Reduntant charging systems?

[BMAN]

So, I’ve been thinking of the dual battery/aux. Power setup for the 60 series lately. For those who don’t know, I have done a GM TBI small block/700R4 conversion in the truck and am running a stock GM serpentine setup.

My plan has always been to run a homebrew on-board welder setup as outlined here: http://www.pirate4x4.com/tech/on-boardwelder/index.html

That, along with all the other self-sufficient goodies that we dream about like, OBA, OBS, GPS/laptop, 2meter, CB, fridge freeze, way too many aux lights, yadda yadda yadda…

I have purchased my Ford alternator for the welder and will be picking up the rest of the items required for the welder in the next week or so. I will be mounting the Alternator down low on the passenger side of my block and will run a v-belt over to my hybrid (serpentine/v-belt) water pump pulley. Since the Ford alternator will be constantly hooked into the system and generating power I had the idea of splitting my “Dual Battery system” into a “Dual Power System”.

My basic thoughts, in not so many words, would be to run the “stock” systems off of my Optima Red top, and wire ALL of my auxiliary systems to my Optima Yellow top (deep cycle). I would keep the Yellow top completely separate from the stock system yet keep it charged with the secondary alternator.

All interior lighting (dome lights) will be changed over to LED per the stuff George sells at TaskLED.com so the drain will be minimized. While it is feasible that both systems could accidentally be drained, my hopes are that it would be unlikely. In the case that it did happen I would be no worse off than if I were running just a single battery and made the same mistake.

I had thought about crossover redundancy (making both batteries available to the primary system) similar to what we traditionally think of as a dual battery system, but haven't figured that one out aside from cables that are long enough to hit both batteries so I could switch over if needed.

Most of the setups I’ve seen wouldn’t allow for the 2nd alternator to be added to the primary system. Thoughts or ideas on doing this are welcome.

I also plan to add battery disconnect circuits to both of the batteries so that I could lock them out of the system completely at any time. Sort of a security system that won’t allow me to drain the primary battery by accident when parked and camping over night.

So what do you guys think? I’ve posted this on another board that I frequent and they’ve actually given me a few ideas on how to tighten things up a bit so as not to accidentally drain both batteries at the same time. Hoping for the same kind of input here.

 

[mobi-arc]

Use a transfer switch to connect one alternator's output to one battery or the other. No point in connecting to both as one alternator will handle most of the load, the second alternator will do very little. I would connect the switch to the alternator not being used for welding as there's a lower probability of alternator failure with the non-welding unit verses the de-regulated welding unit.

 

[CHWTOY]

I have been contemplating something very similar, dual batteries and dual alternators. I still have the 2F and stock alternator, but am running a GM unit in place of the smog pump (sadly right now it literally just free wheeling and not hooked to anything).

Anyways yes leave the stock electrical system alone, that way it’s nice and easy to trouble shoot and no specialty parts are required. Then just run your second alternator to a fuse, block (I like THESE) which can then feed your relay banks similar toTHESE so you don’t have any high amperage wires going into the cab. Also if you want something to only be switchable with the ignition or the lights on you are just taking the small amount of power required to run the switch and relay so no worrying about overloading the stock wiring.

The one thing I am planning on adding that I didn’t see mentioned was a way to connect the batteries together if you wanted to. Say you accidentally ran the main battery dead and wanted to “self jump”. Or the stock alternator died and you wanted a “limp home” mode running the whole system off of the aux alternator. My plan for this was just a cheap marine battery selector switch like THIS. Each battery would be connected to an input with the switch regularly in the “off” position, so electrically there would be no connection between the batteries. Then if necessary just turn the switch to “1+2” and they are connected.

The advantage to the above setup is then when you go to add a winch all you do is hook it to the output of your selector switch. During day to day driving there is no power to the winch, so no vandalism concerns. For light loads and occasional use the switch would be set at “2” meaning just the auxiliary battery is connected to the winch. Then during heavy use and extreme loads you would have the option to connect both batteries to the winch by turning the selector to “1+2”.

*EDIT* It took me too long to write this and I just read mobi-arc's comment. His idea is probably better since the second alternator is un-regulated which can't be good on batteries...

 

[BMAN]

I had actually thought about the regulator for the 2nd alternator and forgot to mention puting it into the circuit for the Aux elements. They would need regulated power to run properly anyway. Once I get the wiring diagram for the second alternator that comes with the Napa power supply this may answer some of the things that are gray in my thinking.

 

[mobi-arc]

I assume you're talking about running both alternators with regulators....two charging systems. The Ford unit would be DE-REGULATED should you need to weld. It would be regulated when charging your aux. battery.

 

[Mark W]

Not quite what you are talking aboiut, but I have run dual alternators on several rigs. Each has it's own alternator, and the simple way I did it was to tie both into the OEM wiring, with dual batteries always in parallel. I left the factory Ammeter just the way it is, showing feed into and oth of the battery. Ran two more aux ammeters showing the feed out of each alternator, Put a voltmeter on it as well. Sounds like a lot of gauges I know, but it let me tell at a glance exactly what was going on with the system. Saved my butt a couple of times, including one run down the Alaska Highway a few years back when one of the alternators (nominally designated as the "primary" failed. Made note of it and drove on. Replaced it at the end of the trip.


Mark...

 

[BMAN]

I assume you're talking about running both alternators with regulators....two charging systems. The Ford unit would be DE-REGULATED should you need to weld. It would be regulated when charging your aux. battery.

Correct.

Mark,

I hadn't thought of doubling up on he guages, good idea!

 

[Mark W]

I've got a 3FE torn halfway down at the moment, replacing a cracked piston. I'm leaning toward losing the air pump and EGR while I'm at it. If I do, I'm gonna add an FJ60 alternator to replace the air pump. Set it up the way I mentioned above (3 aftermarket ammeters and the factory voltmeter).

120 amps of charging for pushing lots of lights or quick battery charging or whatever. Comes in at low rpm unlike most of the high output alternators. And obviously give redundancy to boot.

Might not be the best way to go if you were starting from scratch. But since I've got an empty bracket and a position in the OEM belt system that needs the be filled anyway...


Mark...

 

[kevinmrowland]

I feel bad for not jumping in here, I keep my system separated except for self jump situations (or for winching when I get around to installing the winch that is sitting on my office floor)

To do that I have a marine switch just like CHWTOY describes, separated, together, or together and out to the winch. This also will double as a winch security shutoff.

more details here:
https://forum.ih8mud.com/showthread.php?t=94294

Good luck,

 

[REKCUT]

I have done what your talking about with 2 seperate systems on my 60. I run the factory items off of the stock alt and battery and installed a GM alt inplace of the smog pump and a second battery. The alt is a " one wire" system that doesnt hook into my stock harness or system and I run all aftermarket products off of the second battery with new fuse block. My thinking was like yours in that I can run the second system down and not effect my normal operation. The only part I have not done is to add a way to switch over to the new battery if I kill the stock one. I figure worse case I can just physically switch out the batteries if I have to but would like to find a way to take care of the dead alt option if that rears it head someday.

 

[sandcruiser]

we ran a 2 battery/2 alternator system in Sandy for many years. Most of the time I ran it as a stock system, then a secondary system w/ all the ancillary gear and a deep-cycle battery.
It worked pretty well, but there were a few hassles

1) definitely use internally regulated or 1-wire alts. An external voltage regulator becomes a challenge when you decide to keep the 2 systems isolated. Or at least, for me, it was a challenge

2) Consider getting wiring that is totally different color patterns. Easier to keep the two systems isolated.

3) Be very careful about adding accessories and such--- gotta keep the 2 systems isolated.

In case it isn't yet clear: if you plan to use 2 distinct systems with common ground, it is imperative that you keep the two systems isolated on the + side.

In our case, we had some gremlin that caused the 2nd alt to continuously charge the deep cycle battery, which made for short-lived batteries. I could never find the culprit, but after tearing stuff apart and redoing it, I finally gave up and just ran a single-battery w/ two alternators. I could have redone the wiring completely, that would also have worked, but.... I didn't.

In my opinion, the decision tree on dual alts breaks down like this:

If you have heavy loads while running at low rpm, get two alts

If you have loads while turned off, get dual batteries

If you have heavy loads while running at medium or high rpms, get a high-output alternator

If you run a winch and also a fridge, and crawl along most of the time.... it might be worthwhile to do 2 seperate battery systems that you can tie together for brief periods. Maybe.

Good luck!

 

[BMAN]

Thanks guys! More great stuff for me to ponder.

 

[Mark W]

I gotta disagree with the need to keep the two systems isolated. If you are keeping any opart of it separate, then this is important. But you can run your batteries and your alternators hooked in parallel full time, powering everything off of this source. Works fine, no problems. I've done this long term in several rigs.

If I wanted to isolate a battery, I would simply pull the ground terminal off of it while powering whatever I was using off of the other battery. If I ran it down too much to start, just hook up the untapped battery.

You could also install a switch to do this. I just never bothered since it was abnormal for me to need to isolate a battery.

Something that I have done often is swap batteries on the trail with someone else's rig which has a bad alternator. When their battery goes dead, toss one of my good ones in, and put their's in my rig to recharge. When they wear my battery down, just swap their's back in. I;ve done this a few times. A couple of times for several days on the trail.


Mark...

 

[BMAN]

... Something that I have done often is swap batteries on the trail with someone else's rig which has a bad alternator. When their battery goes dead, toss one of my good ones in, and put their's in my rig to recharge. When they wear my battery down, just swap their's back in. I;ve done this a few times. A couple of times for several days on the trail.


Mark...

Hadn't thought of that either... a saftey net for others who travel with you.

godd karma!

 

[sandcruiser]

Mark:

No battery life problems?
Are you running an isolator on the two batteries?
I've only tried the one system that I described, and found that I killed 4 batteries in abnormally short times. Once I pulled the deep cycle out completely and just ran a single, starting, battery, the two alts did a great job of keeping everything running smoothly... so I don't think that the problem was alternator-related.

 

[Mark W]

If you take the simplified appraoch I mention above, you need to use two matched batteries. Ideally purchased at the same time ven (no age difference this way).

For short peroids such as recharging other peoples batteries, it is not a problem. But for normal long term use, if the batteries are not matched the different recharge rates/capacities will result in improper charging and shortened battery life.

If you want to run different batteries THEN you need to run an isolater and separate the duties of the batteries. You can still run the dual alternators twinned together full time (just looks like a single, more powerful alternator to the the rest of the electrical system).


I wound up adding an addition FJ62 alternator on the 3FE I mentioned above. Easy swap for the smog pump. 160 amps of charging power!

I'm gonna pull the battery box out of the parts rig that the alternator came out of and run matched dual batteries. For now, identical batteries in a completely twinned system. I'll add an isolater and separate the batteries duties if an any point down the road my uses/needs change.


Mark...