Author |
Message |
ChuckS (66.167.143.231)
Rating: Votes: 2 (Vote!) | Posted on Saturday, October 04, 2003 - 3:46 pm: | |
So, I'm considering an MC7 with dead 8D's. It's currently nowhere near AC to enable charging. What are the options? - Can a 24v system be jump started with a car? - If so, would it risk destroying my little Honda with a 4cyl? - Get the seller to buy new batts just to crank the bus? (yeah, right) - ??? I've looked into past posts, but haven't found a similar situation, but then again, I didn't wade through boatloads of posts on batteries. TIA, Chuck |
jim mci-9 (209.240.198.60)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 3:50 pm: | |
i don't think a honda will jump the bus off....but all it takes is a couple of used 12 volt bateries.... maybe 12-15$ each... they dont have to be 8d's...if the engine has been recently run... like the last month or so, it ought to start easily...make sure it has full fuel filters before you start trying....i use 2 group 31 12 volt 550 amp batteries on my mci-9... |
Frank Allen (152.163.252.163)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 3:52 pm: | |
you cannot jump a 24 v system with 12 volts, id get the present owner to strt it for you , he could call a mobile tow co they usually have a big jump strt system, i wouldnt buy one without driving it at highway speeds Frank Allen 4106 |
two dogs (67.30.23.24)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 3:52 pm: | |
try getting two 12 volt batteries (not hooked up to a car) hook them in series to make 24 volts |
John Feld (150.199.209.33)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 5:27 pm: | |
I would not buy a bus that isn't running. If you want to pursue this bus, remove the batties and take them to an AC outlet to charge them. Run the bus on the road before you buy it, unless your getting a real steal. Or, as has been suggested, use two 12 V. to make 24V to start it. John 4104 |
ChuckS (66.167.143.231)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 6:07 pm: | |
Thanks all for the advice - don't worry, I wouldn't consider it without driving/checking out. I have two more questions I'll ask in separate threads. --Chuck |
Peter E (Sdibaja) (64.165.10.27)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 6:35 pm: | |
you can jump ONE of the 8D's with your car, that will probably make it start... if not, try jumping the other 8D... if that does not work, then get a second car with jumpers to jump one, you jump the other been there, done that, works fine. |
ChuckS (66.167.143.231)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 7:29 pm: | |
Ok, Peter, just to be sure I'm not too cornfused about this. you can jump ONE of the 8D's with your car, that will probably make it start... This one's easy - neg to neg, honda's positive to left battery's positive - ok so far? if not, try jumping the other 8D... So just move my two cables over to the right side battery, insuring the car's negative does not now touch the bus's frame - correct?
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ChuckS (66.167.143.231)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 7:34 pm: | |
Ok, Peter, just to be sure I'm not too cornfused about this. <i> you can jump ONE of the 8D's with your car, that will probably make it start...</i> This one's easy - neg to neg, honda's positive to left battery's positive - ok so far?<br> <i>if not, try jumping the other 8D...</i> So just move my two cables over to the right side battery, insuring the car's negative does not now touch the bus's frame - correct?
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Don KS/TX (66.82.9.27)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 7:49 pm: | |
Peter has it just right, no need to buy any batteries for the test. If one honda does not do it, get another. I have done it a number of times. Sometimes you can let the honda "charge" one battery for a while, then move to the other with the jumpers and get it going. I wasted lots of money on those darned 8d jobs until I got smart and put in a couple of Group 31 biggies, best move I made. |
John Feld (150.199.209.46)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 7:51 pm: | |
Chuck, you first have to determine IF the batteries will even take a charge. Do they have anything in them, or are they totally dead? Disconect each battery and use a test light, if nothing, use jumpers to one battery at a time for say 15 min and retest before spending to much time with them. Quickest solution would be two 12v car batteries to get the bus going and run on. John 4104 |
ChuckS (Chucks) (66.167.143.231)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 7:57 pm: | |
Champions all, you guys. Got it. I've done did elect work B4, both 120vac & 12vdc, but 24volts had me a little consternated! |
Craig Craddock (24.127.66.163)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 8:06 pm: | |
