300 amp Delco 40si alternator/isolator/cabling upgrade

Topic: 300 amp Delco 40si alternator/isolator/cabling upgrade (Read 2309 times) previous topic - next topic

300 amp Delco 40si alternator/isolator/cabling upgrade

November 06, 2015, 08:01:42 pm

I finished my 300 amp alternator/isolator/cabling upgrade today and thought I would post some pictures. Following Acousticart's recommendation, I bought a FTZ crimper and used FTZ heavy duty "power" lugs from Bay Marine Supply. I used Ancor Marine Grade adhesive lined heat shrink tubing to cover and seal the lug joints, using a Wagner 1200 watt heat gun to shrink the Ancor tubing.

Previously when doing heavy cabling I have always soldered the lugs, using a good crimper and heavy duty lugs produces a very clean professional result.

I used 2/0 gauge wire for the alternator B+ to the isolator, and for the alternator NEG to the starter negative post (this is then connected to the battery bank NEG with OEM 4/0 cable). The WestMarine ampacity chart rates 2/0 gauge wire at 330 amps.

From the 3 diode 300 amp isolator I used 3 - 2 gauge cables to connect directly to the battery bank, 1 - 2 gauge wire to the chassis battery, and 2 - 2 gauge wires in parallel to the house batteries. The WestMarine ampacity chart rates 2 gauge wire at 210 amps.

I disconnected and left the OEM isolator and cabling in place as a backup.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #1 – November 06, 2015, 09:57:27 pm

Peter,

Nice job.

Assume this has an external sense wire-- and I see a small-gauge red wire coming from the alternator. Where is it connected?

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #2 – November 06, 2015, 10:01:26 pm

Peter, looks great.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #3 – November 06, 2015, 10:16:17 pm

Quote from: wolfe10 – November 06, 2015, 09:57:27 pm

Peter,

Nice job.

Assume this has an external sense wire-- and I see a small-gauge red wire coming from the alternator. Where is it connected?

Brett:

Yes, the sense wire is connected to the starter + post with a 5 amp fuse. I took out the resistor bridge I posted about previously, that was more of an experiment. Now I have 14.0 volts at the batteries - the stock Delco 40si set point.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #4 – November 06, 2015, 10:21:31 pm

Want to make it a "smart" alternator?

http://www.xantrex.com/power-products/power-accessories/alternator-regulator.aspx

We use one on the sailboat. That way we can fast charge (bulk mode), but, if motoring all day, will not overcharge the batteries by keeping them at 14 VDC.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #5 – November 07, 2015, 10:39:50 am

Quote from: wolfe10 – November 06, 2015, 10:21:31 pm

Want to make it a "smart" alternator?

http://www.xantrex.com/power-products/power-accessories/alternator-regulator.aspx

We use one on the sailboat. That way we can fast charge (bulk mode), but, if motoring all day, will not overcharge the batteries by keeping them at 14 VDC.

I have one of the Balmore versions of this regulator new in the box from a previous project...

If a person was to set it up for our application would it be better to optimize for the chassis bank or the house bank?

( I already run a Yandina ACR so the voltage drop of the isolator is gone...)
I have

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #6 – November 07, 2015, 10:54:19 am

Chris,

Assume you mean Balmar.

Good question about which bank to use for the sense wire. Conventional wisdom would suggest chassis batteries, but I would probably use the house bank.

The reason for using the house bank to provide the regulator with its sense voltage is that if discharged, following a good bulk/absorption/float regime is better for them and starting at 14.2 or so will not harm the chassis batteries and once float voltage is reached you won't continue to over-charge both banks if driving all day.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #7 – November 12, 2015, 08:34:01 pm

I have had several questions about how to wire up the ignition excite wire when changing from a L-N alternator to a Delco alternator. I did a quick schematic showing the additional diode required. The diode can be purchased from Radio Shack for $2. The stock Foretravel excite wire should already be fused in the dash fuse block (it was in my coach). If you are installing a new excite wire (or aren't sure if the existing wire is fused) it wouldn't hurt to add a fuse.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #8 – November 12, 2015, 09:34:57 pm

Peter,

So no separate excite terminal? And the excite wires goes to the B+ terminal??

