| Author | Message | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 8 Registered: 10-2007 Posted From: 142.161.49.211 Rating: N/A |
I was wondering if anyone could tell me a few quick tests I can preform to determine where my problem might be. I have new batteries that hold a great charge and have cleaned up the post connections in the battery compartment. Is there something I can do at the generator do tell if it's charging? The NOT GEN light is on in the dash as well. Can anyone help? Also I am not using the factory air, has anyone moved their batteries to the back of the bus where the A/C compessor was originally, and what are the pro's and cons. I would think that would eliminate a lot of cable which would provide better power. Thanks | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 151 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
Grant The idea of shortening cable length is good exept for the fact that batteries do not do well in a high temperature environment. Joe. | ||
| Mark R. Obtinario (Cowlitzcoach)
Registered Member Username: Cowlitzcoach Post Number: 174 Registered: 4-2001 Posted From: 204.245.250.41 Rating: N/A |
First off, you need to make sure all of the relays in the rear driver side electrical panel (on the forward bulkhead inside the driver side engine compartment door) are all plugged in and seated all of the way. There are a couple of them that tend to get loose. Once loose they won't tell the alternator to go to work. If any of them have blown and not reset you may have to replace them. You then need to determine if your alternator is charging at all or if the not gen light is telling you a lie. You will need some sort of voltage meter in order to test your voltage levels. Your alternator should be putting out about 26-27 volts if it is working. You will need to get your engine up to fast idle in order to get the regulator to cut in and tell the alternator to start working. If you aren't getting any power out of the alternator you need to then check the regulator to see if it is telling the alternator to go to work. If the regulator is working then you have an alternator that is gone tango uniform. If that is the case, call Luke @ U.S. Coach. He always has a stock of alternators for sale at very reasonable prices, even including shipping. As far as reloctating the batteries, the MCI battery compartment has more in it than just the coach batteries. Relocating the batteries will require you to relocate other electrical stuff. MCI coaches have gone millions of miles without any problems due to long cable runs from the battery to the starter. Let us know what you find out. Mark O. Castle Rock, WA | ||
| David (Davidinwilmnc)
Registered Member Username: Davidinwilmnc Post Number: 195 Registered: 7-2005 Posted From: 152.20.216.103 Rating: N/A |
Also, isn't there an air pressure switch that 'tell's the system when to start charging? I believe it's mounted on the rear elec. panel (inside the left side engine door). On my MC-8, there's an air line that runs to a pressure switch mounted there, so I'm assuming that's what this switch is. David | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 9 Registered: 10-2007 Posted From: 205.200.119.2 Rating: N/A |
Thank-you guys for your help, Mark that was exactly what I was looking for. Since I have only owned the bus since Aug and am converting it I haven't driven it much, nor do I know much about the charging system. I have noticed the electrical panel but have never opened it. I was also wondering where the regulator is located, and do I just simply test it with a voltage metre? By the sounds of it, I should just leave well enough alone regarding the battery location. I will check these options out tonight and give an update in the morning thanks | ||
| Chuck Lott (Chuckmc8)
Registered Member Username: Chuckmc8 Post Number: 232 Registered: 5-2004 Posted From: 68.211.32.244 Rating: |
Grant, if you want to relocate the batteries to the engine compartment, there is no reason not to. The heat in the bus engine compartment isnt any more than under the hood of an automobile, and batteries are designed for that enviroment. I have had my batteries in the engine compartment,as have lots of other bus nuts. Group 31 batteries are sufficent to start the DD. You'll want a 120V electric engine block heater as well. After the batteries are relocated, the two 4-0 cables that ran to the front battery compartment are easily used to charge the house battery bank from the bus alternator while underway. The former battery location makes a great location to put a pair of BBQ sized propane tanks. Here's a link to my photo page that has pics of the moved batteries as well as the propane setup. Dp you have a maintenance manual for your bus? If not. Email me at the link on my profile and I'll send the info that you need to test the chargine circuit. http://groups.msn.com/July2004Busphotos/shoebox.msnw?action=ShowPhoto&PhotoID=119 hope this helps, chuck | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 277 Registered: 8-2006 Posted From: 76.168.69.233 Rating: N/A |
Grant, Here are your quick tests, and you will need a multi-meter. With the engine idling, there should be battery voltage to the bat terminal of the regulator, and to the ign terminal. (About 24V if the alternator is really not charging.) If the bus circuitry is good, and the regulator is good, there should also be battery voltage on the field terminal of the regulator, AND the field terminal of the alternator. If you have battery voltage to ground on the alternator field terminal, again, about 24V to ground, your alternator is bad. If you have essentially no voltage on the field terminal, the alt is probably OK, the trouble is in either the reg, the wiring, or the protective circuits. To keep Sean happy, (Humor) if your alt has two field terminals, normal operation calls for one to be hot, and the other to be much lower. If the reg is bad in this situation, both field terms will be at batt voltage, (no field current flow.) If the bat or the ign terms of the reg are dead with the master switch on, follow wires to find out why. A two field term alt must have one term hot, (the reg grounds the other to flow current) so both dead field terms indicates a wiring problem. Keep in mind that the ign term of the reg is fed from the front master, thru the low pressure switch, to keep the belt from slipping without enough air pressure for proper tension. If you find high voltage on the alt output cable, something is open between the alt and the batts, shut the engine down 'til you find the problem, as alternators really don't like open outputs! As a fellow MCI owner, my first advice would be to get a 3/8 hollow shaft nut driver, and tighten EVERY nut on EVERY stud in all four junction boxes, and the relays therein! Don't be surprised to find 20 loose wires. George | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 10 Registered: 10-2007 Posted From: 205.200.119.2 Rating: N/A |