Do not hook your Honda 12 volt across the two bus batteries at one time, your cars entire electrical system will not like the 24 volts. You could ruin a lot of your electronics in the Honda. What I think Pete is saying. Is hook your car to only one 12 v bus battery with one set of jumper cables. Positive to positive and negative to negative. Then hook the spare 8D battery to the other bus battery only with another set of jumper cables. That way everything you are hooking up will only be 12 volts like your source. You will only be making parallel connections, that way you will not be mixing voltages. The bus batteries will still be in series giving you 24 volts to the bus starter when you hit the starter button. I have my doubts if the batteries are completely dead if this will give you enough amps through two sets of light duty cables. Wiggle all of the jumper cables connections for good contact. If the cables get hot or start smoking a little and it is not turning over good it is not going to work. Particularily if it has not been started in a while. As Frank Allen said a mobile truck tow company with heavy duty batteries and heavy duty cables will probably be your best bet. If you do not know what you are doing please understand the facts before trying this. Batteries have blown apart and the sulfuric acid has caused some serious personnal injuries. Like loss of eye sight and worse!!! I am not trying to scare you I just want you to understand. Be Careful and Good Luck |
Scott Whitney (66.82.9.25)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 8:20 pm: | |
Unless you are getting a real bargain, like a few thousand or less, I'd think it not at all unreasonable to ask the seller to replace the batteries before you look at the bus. Otherwise, depending on how far the bus is from your or the seller's house, might be easier to bring the batteries to the charger(s). That way you can charge each up over night and have them good and strong (assuming they are just dischared and not toast) If you do the jump start method with a car(s), set something on the gas peddle, or keep your foot on it to increase the RPMs. The voltage my go up a volt or two if you can increase it past idle speed a bit. Will make the charging a lot more effective and less time consuming. |
Don KS/TX (66.82.9.27)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 8:31 pm: | |
Craig made me feel bad for forgetting the safety cautions, merely assuming we all knew that. I had one blow up in my bus, not a pretty sight! |
ChuckS (Chucks) (66.167.143.231)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 8:34 pm: | |
Yup - I should make it the seller's problem! ;} BTW, posting images is quite an unusual experience on this board. FYI, you can't do it from a networked drive, only from local disk. Scott - I'm gonna be contacting you about a motosat, guy! Wish I could come to the rally... Thanks again, Gents. |
Peter E (Sdibaja) (64.165.10.27)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 04, 2003 - 10:28 pm: | |
ChuckS... if it is not crystal clear let me give it another shot Usually only one battery is stone dead, the other often has a bit of life, try one... then try the other You hook the jumpers from a 12 volt battery to another 12 volt battery, leave the bus cables alone, you are just jumping a battery (one of the two) if that does not get you going you get another car and another set of jumpers and jump the other battery at the same time! Simple? I think so, it works for me. use the same cautions you use when ever you jump a battery: hook positive to positive first, then negitive to dead battery, last you hook the other negitive to the frame of the running hot jumper car. the reason for all this is that batteries put off hydrogen gas, it goes pop sometimes... the last hookup can make a spark, that should not be near a battery... the dead battery often has just had a big load put on it and could have put off lots of gas. hydrogen gas is no big deal, but why take chances and have gimped up legs and scars like me? Peter E |
Tom Caffrey (Pvcces) (65.74.64.199)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 12:20 am: | |
One thing I don't think has been mentioned, here, Chuck. Most of the time jumping one battery at a time can work. But if one of the batteries is bad and one is good, you can get a surprise. If you connect to the bad one, you may not see any spark, but if you go hit the starter button on the coach, the good battery can overwhelm your car battery and charging system, causing it to reverse polarity. If that should happen, you can lose the alternator, regulator and maybe other eqipment, even if it only happens momentarily. This would be especially easy to have happen if you had a poor battery or a bad battery connection. Just so you know... Tom Caffrey PD4106-2576 Suncatcher |
Don KS/TX (66.82.9.34)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 9:21 am: | |
Are you sure? I never had that happen, and can't see how it even could. The "good" battery would only be 12 volts too. Or are you referring to the old "series-parallel" switches? |
Sam Sperbeck (206.230.105.248)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 9:25 am: | |
Hi Tom, I'm confused. How can hitting the start button on the coach cause the car battery to reverse polarity if the jumper cables are hooked up properly? Clarification please. Thanks, Sam sperbeck La Crescent, MN |
ChuckS (Chucks) (69.3.74.87)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 9:56 am: | |
