| Author |
Message |
Wayne Buttress (Eagleman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 27, 2005 - 3:59 pm: | |
Sorry Guys,
I know this subject has been beaten to death, but I still could use some advice.
At present both the start and house systems are being supplied by the 2 8D's used for starting and they are charged with the OEM direct drive generator. (PD4104) I am in the process of replacing the generator with a GM 130amp single wire alternator and I'm going to add seperate house batteries. I've been told that an isolator won't work with the single wire GM alternator.
My question is, will a battery separator work? any other ideas?
Thanks in advance, Wayne |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 27, 2005 - 6:24 pm: | |
My '06 had an aftermarket one-wire alt. on it when I bought it. I'd really rather have the OEM alt. back if I could, because of the higher amps. and the ability to add a three-stage regulator to it. One-wires are easy to install, but will take LONG drives to charge your batts at reasonable voltages.
Presently I use a high-amp batt. switch to toggle between charging/discharging starts OR starts & house. It's not a very elegant solution, because I can get myself into trouble if I forget and start discharging both sets. Plus, the switch is in the batt. bay way on the other side of the coach in the back.
I'm considering adding a second alt. for the house side, a P-type externally-regulated and a three-stage reg., and keeping the two charging systems completely separated. Given enough time and $ that's probably what I'll end up doing.
I'm sure someone less "electrically-challenged" than I am could dream up a better way of doing it...
But let my trevails be your guide... I'd advise you to keep the OEM alt. if you can. If it ain't broke... or even if it is broke...
My $0.02,
Brian Brown
PD4106-1175
Longmont, CO
Our Bus Site |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 27, 2005 - 7:26 pm: | |
Isolators:
http://www.pplmotorhomes.com/parts/rv-converters/dual-battery-isolator.pdf
http://www.manson.com.hk/downloads/product_infosheet/SBC5180V2003.pdf
http://www.gmcws.org/techcenter/02-06tc37.html |
James Maxwell (Jmaxwell)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 27, 2005 - 8:07 pm: | |
Brian: Grainger has a 200 amp continuous duty solenoid, in 12 or 24v coil, that could eliminate the necessity of walking back to the switch. Use a switch on the dash to activate the solenoid and put the house batts in the charging circuit. Or, match the solenoid coil to your alternator output for voltage and activate the solenoid with it. Start the engine, the solenoid engages, and the house batts are in the charging circuit, regulated by the same regulator as the chassis batteries. Stop the engine, alternator quits putting out, house batts are disconnected from chassis batteries. |
Wayne Buttress (Eagleman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 27, 2005 - 8:15 pm: | |
Thanks for the info.
I'm still not sure that an isolator will work with a single wire alt. as it wouldn't be able to sense the voltage requirements of the batts.
I could be wrong , but what I think I need is batt. separator or a solenoid.
I'm confused.
Wayne |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 27, 2005 - 9:51 pm: | |
I believe it is possible to mount a 12 volt direct drive alternator to your engine and have the high output. You will need help to get the right number of teeth on the drive but I have been told by an expert that the 4104 671 engine has a reducing adapter for the generator and if you remove that with the generator you can install the alternator like the 4106s directly. Same as the 4905s execpt 12 volt, I believe. That is a very powerful oil cooled alternator and worth using. |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 2:34 am: | |
JM, thanks for the lead on the solenoid. All I've found so far were the low-amp motorhome variety. I'll definitely check it out.
Wayne, yes, I don't think an isolator will be a good solution. It can only sense one set of batts and then there's a voltage drop..., quite a bit for a diode type and a little less for a Schottkey type.
The marine camp face the same issues as us with house and start charging on big-amp diesels. I'd look around West Marine's site for info and then try to find a cheaper one on the ePlace.
