Hello all, i recently picked up a mostly converted 1989 MCI 96A3. Shes a pretty cool bus and is going to be just the thing for me and the wife to make some excursions to see more of this great country, after this whole coronavirus thing blows over of course. The previous owner didn't own it for long and he didn't get any info from the guy that actually did most of the conversion so theres a bit of detective work to do. Most of it i'll just have to muddle through myself. I was however wondering if anyone can help me make heads or tails of this batter box. I have a couple wires, one descent size that don't appear to actually do anything but clearly they are there for a reason. For some reason the clearance lights don't come on with the dash switch but they did come on when you connected the house battery. Or at least they used to, i put a fresh battery in there when i got it home and now no clearance lights and the generators won't start. They crank, but no spark. I wish whomever started this project left some notes :P
I highlighted the wires in question on the last pic. 2 are barely connected and one has a 3 position switch inline that appears to change absolutely nothing.
I'm assuming that those two 8D batteries are BOTH part of the chassis battery system being run in a series format to provide 24v.
Also looks like some of the smaller wires might be tapping into the center of the two batteries to provide a 12v feed to something(s).
Do you have another set of house batteries somewhere?
Have you confirmed if your clearance lights are 24v or 12v? You can probably pull a bulb to check what's in there right now if you don't already know. What about your headlights? 12v or 24v?
Lots of people have done lots of bad things to wiring systems since these buses left the factory. Hard to know exactly what goes where without lots of sleuthing.
A good multimeter and a wiring diagram help greatly.
The Vanner blew a fuse, some have a reset button or the Vanner could be bad
You are correct, those are the start batteries 24V. Yes, someone did tap into them several places. As it sits is how i found it, figure i would start there and try to figure out what may have been done wrong at some point. I would have to guess all the clearance lights are 12v as they only came on when you connected the separate house battery, only one at 12v. Odd for sure, but who knows what they were thinking. Where the heck is the vanner?? I have seen plenty of pics with them right there above the battery but not on this bus. All i have is that 10 amp breaker to who knows where.
Welcome to the party!
You want to get one of those wire tracers that puts a signal thru the wire, so you can find the other end. Harbour freight has cheap ones in US.
That red wire that connects the two batteries together is too small. Typically, the main cables should be 0000 size cable.
Be aware that there is more than sufficient energy to burn the bus down, if you don't get these wires traced and identified as to their purpose.
Be safe, and leave the cables off the batteries when you aren't working on figuring it all out.
Working backwards from the coach electrical schematics, identify what is correct, and reduce the uncertainty.
Happy coaching!
Buswarrior
That wire with the fuse mounted above... has that been connected to the negative/ground post?
Where are these "house" batteries you mention? Those two batteries in the pictures are the coach chassis 24 volt set, not a house and chassis battery side by side.
When wires are not labelled, they end up attached to the wrong places very easily.
I am a big fan of these being collected on a bar, with the battery connections being simplified to as few as possible, because even smart guys screw this stuff up, when swapping batteries.
What is the voltage of each battery? Both should be higher than 12.6 volts with a multi-meter.
Happy coaching!
Buswarrior
Theres a house battery in the rearmost compartment along with the water system. Both of those are chassis batteries, the PO replaced them not long ago, recent date codes. That jumper wire bugs me, already ordered up a heavy duty replacement. Positive and negative terminals look like crap too so those will be getting changed before she really goes anywhere too. Good suggestion on the wire tracer, should have thought of that. That one connected to the ground is what had me start looking closer, and then all these other things that didn't look right started becoming evident. I'm a big fan of simplicity with batteries. I have far too many projects to remember what hooks up where when it comes to some things that don't really need a battery in them all the time. I'll simplify when i figure out what goes where LOL
Also never a good idea to tap 12V out of 24V series battery bank; as it can get the two batteries out of balance, depending on the draw.
Also if it is used for house systems, you can draw down the one battery down to the point where you would not be able to start your bus.
Your start batteries should only be used for one purpose, starting the bus!!!
Some conversions have both 12V and 24V alternators; with house RV systems off of the 12V system.
If the bus only has a 24V alternator then the ideal power flow would be:
1. Alternator output
2. Battery isolator with for dual battery banks to split the power to:
A. Start batteries and bus 24V system
B. 24V to 12V DC to DC converter
3. The output of the DC to DC converter would then be hooked to the 12V house battery bank.
4. 12V house battery bank would be protected from over discharge by a battery protect module.
