2 alternator house and chassis battery

Hi everyone, I made a schematic of a battery system that I want to install in my 95 jeep yj 2.5, I am looking for some advice or someone to check it to see that I am not making any major mistakes Some professional help would put my mind at ease. OH, PLEASE PLEASE PLEASE DO NOT NOT TELL ME THAT THE SAME THING CAN BE DONE WITH A HO ALTERNATOR. I want separate systems so thats the point. K wire the world

I don't get it - unless you are describing 2 separate and independent alternator and battery systems that do not have downstream interconnected +12V sources. That's cool. But otherwise... Firstly you have the power wire coming from the voltage regulator. What are you using - generators?! Alternator power wires come from the alternator (B or B+) and have nothing to do with the Voltage Regulator (except the sensing for single-wire D+ type alternators). Secondly, are you wiring 2 alternators in parallel? Do that at your own peril of suitable advice - unless that Voltage Regulator is a "power" combiner (but it won't be (?)).    Thirdly, if 2 batteries, how are they interconnected? (Presumably a voltage regulator (charge light) controlled relay or one of those dumb "smart battery isolators" (not dumb if you have no charge light or other charge indication).) If the battery/s is/are "electrically" remote from the alternator - ie, there is a reasonable resistance through their inter-GND & +12V connections - then you should have the 2- or 3-wire (etc) voltage regulators - ie, those with an S = Sense terminal that goes directly to each respective battery's +12V post. If using alternators with external voltage regulators, I suggest getting internally regulated alternators, else mounting their voltage regluators on the alternator, else ENSURING real good engine (alternator) to battery- GND connections. The latter is really the crux of the issue - if the alternator's regulator's GND drifts from the battery- (GND), the alternator will increase output voltage and may blow car electrics (except for single-wire D+ alternators).

You are correct about the power wire coming from the regulator. It should come from the alternator itself so thats misguiding. The batteries are not run in parallel but complete separated from use. My biggest question revolves around the regulator, I have been reading about internal regulators but I just want to regulate the second alternator the same way that the jeep does if possible. I was thinking about running a internal regulator but I am not really sure if it is needed. I want to use the stock alternator on a separate system so its not tied in to the electrical/ chassis system and the second alternator runs auxiliary systems that are not crucial when out on the trail. Thanks for the response by the way.wire the world

As long as they are separated except for the common GND, there is no problem. Just be careful if systems are intermixed - eg, a main battery audio feeding signal to the aux battery amp (event though that is probably not an issue since it's not mixing the +12V rails/supplies - merely much lower voltages referenced to the common GND). My recommendation is always for internal regulators. They avoid the external issues - eg; alt-reg GND drift, the vicious circle of alt & reg replacement; extra cost - an internal alt with reg is usually the same price as one without and you save the cost (and hassle) of getting the matching VReg; plus the bonus if either stuffs up, you replace the whole unit (else replace the reg or brushes etc). Excluding modern alternators (ECU interactive), I recommend 2-wire "S&L" alternators. Like the D+, they have the charge-Light wire (D+ or L). But unlike the D+, they have a separate S or Sense wire which goes direct to the battery's +ve post no matter where it is. Hence the battery gets its correct voltage. (Fuses are not required for the S circuit though the cable could be fused, though S-loading is usually well under 20mA - equivalent to a LED. I use thin cable else a section of thin cable from the battery as the fuse.) [ FYI - Vehicle voltages are based on the battery's proper charging - now accepted to be a max of 14.4V long-term. The traditionally 13.8V is too low to "maintain" batteries. These days 14.2V - 14.4V is the norm for 12V lead-acid batteries. ] The only time you might want a single-wire D+ alternator is if the voltage drop to the battery under high alternator loads is so great that if the battery gets its 14.2-14.4V, the rest of the vehicle may bet 15V or 16V or more - hence damaging electrics. Or if there is a risk of bad connections, though modern S type alternators are often limited to under 16V output. But then simply connect the S=Sense wire to the alternator output (B or B+) to imitate single-wire alternator behavior.    Sure, under those circumstances the battery is being undercharged, but that's another issue. But the S-types are good because usually batteries are undercharged due to remoteness, or people want to increase the set voltage of 13.6 - 13.8V etc. The just place 0.6V diode(s) in the S line to boost output by 0.6V (or multiples) or some other suitable voltage reference (0.2V germanium diodes, 0.3V Shottkys etc). The S-types can hence be boosted for batteries that require higher than normal voltages, or for voltage sensitive amps where battery life is a secondary consideration. BTW - I haven't checked your loads & wire gauges etc. My comments are merely on the charging (& battery) system.    But dual (or more) alternators with separate and independent batteries and loads is not uncommon - eg 2 x 250A or larger alternators. Usually they are common ground, but can be separate if the alternator has a floating GND independent of its chassis. And some do connect multiple alternators together with apparent success. This might be because of the alternator design, the matching of characteristics, or adequate inter-cable resistance. But AFAIK, usually it is considered a destructive no-no.    

