Dual Alternator Setup

Topic: Dual Alternator Setup (Read 2663 times) previous topic - next topic

Re: Dual Alternator Setup

Reply #25 – August 20, 2019, 09:58:04 am

Quote from: jcus – August 19, 2019, 11:38:21 pm

Wow! what vehicle needs that many alternators?

I'm sure "need" has nothing to do with it.

This truck is set up for a CB competition(I was told). I dont know if they still do those. I dont know much about the competitions or why they would use so many alternators but I would guess that the more amps your cranking out the stronger the signal. The big alternator at the top left appears to be a delco 50DN 24volt 270 amp, the rest look like leece nevilles similar to the ones in our coaches but, I would assume all to be 24V.

Re: Dual Alternator Setup

Reply #26 – August 20, 2019, 10:03:26 am

Quote from: AncloteJoe – August 20, 2019, 09:58:04 am

I'm sure "need" has nothing to do with it.

This truck is set up for a CB competition(I was told). I dont know if they still do those. I dont know much about the competitions or why they would use so many alternators but I would guess that the more amps your cranking out the stronger the signal. The big alternator at the top left appears to be a delco 50DN 24volt 270 amp, the rest look like leece nevilles similar to the ones in our coaches but, I would assume all to be 24V.

Maybe a Mobile welder or emergency mobile home power center

Re: Dual Alternator Setup

Reply #27 – August 20, 2019, 11:38:50 am

The subwoofer guys also compete to see who has the most alternators. It's all for show, what they don't realize is the high current audio peaks are supplied by the batteries, one healthy alternator (say 250 amps) can easily keep up with the total average power use over time - but who wants to show up with a whimpy looking sound system with just one alternator...🤣

Re: Dual Alternator Setup

Reply #28 – August 20, 2019, 11:41:19 am

If someone wants a LN 160 amp alternator I have one I took out of my coach, make me an offer, pay shipping, it is yours.

Re: Dual Alternator Setup

Reply #29 – August 20, 2019, 11:42:24 am

Quote from: Roger & Susan in Home2 – August 20, 2019, 11:41:19 am

If someone wants a LN 160 amp alternator I have one I took out of my coach, make me an offer, pay shipping, it is yours.

PM sent.

Re: Dual Alternator Setup

Reply #30 – August 29, 2019, 02:35:46 am

Seems to me that 2 alternators running thru a Balmar MC 612 dual feeding the house bank with a charge to the start bank via your inverter/charger if yours has that capability like the Victrons do would feed quite a few amps into the bank. You would need enough of a inverter to run the AC or other stuff. 2 victron multiplus would supply 240 amps into the house bank and 8 into the start bank, while supplying 6000 watts and 12000 watts peak. You would need a big bank or Lifepo4 batteries to power this. Would be a sizeable investment. But it is possible. These Leese Neville 320 amp alternators with the pulley sized to highway speeds to provide 80% of the rated power would give alot of amps.
I can run my front AC via inverter for around 5-6 hours I think it was off the inverter. With this setup I could run 2 ac's down the road and have room to spare.
I think.

Re: Dual Alternator Setup

Reply #31 – August 29, 2019, 06:41:56 am

Thanks Bob,

No plans here for anything like what you are describing. Way beyond my modest ambitions...but feel free to try it on your coach!

Re: Dual Alternator Setup

Reply #32 – August 29, 2019, 08:02:20 am

Nah. Not cost effective. Easier to just run the genny!
But if I planned to drive a lot on hot days it's a thought.

But my dash air sucks too.....

Re: Dual Alternator Setup

Reply #33 – August 29, 2019, 01:33:31 pm

Quote from: Bob and Julie – August 29, 2019, 08:02:20 am

Nah. Not cost effective. Easier to just run the genny!
But if I planned to drive a lot on hot days it's a thought.
But my dash air sucks too.....

Your dash air is supposed to blow, maybe fan is running in reverse?? lol
JohnH

Re: Dual Alternator Setup

Reply #34 – August 30, 2019, 10:23:01 am

Hmmm... never thought of that John....

Re: Dual Alternator Setup

Reply #35 – August 30, 2019, 05:13:20 pm

Continuing my investigation of the original subject of this thread (feasibility of running dual alternators) I have made a interesting discovery. The old LN alternator that has been faithfully serving our coach since we took possession is a pretty weak player. I always assumed it was rated at 160 amp max output. Turns out it is only 130 amp. This alternator was not the original factory installed unit. It was a replacement installed by a previous owner. I decided no matter what else I did, I should at least improve my battery charging setup with a fresh new alternator.

Found a good deal on a Delco Remy Model 8600307. This is a 28SI series, 200 amp, J180 mount with optional remote sense input. It has dual internal fans for extra cooling capability. Good price at $250 and free shipping. Arrived in perfect condition. Looks pretty cool with the radically "vented" casing. Should be a big improvement in my battery charging capability.

8600307 by DELCO REMY - NEW ALT

8600307 28SI New Alternator | Product Details | Delco Remy

Re: Dual Alternator Setup

Reply #36 – August 30, 2019, 07:06:55 pm

You should be able to pull the old pulley and use it, That is what I did with mine.

Re: Dual Alternator Setup

Reply #37 – August 30, 2019, 08:25:59 pm

The batteries will only take so much input. At 130 vs 200 I would be surprised if your batteries charge any faster.

The 130 amp LN you removed does not appear to have the adjustable voltage regulator output that the oem one did?

If you hook up the optional sense wire to make the alternator, for sure, to output 14.15 volts at the battery you may be overcharging both your battery banks on long warm weather drives.

I noticed my replacement LN alternator does not have a adjustable voltage output like the oem.

Brett and Foretravel recommend and set 13.6 volts to lessen the overcharging at warm weather.

Hmmm. Now what?

Using a isolator there is no way to fix the summer overcharging issue that I know of.

My thought was that after i start a drive and both banks are fully charged and the voltages stabilize i would use my combiner to manually disconnect my house mk gels from the alternator.

At that point my solar ,if daylight outside, would output its 13.6 volts output to the house batteries to maintain the house useages while driving and having the inverter on.

So my thought is that a high voltage alternator would benefit from a ability to disconnect it from the house batteries and have a lower voltage, maybe multi staged and /or temp controlled charging like the house does of the inverter?

Of course this requires a combiner that has a remote panel allowing a manual disconnect for the battery banks.

Foretravel had no such thing in 97 when our coach was made so they used an adjustable voltage LN and turned it down as Brett recommends to 13.6 volts.

If you leave the optional sense wire off the delco you start out at 14 volts like my LN and end up around 13.8 at the dash gauges.

Is the Delco made for DUVAC systems?

Re: Dual Alternator Setup

Reply #38 – August 30, 2019, 09:54:16 pm

There is no reason to not use a Delco Remy or any other alternator in your FT or any DUVAC system. These DUVAC systems are simply dual battery systems with a single charging source. The old isolators used big diodes to do the isolating task. There is a significant voltage drop across the diodes so the voltage output of the LN was pushed up to compensate. That is the DUVAC part. The isolators were like a water hose with a Y connection with a check valve in each direction. All things being equal the same amount of water would go in each direction. If one side can accept more water (like a battery that needs more charge, less resistance) then more water goes that way. If you want to push more water faster then you turn up the pressure (voltage). Nothing magic or special here.

The LN is an externally excited version of a common LN alternator. It needs an external excitation (ignition source) to start charging. It uses a sense wire connected to the start batteries as does the Delco Remy to tell the voltage regulator in the alternator to adjust voltage up to increase early amps to speed up charging of the start battery when its voltage is low (after a start).

Today there are lots of zero voltage drop isolators and several zero voltage drop smart isolators (Sterling ProSplitR for example) that manage charging between multiple battery banks. And other smart charging systems that charge the start batteries and manage charge to the house batteries using a multi-stage charge profile.

A properly installed and working alternator will be putting nearly nothing into a fully charged start battery whether the voltage is 13.6 or 14. something. At 13.6 v it will just take a lot longer to charge. The voltage at the battery using the sense wire helps the alternator increase its voltage to what it is capable of producing to reduce the time to charge.

Strategies for managing your batteries have changed considerably in the last 20+ years. As have batteries and available equipment.

Re: Dual Alternator Setup

Reply #39 – August 30, 2019, 10:50:24 pm

If you are charging your batteries for hours at over 14 volts unless you are at zero degrees you are definitely overcharging your batteries. Seriously lowering your batteries life's, anyone disagree? Please post your opinion and facts.

Why would FMCA's tech director (Brett) mention 13.6? It's an rv. Not a car. Built for the use.

If you buy less expensive everything in the battery system for your coach why would you overcharge the parts to shorten their service life? You could have bought oem grade parts and had them last twice or more as long in my experience.

Why save money then damage it quicker by overcharging the parts?

Re: Dual Alternator Setup

Reply #40 – August 31, 2019, 08:41:12 am

RV stuff is relatively new to me, but on a boat, the alternator output is controlled by a regulator that adjusts the voltage based on a number of factors, including temp of the battery, the alternator, the battery type, voltage, and state of charge. Not sure what my coach has on that front. Since I have a lot of solar up there, the victron mppt puts them charge back into the batteries pretty quick when its sunny out, and the victron inverter/charger when its not and the genny is running or hooked up to mains.
The volts will depend on the type of battery you have and where it is in the charging cycle, bulk. absorption or float. It also has a pretty cool belt load manager that will derate the power to protect your alternator.
For a little over 300 bucks its a great way to charge and protect your batteries and alternator.
Bob

Re: Dual Alternator Setup

Reply #41 – August 31, 2019, 09:00:30 am

To address Bob's concern about "over charging on long hot drives", and to satisfy my own curiosity, I plan to do a little experiment when I install my new 28SI alternator. The installation instructions say it will work fine with or without a SENSE wire connected. After making sure all my big battery charging cables are clean, tight and in good shape (I may elect to install fresh cables) I will try two different connections to see what the new alternator actually puts into the batteries.

But first, to establish a "baseline" I will check to see what my old LN alternator has been sending to my batteries. I will pull the start battery down by running the headlights on bright along with the fog lights and the spot light. Then crank the engine and observe the charging output of the old LN alternator with my handy DC clamp ammeter around the charging cable, and my multimeter on the start battery posts.

Next, I will do the same test with the new 28SI alternator, using two different charging cable connection points.

First connection: I will hook the charging cable from alternator B+ post to the ALT post on my isolator, and connect the existing SENSE wire from the START battery isolator post to the alternator. I will then repeat the test.

Second connection: I will hook the charging cable from alternator B+ post to the START battery post on my isolator, and remove the SENSE wire from the alternator. This is basically the same as connecting the alternator directly to the start battery. I will then repeat the test.

Running these tests will give me some valuable info. I will find out what my old alternator has been feeding my batteries for the last 6 years. It can't be too bad because my batteries have not shown any obvious signs of suffering. Or perhaps I just don't ever drive long enough in very hot conditions to cause a problem. One thing to take into consideration: when traveling we mostly stay at places with full hookups, so both battery banks are usually fully charged (start battery by Trik-L-Start) when we pull out in the morning. Our alternator normally only needs to maintain our battery banks when driving, rather than laboring to recharge deeply discharged batteries.

(We also have a PV system that constantly tries to charge the batteries on most sunny days, which adds another confusing factor)

I will also find out if my Victron Energy ARGOFET (low voltage loss) isolator is living up to it's billing. If it does, there should be very little difference in voltage observed at the isolator posts (ALT and START BAT) in the test using the SENSE wire..

Finally, I will find out what voltage the new alternator actually puts into my start battery. This will tell me if I need to worry about Bob's concern.

I'll update this thread when I get around to installing the new alternator. Gonna have to cool off a bit here before that happens.

Re: Dual Alternator Setup

Reply #42 – August 31, 2019, 12:08:10 pm

The engine batteries location in the hot engine compartment negates the use of a temp compensating alternator to charge them. Close to 13 volts is correct for them.

Probably why Foretravel chose spiral wound engine start optimas,

Judging by many 10-12 year battery life reports here the 13.6 volts and mk gels and optimas were a excellent system

Re: Dual Alternator Setup

Reply #43 – August 31, 2019, 10:16:52 pm

A quick look at Optima's website for charging recommendation for yellow top and red top batteries.

14.5 volts from an alternator with no amperage limits looks OK to me for either. 13.6 volts looks like it is at the very low end of acceptable alternator charging for a yellow top.

Re: Dual Alternator Setup

Reply #44 – August 31, 2019, 10:36:59 pm

The float voltage mentioned on the redtops matches what Foretravel shipped our coaches set at.

The limits are to be strictly adhered to.

Re: Dual Alternator Setup

Reply #45 – September 03, 2019, 08:17:19 pm

Quote from: Chuck & Jeannie – August 19, 2019, 03:10:51 pm

1. I only have a Magnum MS2812, so marginal there...but I ordered a EasyStart 364 (3 ton) soft start module from Micro-Air, which should be here today. I am hoping this will sufficiently ease the strain on my inverter. Won't know for sure until I get it installed.

I can attest that the Easy Start from Micro-Air works great. I installed two new A/C units on my boat (15,000 and 20,000 btu/hr) both with EasyStart. My 2000wat harbor freight generator can start either one on eco mode!

Re: Dual Alternator Setup

Reply #46 – September 03, 2019, 09:52:26 pm

Quote from: Caflashbob – August 31, 2019, 10:36:59 pm

The float voltage mentioned on the redtops matches what Foretravel shipped our coaches set at.

The limits are to be strictly adhered to.

My 2001 U320 was shipped with YellowTop Optimas. RedTops are not recommended or warranted in deep cycle applications which is why FT went to YellowTops in 2001. Long term parasitic loads cause deep cycle discharges.
The limits are to be strictly adhered to. Whose rule is this?

Re: Dual Alternator Setup

Reply #47 – September 03, 2019, 11:30:11 pm

Charging OPTIMA® Batteries | Support | OPTIMA® Batteries

Yellow, red and blue all state that float voltage is to be strictly adhered to at 13.2 to 13.8.

Plus the optima website prominently mentions the red top are the ultimate start AGM battery.

Maybe an availability issues or a deal on yellow tops? I understand the factory went back to redtops later?

If you have optimas of any color float charging them over 13.8 volts is not recommended.

After a long drive coming up if both the mk gels and my redtops show over 13.8 volts I may remove the new alternator and put back on the adjustable oem rebuilt lN unit I took off.

Almost every rv and bus manufacturer used the adjustable LN alternator.

And set them at 13.6 volts at the batteries like Brett recommends at his FMCA diesel seminars.

Edit: mk on their technical page on gels states:

No recharge current limitation@13.8volts

Re: Dual Alternator Setup

Reply #48 – September 04, 2019, 11:28:23 pm

I got the coach out today. We have a Delco Remy 40si 240 amp alternator with a sense connection to the start batteries. 14.5 v possible depending on charge demand from the batteries. No isolator, alternator is connected directly to the start batteries. I checked the voltage at the start batteries about 5 minutes after I started it up. 13.6 volts from the alternator. Alternators have voltage regulators. At least Delcos do.

The idea that you are going to be pushing 14.5 volts into your start batteries all day while you drive is not based in reality.

Re: Dual Alternator Setup

Reply #49 – September 05, 2019, 12:58:54 am

According to the Delco website you may not have the sense wire hooked up?

http://www.delcoremy.com/getmedia/90520e29-6966-4656-a04e-9053e59b5929/Delco-28SI-Single-Page-Brochure-12-14.pdf.aspx

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