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Car Forum / Ford / Ford Trucks / January 2007Charging a 3rd battery from the alternator
I've recently installed a 12V 100 AH AGM deep cycle battery in one of the storage lockers of my 2001 F-550 7.3L PSD truck. The purpose of the battery is to power small tools and appliances (read coolers and boom boxes), and recharge tool batteries when we're in out-of-the-way places where there is no "shore power" available. Right now I'm charging this battery from house power overnight. It's desirable that I be able to recharge directly from the (original equipment) truck alternator when we'retraveling. A friend of mine (ex-Army) who is knowledgeable about medium duty trucks has looked at the alternator and advised that I should be able to safely connect the deep cycle battery to the truck starting batteries in parallel, with a "T-handle" disconnect switch in the circuit to separate the deep cycle battery from the truck batteries when we're using it. I'm still concerned about possibly overloading the alternator and possible complications with direct-connecting a deep-cycle battery in parallel with dissimilar 12V starting batteries. Any suggestions, comments or cautions would be appreciated. Regards, John Kinney There shouldn't be any problem. Assuming you don't wire it with 00 welding cable, the resistance of the connecting cable will limit the current to the battery. You'll probably use at least 10 ft of wire so say, #4 should be about right. You might consider a battery interconnect solenoid (looks just like a starter solenoid but with a continuous duty coil) instead of the T-handle. Connect the coil to an ignition-hot circuit so that it energizes and connects the battery to the truck electrical system whenever the ignition is on. That way the battery is always charged and if you leave your lights on and run down the main battery, the aux battery is available to jump with. John >I've recently installed a 12V 100 AH AGM deep cycle battery in one of the >storage lockers of my 2001 F-550 7.3L PSD truck. The purpose of the [quoted text clipped - 19 lines] > >Regards, John Kinney --- John De Armond See my website for my current email address http://www.neon-john.com Cleveland, Occupied TN Don't let your schooling interfere with your education-Mark Twain > There shouldn't be any problem. Assuming you don't wire it with 00 > welding cable, the resistance of the connecting cable will limit the [quoted text clipped - 40 lines] > Cleveland, Occupied TN > Don't let your schooling interfere with your education-Mark Twain I like Johns answer to this only thing I would do different is run a minimum of #2 guage cable from the front to the rear battery. The only reason diesel engines are equipped with dual batteries is due to the large amount of power required to start the truck in the cold. There are alot of trucks out there with only one battery with diesel engines. You will be fine with that deep cycle. Ford Tech >> There shouldn't be any problem. Assuming you don't wire it with 00 >> welding cable, the resistance of the connecting cable will limit the [quoted text clipped - 49 lines] > >Ford Tech I have a different take on all of this. The poster stated that the purpose of the battery was to run tools not start vehicle. Because of this I would connect it to the altenator directly with a 12 ga wire and a in line 30 to 35 amp breaker (you can install a cutout switch too). The reason for this is that the 12 gas wire would limt charge rate due to wire resistance and therefor the load on charging system so that priority is given to charging vehicle battieres first. Also by limiting charge rate you would extend deep cycle battery life and a cutout switch (or pulling break) would let you isolate battery for truck and run it flat and not pull down truck batteries. On my plow trucks which are always gas powered I run dual batteries and power plow off of second battery and charge it with a 12 ga wire hooked to altentor output for same reason as it keeps battery topped off but keeps plow loads mostly off main system due to wire resistance tending to block big loads transfering back to main system and voltage on truck for accessory stays more stable too. ----------------- TheSnoMan.com > I have a different take on all of this. The poster stated that the > purpose of the battery was to run tools not start vehicle. Because of [quoted text clipped - 3 lines] > to wire resistance and therefor the load on charging system so that > priority is given to charging vehicle battieres first. Am I correct in assuming I would only have to run a single hot power cable front to back and simply connect the