Setting your Trace Auto Gen Start Parameters

[davidbrady]

So true Al.

[cubeman]

(11-09-2018 20:12)davidbrady Wrote:  I've been drydocking for two weeks. The auto start feature of the Trace SW4024's is factory default set as follows:

24hr: 24.6V
2hr: 23.6V
15min: 22.6V

The generator will start if the battery voltage is below any of the above three parameters for a time greater than that above. The problem is these values will allow your batteries to discharge far below 50% before the generator starts.

Here are the SOC vs OCV (open circuit voltage) values for the Lifeline AGM:
60%: 24.6 VDC --- Trace 24hr genny start timer begins
50%: 24.36
40%: 24.12
30%: 23.88
20%: 23.64 --- Trace 2hr genny start timer begins
10%: 23.4
0%: <23.16
-- Trace 15min genny start timer begins

The problem I've been seeing is the batteries are being discharged to well below 50% and as low as 20% before the generator is auto started. Turns out the default factory generator settings aren't suitable.

If the discharge rate is between 10 and 20 DC amps, which is our expected load when not running air conditioners, then in my case with an 800 A-hr battery bank, the batteries will be discharged to 50% in 20 to 40 hours. This doesn't line up well with the factory auto genny start parameters. Say we're in the middle at an average 15A DC draw. The 24hr timer will begin at 60% SOC which will be after 21 hours. When the timer expires 24 hours later my battery bank is well below a 20% SOC which is terrible for the longevity of AGM's. What happens in my case is that when the 24 hr timer is around the 20 hour point the 2 hour timer kicks in and the batteries start at a SOC slightly below 20%, which is still bad.

The matter is even worse if you're using a battery which isn't quite as high performance as a Lifeline such as an East Penn. These batteries all have SOC vs OCV values which are a good 0.1V above the Lifelines which means the default Trace auto generator start timer parameters will leave these batteries even further discharged.

The answer is to configure you generator start timers to start at higher battery voltages. I view the 24hr timer as a no load genny start parameter allowing the batteries to be topped up every now and then during periods of non use. The 2hr timer is the one I consider to be the most effective for our typical use case. The 15min timer is for cases of heavy draw, air conditioners for example, where you want the generator to start almost immediately. I have my auto gennerator start configured as follows:

24hr: 25.0V
2hr: 24.6V
15min: 23.6V

The important change is bumping up the 2hr voltage to the battery's 50% state of charge voltage level.

Changes have been made David and Tyler from Tradewinds who worked for Vantare Agreed Thank you brother Vantare Owner , lol

---

(11-09-2018 20:12)davidbrady Wrote:  I've been drydocking for two weeks. The auto start feature of the Trace SW4024's is factory default set as follows:

24hr: 24.6V
2hr: 23.6V
15min: 22.6V

The generator will start if the battery voltage is below any of the above three parameters for a time greater than that above. The problem is these values will allow your batteries to discharge far below 50% before the generator starts.

Here are the SOC vs OCV (open circuit voltage) values for the Lifeline AGM:
60%: 24.6 VDC --- Trace 24hr genny start timer begins
50%: 24.36
40%: 24.12
30%: 23.88
20%: 23.64 --- Trace 2hr genny start timer begins
10%: 23.4
0%: <23.16
-- Trace 15min genny start timer begins

The problem I've been seeing is the batteries are being discharged to well below 50% and as low as 20% before the generator is auto started. Turns out the default factory generator settings aren't suitable.

If the discharge rate is between 10 and 20 DC amps, which is our expected load when not running air conditioners, then in my case with an 800 A-hr battery bank, the batteries will be discharged to 50% in 20 to 40 hours. This doesn't line up well with the factory auto genny start parameters. Say we're in the middle at an average 15A DC draw. The 24hr timer will begin at 60% SOC which will be after 21 hours. When the timer expires 24 hours later my battery bank is well below a 20% SOC which is terrible for the longevity of AGM's. What happens in my case is that when the 24 hr timer is around the 20 hour point the 2 hour timer kicks in and the batteries start at a SOC slightly below 20%, which is still bad.

The matter is even worse if you're using a battery which isn't quite as high performance as a Lifeline such as an East Penn. These batteries all have SOC vs OCV values which are a good 0.1V above the Lifelines which means the default Trace auto generator start timer parameters will leave these batteries even further discharged.

The answer is to configure you generator start timers to start at higher battery voltages. I view the 24hr timer as a no load genny start parameter allowing the batteries to be topped up every now and then during periods of non use. The 2hr timer is the one I consider to be the most effective for our typical use case. The 15min timer is for cases of heavy draw, air conditioners for example, where you want the generator to start almost immediately. I have my auto gennerator start configured as follows:

24hr: 25.0V
2hr: 24.6V
15min: 23.6V

The important change is bumping up the 2hr voltage to the battery's 50% state of charge voltage level.