Good Morning Well my bus is charging, or at least it appears that way. Thanks for everyone's help, you all has been a big help. I went back to the junction box at the rear of bus as Mark suggested, I removed the breakers and replaced them, and at this point I looked at the feed wire on the outside of the junction box. It was quite corroded, so I also took it off cleaned it and replaced it. At this point I restarted the bus and the NOT GEN light was off. I then turned on all of the acc and checked the volts at the batteries. with the bus off. It read 11.5 and dropping , then I startd the bus and it jumped up to 12.44. So I take it the bus is charging. However when I was in the rear junction box I noticed that one breaker was missing. On the right side of the box, agaist the back, there are spots for three breakers, I have the bottom 2 but the top one is missing. There are plenty of wires going to it. Anyone know what this breaker is for and if I need to instal one?? The other issue is along the very bottom of the junction box there are some type of circuit breakers( or at least that's what I think they are) While checking these conections the 2nd one from the left broke, the terminal came right out of it. I can't seem to find what this does my manual. The bus seems to work fine without it but once again, does anyone know what this might do and do I need it?? | ||
| David (Davidinwilmnc)
Registered Member Username: Davidinwilmnc Post Number: 197 Registered: 7-2005 Posted From: 152.20.216.103 Rating: N/A |
Grant, The lid to my junction box has a diagram of all the breakers and connections on it (on its inside). You should be able to determine which breaker controls what there. I know that there are several missing from my MC-8 as well as wires that appear to be factory capped off. I imagine these are for things that aren't installed, like tax axle unloaders, that speed/time chart thing, jakes, some other sensors, etc. If you can determine what the amp rating of that breaker is, you can install an inline fuse holder (with pigtail wires to connect it) as a temporary or even permanent solution. David | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 11 Registered: 10-2007 Posted From: 142.161.57.21 Rating: N/A |
Thanks David, I really appreciate the info. I did notice one other in line fuse , so that's probably been done once already, great solution. When I was working on it last night it was dark and I was doing everything with a flashlight so I guess I never noticed the diagram on the inside of the panel. It get dark so darn early here this time of the year. Thanks again | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 537 Registered: 7-2006 Posted From: 66.217.107.122 Rating: N/A |
Uhh... "At this point I restarted the bus and the NOT GEN light was off. I then turned on all of the acc and checked the volts at the batteries. with the bus off. It read 11.5 and dropping , then I startd the bus and it jumped up to 12.44. So I take it the bus is charging. " 12.44? Isn't that kinda' low for a 24v bus? Der man-U-L says the charge should be around 28vdc, and to check for boiling to insure too much water isn't being displaced due to overcharging... 27-28vdc is about right for mine, 32vdc will produce a boil (although it was set at 32 when I bought it). I seriously doubt you're going to do much battery charging, if the rate is kept at 24vdc... | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 14 Registered: 10-2007 Posted From: 142.161.44.205 Rating: N/A |
Good Morning John Well that was my thoughts as well, so I was hoping someone would mention something. I only have a 12 volt meter, and since the voltage did jump when I started it I thought it must be alright. I suppose I should purchace a different meter and check it at the regulator rather than the battery? | ||
| JR Lynch (Njt5047)
Registered Member Username: Njt5047 Post Number: 185 Registered: 7-2006 Posted From: 69.132.233.230 Rating: N/A |
Charging voltage on one battery should be in the 13.2 to 14V range. As already stated, 26-28V across both batteries would be expected. Unless something else is charging the batts. If you have a charger on the batteries, the "not gen" light may come on. Placing batteries in the engine room works OK. The bus engine room is much cooler than under the hood of a car. I've got two group 31s for cranking batteries that have been sitting on the old AC mount for 3 years and they don't seem to be suffering. Still use the 8ds for house batteries. 8ds are not ideal for house batts, but they work for what I do. And, they'll fire the bus up if necessary. Either pair will light the bus. Not a lot of wiring necessary either. Leave the OEM wiring in place. Get a large batt switch and attach the hot/switched side to the alternator/starter post on the frame in the engine compartment. Make sure that the OEM battery master is OFF when working with the alternator junction. It should be off anyway unless you are testing or running the engine. I isolate the rear batts from the system when parked, and turn off the front batts so that the bus chassis isn't powered up. If you have a DDEC unit, don't isolate that. The "not gen" relay (RJB) is air powered. Keeps the bus from charging until about 70 lbs of air is reached. Then everything comes on. Be sure the bus is aired up. Best, JR | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 15 Registered: 10-2007 Posted From: 142.161.48.203 Rating: N/A |
Thank Jr The idea of having a set of batteries in at the rear of the bus does make a lot of sense to me, let alone much less work to maintaine battery charge while the bus is running. I guess I have one more question, where is the air valve that controls the charging system. You noted that the bus won't charge yntil it reaches approx. 70lbs of air. Thanks | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 152 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
Grant Canadian Tire has on sale a digital voltmeter with wire stripper and small pliers for 10 bucks. normal price 50. I have bought several in the past and quite happy with them. Joe. | ||
| JR Lynch (Njt5047)
Registered Member Username: Njt5047 Post Number: 186 Registered: 7-2006 Posted From: 69.132.233.230 Rating: N/A |
The gen relay is located in the rear junction box. I'm not sure about all MC9s, but the relay is located in the lower RH rear junction box on mine. The RJB is inside the LH side service door...right in front of the air cleaner. Do you have a service manual? Components related to the charging system are listed in the electrical section. www.coachinfo.com has the correct manual. JR | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 16 Registered: 10-2007 Posted From: 142.161.45.226 Rating: N/A |
Thanks again guys!! |