ground terminal on the deep-cycle battery directly to the truck chassis? Also, I got an email response from somebody who suggests a 2-battery isolator as an automatic way of making sure using the deep-cycle battery did not discharge the starter battery. Apparently the isolator does something to protect the generator. In a slightly more expensive way, that makes sense to me. I assume the 12 ga wire trick would also work in that arrangement for limiting charge rate to the deep-cycle? Regards, John Kinney >>I have a different take on all of this. The poster stated that the >>purpose of the battery was to run tools not start vehicle. Because of [quoted text clipped - 18 lines] > > Regards, John Kinney IMHO, if you take advice from SnoMan, you at risk. Get some GOOD advice. Lon >>>I have a different take on all of this. The poster stated that the >>>purpose of the battery was to run tools not start vehicle. Because of [quoted text clipped - 22 lines] > >Lon You are such a child Lon, A isolator can have a blocking diode setup that will let it charge while preventing discharge. If you want a no brainer but myslf I have been using a breaker cutout setup for many years. If something shorts out the breaker will pop and a single 12 ga wire can safely handle over 40 amps without heating issues (when it is in a sheath with other wires carry same load it can carry less power safely) I have put together a few charts on voltage drops in circuits and I have some for single wire feeds for SUV's and such that I need to get posted sometimes. If you look at the chart in link below it covers extention cord voltage drop which will show you the voltage drop with distance under load and you will see how as load increases at a given distance so does voltage drop and since charge rate it limited or controlled by applied voltage vs internal battery resistance in it current state the drop in the feed circuit will limit charge rate to battery. Basically all battery now are low maintaince (they have calcium in plates to limit gassing which also raises voltages a bits) so no need to disconnect when sitting overnight or for a few days. There can be a problem with old stlye non low maintainance batteies and new low maintanance ones because the old style would tend to discharge the new style a bit due to differing voltage requirements for charge. YOu can also connect negative on battery to chassis ground so that one wire is all that is needed. http://forum.snoman.com/viewtopic.php?t=254 ----------------- TheSnoMan.com I ran a spare battery in a Dodge van for many years. It was inside. behind the seats, connected with a piece of RG-8 to a starter solenoid and then to the regular battery. No, the starter solenoid worked great, it did not overheat, etc. Yes, the battery charged up and lasted darn near forever, powering a quantity of radios and gadgets. I produced more gas than it did. I never used it to start the engine as the engine battery never failed. It was a great system that worked perfectly for many years. Steve > There shouldn't be any problem. Assuming you don't wire it with 00 > welding cable, the resistance of the connecting cable will limit the [quoted text clipped - 8 lines] > and if you leave your lights on and run down the main battery, the aux > battery is available to jump with. It's not that hard to do it right. Go to your local RV parts house and get a battery isolater. It wires in to the charge circuit, has three terminals, one terminal is the main fed from the alternator, continuing on to the normal circuits. The second terminal feeds the spare battery. when the engine is running, and the third terminal is a switrched battery feed. when the ignition switch is off, the spare battery is "isolated" from the others so you dont have to worry about accidently draining your starting battery. Thy come with very clear wiring instructions. Whitelightning > It's not that hard to do it right. Go to your local RV parts house and get > a battery isolater. It wires in to the charge circuit, has three terminals, [quoted text clipped - 6 lines] > > Whitelightning Agreed. A battery isolator is what you want. Don't listen to the Snowblower, his bad advice (on many topics) will get someone killed.  SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 28 days 21:29 >Agreed. A battery isolator is what you want. Don't listen to the >Snowblower, his bad advice (on many topics) will get someone killed. You know the wise man avoids the advise of name callers because it shows inmaturity of responce as does the anominity of your posts as well also show lack of accountablity. I do not hide at all. Never take advise for someone that is mere smoke in the wind. ----------------- TheSnoMan.com Anonimity? You don't see his sig or something? I notice you snipped it out.... Ask him what he does for a living and then you'll know he's more than qualified to make determinations about battery isolators or anything else that has to do with the flow, management and utilization of electrons... Remember, no one ever learned anything by telling everyone what he thinks he knows. >>Agreed. A battery isolator is what you want. Don't listen to the >>Snowblower, his bad advice (on many topics) will get someone killed. [quoted text clipped - 5 lines] > ----------------- > TheSnoMan.com > You know the wise man avoids the advise of name callers because it > shows inmaturity of responce as does the anominity of your posts as > well also show lack of accountablity. I do not hide at all. Never take > advise for someone that is mere smoke in the wind. A wise man knows that he must present himself well if he intends to be taken seriously. Perhaps you could consider using a spell checker, and in longer posts, the <Enter> key. > There shouldn't be any problem. Assuming you don't wire it with 00 > welding cable, the resistance of the connecting cable will limit the [quoted text clipped - 8 lines] > if you leave your lights on and run down the main battery, the aux > battery is available to jump with. I discussed this and some other suggestions with my friend and he agrees that a solenoid arrangement is a good idea if I can get the parts at a reasonable cost. He also says that battery isolators will work, but apparently all of them seriously limit the charge that the alternator will pass on to the deep-cycle battery. I checked this with several sources on the Internet and it appears to be true. He agrees that if I'm only using the connecting wiring to charge the battery, that #4 wire should work. I looked up the F-550 alternator, which appears to be rated at 12V 105A. I haven't measured exactly how far I have to run, but 10-12 feet seems about right. Now I gotta go figure out solenoids! Regards, John Kinney >>On Sun, 07 Jan 2007 03:14:06 -0500, Neon John wrote: >>Connect the coil to an ignition-hot circuit so that it >> energizes and connects the battery to the truck electrical system >> whenever the ignition is on. That way the battery is always charged and >> if you leave your lights on and run down the main battery, the aux >> battery is available to jump with. That's the usual setup. >I discussed this and some other suggestions with my friend and he agrees >that a solenoid arrangement is a good idea if I can get the parts at a >reasonable cost. The solenoid you are looking for, looks like a starter solenoid, BUT must be desigated as a "continuous duty" solenoid. Readily available at any auto or RV parts outlet for less than $20. > He also says that battery isolators will work, but >apparently all of them seriously limit the charge that the alternator will >pass on to the deep-cycle battery. True. > He agrees that if I'm only >using the connecting wiring to charge the battery, that #4 wire should >work. I looked up the F-550 alternator, which appears to be rated at 12V >105A. I haven't measured exactly how far I have to run, but 10-12 feet >seems about right. Sounds good. Not to worry about overloading the alternator: They are thermally regulated. If they get overheated, the regulator reduces the output voltage (and consequently, current output) to compensate. the alternator circuit will typically start up at around 14.2 to 14.5 volts when the engine is cold. As it gets warmed up, the output voltage will be reduced to somewhere between 13.2 and 13.8 volts. >I discussed this and some other suggestions with my friend and he agrees >that a solenoid arrangement is a good idea if I can get the parts at a [quoted text clipped - 8 lines] > >Now I gotta go figure out solenoids! Everything you need to know. http://www.neon-john.com/RV/Electrical/rv_battery_isolation_relays.htm You can get the solenoid at NAPA for under $20 even if you get the sucker-just-walked-in-off-the-street price column. Camping world sells it for about $14 last time I looked. Our local RV dealer gets $11. John --- John De Armond See my website for my current email address http://www.neon-john.com Cleveland, Occupied TN Don't let your schooling interfere with your education-Mark Twain > You can get the solenoid at NAPA for under $20 even if you get the > sucker-just-walked-in-off-the-street price column. Camping world sells > it for about $14 last time I looked. Our local RV dealer gets $11. Hmmm... Was *I* surprised earlier this week when the local NAPA store wanted more than $50 for the ST85 solenoid and then