You need to size the battery isolator according to the alternator output. Here are some example parts:
https://www.amazon.com/Victron-Energy-Battery-Isolator-Batt/dp/B00NT9MTMQ/ref=sr_1_5?dchild=1&keywords=200%2Bamp%2Bbattery%2Bisolator&qid=1588787621&s=automotive&sr=1-5&th=1 (https://www.amazon.com/Victron-Energy-Battery-Isolator-Batt/dp/B00NT9MTMQ/ref=sr_1_5?dchild=1&keywords=200%2Bamp%2Bbattery%2Bisolator&qid=1588787621&s=automotive&sr=1-5&th=1)
https://www.amazon.com/Renogy-Isolator-Compatible-Lead-acid-Batteries/dp/B07JQ98RQJ/ref=sr_1_6?dchild=1&keywords=200+amp+battery+isolator&qid=1588787621&s=automotive&sr=1-6 (https://www.amazon.com/Renogy-Isolator-Compatible-Lead-acid-Batteries/dp/B07JQ98RQJ/ref=sr_1_6?dchild=1&keywords=200+amp+battery+isolator&qid=1588787621&s=automotive&sr=1-6)
Here's what I use for my DC to DC converter (not exactly in this scenario).
https://www.amazon.com/gp/product/B01BF5BQLA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B01BF5BQLA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
In my application I then protect the 12V house battery with:
https://www.amazon.com/gp/product/B07LGCY3RR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B07LGCY3RR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
Also note that the battery isolator depending on manufacture can have a 0.5 voltage drop; so, you may need to adjust the voltage regulator with it in the circuit.
Might be a good idea to invest in a hydraulic cable crimper and a few sizes of copper lugs - then you can start making your own cables as needed. I found quickly that having to order cables every time I wanted to move something around got old (and expensive) quickly.
Quote from: freds on May 06, 2020, 11:14:03 AM
Also never a good idea to tap 12V out of 24V series battery bank; as it can get the two batteries out of balance, depending on the draw.
Also if it is used for house systems, you can draw down the one battery down to the point where you would not be able to start your bus.
Your start batteries should only be used for one purpose, starting the bus!!!
Some conversions have both 12V and 24V alternators; with house RV systems off of the 12V system.
If the bus only has a 24V alternator then the ideal power flow would be:
1. Alternator output
2. Battery isolator with for dual battery banks to split the power to:
A. Start batteries and bus 24V system
B. 24V to 12V DC to DC converter
3. The output of the DC to DC converter would then be hooked to the 12V house battery bank.
4. 12V house battery bank would be protected from over discharge by a battery protect module.
You need to size the battery isolator according to the alternator output. Here are some example parts:
https://www.amazon.com/Victron-Energy-Battery-Isolator-Batt/dp/B00NT9MTMQ/ref=sr_1_5?dchild=1&keywords=200%2Bamp%2Bbattery%2Bisolator&qid=1588787621&s=automotive&sr=1-5&th=1 (https://www.amazon.com/Victron-Energy-Battery-Isolator-Batt/dp/B00NT9MTMQ/ref=sr_1_5?dchild=1&keywords=200%2Bamp%2Bbattery%2Bisolator&qid=1588787621&s=automotive&sr=1-5&th=1)
https://www.amazon.com/Renogy-Isolator-Compatible-Lead-acid-Batteries/dp/B07JQ98RQJ/ref=sr_1_6?dchild=1&keywords=200+amp+battery+isolator&qid=1588787621&s=automotive&sr=1-6 (https://www.amazon.com/Renogy-Isolator-Compatible-Lead-acid-Batteries/dp/B07JQ98RQJ/ref=sr_1_6?dchild=1&keywords=200+amp+battery+isolator&qid=1588787621&s=automotive&sr=1-6)
Here's what I use for my DC to DC converter (not exactly in this scenario).
https://www.amazon.com/gp/product/B01BF5BQLA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B01BF5BQLA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
In my application I then protect the 12V house battery with:
https://www.amazon.com/gp/product/B07LGCY3RR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B07LGCY3RR/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)
Also note that the battery isolator depending on manufacture can have a 0.5 voltage drop; so, you may need to adjust the voltage regulator with it in the circuit.
WOW, thats a lot of info for one post. THANKS
I have a friend that buys a lot of govt surplus stuff and he has a rather large 24 to 120 converter that came from i think an ex police boat. He really has no use for it so offered it to me, might have to see about having a 24volt house battery bank. So i'll have some juice to keep the fridge cold running down the road. Then dropping some down to 12v for the few things that are 12volt. As far as i have ascertained the only 12v i need is for the lighting via LED, the water pump and to start the generators. I only have the bus alternator at 24V for charging at the moment.