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #9 – November 12, 2015, 10:42:18 pm

Brett:

Yes, see attached DelcoRemy Application Engineering Bulletin. I underlined the key points. The diode circuit I posted is what is done within the isolators that have an excite post (a diode is connected from the excite post to the B+ post). The external diode allows you to use a standard isolator without the excite post feature - like I used in my Delco 40si upgrade.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #10 – November 13, 2015, 08:52:35 am

Peter,

Great write-up, excellent photos, very professional looking wiring job!

Question: Is the isolator OK with the high temps present in the engine compartment?

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #11 – November 13, 2015, 09:08:44 am

Excellent, thanks Peter.

And, yes, that diode is necessary, or the alternator output would be trying to push through that small excite wire and would quickly burn it or what it is connected to.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #12 – November 13, 2015, 09:20:08 am

Peter,

Interesting updates on your project! We look forward to additional updates as you start using the new system. Thanks!

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #13 – November 13, 2015, 12:55:20 pm

Quote from: Chuck & Jeannie – November 13, 2015, 08:52:35 am

Peter,
Question: Is the isolator OK with the high temps present in the engine compartment?

In my testing so far, I drove for an hour or so with headlights on and fridge on the inverter - a draw of approx 100 amps. I lifted the bed and the isolator was warm, but I could hold my hand on it. I'm thinking at the front of the engine room there is outside air coming in from below, and with the rear radiator the heat is going out the back.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #14 – November 17, 2015, 08:15:12 pm

For a winter project I am going to upgrade from the Delco 40si to the Delco 55si. This is the best deal I have found, it is a "real" Delco alternator, not a China imitation:

Delco 55si Alternator

I have designed a J-180 to pad mount adapter and will be using the double V pulley. My brother (a machinist and a welder) is going to help build the adapter.

Will post progress and plans for the J-180 to pad mount adapter.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #15 – November 18, 2015, 07:04:03 pm

Update:

I located a Canadian company Dixie-Electric that manufactures high capacity DelStar alternators (I called and verified - not made in China). They make direct replacements for the Delco 40si and Delco 55si, and both with a J-180 mount option. The DelStars actually have higher idle and running amperage ratings than the Delcos.

Delco 40si replacement
DelStar 170 series
D100-17102 J-180 Alternator

Delco 55si replacement
DelStar 180 series
D100-18101 J-180 Alternator

They sell through US distributors. The one in Minneapolis is C&J Bus repair. For their Delco 55si version the price is $1,358.00, quite a bit cheaper than the Delco 55si. I didn't price the Delco 40si version but I'm thinking they will be competitive. For a self-installed purchase they offer a 1 year warranty.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #16 – November 20, 2015, 10:08:50 am

Is there a ballpark total cost to this upgrade?

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #17 – November 20, 2015, 11:17:12 am

Good find! Looks like the ultimate alternator upgrade... Using two alternators offers redundancy, but I like the simplicity of the single option. Less belts, half the moving parts...
Don

Quote from: prfleming – November 18, 2015, 07:04:03 pm

Update:
...They sell through US distributors. The one in Minneapolis is C&J Bus repair. For their Delco 55si version the price is $1,358.00, quite a bit cheaper than the Delco 55si. I didn't price the Delco 40si version but I'm thinking they will be competitive. For a self-installed purchase they offer a 1 year warranty.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #18 – November 20, 2015, 08:43:19 pm

Quote from: krush – November 20, 2015, 10:08:50 am

Is there a ballpark total cost to this upgrade?

As Krush asked – just how much does it cost to upgrade the 12V charging system in a coach?

Let me start out by saying that this is not an "incremental" upgrade, i.e. just replacing a 160 amp alternator with a 200 amp alternator, wiping your hands, ah, that should do it!... This is an overhaul of the entire 12V charging system. Like adding high capacity 12V compressed air, a high capacity 12V charging system WILL cost some money, and is a fair amount of work.

Some are asking "why on earth would you want to do this?" Well with the higher power 12V inverters , and higher capacity 12V air compressors, adding additional batteries, etc. its nice to have some reserve alternator capacity.

I also agree that upgrading a system with one alternator and one isolator is simpler and much easier to implement, using stock mounting brackets, engine drive pulleys, etc.