Whew! And to think this is the _simplest_ thing I'll have to get into with a conversion! ;) OK, let's visit this one more time. I've taken up way too much of your time with this issue... If I was successful posting an image again, let's take this photo and work from that. Tom, you're saying that if I hook up to the right battery and it's bad, (tends to be an 'open' connection I suppose) that since I've connected the car's neg to the right battery's neg, and the car batt's positive to the rt. batt's positive, that the neg becomes positive from the bus's left battery, (again, if the right battery is 'bad') sends positive juice throughout the car backwards and comes back out into the bus, even if only for a millisecond. (long enough to fry the car's components) So this would essentially be like wiring the car in series between the left battery's positive and the bus's positive input backwards, as if the right battery weren't even there, correct? Am I getting close? Thanks again, folks - go have Sunday breakfast! |
John Feld (150.199.209.19)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 10:48 am: | |
Chuck, just do the simple thing, remove the jumper cable and put a charge on each battery. You need to clean the terminals anyway. Ten minutes of charge on each batt. and a 12V test light will let you know if the batteries are toast or not. John 4104 |
Scott Whitney (66.82.9.26)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 11:53 am: | |
I diagramed it out and am trying to understand Tom's warning. I am not an EE but have a basic understanding of electricity. My guess is that if/when this happens, it is not a polarity reversal to a complete 12v, but maybe just reverses polarity up to a volt or two? Seems like this could only happen with a small car battery and an alternator not putting out much current (like a Honda at idle???) What I am guessing is that when you jump one battery in a set of batteries that are wired in series, if one of those batteries is flat dead, you are, in a way, conecting the jump battery to two positive posts. But I am vague on how that becomes a reverse polarity and would be interested in more theory on the subject. Scott |
Stan (216.95.238.112)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 4:10 pm: | |
I will try and theorize the Honda car in series with the 8D. Let us assume you put jumper cables across the battery that is connected to the starter (with the 8D connected to ground). The 8D can source about 2000 amps into the starter which is almost a short circuit in DC resistance. If the Honda battery cannot source enough current to crank the engine or something is seized and can't turn then nothing happens except the cables get hot. When you have the Honda alternator tied across the Honda battery, you have the 8D positive post tied to the negative side of the alternator. If the current can't flow through the Honda battery, it will try to flow through the Honda alternator to ground, through the starter because the starter is just a short circuit to ground until it start to turn. This is the same as hooking up a booster battery to a car backwards and having bad things happen. Am I wrong on this? |
Mark R. Obtinario (Cowlitzcoach) (204.245.228.93)
Rating: N/A Votes: 0 (Vote!) | Posted on Sunday, October 05, 2003 - 8:57 pm: | |
Currently, NAPA has 8D batteries on sale for $118.00 a piece. At that price, it shouldn't be too much to expect to have the seller put in a set of new batteries. Mark O. |
Phil Dumpster (12.230.214.167)
Rating: N/A Votes: 0 (Vote!) | Posted on Monday, October 06, 2003 - 7:53 am: | |
I recently replaced the 8D side terminal batteries in my bus for $75.00 each. They were not new. Turns out the local transit agency has a deal with this particular battery supplier (Dyno) to provide batteries for the entire bus fleet. If a coach develops problems and discharges its batteries enough to where the coach won't start, they remove them and send them back to the distributor. They do not service their own batteries. They don't even attempt to jump-start a bus. If the bus won't start, they put in new batteries. The distributor then charges them, checks them thoroughly (load test, etc.), and offers them for sale to the public at half the price of new. Since not too many vehicles other than a transit bus uses the side terminal 8D, they end up converting most of them to top post. I was lucky that they just happenned to have a pair of side terminal batteries in stock. They were only 6 months old when returned and test out to an equivalent CCA of 1100 amps each. Perhaps you can find a similar deal in your locale. I had tried charging my old batteries over a four month period but all they would do is boil off whatever water I added and not hold enough of a charge to crank my pickup truck. If the batteries in that MCI have been sitting in a discharged state for more than 6 months, they are probably sulfated quite badly and will have too much internal resistance to take a charge. Unless you have something with a big battery and a huge alternator and industrial-strength jumper cables, you won't be able to jump start it using only a car if the batteries won't take a charge. |
smoky (12.222.48.5)
Rating: N/A Votes: 0 (Vote!) | Posted on Monday, October 06, 2003 - 8:12 pm: | |