bb |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 6:43 am: | |
Gee, here I thought those links would have helped. But if
anyone looked, they would have found this at the first one:
http://www.surepower.com/isolator.html
Solenoids have a famous way of failing, they stopped using
them on RVs long ago. The isolator is near foolproof, and
had always worked well for me (being the fool I am) and
millions of other fools as well. |
James Maxwell (Jmaxwell)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 11:08 am: | |
J MC9: I guess each of us have had different experiences. I have had nothing but a record of failures with isolators, 5 of them in all. The last set was a pair of 175amp wired parallel (not cheap) on a 300a 12v Delco Alt. Literally melted down in only 3 months. Diode type isolators also have the additional disadvantage of causing about a 1 volt drop in voltage delivered. Replaced w/400amp capacity solenoid--still going strong after 7 yrs. New bus has a 200 amp 24v from Grainger, working as supposed to after 1 1/2 yrs. |
Wayne Buttress (Eagleman)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 12:43 pm: | |
Thanks again for the input Guys,
I have found a battery separator made by Wrangler NW Power Products, www.wranglernw.com, that will work with my alt.. The GM single wire alt will not work with an isolater. I'm to cheap to buy a different alt. with an external regulator.
Wow, what a learning experience.
Wayne |
John MC9
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 12:45 pm: | |
Jim-
"The last set was a pair of 175amp wired parallel
(not cheap) on a 300a 12v Delco Alt. "
That last link I provided gives the specifications of their various
models of isolators. Some are made for 300+amps and designed
for heavy service applications. They would better serve the
purpose, than attempting to use two in parallel.
Not to argue with you, but to simply illustrate the difference. |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 3:51 pm: | |
I'd just use some MOSFETS and photovoltaic-optoisolators... You can build a **quiet/contactless** circuit up to whatever amperage you need and switch it with about the same current as an LED. (I always preferr to DIY)
Tim |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 4:08 pm: | |
Tim: I am glad to see someone else likes Mosfets. Somewhile back I recommended them for light dimmers, fan speed controls and multiple point light switching (based on my own experience). One of the resident experts shot me down with dire warnings that they would not survive the transients in a bus so I said no more but just went on using them myself.
Anyone who doesn't like Mosfets should have used one of the original Heart inverters with bipolars. |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 4:37 pm: | |
Haha! Yeah those were a ball of fire, err fun... With the advent of the new generation of optos, MOSFETs are getting even more attractive for just about everything. Being voltage controlled instead of current controlled like bipolars, engineers/hobbiest's can get lazier and still make very successful designs without worrying about current balance, biasing, etc.
Mmmmmm, someone tried to shoot down MOSFETs? Must've been an ENIAC-era "double E". Almost all power MOSFETs now have reverse protection diodes built in, and if you manage to pick a MOSFET voltage rating that suits your task (anywhere from 12Volt-1KVolt using International Rectifier's product line as an example) you'll be able to run a cooler system with MOSFETs - Longer.
And we can dispell any "Myth" that MOSFETs won't survive in a bus/automotive/rail environment... They are just about the standard now, used from voltage regulators to your new electric power steering and braking (Anyone still not want to trust them? They're already there! Too bad you can't build your own car!)
Cheers!
Tim |
Michael/4905MD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 4:43 pm: | |
I have recently posted on a similar problem on another board. Responses to my post (at least indirectly) left me feeling others thought the solution offered in my post is at least undesirable, but without saying why this might be so. I write to ask your opinions as to the quality and, or effectiveness of my approach, and the soundness of the rational behind it.
First post:
“I have a 1989 model 20 Eagle converted 2002. I use the bus 300 Amp alternator to charge both bus and house batteries through a 300A isolator which delivers 13V while on the road. It seems to me, the bus batteries when charged, through the bus regulator, shut down the charge to all batteries.
I would like to instal a small belt driven alternator for the bus and use the bus 300A alternator just for the house batteries, thus eliminating the isolator. I am not sure of of how to switch things around. i.e. Regulator etc.”
Second:
“I mounted a one wire GM alt on my MCI MC8 to charge my house batts. You only have to run one wire to your batts. The alt. has a built in Reg. It is the easy way to do it. Total cost around 50$ Works for me. “
Third:
“I'm not sure to which regulators you referred in saying "Those are awfully dumb regulators" The "Pathmaker" is not a regulator and I don't think it performs any functions of a regulator. As I understand it the Pathmaker's function is to simply monitor the two (or up to three) battery banks that are attached to it. It causes those banks attached to it to be connected together (as if they were all one battery bank) for the purpose of charging. At any time loads are placed on any of the banks that bank then is automatically disconnected from the others by means of a solenoid to effectively isolate that bank from the others. On example of such a situation would be when you are starting the engine, you want the house battery bank isolated in order to avoid inadvertently running down the house bank (though as stated earlier the house and engine banks may manually be combined when that's needed). Because it uses a solenoid, unlike isolators there is no voltage drop across the banks charging multiple banks.”
