Running 1 Roof Air on Inverter While Driving

Topic: Running 1 Roof Air on Inverter While Driving (Read 2157 times) previous topic - next topic

Re: Running 1 Roof Air on Inverter While Driving

Reply #25 – September 21, 2015, 06:59:31 pm

I think it would probably be more cost effective to do what the Prevost currently does which is to tie several smaller alternators together. There is one on the engine and a long belt that sends power to a bundle of 3 more of them off to the side. It all looked very elaborate. I imagined the headache of it all wearing out as it aged. I would probably add a pair of 160 amp alternators to my existing setup.

Re: Running 1 Roof Air on Inverter While Driving

Reply #26 – September 21, 2015, 08:16:22 pm

Update:

With the installation of the AIMS 4000 watt inverter complete, I'm upgrading the rest of the 12V charging system to handle 250 amps continuous current flow. I'm ordering this 3 battery isolator, and will tie 2 legs together to have a 100 amp current capacity for the chassis battery, and a combined 200 amps current capacity for the house batteries. I know a lot of folks have suggested battery combiners, but I feel a diode based isolator will be more reliable.

Sure Power 300 Amp 3 Battery Isolator

Re: Running 1 Roof Air on Inverter While Driving

Reply #27 – September 22, 2015, 12:07:51 am

I mean as long as it is rated high enough - my isolator has been alive for 16 years now

Re: Running 1 Roof Air on Inverter While Driving

Reply #28 – September 22, 2015, 05:24:00 am

When i was getting ready for Residential Fridge project i had also looked in to this to find out what would it take to also run a overhead AC with battery power. At the time I had installed a residential refrigerator i also had to purchase and install a new inverter along with upgraded batteries. So I wanted to hit two birds with one stone. We live in TX and we love air conditioning.
For us i ended up determined that running the dash AC with occasional need to run a overhead AC with a generator is more than good enough. There are times such as when i was traveling from TX to OR last August I was running the dash AC with a small fan running on the floor from bedroom facing front. Fan was running from the inverter as well as the fridge ... while under way.

I plan on upgrading our overhead AC units to less noisy one ... I did not look in to it yet but perhaps the new ones also draw less amp .... perhaps then it maybe worth while looking in to this again to see if it will be cost effective to operate one via "DC" power.

For now i chose to have FT convert the Dash AC to new a134 refrigerant. That turned out great. It works better than ever now.

Re: Running 1 Roof Air on Inverter While Driving

Reply #29 – September 24, 2015, 07:15:58 pm

12V charging system update:

The Sure Power 300 amp isolator arrived today. It is a beast - it weighs 16 lbs, and has 1/2 inch studs. I took a picture next to a beer bottle for comparison. Also, note in the detail photo: MADE IN USA.

Now that I have it I will temporarily mount it and measure length of new 3/0 cables from the alternator positive to isolator, from isolator directly to each battery bank and from alternator negative to battery negative. I will be ordering custom made cables from Bay Marine Supply:

Bay Marine Supply - Custom Cables

I'll post more pictures as the 12V charging system upgrade progresses.

Re: Running 1 Roof Air on Inverter While Driving

Reply #30 – September 24, 2015, 07:20:12 pm

Blue Moon..

Re: Running 1 Roof Air on Inverter While Driving

Reply #31 – September 25, 2015, 01:02:11 pm

So why not put on an engine driven generator? If the point is to run one AC while driving without running the generator than about $1100 gets you a 3500 watt 120 v engine driven generator with a constant voltage regulator.

http://www.fabcopower.com/generat/bgen.htm

I appreciate the direction and effort (and $) Peter is putting into this. When he is done he is going to have a very powerful 12 v system while underway. When he stops what ever batteries he has (and I bet they will be fully charged) without any other power source are still the limiting factor. More batteries, more solar. What he learns and discovers will be valuable to all of us power nerds.

Re: Running 1 Roof Air on Inverter While Driving

Reply #32 – September 25, 2015, 04:58:14 pm

Quote from: Roger & Susan in Home2 – September 25, 2015, 01:02:11 pm

I appreciate the direction and effort (and $) Peter is putting into this. When he is done he is going to have a very powerful 12 v system while underway. When he stops what ever batteries he has (and I bet they will be fully charged) without any other power source are still the limiting factor. More batteries, more solar. What he learns and discovers will be valuable to all of us power nerds.

I came to realize that the older coaches and even some newer ones, have basically enough 12V capacity to keep the coach running with the headlights on, and maybe charge the house batteries when needed, for a short time, until fully charged. But, as soon as you put a continuous demand on the 12V system, like running a fridge, or a roof air, you reach limits pretty quickly.