couldn't tell me whether it was a starting type or continuous duty type! So I went to the NAPA website, struggled through their multiple search choices, and found the ST85 for which they wanted $48.99 plus shipping! I also discovered that it was listed only as a starting type solenoid. There is another starting type solenoid (ST95) listed for about $28. No specs are provided for either; the apparent physical difference is that the ST95 has 3 connectors and the ST85 has 4 connectors. So I did a search of the Camping World website and found one battery isolator listed and no solenoids. My local RV dealer gave me a sort of blank stare when I asked him about solenoids and offered to sell me a battery isolator. So, the plot thickens... Can anybody tell me if a NAPA ST85 solenoid is rated for continuous service? I hate to spend $50 for something that's going to burn up. Is there another similar or hopefully less expensive solenoid available that will do the job of isolating a vehicle starting battery from a deep cycle battery in a 12V system? Otherwise, what am I missing? TIA and best regards, John Kinney >> You can get the solenoid at NAPA for under $20 even if you get the >> sucker-just-walked-in-off-the-street price column. Camping world sells [quoted text clipped - 26 lines] > > TIA and best regards, John Kinney Is this what you're looking for? http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?xi=xi&ItemId=1611784830 Max http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?xi=xi&ItemId=1611784830 Max, Thanks, that's just what I was looking for, too. SignatureJerryD(upstateNY) > Thanks, that's just what I was looking for, too.<<<<<<<<< I found out I can't buy from Grainger's because I don't have an account there. I went on-line a bought one from patriot-supply.com. I bought the White-Rodgers 120-105711 for $24.95 including shipping ($6.49) and tax ($1.85) SignatureJerryD(upstateNY) >> Thanks, that's just what I was looking for, too.<<<<<<<<< > [quoted text clipped - 3 lines] > I bought the White-Rodgers 120-105711 for $24.95 including shipping > ($6.49) and tax ($1.85) I forgot about the account bit. I still have my state sales & use tax permit. Allows me to have an account. Max >> Thanks, that's just what I was looking for, too.<<<<<<<<< > [quoted text clipped - 3 lines] > I bought the White-Rodgers 120-105711 for $24.95 including shipping ($6.49) > and tax ($1.85) Anyone can buy from Grainger. All you need is money. SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 9 days 16:45 > Anyone can buy from Grainger. All you need is money. Actually if you dont have a business, then Graingers wont sell to you. You have to register your business with them and then they will sell you all you want. I used to get away with buying from Graingers at a local branch, cause I was in the Navy, but I would have to pay cash for everything or they would charge it to the ship... LOL Either that or I would have it charged to the Horse farm I worked for as a equipment maintenance guy. But I digress, you have to have a business or work for a business that is registered with them to buy direct from them. Ford Tech >>> Thanks, that's just what I was looking for, too.<<<<<<<<< >> [quoted text clipped - 6 lines] > > Anyone can buy from Grainger. All you need is money. No, granger has changed that, they will sell to anyone, account or no, if the purchase is under $100. >>>> Thanks, that's just what I was looking for, too.<<<<<<<<< >>> [quoted text clipped - 9 lines] > No, granger has changed that, they will sell to anyone, account or no, if > the purchase is under $100. Well, I usually show my company ID when I buy stuff from them... (most of the time it's less than $100). I then get a discount off the catalog price. :-) >> -- >> David M (dmacchiarolo) >> http://home.triad.rr.com/redsled >> T/S 53 >> sled351 Linux 2.4.18-14 has been up 9 days 16:45 SignatureDavid M (dmacchiarolo) http://home.triad.rr.com/redsled T/S 53 sled351 Linux 2.4.18-14 has been up 10 days 2:18 No, granger has changed that, they will sell to anyone, account or no, if the purchase is under $100. Maybe your Graingers will sell to anyone but the one here won't. I called and the first thing she asked was the telephone number of the company I was calling for/from. When I said I was just a home owner, she said they were wholesale only. SignatureJerryD(upstateNY) On Sun, 21 Jan 2007 10:06:19 -0500, "JerryD\(upstateNY\)" <jerryd@wherever.com> wrote: >No, granger has changed that, they will sell to anyone, account or no, if >the purchase is under $100. [quoted text clipped - 3 lines] >company I was calling for/from. >When I said I was just a home owner, she said