Third:
“Those are awfully dumb regulators, generally. But, if the needs aren't too great and the climate is moderate, one might fill a gap in a charging system.
They're not at all adequate for a serious house system, however.
For what it's worth.”
Forth:
“I am just getting around to addressing the same problem on my conversion of a 1978 GMC 4905A w/DD8V71-V730-24V. The 24V output of the DD8V71's alt that ordinarily re-charges the coaches batteries as well as power the coach AC, heater blowers, and all other coach electric systems will also connect to a device called a Xantrex "Pathmaker". The "Pathmaker" will run on both 12v and 24V systems. It will charge the engine and house bank's while I'm driving down the road, but not allow the house bank's to be discharged when starting the engine. A special feature of the "Pathmaker" permits me to join the house bank with the coaches engine battery bank if I need the added boost of the combined banks for starting. Also installed is a Xantrex SW4024 to keep the house banks charged from two different AC sources (either the on board generator or land based hook-up). This way when I arrive at my destination I always finish that leg of the trip with a topped off house bank.
I'm no expert, but that's what I plan to do. Sounds like it might work for you.
Good Luck!
Michael 4905/MD “
Fifth:
“You have a problem you shouldn't have, better to fix it than add another alternator.
First 13 volts is to low to fully charge a 12 volt battery. A good digital voltmeter should show 13.8- 14.2 volts when the batteries are being charged. Check both the house and start battery, it could be the isolator isn't wired properly. The regulator's voltage sensing needs to be on the start battery's +, not the alternator's output. If it's wired properly both batteries will show nearly the same voltage. If you can adjust the regulator, if it's wired properly then it sounds like the regulator wasn't set up to take the drop of the isolator into account. You really should remove the isolator and use a continuous duty contactor to tie the house batteries in parallel when the alternator is 'putting out'. The usual way to drive the contactor is with a relay that has it's 6 volt coil driven off of the 'r' terminal on the alternator. I'm not sure about Eagles but GMs used the 6 volt relay and contactor to power the big fans in the HVAC only when the alternator was working. So much of the wiring could be there already.”
What do you think? Is there something wrong with the solution I’ve found, or is there a better way?
Thanks.
Michael/4905MD |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 5:21 pm: | |
Hmmm your post is kinda difficult reading so I'm going to truncate a bit and see if I grasp what you're trying to do:
From the "first" section, it sounds like you desire to eliminate an isolator by installing a second alternator on your second battery(s). This is fine, it's the way I'm doing it, and it works very well. Lots of redundancy.
From the "second" section, I'm not sure if you're looking for validation of the information, but yes, the one-wire alts only need the + wire run to the battery (after a fuse of course) so long as the ground is good (I've seen people run a same-wire-gauge negative to the batteries just-in-case).
From both "third" sections, I have no experience with the "Pathmaker" you speak of, and the post information you put up wouldn't help me figure out what it is... Someone else could help here...
From the "fourth" secion, it sounds more like the "Pathmaker" is an automatic transfer switch. When there is no alternator current it'll shut off the tie-in automatically (so the two banks would be parallel normally but isolated when the rig is off), and a temporary tie-in ability with no alt current for starting.
From the "fifth" section, I think the individual is not giving you the information in a consumable format. To charge a 12 volt battery, the + terminal of the battery should be brought to ~14.2 Volts DC. If you have an isolator beween the alternator and the batt, it will drop anywhere from .4 volts to up to 1 volt. You would have to adjust the regulator so that the alternator overcomes the loss of the isolator. I believe that even with the self-exciting alternators like the one-wire you're after, there is a trimmer on the back which allows you to varry the voltage out of the alt about 2 volts in each direction (you may have to remove a cover). That should be enough to over come the isolator, but you mentioned that you wanted to separate the whole works anyway.