I would not use a honda to jump start anything except in a emergency. some honda reman alts are upwards of 300 bucks they have a very senstive diode bridge that will be damaged if over surged this happens when the alt is at full field and jumpers are disconected suddenly you have 60 amps with no where to go ZAP! Also if the bus batterys are shorted you'll blow your diodes as soon as jumpers are connected. Smoky, |
Don KS/TX (66.82.9.37)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 10:12 am: | |
Thanks for the heads up on Hondas, I suppose the owners manual probably prohibits jump starting with a Honda too? Not all cars are that way, some can take the punishment apparently, they allow it while under warranty, so I guess they are confident it will work without tearing anything up. |
ChuckS (Chucks) (66.167.165.139)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 12:55 pm: | |
To all - again, thank you for your instructive experience. Probably like most things in this busworld, what seemed like a simple question has been the source for much lurnin & consternation! ;) Thanks to your comments, I will _not_ be hooking my Accord to dat bus and will let the current owner figgur it out. (and I will be standing far in the background when he does hook it up! ;) There's so much to be aware of in every aspect of ths busworld! --Chuck |
Johnny (67.242.221.170)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 9:09 pm: | |
"I would not use a honda to jump start anything except in a emergency. some honda reman alts are upwards of 300 bucks they have a very senstive diode bridge that will be damaged if over surged this happens when the alt is at full field and jumpers are disconected suddenly you have 60 amps with no where to go ZAP!" If this is true, that's one of the most inexcusable engineering defects I've ever seen. each wrecker at work has probably jump-started at least 2000 vehicles (even the 2001 F-550 has probably done close to 3-400). The ONLY trucks without the factory alternators are a 1972 F-800 & a 1974 GMC--and the GMC was only replaced because the old one wasn't powerful enough. Three other trucks, ranging in age from 11 to 18 years in service, all with the factory alternators, which are big enough to light up a small town (well, not really...but all are well over 100 amps). And now, I'm sure we'll lose at least one alternator in the next 2 weeks. $300 for an alternator is insane (and one of the many reasons I won't own a Honda)...I can get one (NEW, not a reman) strong enough to run a welder for less than that. |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 9:52 pm: | |
I'm still trying to figure out how jumping anything with anything looks like anything but a short, like a tire Iron across the terminals. I don't buy the "60A and nowhere to go" bit. Current is a measurement of demand, not a measurement of supply. that's right up there with "It's not the volts that kills ya, it's the amps". I can imagine numerous ways to turn Honda Diodes to junk though.... In the case of jumping an 8D while another was still in Parallel...I need to draw it out....Wait a minute.....I think Tom's right in one sense, when 2 - 8D's are in series for a total of 24v, the negative side of one battery is connected to the positive side of the other. As soon as you place a load, and if you only have one 12v battery in a 24V system, almost any load will look like a short. Viola, reversed polarity, sure enough. I'll be dammned. Gary |
Don KS/TX (66.82.9.48)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 10:41 pm: | |
Now all you got to do Gary, is to explain why it never does it in real life! Have I just been so lucky all these years? Have other people been so lucky too? Could be, I still don't think so. I will volunteer my 12v Lumina to jump anybody with a dead 24v bus, with no fear - yet. (If I can explode tires with ether onto rims, I can sure jump start a 24v bus.) Stubborn bastard, aren't I? |
Don KS/TX (66.82.9.48)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 10:44 pm: | |
I have also jump started the 12v toad when I forgot to turn stuff off. Just push it up to the 24v bus and hook on and crank up. Suppose you will tell me I can't do that either? |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 11:04 pm: | |
If you go back and read what Tom originally said (I had to): "Most of the time jumping one battery at a time can work. But if one of the batteries is bad and one is good, you can get a surprise. If you connect to the bad one, you may not see any spark, but if you go hit the starter button on the coach, the good battery can overwhelm your car battery and charging system, causing it to reverse polarity. " In order for the Phenomenon that Tom is describing to occur, three criteria must be met. 1) Only one battery is dead 2) you are jumping the dead one 3) the other is fully charged It didn't make sense to me either until I drew it on paper. Gary |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 11:20 pm: | |
Oh, and the toad probably starts REEAL GOOD on 24v! or if you were just starting across one battery it would start normally. the problem is when there's NO juice in the one you're jumping, and you hit the starter in the coach. Gary |