Whoever did most of the work did a descent enough job for the most part. There are just some things that leave you wondering though. I was just out poking around on it. The one wire on the negative with the switch runs the length of the bus only to be capped off in the rearmost bay. Thats one figured out...no idea what the deal was with that but whatever. Generators started, seems that the pesky automatic choke mechanisms are not so great. Little shot of ether and they both fired right off. It has a pair of 5500w gas rv gen sets in half of the front storage bay. Why 2?? You got me, not a clue. My guess is that it was a LOT cheaper than one larger diesel generator.
Quote from: richard5933 on May 06, 2020, 11:23:19 AM
Might be a good idea to invest in a hydraulic cable crimper and a few sizes of copper lugs - then you can start making your own cables as needed. I found quickly that having to order cables every time I wanted to move something around got old (and expensive) quickly.
Yeah, you aren't kidding. For what they cost large battery cables ought be gold plated !!
Fortunately the 8 inch jumper i needed was cheap enough at the place i order my dump truck parts.
A Vanner is battery equalizer and will keep the batteries equal that bus should have one some place for the head lamps unless the PO design his own system People leave the system 24v and will draw 12v from the Vanner which is not a good idea even though it has a 12v terminal.you have work ahead of you trying to figure that one out for sure
What kind of juice is the vanner drawing?? Any chance that wire running up the the 10 amp circuit breaker runs to it or are we talking a lot more capacity?? Just looked all over the place and see no vanner, but also don't see much monkeying with the stock wiring, which is good.
Welcome to the world of owing a bus. This is one of a small handful of site with lots of real world expertise so make sure to bookmark and visit often.Quote from: luvrbus on May 06, 2020, 12:32:20 PM
A Vanner is battery equalizer and will keep the batteries equal that bus should have one some place for the head lamps unless the PO design his own system People leave the system 24v and will draw 12v from the Vanner which is not a good idea even though it has a 12v terminal.you have work ahead of you trying to figure that one out for sure
BW, I probably misread your comment about how to connect and use a battery equalizer like a Vanner 24v to 12v unit. Isn't the purpose to step down the voltage in a way that keeps the 24v source in balance, use the 12v output terminal to feed 12v devices in the bus?
It is probably better to think of a battery equalizer as a device that keeps the batteries equal, not so much as supplying power for other things.
You take the power from one of the 2 batteries in a 24 volt set, a centre tap.
The equalizer works at correcting that imbalanced theivery, with it being connected to both sides of both batteries, by working the stronger battery to bring the weaker one up to match it.
A 24 to 12 volt converter is going to work both batteries at the same time to provide a separate 12 volt power source. It isn't connected to the centre of the 24 volt battery set, and cares not the health or balance of the batteries. It just consumes 24 volts from the whole set.
If a converter dies, no more 12 volts
If an equalizer dies, you still have power, but will eventually have battery life problems, because of imbalanced charging and discharge. IF you don't do any periodic inspection of your electrical, which is always a busnut problem...
The multimeter will quickly show you your batteries aren't equal, if you bother to check once in a while. Equalizer operation is pretty simple, the 12 v connection should be exactly half of the 24 v connection.
With led lighting now, most conversions are using a fraction of the power we did a few short years ago, with incandescent bulbs burning everywhere, so the 12 volt loads are historically much smaller than they used to be. I don't think most users need a dedicated 12 volt power supply, an equalizer and centre tap takes care of business?
Happy coaching!
Buswarrior
Some people try to pull all the 12v from stud 55 or is it 59 on a MCI and they make it work not great but it works for some
On our 89 96A3, the Vanner is in the battery bay just above the batteries.
It appears as though your bus either had the Vanner removed or it never had one.
In your picture the circled wire on the right, the wire with the yellow sleeve sticking out of the insulation that is attached to the Jumper between the batteries is most likely the 12 volt feed for the bus, it should run across to the AC breaker/connection box that is on the top front of the first bay on the driver's side, from there it runs to stud 55 in the connection panel under the driver's window, supplying the bus with 12 volts.
On our bus that wire runs to an on/off switch and then to the 12 volt connection on the Vanner that is connected to the batteries.
The circled middle wire with the switch on your bus, appears to be the wire that on our bus goes into the curb side of the front bay and goes to a 24 volt to 110 converter mounted on the top of the bay, this 24 to 110 converter appears to be original to bus from MCI.
I have no idea what the circled wire on the left does, a breaker protected ground wire?
The clearance lights on ours are 24 volt and come on with the same switch that turns the headlights on.