In the research I have done, I would say there are 2 levels of 12V charging system upgrades, roughly doubling the stock charging capacity to approx 350 amps. Or, roughly tripling the stock charging capacity to approx 435 amps.

The more I read about the DelStar alternators, the more I like them. I called Dixie-Electric today and got the pricing on the DelStar version of the Delco 40si.

These prices are what I have found by researching and calling for information and are ballpark estimates. The super flexible welding cable prices are estimates – you may need more or less wiring depending on your coach layout. Also, tinned Marine flex cable is much more expensive. You do want to run upgraded cables from the isolator all the way to the battery terminals. I left my OEM isolator and wiring installed to use as a backup.

Note that the DelStar pricing came from the Minneapolis distributor. The distributor in your area may have different pricing.
I didn't include the cost of the FTZ crimper. My thinking is when you do the work yourself, the tools pay for themselves.

350 Amp 12V system upgrade

DelStar 350 Amp J-180 Alternator $1125
SurePower 300 Amp Isolator $525
Super flexible 2 and 2/0 gauge welding cable $150
Heavy Duty FTZ cable lugs $40
Heavy Duty Ancor shrink tubing $40
Total $1880

435 Amp 12V system upgrade

DelStar 435 Amp J-180 Alternator $1420
PowerLine 400 Amp Isolator $770
Super flexible 3/0 and 4/0 gauge welding cable $400
Heavy Duty FTZ cable lugs $80
Heavy Duty Ancor shrink tubing $80
Total $2750

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #19 – November 21, 2015, 02:07:38 pm

Quote from: prfleming – November 20, 2015, 08:43:19 pm

The super flexible welding cable prices are estimates – you may need more or less wiring depending on your coach layout. Also, tinned Marine flex cable is much more expensive.

Peter,

Have you had enough experiences with 4/0 cable to discuss the differences between standard, welding cable, and marine grade 4/0 cables? It seems like standard 4/0 may work from batteries to the bus bars and possibly from there to the isolator. But any more complex routing would definitely benefit from more flexible cable.

How about the price differences? Anybody know how the prices compare for, say 50 feet of the three types of 4/0 cabling?

BTW, I noticed that your two upgrade systems specified a lower isolator rating than the alternator ratings. I am sure it is supposed to be higher. Unless you are implying that your alternators will never run at their rated outputs.

Thanks,

Trent

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #20 – November 21, 2015, 02:21:20 pm

Peter,

Thanks for all the information and links.

One thing i noticed from the graphs is that the alternators were based on an idle speed about 2000 rpm, and go up to 8000 rpm. Newer Foretravels may be different, but mine idles about 800, with fast idle at 1200 rpm. I haven't paid that much attention to my tachometer, but it seems like my cruising speed is about 1600 rpm. The new alternators do not seem to reach their peak rating until about 5000 rpm.

I am not sure how this applies to our Foretravels, but it sure seems we would not really generate 350 amps, for example. Or is there something I am missing here? Don't get me wrong, brushless certainly seems the way to go, and you seem to have found the best prices out there. Just wanted to point out you may not be able to achieve the rated amps in your Foretravel.

Trent

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #21 – November 21, 2015, 02:30:54 pm

To translate engine RPM to alternator RPM you need to know the circumference of the crankshaft pulley and alternator pulley. Many give more than 2X the engine RPM for the alternator.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #22 – November 21, 2015, 04:05:21 pm

Brett,

Ah, sooooo!

As I was finishing up that message, I started thinking of the pulley size. I was wrestling (in my mind) about whether a larger or smaller pulley would speed it up. Having reached the limit of my brain activity for the day, I clicked post.

Thanks,

Trent

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #23 – November 21, 2015, 05:06:46 pm

Big crankshaft pulley and small alternator pulley= much higher alternator RPM than engine RPM. Virtually all engines are set up this way.

Re: 300 amp Delco 40si alternator/isolator/cabling upgrade

Reply #24 – November 21, 2015, 05:07:56 pm

It's like simple 1-speed bicycle gearing. Big primary sprocket (crank pulley) plus a small secondary sprocket (alternator pulley) makes the rear wheel (alternator) spin really fast.

EDIT: DANG! Brett beat me to the draw by <1.0 minute.

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