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Old 07-05-2019, 03:17 PM   #1
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Low SOC after trip Alternator charging

Hello Everyone,
this post is not so much for a question as it is more an entertaining read for you in my trouble shooting path for the discharging of my chassis and house batteries after a trip.
Couple infos first A) I have never seen another alpine or peaked my head into the battery bay and B) I have just recently changed it over to Lithium batteries, I own it since Feb of this year (2019).

On my first test run using my new installed Lithium batteries I was a bit surprised that the voltage was much lower arriving at our destination ... must have remembered the state of charge wrong - I thought.
On the next trip I placed my Ipad on the dash showing the Victron app ... oops while driving I have a negative current draw of 12-20A depending with what I am playing around like driving lights on/off, dash AC etc. all gets picked up.
Chassis voltage is reported between 13.0 and 13.2 V rather consistent and my house battery is at 13.5V declining. I consumed about 160Ah on the trip and was worried and curious what would happen if the battery hit 13.2V.
On the way home it did and at that time the current draw dropped all the way to 0 and bouncing to +2A. O.k. somewhat relived I knew my alternator was charging ... but something was wrong.
I have the original Leece Neville 160A alternator that I thought I just have to replace with the 200A Delco.
I then learned that this alternator is self exciding (so a one wire set up) and needs to see the battery voltage ... interesting I also have a battery isolator, the correct one with the ignition terminal.

So why would I have a battery isolator if the VMM will combine the batteries for charging? On top of that the isolator is a diod version loosing 0.7V across from alternator voltage to batt voltage.

Next I placed the alternator charge wire directly on the chassis batt pole and voila 60A charging current into the batteries with the coach running in idle.

Looking at pictures posted here for battery bays I did not find a battery isolator on the later model year coaches using the multiplex system. And knowing how the Vansco uses the trometta it makes complete sense to me that it is not necessary ... I guess someone else thought different.

So today I took it out. For a second I toyed the idea to replace it with a FET MOS isolator (no voltage drop) but reading more posts from long time owners here I made the decision to take it out.

If I have a question then it would be: where is the original landing of the alternator charge wire? at the starter or somewhere in the battery bay?

Thanks for reading all the way to the end.
Joerg
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Old 07-05-2019, 09:09 PM   #2
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Joerg,

I have not dissected the battery wiring on my coach. My rudimentary understanding of the 12v charging in a VMM equipped Alpine leads me to believe that the charging voltage/current from the alternator would terminate at a post in the battery compartment that is tied to the +battery post as well as one side of the trombetta.

To rehash the charging protocol, with the engine running and the alternator providing a charging voltage/current to the chassis batteries the trombetta remains open until the chassis batteries are sufficiently charged. At that point the trombetta closes, allowing the charging voltage/current to charge the house batteries. The procedure is reversed when on shore power.

I suppose all batteries could be charged simultaneously from either the alternator or the shore powered charger without the need for a battery isolator.
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Old 07-05-2019, 09:33 PM   #3
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RVPioneer,
Yes I think so too you are correct the isolator is not necessary. It caused a big problem as it creates a voltage drop of 0.7V from the alternator to the battery. Because the system voltage was reported right above 13v shortly after starting the engine the VMM energized the trombetta via output 19 and that in turn now depleted my higher charged lithium battery until it also had only 13.2V. Current flows from the higher potential to the lower.
I have now tested that I can get up to 14V out of the alternator at that voltage the current delivered to the batteries gets rather low - I am happy with that as it prevents the lithium’s from overcharging on longer trips automatically.
I can really recommend the Victron BVM 712 battery monitor. Without it I would have never figured this out. You will get such a better understanding how much power is used for what. Fridge, fans, lights, water pump, and you see the real capacity taken from your battery bank ... overall very cool.
The wire from the alternator is long enough that it will reach to the chassis main positive post in the battery compartment I think I will connect it there. Function wise it will be fine I think.
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Old 07-06-2019, 11:31 AM   #4
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Low SOC after trip Alternator charging

Joerg, you should consider joining ACA (Alpine Coach Association and ACE (Alpine Coach East). ACE has over 20 members east of the Mississippi, and we usually get together 2 or 3 times a year. Since WRV was based in Yakima, WA the western chapters have many more coaches in their membership. If you want more information PM me. ACA and ACE are FMCA sub chapters. There is at least 1 other Alpine owner (2000) in Kentucky, greenmachine in Boston, KY, about 100 miles from you, PM him. You can also look at the Alpine Register in the stickeyís above to get the latest list of those Alpine owners that have submitted their information for inclusion in the register. I sort the list by VIN and by state so you can easily look up local Alpiners or by the year. I will be sending out an updated list in the next 2 weeks.

