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Old 05-01-2014, 09:06 PM   #1
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Understanding house batts and charging them

SO, I got 4 new Trojan house batts a couple of months back. 440 total AH at 20 amp draw; that's the rating. Of course that's really only 220 cause I can only draw them down to 50%, right??

So last night I pulled about 9 amps total for just 3 hours. Even though the starting voltage was over 13 V, the batts came down to 12.2 (50%) after those three hours. What's up with that?? I figured at a 10 amp draw that 220 AH should last at least 22 hours; do I misunderstand something??

Then even though I drove 9 hours today (which I thought would fully charge the house batts), as soon as I plugged into shore power, the Magnum went into bulk charge mode at 26 amps.

I also ran the genset a couple hours this AM. Shouldn't that have been charging the house batts as well??

I'm really confused.

Boowho??
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Old 05-01-2014, 09:22 PM   #2
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Boohoo, The way I understand it and in my experience, the only way that the house batteries will charge when you are driving, is if you have the generator on. The house batteries will not charge from the alternator. As for the draw down, I assume your house batteries were fully charged when you stated. I would take a hydrometer test of the batteries and see if they are okay. As you may or may not know, all of the batteries will seek the lowest output level of the weakest. This is why they suggest that you equalize your batteries periodically. If you have the new inverter remote, it has an equalizer setting on it. If you have the original inverter remote with the 6 lights, you can not do this. Hope that helps. Craig
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Old 05-01-2014, 10:06 PM   #3
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Boohoo, if I remember a prior post you had concerning batteries, I believe you said that you set your charging rate to 30% to keep the batteries from gasing. If that was you, did you raise it when you tried to charge them with the genset in the AM? Side note: After I saw that post, I also set my charging level to 30%, that is the only reason I remember this posting. Craig
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Old 05-02-2014, 08:47 AM   #4
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Boohoo, if I remember a prior post you had concerning batteries, I believe you said that you set your charging rate to 30% to keep the batteries from gasing. If that was you, did you raise it when you tried to charge them with the genset in the AM? Side note: After I saw that post, I also set my charging level to 30%, that is the only reason I remember this posting. Craig

Good point.... No I did not..... Thinking that the alternator would charge them as I drove.

Still, I think I should get more than 3 hours at 10 amp draw (on fully charged batts)..... I will try the 100% next time I charge from the genset.

Other interesting thing (unrelated, I hope) is that this morning it was quite chilly here in Colorado, and my thermostat was alternating between HP and FURN (every few minutes), even though I had set it to HP. Gremlins, I guess...

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Old 05-02-2014, 09:04 AM   #5
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Bill/Craig,
I was under the impression that the alternator charges the house batteries as well as the chassis batteries. I don't know where I heard this but that is my understanding.
Tom
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Old 05-02-2014, 09:43 AM   #6
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Tom, I have some memory of that post, but I thought it was about the genset first charging the house batteries and then the chassis battery. I didn't think that was possible either. I will have to research that more. Craig
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Old 05-02-2014, 09:55 AM   #7
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Tom, I think it was Hallen1 post to Phil a couple of months ago:
Quote:
Originally Posted by Phil57
I think you just left FR when I got there last Oct 28. Andy and Warren were telling me about the AGM batteries. I almost went for them but didn't. We had the old controller boil the old batteries twice and had to paint the compartment. Hopefully the new Magnum controller will help avoid that mess. It will be interesting to see how the AGM hold up. Do you have the new or old controller?
Phil57:

I ask your patience on this request for comments and/or info; it sounds to me like you have studied this topic to the nth degree, and might be able to help me.

I was out to visit Randy and Mitch for minor warranty issues earlier last fall, and asked why my house batteries discharged while going down the road with the inverter turned on and no load (but not when the inverter was off).

Their highly capable inverter tech/electrician gave me a rundown on the operation and design of the inverter, and I learned that:
The inverter with no load will draw power from the batteries
The alternator charges the chassis batteries first, then the house batteries second while driving
The reverse is true when not driving, and hooked to shore power
Holding the spring loaded "alt start" switch down will reverse this order
Confirmed that the inverter will provide AC power to only the non-GFCI outlets

The tech didn't address the advanced issues/settings mentioned elsewhere in this thread. I have the house batteries on charge full time, and they don't boil over, but they do need a little distilled water once every couple of months.

Do you have any specs and mfg/model info for the AGM batteries Randy has? I assume they are 6V and hook up in the same fashion as the ones that come out (two in series, and the two pairs in parallel).

What is the difference between the "old" and "new" Magnum Inverters? How/where do I change the inverter settings for the new AGMs?
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Old 05-02-2014, 09:58 AM   #8
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Quote:
Originally Posted by tmmar View Post
Bill/Craig,
I was under the impression that the alternator charges the house batteries as well as the chassis batteries. I don't know where I heard this but that is my understanding.
Tom
Tom, you are correct. The engine alternator will charge both the starting battery and the house battery bank through the BCC (Battery Control Center) provided everything is working as designed.
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Attached Files
File Type: pdf BiDirectional Isolator Relay Delay.pdf (105.0 KB, 42 views)
File Type: pdf Battery Control Center Information -1.pdf (1.34 MB, 47 views)
File Type: pdf Battery Control Center Information -2.pdf (400.2 KB, 39 views)
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Old 05-02-2014, 10:22 AM   #9
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Herk,
Lots of good info.
Thanks,
Tom
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Old 05-02-2014, 11:08 AM   #10
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Herk, Thanks for the info. Now I have to see and/or find out if I have one of these and if it is installed correctly and working. I'm pretty sure, if I do have it, it has never worked. Give me something to do in my spare time.