The wiring for them ran up along the overhead bins, I accidently ripped it out when I ripped out the overhead bins and had to replace it, possibly the same issue occurred and they were rewired differently on your bus.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.peterbylt.com%2Fmci96a3%2FBatteries.jpg&hash=52f3f5ea98275de11924495426036b9ba59547b5)
Peter
What's the starter voltage for the generators? If 12V then have a separate generator battery that doubles as the house 12V feed. You would keep it topped off with the battery isolator -> 24V to 12V DC to DC converter.
If you go with a 24V house bank because of the inverter that it might be time to add some solar!!!
You need to check out the flexibility of the inverter, it maybe so old that it is not a true sine wave inverter or it's standby power usage will be horrible.
Then you have decide lead-acid or Lithium Ion for your house batteries.
Some YouTube channels that you might want to watch are:
Beginning from this Morning https://www.youtube.com/channel/UC-xTux7NNRrOTE_74WbU5cg (https://www.youtube.com/channel/UC-xTux7NNRrOTE_74WbU5cg)
DIY Solar Power with Will Prowse https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q (https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q)
DavidPoz https://www.youtube.com/channel/UCXJ7onrDcxo2zy8yAsxqwgg (https://www.youtube.com/channel/UCXJ7onrDcxo2zy8yAsxqwgg)
Bus Grease Monkey for his recent solar adventures https://www.youtube.com/channel/UCTeteRfN_uu-odJld157e6Q (https://www.youtube.com/channel/UCTeteRfN_uu-odJld157e6Q)
Finally had a chance to review the actual wiring of the Vanner Voltmaster 60-50 battery equalizer. It is wired per the diagram in the manual with one exception; the 12v tap is on the equalizer side rather than the battery side. Electrically the same except the manual shows fuses in the line and tapping on the battery side as stated here.
The way it is wired works the same except does not have the added protection of the fuse in case of power spike from the battery side hitting the equalizer. Not sure if I will modify as it has been serving for 20 years and seems to be working fine. That said, can't hurt so will put on the to do list. Thanks again.
Quote from: freds on May 07, 2020, 08:15:25 PM
What's the starter voltage for the generators? If 12V then have a separate generator battery that doubles as the house 12V feed. You would keep it topped off with the battery isolator -> 24V to 12V DC to DC converter.
If you go with a 24V house bank because of the inverter that it might be time to add some solar!!!
You need to check out the flexibility of the inverter, it maybe so old that it is not a true sine wave inverter or it's standby power usage will be horrible.
Then you have decide lead-acid or Lithium Ion for your house batteries.
Some YouTube channels that you might want to watch are:
Beginning from this Morning https://www.youtube.com/channel/UC-xTux7NNRrOTE_74WbU5cg (https://www.youtube.com/channel/UC-xTux7NNRrOTE_74WbU5cg)
DIY Solar Power with Will Prowse https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q (https://www.youtube.com/channel/UCoj6RxIAQq8kmJme-5dnN0Q)
DavidPoz https://www.youtube.com/channel/UCXJ7onrDcxo2zy8yAsxqwgg (https://www.youtube.com/channel/UCXJ7onrDcxo2zy8yAsxqwgg)
Bus Grease Monkey for his recent solar adventures https://www.youtube.com/channel/UCTeteRfN_uu-odJld157e6Q (https://www.youtube.com/channel/UCTeteRfN_uu-odJld157e6Q)
Thanks for the info. The starters on the gen sets are 12v. The inverter is supposedly newer and was running computers and whatnot in its previous install so i believe ( haven't personally checked yet) that its plenty clean enough power for the house items i intend to power with it. Lots of other stuff to be dealt with before i go all hog wild on solar. Mechanical work to do, rust repairs etc. Just trying to get a basic handle on things so i can have things powered up reliably to get everything working as it should.
Quote from: peterbylt on May 07, 2020, 03:21:50 PM
On our 89 96A3, the Vanner is in the battery bay just above the batteries.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.peterbylt.com%2Fmci96a3%2FBatteries.jpg&hash=52f3f5ea98275de11924495426036b9ba59547b5)
Peter
Thanks for the great pic. LOVE your conversion by the way, very well documented. I'm quite positive that " breaker protected ground wire" is very much in the wrong spot, not sure just yet where the right spot is but its been removed till i figure that out.
Nothing wrong with putting a breaker on the ground side as long as it's large enough to handle the full load.
Jim
Quote from: Jim Blackwood on May 12, 2020, 09:02:55 AM
Nothing wrong with putting a breaker on the ground side as long as it's large enough to handle the full load.
Jim
But MCI didn't do it like that. The cable is attached to wrong place, and has to be confirmed for function before choosing which post to re-attach to.
Happy coaching!
Buswarrior
I don't disagree. But still there's nothing inherently wrong with it being there. I'd still want a breaker or disconnect on the positive side but maybe that's just me.
Jim