Fast forward to 2015, we have available a new class of "super" inverters that are ultra efficient, and have a 300% surge capacity. We have high current isolators, and high current alternators, and new battery technology.

As I said in the beginning, for me this is a "proof of concept", using some of the new technology available today. Plus, I have always wanted to "modify" what ever I have to make it better...

It used to drive my Mom crazy...

Re: Running 1 Roof Air on Inverter While Driving

Reply #33 – September 25, 2015, 06:11:19 pm

Thanks, Peter,

A fellow "fixer". I am very interested to see what improvements and enhancements are available.

So what is the prevailing choice for a bigger alternator? I have a 250 amp capacity Sterling Zero Voltage Drop three battery bank smart isolator. I think I have enough demand that batteries never get fully charged while driving. I think I can increase the output voltage on the incumbent alternator but it seems I need a bit more. I believe I can get the 160 amp alternator rebuilt to about 200 amps for about 1/4 the cost of a Delco Remy 40si J180 Mount 12v 240 amp 8600339. How do you know what mount you need?

Re: Running 1 Roof Air on Inverter While Driving

Reply #34 – September 25, 2015, 06:47:42 pm

Quote from: Roger & Susan in Home2 – September 25, 2015, 06:11:19 pm

Thanks, Peter,

A fellow "fixer". I am very interested to see what improvements and enhancements are available.

So what is the prevailing choice for a bigger alternator? I have a 250 amp capacity Sterling Zero Voltage Drop three battery bank smart isolator. I think I have enough demand that batteries never get fully charged while driving. I think I can increase the output voltage on the incumbent alternator but it seems I need a bit more. I believe I can get the 160 amp alternator rebuilt to about 200 amps for about 1/4 the cost of a Delco Remy 40si J180 Mount 12v 240 amp 8600339. How do you know what mount you need?

I have a feeling this thread is going to break some records...ha ha, it just keeps on goin'...

If you originally had a Leese-Neville, which is a favorite of Foretravel, this is the J-180 Long Hinge (3 point mount). The alternator of choice for replacement/upgrade I think is the Delco 40si at 300 or 320 amps. There is a 300 amp 40si on ebay that I am watching, but I haven't made an offer yet.

In 2012 Delco released the 55si for the fire truck market, which can output 430 amps, but this only comes in pad mount, and is designed to use a serpentine belt with an active tensioner. This won't work well with a double V-groove pulley like most of us with older coaches have.

Re: Running 1 Roof Air on Inverter While Driving

Reply #35 – September 25, 2015, 10:07:55 pm

I'm curious to what the bill is thus far? looks to be about $1500 and still need an alternator?

Another idea is to install a larger A/C compressor, or install another one and have more A/C capacity.

Re: Running 1 Roof Air on Inverter While Driving

Reply #36 – September 25, 2015, 11:27:16 pm

I think you could spend $245 for a soft starter and run it off the standard 2500W Inverter and stock alternator. Will get around to doing that in the next few months and see how it works.

Re: Running 1 Roof Air on Inverter While Driving

Reply #37 – September 26, 2015, 10:02:32 am

If you're looking at upgrading the alternator, have you also considered hydraulic generators or PTO driven generators?

HYDRAULIC GENERATORS 3KW - 12KW | HYDRAULIC GENERATORS FOR UTILITY TRUCKS,...

Re: Running 1 Roof Air on Inverter While Driving

Reply #38 – September 26, 2015, 10:32:19 am

If I was really interested in this type of science project, I'd take the 3phase of an exisiting alternator (before the rectifier) and figure out how to run it through the inverting box on say a Honda eu3000i generator. Higher voltage and more efficient..no wiring issues.

Re: Running 1 Roof Air on Inverter While Driving

Reply #39 – September 26, 2015, 12:13:26 pm

Quote from: rsihnhold – September 26, 2015, 10:02:32 am

If you're looking at upgrading the alternator, have you also considered hydraulic generators or PTO driven generators?

HYDRAULIC GENERATORS 3KW - 12KW | HYDRAULIC GENERATORS FOR UTILITY TRUCKS,...

Great, more ideas are coming in...

Does someone with more hydraulics knowledge than I have know if the on-board hydraulic pump for the power steering has the capacity to run one of these - 8 GPM @ 1500 psi? My gut feeling is maybe not...

Re: Running 1 Roof Air on Inverter While Driving

Reply #40 – October 03, 2015, 08:39:20 pm

Update:

Well, the guy on eBay and I came to an agreement...the Delco 40si 300 amp alternator arrived today!

