| Author | Message | ||
| marty Rating: N/A |
when you set up your house battery bank to be charged by an engine driven alternator, do you run a positive cable and also a cable from the negative battery terminal to ground? Marty | ||
| FAST FRED Rating: N/A |
Basically yes , but a better way is to use an RV ($17) relay that puts the pos house bat in the charge circuit in parallel with the start bats , only when he engine is on. This lets you run the household loads on the house batts , and saves the start bats for just engine starting. Get a West Marine catalog (free 800#) and look for the wiring diagrams there. Just dont buy anything , their prices are frequently over "list". But its a great catalog for info. FAST FRED | ||
| Scott Munrow Rating: N/A |
Fred, I'm kinda dumb. What do you mean an RV relay for $17.00 I follow what you are saying but have been trying to find a continuos duty solenoid, relay, or something reasonably priced to charge my house batteries while traveling. I thought I would need something with a 300 amp capacity giving the 50 DN alternator, but I must be wrong. Where would I purchase this relay. thanks for your kindness in advance. Scott | ||
| waynewland@earthlink.net
Rating: N/A |
I use a Yandina Combiner (google) instead of an isolator. It will allow charging of engine and house battery banks while running, on generator or shore hookup. This is a major upgrade from the isolator. This setup keeps the battery banks seperate when you are parked. | ||
| R.C.Bishop
Rating: N/A |
Scott....if you are dumb...so am I. Even dumber  I have been attempting the isolator thing for about a year now. Still don't have it worked out. I put the house bank on one post, the coach on the other.....the coach showed no charge whatsoever. Changed it around ( reversed the connections)....same thing. I have finely , but with no experience thus far, put both house and coach on the alternator. I have a large alternator. The coach went to the hospital today for a new clutch, so have nothing to report on that method. Wish I were a whiz to figure this thing out the way an engineer would, but meantime, it's trial and (hopefully not too far fetched or expensive )error. There has to be a way. RCB | ||
| R.C.Bishop
Rating: N/A |
FF.....I did not find this in my west Marine Catalog...only the isolator and the combiner diagrams... Thanx for your usual great help!! ( no facetiousness here, just gospel) RCB | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
The problem with an "isolator" is that they have two diodes inside that do the isolation. For a free bonus, each diode has an inherent .7 volt drop associated with it, which means you'll never get a full charge because the alternator would have to be set .7 volts higher to properly do it's job, which it's not. Add to that two different kinds of batteries with different potentials, and you'll find what RC finds... it don't work. I totally agree with Fred. Simply get a continuous duty solenoid that can handle a couple hundred amps, and hook it's contacts between the positive of your house batteries and the positive of your starting batteries. There are plenty of ways and schemes to energize the solenoid- I simply put it's coil in series with a dash switch, then hook that to the "aux" treminal of my keyswitch. So I can only turn it on if I'm driving, or if I put the key in the "aux" position while on shore power. All other cases it stays off. This way, either driving or on shore, my alternator or my 3-way converter keeps both batteries happily charged, and while I'm in the boonies they stay separate. Not a problem in 4 years... Solenoid: search "12 solenoid" on ebay and you'll find a bunch of them. Get a continuous duty type (golf cart types are ok, but NOT starter solenoids)... for instance item 7206442280 | ||
| morgan Clough (Mclough777)
Rating: N/A |
on that solinod, both poistives go on big bolts anything on 2 smaller ones | ||
| FAST FRED Rating: N/A |
For the hookup the full output of the alternator is seldom needed by the solenoid. If you have 2400Amps of house batts (about a ton) the charge rate of 25% would be 300A on 50% discharged batts. Not likely just from a cost point. The RV units easily handle 75A which suits most folks needs , if not 2 can be paralleled for 150.A Simplest method for hookup is to get a good (preferably marine) keyed switch With Off ON & ACC positions. Use it to start the coach and make it harder to "liberate". When in ON the solenoid is energised , just as in a sticks & staples RV.When you turn the key off the paralleling stops. Seamless , automatic & no thinking involved. Only "trick" is the ACC position will hook up the start & house batts while camping with a batt charger to service the start if sitting for a month or more. KISS a way of life! FAST FRED | ||
| Sam Reenu Rating: N/A |
Gary, actually, if the isolator uses Schottky (sp?) diodes, the drop would be more like 0.3V. Regardless, it doesn't matter how much drop there is, if you set up the alternator to sense voltage at either of the batteries, instead of at its own output terminal. And then you have the advantages of no moving parts and nothing to remember to do. As long as the banks have similar chemistry, as regards charging voltages, an isolator will charge them all just fine, with no under- or over- charged banks. The isolator will split the output current according to the relative state of charge of the different battery banks, giving more current to the one that's less fully charged. Of course, that may not be what you want, i.e. you might prefer some other kind of prioritization scheme. | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Sam, that is a "maybe"... Many (most?) isolators don't have shottkys. Shottkys do have much lower forward drop but the penalty is that they also have a very limited reverse voltage range and can be easily poofed by automotive voltage spikes. Not as robust as a regular diode in this application.... No matter, .7 volts or .3 volts, either way it's not good on the batteries- if you want your batteries to last a long time, you have to pay attention to the charging voltage to a few millivolts... being sloppy by 300 millivolts is bad on them...you'll never get a full charge. Yes reconnecting the alternator's reference input will fix this BUT how many alternators can you do this with, and how many people actually do it? Not many I'd guess. The solenoid is still the simplest and best way to go in my book.... | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Gary, I do not understand. If you are sensing the charge voltage at the battery, then it really does not matter how much is dropped across the diodes. The proper charge voltage would be applied to the battery banks. Richard | ||
| sylverstone (Sylverstone_pd4501864)
Rating: N/A |
i've got a stretched dodge van with a tag axle i use to tow a really heavy trailer with. we do ren faires and the like. it's got two alternators in it. one charges the stock battery. the other one charges the house bank that drives everything else (rig was a limo, tons of accesories) i have a toggle switch that turns on my trailer brake controller and a 100 amp continuous duty relay, *if* the engine is running. the trailer has a pair of huge deepcycles in it. the relay ties them in paralell with the bank in the van. basically, i hook up the trailer, i plug it into the van, and then i get in, turn on the trailer brakes, and away i go. the relay is there to prevent arcing of the connector when i plug it in, and the toggle switch is because i didn't want my trailer brake controller on all the time. there may be a better way, but this is working for me... (it's really hard to go terribly far without realizing your trailer brakes aren't turned on... ) -dd | ||
| Sam Reenu Rating: N/A |
Gary, thanks for the education re. shortcomings of schottkys. | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
We use a Pathmaker solenoid design combiner. With settable parameters, it doesn't care which battery bank has an operating charger; when the set voltage is reached on one bank, the combiner ties the banks together. As soon as the voltage drops on the combined banks to the set disconnect point, the combiner disconnects. If the voltage goes too high on one bank, it disconnects. After setting the connect and disconnect voltages, the unit has performed flawlessly, so for us, it's been very worthwhile. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska |