Submitted: Thursday, Dec 16, 2004 at 20:16
ThreadID: 121650 Views:3294 Replies:0 FollowUps:0
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Kind Regards to all,
More on technical planning....

Some people are still interested in putting on large battery cable and 175 amp plugs on Tow Vehicles like Fords and Toyotas, and because we will not do it, they are seeking this modification from others... Be warned of the following summary of our own experience and why we will not do the 175 amp electric forklift connection with large battery cables. Never mind that the Alternator will sense the vehicle batteries as an average voltage between them and the caravan batteries and continue charging a high output pushing the vehicle batteries too high as it struggles to charge the lower potential voltage as combined with the caravan.. You see, it will read the average potential of all the batteries together and charge accordingly.. OK, so go up a notch in money and put in a directional electronic device (they make them) that could top of the tow vehicles batteries one and two first, and then direct all of the charge back to your van.. The real problem is the next weakest link: You would grossly shorten the life of the Alternator. It is designed with a heat sink and fan cooling for much shorter duty cycles on full output than you would be loading it up for. It is designed for maximum output in short time intervals, as the regulator cuts it back proportionally as the voltage rises on the batteries, which is nearly immediately in each of the vehicles batteries. You hook it up to 500 amp hours of batteries, and you will fry the alternator. Maybe not this week or month, but it will cook itself regularly. I have personally cooked a half dozen alternators in Fords and Toyotas trying to beat this problem. Not to mention the cost of that size of battery cable that would have to run full length of truck and van, in both positive and negative as you cannot use the chassis ground.. Even with money no object, the normal three batteries in the caravan are only supposed to be charged at a maximum of 50 amps before you need temperature sensors to cut back the charge as they heat up. Never mind the cost of 200 amp circuit breakers on each end to protect the cable from chaffing through on the corrugation to a massive electrical fire Never mind that 175 amps is enough to kill someone. (Yes in DC too, trust me). We are not going to do some crazy things that are fraught with disaster. We are not doing this. But YES,there is someone out there doing it successfully, read on:

IN CASE YOU HEAR ABOUT IT THROUGH THE GRAPEVINE, it has been done, someone showed up here with a 175 amp plug on the tow vehicle and van, and is successfully charging all batteries. BUT, he has a Custom continuous duty alternator built into the engine compartment on custom mounts, and it is a MONSTER.... You do not want to even know what that cost of it with an inch wide serpentine belt drive system.... It is an alternator about three times the size of the normal alternator with a dedicated fan drive unit on the back. WOW, He has accomplished the engineering of massive alternator input, but also at an enormous cost. He has even beaten the over heating of normal batteries as he has also installed massive batteries to take that kind of massive charge, at a couple of hundred kilos, and most people could not afford that kind of ridiculous weight... Yes his system will work, however, there are some serious problems, not the least of which is cost: We are probably talking about $8000, or more plus incredible time, and too much weight to be practical. Does it work, Yes! But think a minute about what he is doing, he would have to have the Worlds most expensive generator, running a $14,000 engine to charge his batteries? But when on the road yes it does the job. However, without the weight of huge Caterpillar sized 100kg batteries, he would have to have temperature probes to keep from cooking the smaller practical sized batteries that are weight efficient to carry. He has done the engineering properly and it will work just fine, but most people cannot afford the cost or the weight involved. This is a very fine example of how to do it properly if money and weight are not an issue as in a very large Cruising Yacht. And yes I have successfully done it myself with a 3.5kw Alternator of about 100 lbs, and double belt drive to the diesel in the yacht with an electric clutch, at huge expense and charging three 150lb 8-D yacht batteries. But that was thirty year ago engineering. Is it right now? No not for most people and why we will not do it: From an Engineering perspective, this is dinosaur engineering, not cost effective and too heavy for road transport. And when he is not traveling, he is running the Worlds most expensive diesel generator as he runs his $14,000 Ford engine four hours at a time to charge up the batteries while he sits still. (It's OK, he is not on the internet or computer literate, and probably won't take offence if someone tells him what I have said, as I have already done it myself in person, and he is now on solar for all the right reasons.) Probably the worst thing you can do to a diesel is run it unloaded for long periods of time… I won’t get into glazing of cylinder walls and such, trust me it is terrible on your engine. Enough solar even puts in power in the dark days of constant rain and much more environmentally friendly and quiet and efficient... I get one amp in a full moon with four panels, and have seen 3.5 amps on a dark rainy day with clouds so thick you could not tell what direction the sun was in. In short, you might get away with such wild engineering, but overall it is fraught with disaster so we will decline to do it for you and we discourage anyone from attempting... We may at times be unpopular as we don't tell people what they want to hear, but we do make an honest effort to take care of people and tell them what they need to hear...

If you were trying to do this with a normal Ford or Toyota alternator, it would be like trying to hook up a beer wagon to a Shetland pony and lighting the beer wagon on fire to try to win the race.. It will get going, but not for very long.. Thank me for holding you back from the edge. Ha!

If you are sick of me already on the BOG site, take heart, when things get busy I will not have the time. This is just a traditionally slow time of the year for me with enquires as people turn their attention to Christmas; and since I am new in participation on the BOG Forum, I am loading it with useful tips and help documents... Ha!

Happy Trails in the words of Roy Rogers,
stg at Bushtracker
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