I swapped out the Delco 28si I was using, the install was easy. I am still using the stock 2 gauge cabling until I do the upgrade to 3/0 cabling. I roughed out the amount of 3/0 cable I'll need today to completely re-wire my alternator-isolator-battery-ground wiring and with a little extra I'll need to order 75 feet. After consulting with Don & Tys (AKA acousticart) I am going to order the FTZ crimper from Bay Marine Supply and make my own 3/0 cables.

It was getting dark, but I confirmed the alternator was working, and did some preliminary load testing at idle, and it produced approx 176 amps at 600 RPM with an inverter load. I will take the coach out tomorrow and road test it.

Note: On my coach the alternator ground wire is red.

Re: Running 1 Roof Air on Inverter While Driving

Reply #41 – October 03, 2015, 10:29:31 pm

For everyone that is asking, my 2nd offer of $600 won the 40si alternator.

Re: Running 1 Roof Air on Inverter While Driving

Reply #42 – October 03, 2015, 10:34:31 pm

Peter,

Did your 28si use the same wiring as your L-N original FT alternator?

Did you have to make any changes to that to go to the 40si (brushless, right?)?

What is the gauge of that red ground wire in your new alternator picture?
(BTW, my plan is to use mostly black 4/0, but use red heat shrink on the ends of positive wires.)

Thanks,

Trent

Re: Running 1 Roof Air on Inverter While Driving

Reply #43 – October 04, 2015, 12:30:05 am

The Delco 24si, 28si and 40si alternators need ignition excite when connected behind an isolator. This is why un-informed truck repair shops add jumpers to isolators when installing new Delco alternators - to get the 12v excite that Delco alternators require, not realizing that there are better ways to do this.

This can be accomplished in 2 ways - an ignition wire with a diode connected to the alternator B+ (as was stock on my '91), or install an isolator with an ignition exciter post to provide the excite (diode is internal to the isolator connected to the alternator B+).

So, on my '91, the ignition excite-diode wire is connected to the alternator B+ and provides the voltage the 40si needs to start charging.

The diode (in the exciter, or externally connected to the ignition wire) prevents "back flow" when the alternator starts charging. Without the diode, this back flow would exceed the current capacity of the small gauge ignition excite wire.

The gauge of the red ground wire is 2 gauge. All my stock alternator and isolator wiring is 2 gauge, I will be upgrading this to 3/0 gauge. I also plan to buy all black wire, and use red heat shrink on the positive wires.

Re: Running 1 Roof Air on Inverter While Driving

Reply #44 – October 05, 2015, 01:13:20 pm

Quote from: TulsaTrent – October 03, 2015, 10:34:31 pm

Did your 28si use the same wiring as your L-N original FT alternator?

Quote from: prfleming – October 04, 2015, 12:30:05 am

The Delco 24si, 28si and 40si alternators need ignition excite when connected behind an isolator.

To clarify some questions:

The Delco alternators have 3 small terminals in addition to the B+ post:

"S" - Remote Sense
"R" - Relay
"I" - Indicator Lamp

The sense wire from the isolator start battery post connects to the "S" terminal. The other 2 terminals should not be used. The "R" terminal is not the remote sense terminal. The "I" terminal is not the ignition excite terminal. The ignition excite needs to be provided with an ignition wire with a diode connected directly to the alternator B+, or by using an isolator with an ignition excite post (diode is internal to the isolator connected to the alternator B+ post).

The L-N alternators set up for DUVAC have an ignition excite terminal, and the ignition wire is directly connected to it. So when changing from a L-N alternator to a Delco alternator you need to be aware of the above requirements.

Re: Running 1 Roof Air on Inverter While Driving

Reply #45 – October 08, 2015, 11:35:07 am

Do you think the alternator will overheat drawing 176 amps at idle? I'd imagine with an a/c you could have a theoretical max draw of 200 amps so it really could sit pulling full load at idle for long periods right?

Re: Running 1 Roof Air on Inverter While Driving

Reply #46 – October 08, 2015, 01:19:15 pm

Piku

The 40si is rated at 190 amps at idle on the spec sheet. But, yes, I think you would not want to draw high currents for long times sitting idling. I plan when running the a/c, to just use common sense and switch to the genny when the coach is not going to move for an extended time.

Re: Running 1 Roof Air on Inverter While Driving

Reply #47 – October 08, 2015, 01:30:21 pm

Here is a pretty good deal for a Delco 40si 275 amp alternator with a L-N J180 mount.

Delco 40si 275 amp alternator

Re: Running 1 Roof Air on Inverter While Driving

Reply #48 – October 08, 2015, 05:57:47 pm

This isolator would match up nicely with the above alternator, and has the exciter post for the ignition wire for Delco type alternators.

If upgrading, I would recommend at least beefing up the wire from the alternator to the isolator, and wire from the alternator to ground.

270 amp isolator with ignition post

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