ChuckS (Chucks) (69.3.75.132)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 11:27 pm: | |
"... I will volunteer my 12v Lumina to jump anybody with a dead 24v bus, with no fear..." You're on, Don. Come on over if you're in TX this week. I'll be in FtWorth with a video crew to share the event with this board. --c |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A Votes: 0 (Vote!) | Posted on Tuesday, October 07, 2003 - 11:42 pm: | |
In order for this to be a valid experiment, you need one real dead 8D and one real good one ;-) What the hell, It's a lumina for crying out loud... Gary |
Don KS/TX (66.82.9.42)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 7:03 am: | |
Chuck, as a matter of fact, I WILL be in Ft Worth this week with the Lumina! As Gary indicates, I don't have much to lose, can you get the cameras on such short notice? I never tried it on the toad, but we used to start the old stubborn 6 volt stuff routinely with a 12v jump, as you say, it spins it pretty good, I never burned up a starter either. I think I can agree and see the possibility of car/bus jumping causing a problem with the just right and not at all normal situation you described. Hope I have a chance to try it on some old junker some time when I have plenty of spare alternators laying around. |
Richard Bowyer (Drivingmisslazy) (24.196.191.70)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 9:38 am: | |
I used to run sand buggies in the desert and we all had 12 volt sytems with a 6 volt starter (VW's) and in all the years I did this, I never experienced or knew anyone that did experience a failure of the 6 volt starter. It does crank the engine fast for a fast start. If anyone is going to jump a 12 toad with a 24 volt system then they should be sure the radio and lights and anything else electrical are turned off. Richard |
mel 4104 (208.181.100.48)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 11:45 am: | |
wellows if you want to start a 6 volt car with a 12v system it will work but be sure that the veh. does not have a computor system on it as if you have you will spend a lot of money for a new board. as with a vw they still have points in them and not much else to cook and as richard says be sure that every thing else is torned off. also i think that the reason that batteries blow up is they have a very resistance in them and when you hook up the jumper cables the point of higest resistance will arc [ cause sparks to fly] and if there is any hydergine gas either on the top when hooking up jumpers or in the battery if there is a very high resistance inside the battry caused by many things such as sulphating , plates shorting ,etc, be sure that you hook up the jumper cablesthe right way as this causes masive arcing. if you have ever had an 8d blow up you will know that you never want it again. at the time i was 18 and smart but when i screwed up and the battery blew the battery box and fender of the truck i will admit that i was one very stupid kid. donot hook them up wrong any more. mel 4104 |
Jack Conrad (Jackconrad) (207.30.189.109)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 5:09 pm: | |
We used to use 12 volts al the time to spin a 6 volt starter, but I am not sure I would want to try using 24 volts to jump a late model 12 volt car with all the electronics they have on them. It might fry a computer, senser, etc. Jack |
Sam Sperbeck (206.230.105.248)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 5:15 pm: | |
Hi Gary, I know this is beating a dead horse, but getting back to your post about the possibility of getting reverse polarity when jumping a 24 volt bus with a 12 volt car you state that it could happen if: 1) Only one battery is dead. 2) You are jumping the dead one. 3) The other is fully charged. First question is how can you have one dead battery and one fully charged battery? Numerious people have said that the dead battery will pull down the charged battery if the dead battery is shorted. If the dead battery has no continuity then the fully charged battery won't be drawn down but then the car battery simply replaces the dead battery by being hooked up through jumper cables in series with the fully charged battery and it seems to me you would have a normal 24 volt arrangement. In either case I can't see a reverse polarity situation. It is too bad the person who posted this reverse polarity theory didn't come back and explain himself when I asked for clarification. Perhaps this is a situation like one of my wife's friends response when I questioned her about an illogical statement on religion. She said "To those who beleive no explanation is needed, to those who don't believe no explanation is possibly". And as Forest Gump would say, thats all I'm going to say about that. (Religion) Thanks Sam Sperbeck La crescent, MN |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 5:56 pm: | |