Other Berkshire Owners??? Does this system work on your unit and do you know where it is located. Boohoo - I think your is not operational or you don't have one.

Craig
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Old 05-02-2014, 11:10 AM   #11
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The FR Schematic and the SDC Schematics HERK provided, definitely apply
to a gas chassis, however I would check with FR to confirm their application
to a diesel chassis.

Gary
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Old 05-02-2014, 07:30 PM   #12
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I seem to see the same behavior that Boohoo does, and what SuperChief is describing...that the alternator won't charge my house batteries. However, I read the cross post from the factory visit (in this thread), and I also read in the manual that the alternator would charge the house after the chassis battery while driving!

Now I'm going to have to dig into the PDFs posted just above me to see if mine is installed/working correctly. Something is certainly seeming to not charge the batteries, or to drain them. I just parked from driving most if the day, and with everything off, my batts show 12.4 volts. That should be higher, imo.
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Old 05-02-2014, 08:17 PM   #13
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Originally Posted by chesterhull View Post
I just parked from driving most if the day, and with everything off, my batts show 12.4 volts. That should be higher, imo.
I agree....... When my batts are completely charged (from the Magnum inverter/charger) they are at 12.7+ volts. I would think that 8-9 hours from the chassis alternator would do the same thing.

And I'm still curious as to why my batts willl drop from 12.7+ to 12.2 after running the inverter for less than 4 hours at a 9 Amp draw. I previously thought that it was because my original batts were completely "cooked", but now I have 4 brand new Trojans and I still don't get the capacity I think I should.

Guess I'll try equalizing next, but since the batts are less than 3 months old, I doubt that will help.

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Old 05-02-2014, 08:55 PM   #14
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I had an issue with my 2014 berkshire chassis batteries being dead after my coach sat for a few weeks (plugged into a 50amp plug at my house). I brought it in to service and they had to call Randy to figure it out. Randy sent them the info and my isolator was bad. Like all the previous posts stated, your chassis batteries charge after the house batteries are full if plugged into shore power or gen set running and the opposite while the coach is running. This was what Randy told me over the phone and also told my service place. Hope this helps

Jason
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Old 05-03-2014, 10:50 AM   #15
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Been doing some research after Janson's post about the bad isolator. I looked on the internet for a picture of a isolator, so that I could find mine. Thought I could find it from the pictures that I saw. I just went out to my unit and found this;Click image for larger version

Name:	ImageUploadedByForest River Forums1399131624.856895.jpg
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ID:	51493. Nothing like I had seen on the internet (Fin looking things with three wire posts). I also looked at the wiring diagram on the inside of the door to the inverter compartment:Click image for larger version

Name:	ImageUploadedByForest River Forums1399131746.485742.jpg
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ID:	51495. Have I found the right thing? Also how do you test it to see if it ok? I had thought to test to see if my charging system worked both ways, was to discount shore power, start the engine and see if the alternator was sending a charge to the inverter/charger to charge the house batteries. My only concerns there: 1) how long will I have to run the engine before the alternator has the chassis batteries charged to start charging the house batteries, and 2) Does the alternator charge even pass through the inverter/charger when and if it charges the house batteries? Any ideas would be appreciated. Thanks! Craig
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Old 05-03-2014, 12:25 PM   #16
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Here is the Isolation Manager document: Click image for larger version

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ID:	51499Click image for larger version

Name:	ImageUploadedByForest River Forums1399137840.553903.jpg
Views:	146
Size:	49.8 KB
ID:	51500. In looking at some Internet posts about problems that others were having with this system, they traced out the ignition wire from the Isolation Manager was not connected. Going to trace mine out.
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Old 05-03-2014, 02:52 PM   #17
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Craig,
Hopefully it will just be a matter of connecting the wire. Hope it is that simple and an easy fix.
Tom
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Old 05-04-2014, 12:54 AM   #18
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I don't think my house batteries get charged by the alternator at all. I think those two systems are separate unless you hold down that switch on the front panel.

Boohoo, on the expected output of the batteries...the voltage does not drop linearly with the total current output. So, you will see a voltage drop down into the design range with a smaller total amp-hr draw, then it will stay in the design voltage range for a long time, getting the majority of the rated amp-hrs, then the voltage will fall more dramatically when the batteries become rather depleted. I'm sure Herk will chime in if I'm not remembering this correctly (disclaimer: I am a trained civil engineer with limited electrical knowledge)
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Old 05-04-2014, 07:19 AM   #19
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You kids have everything. I did not get a electrical diagram with my 2008 39QS. I have to trace out the wiring and figure it out for my self. I also have two mystery fuses coming out of a black box in my Magnum compartment.
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Old 05-04-2014, 08:20 AM   #20
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Any ideas would be appreciated. Thanks! Craig
Check for corrosion under the terminals before you buy a new one.
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