they were wholesale only. Just make up a company name and use your cell number. They don't check and they don't telephone spam you so that's safe. The cell number won't be in any commercial business directory, in case they ever do check. I've used a long-defunct company name for decades with them. I pay with a credit card or cash and everything's fine. A company name and checking account is a handy thing to have around for a number of reasons. Very often it'll get you wholesale pricing at places like HVAC and appliance parts wholesalers. As long as it's not a corp or LLC and no income flows through, there's no paperwork. When you set up the bank account you use your SSN as the "business's" EIN. Only possible expense is whatever fees the bank might charge, usually zero if you keep a few dollars in the account. Having some business cards printed up with the company name is handy too. Couple hundred for under $10 at most quick print places. John --- John De Armond See my website for my current email address http://www.neon-john.com Cleveland, Occupied TN Don't let your schooling interfere with your education-Mark Twain A company name and checking account is a handy thing to have around for a number of reasons. Having some business cards printed up with the company name is handy too. <<<< But, but, but...............I retired and I am trying to do LESS work. The solenoid is for my pallet truck that I use for an elevator from the garage to the basement. SignatureJerryD(upstateNY) >>> Thanks, that's just what I was looking for, too.<<<<<<<<< >> [quoted text clipped - 6 lines] > > Anyone can buy from Grainger. All you need is money. Not in El Paso, TX Max Ya that is a crappy change they made like a year ago... You can still buy up to $100 worth from Granger without an account. And if you know anyone who does have an account, Granger will sell over $100 sales to you under that persons account... :-) >> Thanks, that's just what I was looking for, too.<<<<<<<<< > [quoted text clipped - 3 lines] > I bought the White-Rodgers 120-105711 for $24.95 including shipping > ($6.49) and tax ($1.85) >> You can get the solenoid at NAPA for under $20 even if you get the >> sucker-just-walked-in-off-the-street price column. Camping world sells [quoted text clipped - 3 lines] >wanted more than $50 for the ST85 solenoid and then couldn't tell me >whether it was a starting type or continuous duty type! Here ya go http://www.evparts.com/shopping/product_details.php?id=610&product_id=940 $18. Still too much, though. I paid $14 (not sure if that was with or without tax, just looking in my log) for the last one I bought. I got it from Shipps RV sales in Chattanooga, TN. Shipps is also a $CW$ store. I recall the first one being $11 so maybe the $14 is with tax. I despise Shipps for they way they shafted my mom on some repair work but I do know that they have these on the shelf. Oh, "4 wire" vs "3 wire". Four wire brings both coil leads out of the case as in the one pictured above. Three wire has one side internally grounded to the case. I prefer the 4 wire type, as the steel case of the solenoid tends to develop corrosion against its mounting and that can make the circuit intermittant. With the 4 wire, you simply run the other wire to a good ground. John --- John De Armond See my website for my current email address http://www.neon-john.com Cleveland, Occupied TN Don't let your schooling interfere with your education-Mark Twain >> You can get the solenoid at NAPA for under $20 even if you get the >> sucker-just-walked-in-off-the-street price column. Camping world sells [quoted text clipped - 26 lines] > > TIA and best regards, John Kinney I found this solenoid at the bottom of the page that the other solenoid was listed. I like it better cause its cheaper by about $0.50, has a rating of 100amps, and has silver alloy as the contact material not Copper which is quite soft. They are made by the same manuafacturer and it is rated for continuous duty cycle. You want to make sure this thing only powers up after the alternator starts producing, so I would run the energizing poles off of the ignition in the RUN position. http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemKey=6C017&BaseI tem=6C028 >> There shouldn't be any problem. Assuming you don't wire it with 00 >> welding cable, the resistance of the connecting cable will limit the [quoted text clipped - 23 lines] > > Regards, John Kinney Get a Sure Power 315 then you do not have to worry about discharging the truck battery when running off the aux battery. Sometimes hard to find a live only when running connection. In article <pan.2007.01.08.22.52.03.125000@www.smoke-island.com>, > I