your inverter wiring sounds O

"Your inverter wiring sounds OK. Make sure hot (+12v) terminals are covered. #1 or #2 AWG should be fine between house batteries.
btw, isolators are in the charging circuit, not the load circuit; they are sized for max. alt. output. You might reply on how your batt. switch is managed on start-up and running? ie. must you switch it while running? or, do you leave the switch on both during/after start? On "both", are the alternators in parallel?"
 
"Thanks Diver Dave for your pr

"Thanks Diver Dave for your prompt response. Battery switch is on starting battery when starting both engines, let engines run for a while then switch to house batteries. The alternators are with built in regulators. They both go to the starter and then wired to the main buss.From the buss one cable carry the load to the batt. switch. From the switch two cables go down to the batteries. One cable to the starting and one to the house batteries.I also like to clear my mind if the 200 Amp fuse I used between the house batteries and the inverter is over size. I appreciate you sharing your knowledge thanks."
 
I blew out a 250 amp fuse when

I blew out a 250 amp fuse when my inverter shorted out! God help us if there hadn't been a fuse there.

Jeff
 
"#2 is good for 210 amps outsi

"#2 is good for 210 amps outside the engine space, 180 amps if in a high heat area. I'd say 200 is the correct value to protect the wiring. Does the inverter instruction sheet say different?"
 
"Thanks Diver Dave you just to

"Thanks Diver Dave you just took a load off my mind, regarding the inverters inst. all it said max. 200 Amp fuse. Thanks for sharing you knowledge."
 
I can't tell you how many

I can't tell you how many T and ANL fuses I had installed when I put the inverter in. I have 350A fuses in the battery leads and 200's in the inverter leads. The bigger expense was the fuse blocks that hold these monsters in place. Given the opposite end of this spectrum....its' worth it
 
"Hello bob....I kind agree wit

"Hello bob....I kind agree with your sugestion,thats possible the counter weights became sluggish. The boat is out of the water and winterized, since I live in Canada and we already had some snow. So this would have to wait till next spring. Is it necissery to take the distributer out ? or it could be done on the engine? Though is on the back of the engine and under a part of the boat deck.,"
 
"Hello jeff ... reguarding you

"Hello jeff ... reguarding your comment about the batteries, can you make some suggestions about rewiring. Thanks"
 
"For those of you experts in o

"For those of you experts in oil gauges.Sorry Idont know the make of hand 1989. Electrical only no electronics or Oil tubes fed. One of the gauges gets pretty eratic at times. I changed the sensor on the engine no results, I also switched the gauges around still no results. I am wondering if its a wiring problem or there is some other goblin to look for? Also on this engine the pessure reading I am getting is between 20 to 40 while on the other engine 35 to 60 lbs. what is the normal oil pressure? I cant find it any were in the manuel.(engine type GMC 4.3 LTR. Thanks for sharing."
 
"Peter:

Don't let absol

"Peter:

Don't let absolute oil pressure readings drive you crazy! Gages are not that accurate, nor do they need to be. Long as you have 'enough' oil pressure, as proven by a mechanical gage on the engine, then you're okay.

Per the established dictum, you need 10 psi oil pressure per 1,000 rpms (and with modern oils, even less than that).

On your batteries, please explain what you're looking to do.

Jeff"
 
Go down to the auto parts stor

Go down to the auto parts store and buy a cheep mechanical gauge. install it in place of the sender or Tee off the fitting and you can get a reading on what your pressure is. I keep on on the boat as I've had two sender failures of the electronic sender on my engine.

I'm going to install a mechanical sender in addition to the electronic one that feeds the ECM and send it to the gauge instead of the signal coming from/thru the ecm. It generates the warning buzzer and the oil pressure gauge signal.
 
"Hi jeff thanks for your quick

"Hi jeff thanks for your quick response. Regarding the oil gauge Should I be sadisfied with the reading I am getting since the pressure does go up with higher revs? Goin back to the battery situation. I originally had two batteries, one for each engine. Now I added a 1500w inverter to power up a 1000w micro wave for total time of max.30min a day for 2 days weekend, so now I put in two deep cycle batteries for the house and one starting battery to start both engines. The switching wiring still the orginal which was between the two starting batteries. So on one side of the switch is the starting battery and on the other are the two house batteries. How safe is this? After starting both engines and running for a while I switch to the house batteries. I am trying to do this as economicly possible with safty in mind. thanks for your support."
 
"Peter:

You've got enou

"Peter:

You've got enough oil pressure.

On your battery setup, only two batteries for the inverter is pushing it-especially if your refrigerator is eating into them as well. I have a total of 4 batteries on the house side alone, with another to start Mr. Port.

Jeff"
 
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