Outstanding, this is exactly the info I was looking, I will be pouring over this for a while.... I suppose the last question is the viability of this system. If done right, will this work well in the sense of reliability and upgrades in the future? I plan on including a 8000 lb wench through the chassis side of the battery so in the middle of the night I can still have all my lights on/run the wench without A) overloading the system and B) without one system effecting the other. If I kill weaken a battery on either side,I can still shut down any running auxiliary equipment to recharge the batteries or even switch them in a emergency. I suppose this is a search and rescue application so the idea revolves around backup.    Is it possible to put a one wire internal regulator on an existing alternator? basically converting it for this application.wire the world

Usually for heavy loads, it's best to combine batteries so as to share the load and hence increase battery life. Alas that has the hazard of a flattery (flat battery) - ie, the main cranker - but batteries can self recover a reasonable amount - especially after a heavy discharge. But otherwise an low-volt alarm or cut-off could be used... Regulators are matched to the alternator. If external, they may have different types - eg single or multi-wire. (Regulators usually have 3 wires to the alternator itself - the field, the gnd, and something else (the "neutral? ie - the center of the main windings?). Not that I see any advantage in "converting to single wire (D+) except as I explained (ie, a 2-wire S&L with S to B+). The only complication is if it has the 3rd wire (IGN +12V), or is the 2nd wire is IGN +12V which may also be the sense wire (not always - it could sense output like the D+, and if not, problems occur if the IGN +12V is not the same as the battery +12V - hence an IGN controlled relay may used between battery +12V and the Ig terminal). If it's an internal reg, but bother? Connect S to B+, or if a 2 wire I&L or 3 wire SIL, connect I/Ig via and IGN relay to battery +12V. I still reckon if seeking a new alternator, always a 2-wire S&L internal reg. That can be boosted as I described previously; can properly charge remote batteries; or can be converted to a single-wire D+/L type.

Ok, I have been researching alternators and to my surprise there are many that will fit my application. I am thinking about the 21SI by Delco as it is 14.0v and a 1 wire. It IS a way better idea to get this alternator as buying a regulator will increases cost and I can have everything I need in one purchase(like stated). Here is a link from Ebay for the one I am thinking about... http://www./itm/DELCO-HEAVY-DUTY-ALTERNATOR-21SI-160-AMP-14-0V-1-W-/330614456220?hash=item4cfa283f9c&item=330614456220&pt=Other_Vehicle_Parts&vxp=mtr Oh, Is it necessary to have a common ground? I was planning on grounding each battery with 0 gauge to different spots. One to the the body in different areas and one to the frame at different spots. I have a separate ground on my battery in my Acura that grounds this way and I get way better performance from my battery. But I am not sure about a dual system. So let me sum it up. Internally regulated alternator Do not mix the +12V rails/supplies in any way well grounded batteries (common ground) low-volt alarm or cut-offwire the world

Here is the right link for the alternator http://www./itm/DELCO-HEAVY-DUTY-ALTERNATOR-21SI-160-AMP-14-0V-1-W-/330614456220?hash=item4cfa283f9c&item=330614456220&pt=Other_Vehicle_Parts&vxp=mtrwire the world

Keeping in mind what I said about using a 2 wire S&L type instead - you can't change the voltage of a singe-wire alternator (like the D+ only; the power wire B+ and GND don;t count as "wires"). And yuk - they still have external fans? The Japs have been internal since the 1980s. It was something I hadn't thought about until I ditched my experimental 1980s internal reg Bosch's for the Jap equivalent. But for 160A it seems ok, provided it has a suitable pulley & offset. Incidentally, I am only a recent convert to internal regs (and alternator knowledge for that matter). My experience was the early 1970s versions (Lucas) which were not that reliable - ie, be prepared to convert them to external regs. But ~5 years ago, someone showed how easy it was, and that various alternators could physically fit. I found many alternators were similar in their mounting. The front mount to pulley-center distance was often the same; the front bolt distances were generally the same; and different depths between the "main" mounting bolts were often fixed with shims (washers, bigger nuts, sleeves, etc). But the conversion to internal regulator is permanent - never again will I use an external regulator (not for typical applications anyhow). And BTW - eBay links do not work here. But it's sufficient to post the item number - that's how I found your link.    

Is this a correct diagram for wiring. I see that the S/sensing wire is connected right to the B+ and then the (L) would be wired to the battery post like explained. Could you recommend an alternator that would work well or one thats a good example. I am not exactly sure which alternators I should specifically use that is a 2 wire.wire the world