discussed this and some other suggestions with my friend and he agrees > that a solenoid arrangement is a good idea if I can get the parts at a [quoted text clipped - 8 lines] > > Now I gotta go figure out solenoids! NAPA part number ST-85 > There shouldn't be any problem. Assuming you don't wire it with 00 > welding cable, the resistance of the connecting cable will limit the [quoted text clipped - 42 lines] >>Regards, John Kinney > --- Instead of the solenoid, use a battery isolator. That way, you can leave it connected all the time and whatever tools you might run off of the aux battery will not drain the main battery. > > There shouldn't be any problem. Assuming you don't wire it with 00 > > welding cable, the resistance of the connecting cable will limit the [quoted text clipped - 46 lines] > it connected all the time and whatever tools you might run off of the > aux battery will not drain the main battery. Umm, that's what the solenoid does without the voltage drop. > I've recently installed a 12V 100 AH AGM deep cycle battery in one of the > storage lockers of my 2001 F-550 7.3L PSD truck. The purpose of the [quoted text clipped - 19 lines] > > Regards, John Kinney John... I have a E 250 van made into a camper. At first used the isolator type. The diodes have a voltage drop of 7 tenths of a volt. So the battery would never get full charge ( this was observed with a installed voltmeter. I changed this to the solenoid type (one made for this purpose) and now get a full charge. Also a 35 amp circuit at the solenoid to prevent fire in case of short to ground through to wiring to 2nd battery located in rear of van. Made negative connection to chassis ground. W W > I've recently installed a 12V 100 AH AGM deep cycle battery in one of the > storage lockers of my 2001 F-550 7.3L PSD truck. The purpose of the [quoted text clipped - 19 lines] > > Regards, John Kinney John, I agree with the posts that say you shouldn't harm your alternator with your proposed set up, however, I do have some concern about the battery. A deep cycle battery is constructed differently from an automotive battery. They are designed for a low discharge (relatively speaking) over a long period of time as opposed to a high discharge rate over a short period of time such as an starting battery in an auto. The deep cycle battery (ideally) should be charge at a low rate (2A or so) over a long period of time. Most makers recommend several shorter periods with rest periods in between charges. Admittedly, this is an ideal situation and would not cause the deep cycle battery to fail immediately. Just my observations. DaveD >> I've recently installed a 12V 100 AH AGM deep cycle battery in one of the >> storage lockers of my 2001 F-550 7.3L PSD truck. The purpose of the [quoted text clipped - 31 lines] >Admittedly, this is an ideal situation and would not cause the deep cycle >battery to fail immediately. Just my observations. None of that is true as a generality and particularly not in this case since John said that he'd bought an AGM battery. Even wet cell batteries can be charged at 1C or better during the bulk stage. Companies like Trojan will tell you that if you convince the application engineer that you know what you're doing. I do it routinely. AGMs as a class are capable of much higher charge and discharge rates than ordinary wet cells by virtue of the construction. 5C charging and >10C discharging is common. Hawker Genesis, the Orbitals and other similar batteries are rated for thousands of amps of discharge and have proven to hold up in electric drag racing applications for both charge and discharge rates like that. The 30AH Hawkers in my hotrod electric scooter, for example, will sustain a discharge rate of greater than 500 amps and have been doing so for years. In this particular application, no charge rate the alternator is capable of will harm the AGM. John --- John De Armond See my website for my current email address http://www.neon-john.com Cleveland, Occupied TN Don't let your schooling interfere with your education-Mark Twain >I've recently installed a 12V 100 AH AGM deep cycle battery in one of the >storage lockers of my 2001 F-550 7.3L PSD truck. The purpose of the [quoted text clipped - 19 lines] > >Regards, John Kinney What you describe is exactly what happens when you connect a travel trailer. The trailer batteries are charged by the alternator. My 2000 250 7.3L PSD has the trailer towing package, and there is a relay that connects the charging power to the trailer connector when the engine is running to prevent the trailer from discharging the starting batteries. |
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