Changes have been made David and Tyler from Tradewinds who worked for Vantare Agreed Thank you brother Vantare Owner , lol

[cubeman]

Question ? If 1 invertor reads Float and the other Charge do I have a issue ?

[davidbrady]

No. You don't have a problem. That's a common scenario. The thing is our dual Trace inverters aren't working in Parallel or Serial fashion using the DB25 pin cable to connect the two. They're simply two independent inverters both charging the battery bank. Inevitably one inverter will transition to float before the other an you'll end up with one in Float and one in Bulk. This condition is somewhat short lived in that the inverter in Bulk should transition when it's bulk/absorption timer expires. If you want to speed up the process you can reach into the Charge menus and decrement the Absorption timer for the inverter still in Bulk. At some point the red LED will go out and the inverter will transition to Float, then you can set the Absorption timer back to it's default of 3 hours.

[cubeman]

thank you . No need to change just knowing is good enough . Well we left Palm Beach and are now in NC . Lets just say in 1 day we went from 85 to 34 degrees. Ok , time to check out these Heat options .

[davidbrady]

Al,

The dual Trace inverters get even more interesting when you're traveling with the generator running and all the Cruisair AC's running. In this case you may notice some strange amperage draw from your inverters when one is in Float and the other is in Bulk. Before I travel I'll often set the Bulk/Absorption timers in both inverters to something extraordinarily high like 8 hours, or my expected daily driving time. This way both inverters will stay in Bulk for the full duration of my driving and generator runtime for the travel day. Keeping them both in Bulk means that they try to keep the battery bank voltage at 28.6V which is also what the 50DN alternator is doing, and more importantly it means that the generator is fully supporting the load of all the air conditioners. If you don't do this what you'll find is one inverter in Float and the other in Bulk. The one in Float wants to pull the battery voltage down to 26.6V but the 50DN and the inverter in Bulk are happy to keep the battery bank at 28.6V. An inverter can attempt to pull the battery bank voltage down by powering loads. Since you have plenty of loads, 4 cruisairs, the inverter can easily accomplish what it wants, so what you'll find is a positive inverter amperage on the inverter that's in Bulk and a negative inverter amperage on the inverter in Float. IOWs, the generator isn't powering all the air conditioners. You'll see that the Float inverter is actually powering one or more of the air conditioners using battery power. Confusing, I know, but when you see it you may now have an idea of what's going on.

[cubeman]

your going to need to give me some time to ABSORB lol all this David . For now I'm working on a squeak issue when bouncing . Thinking maybe I'm ridding a little low but there is no damage to metal ? Norgan Valve Maybe , still in the research mode . Man do I love this coach

[davidbrady]

Most coaches at this age need suspension bushings. At a minimum you probably need anti-sway bar dog leg bushings. These are notorious for wearing out early. Also, I'd probably dig in and replace all the shock absorbers. Just put OEM back on. They're good for around 40K miles. Some folks go to Koni's but I think they're too stiff. It's always a compromise between handling and ride and I always trade off for a good quality ride. Your preferences may differ.

Also, if you have Prevost adjust the ride height be sure to check your owners manual for the proper height and insist they set it to that height. They often don't get this right!

[cubeman]

thank you David for the reply . I guess the ride comes at a bit of expense and annual front end work . I think I read the anti-sway bushing wear out yearly if you put enough miles on them . Seems they take a beating . As to ride height you would think Prevost shops would know that number . I think I remember reading it is 12"+- .

Now as to your statement quality ride vs handling ? I would say I would prefer a better handling coach for construction areas and bad roads .

[davidbrady]

Al,

I went over here: https://techpub.prevostcar.com and I put in 1997 (chassis year), 45' motorhome conversion, XL, and I got the below manual which says all airbags should be 11.5" +-0.25". I set mine to the lower end of this window for a more planted feel. There's a ton of documentation on the PrevostCar website for all of our buses.

PrevostGurus->ForumTools->Library->Other->XL_Maintenance_Manual.pdf

Don't let them set it to 12", they did on mine and it was amazing how topsy turvy the bus became.

One time I went to Prevost in Goodlettesville, Tn and the shop Foreman argued with me over what weight capacity steer axle SpongeBob has. I said it was 18K, he said "no it isn't", I said "yes it is", he said "no it isn't". You can imagine how long this went on. LOL! So he grabbed me and we went to the bus where he enjoyed a little crow in the morning. Another time they were going to install new steer axle air bags. The techs already lifted the bus and started removing the old stuff. I took one look at the tiny air springs they brought out and I said, "stop, those won't work on my bus", again... a bunch of head scratching on their part before they realized I have an 18K lb steer axle. They went to parts and guess what? No air springs in stock for my axle! Glad I stopped them! You need to stay on top of things when you have them do work on your bus. It's a wonderful resource and I really don't think there's room for excuses, but they have a lot of different bus models and a lot of different springs and axle setups and the techs don't have it all in their heads.