As far as the SOC issues, tell us about who installed the Lithium batteries and inverter/charger (brands and models) so we can give you more information. There has been at least 1 and IIRC more, threads about converting from the Leece Neville to Delco alternators including the proper wiring, you might want to search for those.
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Old 07-06-2019, 12:36 PM   #5
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Thanks Dave,
I found one other Alpine owner right here in Cinci, I have not contacted him yet.
I looked at the list in Feb before I bought my Alpine to see if the former owner by chance was a member here ... unfortunately not. However I did get a hold of him and was able to obtain some information about my coach.
He mentioned he had issues with the batteries and that he "had all that rewired". Well now I know what was rewired. A RV technician will assume that the trombetta is just actuated by the boost button... I think that would be normal for coaches of that area. Naturally they probably suggested adding a battery isolator. What they did not understand is that without a sense wire directly going to the battery the alternator will have very limited charging capability as the regulator cannot see the batt voltage.
Anyways I did read about every thread for the Delco Remy 28SI 200A upgrade and when mine fails I will upgrade then as it is properly working as of yesterday.
I installed the Lithium upgrade and also all the BMS features and added 500W of solar to the 120W already existing panel. All worked great on the last trip and I love this coach.
Link here:
http://www.irv2.com/forums/f104/upgr...es-440941.html
Joerg
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Old 07-10-2019, 04:43 PM   #6
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Joerg,

Youíre clearly at the head of the class on this topic. I did not intend to imply that the battery isolator should be eliminated. In fact, sometimes when I have nothing else to think about, I wonder if control of the isolator should be taken away from the VMM.

My daydream goes like this. When driving the isolator would be in the open position at all times. This would allow the alternator to charge the chassis batteries and then it could more or less take a break. Since the alternator isnít the ideal tool for charging a bank of deep cycle batteries, why use it for that purpose? Lithium may be more tolerant of a less than perfect charging protocol, but most of is still have LA or AGM.

When AC power is available the charger would charge the house batteries. The isolator could be closed at this point or left open until the house bank is fully charged. Once charged, the isolator would then be closed (automatically or manually) in order to maintain a charge on both banks.

I have no idea if this would work or how to make it happen.
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Old 07-16-2019, 03:49 PM   #7
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RVPioneer,
The part that I took out looks like this.
Attachment 253459

The VMM has still control of the relay that connects both batteries. Silver Leaf calls this the charge bridge. I really like that term as it is so clearly describing its function.
Anyways the Lithium can cause a problem for the alternator as it is very ďabsorbentĒ of all the power there is if it is low on charge. This means you can blow up an alternator quickly.
Just as you described above I was also thinking to take the control of the VMM out.
There is a device made by Victron that I like itís called the Cyrix. It is also good because I have two different battery chemistries for the house and chassis. And it can manually connect the two (think boost switch).
It is smart enough that the software will inhibit a constant on - off loop that some have described as a VMM symptom. Also it protects itself by monitoring its temperature.

Here a tip ... if you want to charge your chassis battery while the house is charging set the ignition switch to ACC the VMM will connect the two.
Joerg
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Old 07-16-2019, 05:44 PM   #8
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I think the picture did not upload
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Old 07-17-2019, 10:29 AM   #9
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Are you concerned about the max alt amps rating of 130 with a 160A or 200A alternator?
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Old 07-17-2019, 11:04 AM   #10
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Mine is a 160A. But it is not protected in any way and all ratings are really not continuous duty. So at the moment I am still looking what a good option is to limit the output. There is a company in England that throttles the alternator output by monitoring its temperature. Thatís good but if I remember right it was expensive. The VMM connects both batteries and at that moment I have no control (but visibility) how many amps flow into the lithium battery. The bigger the battery the higher the risk of blowing up the alternator.
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