My advise? Do it. Keep your high-current wire lengths short, and your wire gauges large especially on the house batts (2GA or bigger would be required for 12V of any significant current). Make sure your alt/regulator combo (or one piece) is getting the correct voltage to the batteries when they are being charged, as under volting them will kill them quickly (consider line-loss, terminal resistance, any other components that "eat" trace ammounts of voltage). Make sure you put a fuse for the rated current of the alt within 16 inches of the + lug on the alt, and on large house battery packs (~400 CCA amps+) put a catastophe fuse on the neg side before ground. You could use this "Pathfinder" thing if it is a tie-in switch, but it's cheaper to go with a marine-type battery switch that does the same thing (but not automatic, which may be what you're after).
The final word is the famous Do-It-Your-Way (DIYW).
Cheers!
Tim |
Craig (Ceieio)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 5:50 pm: | |
Michael - I saw your post and at the time I had never heard of a pathmaker (no one should be surprised at that though). I investigated it based upon your post and it seemed like a good solution on paper. Who knows what the reality will be, but it looks like it ought to work just fine.
Craig - MC7 Oregon |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 6:18 pm: | |
Tim, Stan, and other gurus of electricity:
Is a making a D.I.Y. MOFSET circuit for sharing/isolating the charging/ discharging of multiple batt. banks within the abilities of a rather novice "armchair solder-er"? If so, I'd really appreciate any online resources you might share for making one of these.
I never ceased to be amazed/ humbled by those that are willing to share their knowlege and experience on these Boards. It's very much appreciated.
BB |
Michael 4905/MD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 8:07 pm: | |
Thanks Tim!
Now that you point it out the way I listed the prior post did not help to make clear the order of dialogue.
Below I have included information about the Xantrex's Pathmaker.
Xantrex Multiple Battery Bank Charging
PathMaker is a battery combiner that automatically connects two or three battery banks for simultaneous
charging and isolates them during discharge. A toggle switch allows the user to manually parallel battery
banks for emergency starting power. For use with 12 or 24-volt systems, PathMaker has user adjustable
settings for connect and disconnect.
Product Features
Automatic, high current switch for simultaneous two to three bank charging
Connects batteries together when the voltage is sufficiently high and disconnects when voltage drops
during discharge
No voltage drop in charging voltage
Manual connect feature for emergency starts
Compatible with all DC charging sources
Convenient front panel LED status indicators
User-selectable connect and disconnect voltages
Optional Remote Control - indicates Off, Auto and Combine
One year warranty
Options-Four models available-Available in two or three battery bank versions with models at 100 and 250 Amps
I hope this will help clarify my post.
Thanks.
Michael 4905/MD |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 8:10 pm: | |
Brian,
I've looked at your web-page and have seen your rig. While your experience may not be the same as mine, I do appreciate YOUR efforts in sharing your experiences (both the good and bad).
I typically don't recommend that "novice" electronics people get too far into high-current DC area (over 30 amps...). However, I can give you some advise on minimums to look out for.
If a DC alternator's regulator fails, the output voltages can jump to twice the rated votage before blowing your fuses. The best way to start with a MOSFET is pick a voltage range well above the actual system voltage for basic safety. On a 24V system, 55 Volts is a commonly available voltage, which is fairly cheep. This International Rectifier IRFP2907 N-Channel MOSFET ($6.60ea @ www.digikey.com) can handle 75VDC @ 148 Amps. In order to get this device to turn on, you need to apply a voltage of more than 4 Volts DC across the G (gate/+) pin and the S (source/-) pin. The current draw will be VERY LOW (around 1-20uAmp), as it is an electrical field thus its name: Metal-Oxide-Semiconductor-Field-Effect-Transistor. The problem most people have though, is turning them off. Once the field is established, it requires some form of load or drain to collapse the field. This can be done with a 100KW resistor. Now depending on where you want to switch the power, the design can get a little complicated. An N-Channel MOSFET is desinged to switch the low side of a load (between the lightbulb and the ground line). With the P-Channel MOSFET, it will switch the load on the high side (between the lightbulb and the + terminal) BUT the gate line must get 4 volts away from the source line (on a 12 volt system, usually one would pull the gate down to ground with an N-Channel MOSFET) then use a resistor to pull the gate back up to +12V to turn it off).