Hey Sam, You can have one good battery and one bad if one was older than the other or just some condition existed that did not exist for the other. If one battery was completely sulfated out, it would have infinite (Or Nearly so) resistance, looking like an open, and of course it would have no charge. at that point, your positive jumper is connected to the Negative side of the other battery, the Positive side is connected to the starter Relay/Solenoid. Let's say the 24V Starter draws ~500A (I don't know the Starter's requirements but I imagine it's about ~500A). You're batteries now, When you hit the Starter, you have an 1300Amp supply (The 8D) in Series with a Honda with a 450A supply. since the current load of the DD starter exceeds that cranking amps of the Honda battery (Remember, it's in Series), the starter acts as a short circuit, or....A wire running from the positive side of the 8D, to the Negative side of the jumper cable. Boom! I agree with you about people looking at electricity as a religion. I'm not one of them. Gary |
jim mci-9 (209.240.198.60)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 6:56 pm: | |
when i worked for united engines.... the dd dealer in shreveport, we would jump a 12volt truck off with 24 volts... series 60's...no problems... it would not hurt the computer....all it did was spin the engine faster.... we did this when we were having trouble getting an engine to start... lost prime... fuel problems...its not for an everyday thing, but once in a while wont hurt anything....its a 2-man operation.... as soon as the truck started, we'd unplug the jumper....we used 1 of those roll-around booster machines...most of the computers are designed to work on multiple voltages... dd's shut down at 4vdc....cats at 4vdc...but will operate at up to 40vdc....been there, done that, seen it... |
Don KS/TX (66.82.9.26)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 7:09 pm: | |
Darn it Sam, now I lost my faith in Gary's explanation, now I think YOU are right. I have to agree, I have never seen a dead open circuit battery and a good one, but lets say it exists. What you say is right, ALL YOU ARE DOING is substituting the car battery for the open dead one. If we follow that to conclusion, then everytime we start a 24v bus we should blow up one of the batteries! Your turn Gary. |
ChuckS (Chucks) (66.167.143.61)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 7:52 pm: | |
This thread is getting somewhat maniacal! (and probably somewhat academic at this point) Do I get a prize for the longest thread started by a newbie? Maybe a gallon of Amsoil or sumthin? ;) BTW, I ain't gonna thank you again for the advice on this post - I've done that 4-5 times already - you're on your own now! For entertainment value, it's a close tie with Dukes of Hazzard or somethin. |
Johnny (67.241.224.248)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 8:34 pm: | |
Here's a safe idea: pull the ground cable from the bus. Then, hook jumpers from the car to the batteries, one at a time. Charge them off the car, pull the jumpers, hook up the ground, & start the bus. I've seen 6V starters on vintage cars (street rods with Ford flatties) run for years on 12V without problems. |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 8:35 pm: | |
Hey Don, maybe you didn't see my post right after Sam's. I think I explained it OK...Let me know what doesn't make sense. the key to remember is that the Battery isn't in Parallel, it's in Series. It was Tom who brought up the "Reverse Polarity" thing, and I wasn't going to say a thing until I read Johnny's post and I had to diagram the whole thing out. I'm pretty much in agreement with Johnny, jumping something shouldn't kill the alt. There is a point where the Battery might detonate though. This is the thread that won't die though. I have, Many, many times seen one battery in an array go out. Especially in house battery setups. Chuck--the message I got in my inbox has more stuff than is on the post--did you go back and edit? Just wondering. Gary |
Gary McFarland (Gearheadgary) (209.128.99.4)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 8:38 pm: | |
Hey Johnny, I think we've long since departed from any pragmatic problem-solving and entered a realm of theoretical busology. Gary |
ChuckS (Chucks) (69.3.74.58)
Rating: N/A Votes: 0 (Vote!) | Posted on Wednesday, October 08, 2003 - 11:35 pm: | |
T H I S T H R E A D O F F I C I A L L Y C L O S E D ! Gary - yes I did edit my previous post but realized I was just adding fuel to the fire with more of the same words in different order yet again. ;) t h a n k s a g a i n , f o l k s ! |
Tom Caffrey (Pvcces) (65.74.64.199)
Rating: N/A Votes: 0 (Vote!) | Posted on Thursday, October 09, 2003 - 12:02 am: | |
Thanks for your clarification, Gary. And I've never seen a starter ruined by high voltage, only low voltage. Then, it happens easily enough. If batteries need help starting an engine, connecting to a higher voltage source just during the cranking shouldn't hurt anything. But, if batteries are down to where you can't crank the engine, the hazards increase, as I think this thread has done a good job of pointing out. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher |
Mike Eades (Mike4905) (206.148.132.112)
Rating: N/A Votes: 0 (Vote!) | Posted on Saturday, October 25, 2003 - 8:08 pm: | |
Chuck Go get a load tester at NAPA. Unhook the batteries and check them. If you have batteries worth working with R & Charge them and then put them back in and start the bus. But be wise and let the seller worry about getting it started for you. Mike |