Ah! Enter the PhotoVoltaic-OptoIsolator! As it's name suggests, there is a solar cell (thus the photovoltaic) and there is a Light Emitting Diode (just like in every other optoisolator). This works like a little battery that you can turn on and off on a whim, and put it anywhere you need. International Rectifier makes them, so does Texas Instruments, Motorola (under the ON Semiconductor name), but my favorite id Dionics. They have one of the fastest industry turn ot times (3 microseconds).
Now that I've gotten into timing a little lets take a look at a few data sheets:
MOSFET
RELAY
I've come back to the IRF MOSFET and we have here a Tyco Electronics Relay. On the MOSFET data sheet look at the second page at turn on time and rise time. Here we have 23/190 nanoseconds respectively. Turn on time is the time it will take between the gate getting an "on" voltage and the Mosfet beginning to allow current through, rise time is the time it takes from beginning conducting to full conduction. This gives us a total turn-on (from off to full conduction) of 213 nanoseconds. On the relay datasheet, page 4, they again have turn-on/off time published. For this relay, it takes 4 miliseconds (4,000,000 nanoseconds) to conduct after getting its control voltage. This may not be a big deal with some loads (lights, fans, etc...) but I've come across car alarms that trip themselves when trying to lock the doors because of a long delaying relay.
A photovoltaic-optoisolator by dionics will add 3 microseconds to the turn on time (so the final turn on would be 3.213 microseconds, still less than ONE TENTH OF A PERCENT of the time required to turn on a relay).
So all of this just gets to turning on a MOSFET. The MOSFET itself has a reverse polarity diode, so it'll only control voltage one way. You'll be able to tell if you've hooked one up backwards if it immeadiately starts conducting power. But if you used the MOSFET, photovoltaic-optoisolator, and a 100KW, you now have a one direction switch. If you put two of these on one battery line (one facing each direction one +to- and one -to+) you'll be able to control the current flow bidirectionally into and out of each battery. This way, if you want to boost your start battery with your house bank, you would turn on the correct MOSFET pushing power from the house bank to the alternator lug, and the MOSFET allowing the power from the alternator to the starting battery. To charge both battery banks, you would activate the MOSFETs for each battery that allow the power to travel from the alternator to the battery banks. You could further chang ethis with two lower power MOSFETs to switch the sense line of the regulator between the two batery banks, to further enhance the charge of the larger battery.
Since the photovoltaic-optoisolators only need about the same power as an LED, you can switch them with low-voltage/current circuits or even with a microprocessor. You could also elect to wire the LED side of the optoisolator to the ignition to allow charging automatically.
What it comes down to though, it that you'll have to decide exactly what you want the system to do then design out from there.
Hopefully you're not totally confused now, just remember, you need to spec a MOSFET above its intended use, or it will overheat. the use of a properly sized heatsink is also a good idea.
Cheers!
Tim |
Michael 4905/MD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 8:33 pm: | |
Thanks Craig!
I hope so! Look above. I posted specs for the Pathmaker.
Michael 4905/MD |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 8:34 pm: | |
Yeah Mike,
It sounds like it's what you'll want to use if you have one alternator. There also seems to be a plethera of mechanical failure points. I though you were looking for a two alternator solution...
I looked at the manual online, it doesn't look bad (the theory is very sound), but again I have no first hand experience with this other than my caution that I have seen high-current solenoids fail with the contacts closed (turned on) because they welded together under load. MOSFETS have a non-mechanical switch which can be pulled to "off" with the resitor in the event of no power for the control. Just be sure to use fuses rated for the system (something that is curiously missing from the manual, except for two small phrases saying that you need to referr to safety standard publications they didn't have procurment info for, in order to fuse correctly).
Tim |
Michael 4905/MD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 8:49 pm: | |
Yeah Tim!
I hear ya! I have a friend who knows what he's doing helping me on this. It will be well protected.
Thanks.
Michael 4905/MD |
Brian Brown (Blue_velvet)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, July 28, 2005 - 10:58 pm: | |
Tim:
Wow, that's a lot of good info! I'm going to digest this and see if it's something I can attempt, or maybe get built for me by someone locally that knows what they're doing.
I truly appreciate you taking the time to write all of this down for me. Hopefully, I can reciprocate in some small way in the future.
Regards,
Brian |
Craig (Ceieio)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, July 29, 2005 - 4:45 pm: | |
Tim - nice write up!
Craig MC7 - Oregon |
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