Electrical problem

[Webz]

Evey now and then, when there is a large electrical load, the ceiling lights will flicker and the voltage will drop to 10.1 volts on the panel in the front overhead cabinet. Then it bounces back to 12.6 volts. During the low voltage, the inverter switches to inverting. When the load drops, the inverter goes back to float charging.
Every month I check the house batteries, clean up the posts and add distilled water as required.
I'm thinking (which gets me in trouble) there's a continuity problem with the battery cables. I've seen cables corrode under the insulation. Would bad battery cables cause the problem I'm having? Or is it something else.
I'm open to any suggestions. TIA

 

[Joe Hogan]

What is causing the load? Is it a motor, a/c or refrigerator? During startup these pull large amounts of current.

 

[Richpatty]

So this occurs when on shore power and the inverter flips to “inverting” when a large load comes along? And then back to float? That is odd. Why would the Magnum flip from charging to inverting while plugged in?

Am i reading that right?

 

[Webz]

Heavy load is 2 or 3 ACs running, clothes dryer running, AC heat on the Oasis heating water. Maybe dishwasher running also. Then use the microwave.
Plugged in to 50 Amp.
I know that is a large demand on the electrical system.
Just started having problems recently.
Going to replace the batteries and the cables. Been looking for an excuse to go to AGMs anyway. Tired of cleaning batteries and adding water.

 

[Richpatty]

Ok. This actually makes sense now. What may be happening is the precision circuit load manager is sensing that you are maxing out the 50amp connection and startinfo to shed load….and the Magnum charger is being dropped off to save amps. Then the load drops, it allows the magnum to come back online and resume charging. If this only happens at times of high 120 v load, then I don’t think it’s your batteries or cables.

my 2 cents

 

[Joe Hogan]

Interesting to know what the load is as a 50amp circuit is "only" 6000 watts per leg. The loads are separated between L1 and L2. If you exceed the load on one leg it sounds like the Invertor is taking up the shortfall automatically. The voltage drawdown is what I would refer to as normal for an acid battery bank take on a large load. AGM probably won't be much different.

 

[Webz]

Thanks for all the info. Shedding makes sense. But I'm still replacing the batteries and cables. They look bad. Even the four copper tie bars are getting thin from corrosion eating at them. May be some voltage drop due to poor connections between batteries.
Batteries on order. Got 1/4 inch thick copper bars for replacement. Using 4/0 cables to go from the batteries to the coach and 1/0 cables between the batteries.
It will be better not having the off gassing from the lead acid batteries.
Thanks again. I'll let you know how it works out in a few days.

 

[Old-RV'er]

Ok, not engineer, but a 50A connection is two/120VAC hot leads at 50A each, for a total of 100 amps, quite a bit more than 6000 watts per leg for total of 12,000. FWIW-That is about half of a normal house incoming load. FWIW2-I had the same experience as OP, but I was plugged into 30A, and although no A/C use, we were using the oasis electric element and heat pumps occasionally. The system seemed to work as advertised.
Yes, fan of AGM's, but just aint going to spend money now, will wait until batteries are 4 years old first. Don't believe it's your batteries anyway, believe you should make sure the park pedestal is really a dedicated 50A plug, and not some hosed together 30A jury-rigged thing. I have seen lots of those for sure. Normally they bring in true 50A circuit, and pull the 30A connection off one side of the hot leads, but in some older parks, what is behind the cover of the box could be anyone's guess. Before you spend money, hook up to known good power and see if issue happens again.

Also , if handy with tools, I personally would make sure all the 120V circuits are tight in the box, I did that couple months ago, none were lose, but i was able to tighten a few which were not as tight as they should be. Their is a torque value for them, amazon sells a good 1/4" drive torque driver which will assist you in checking them. Ensure all power is off, unplugged from shore power, master chassis and house switch are off.

 

[Webz]

Batteries are over 4 years old.
We've been at this same park for over a year, unfortunately.
Got a Progressive Industries EMS at the pedestal and it shows no errors now and no past errors. Haven't had this problem until a couple weeks ago when it started getting above 90° Even if the batteries and cables are not the problem, they are being changed. Tired of the monthly maintenance and the corrosion.
Thank you for the food for thought.
I'll post here the results in a few days. I'm guessing it will take me two days to clean and replace everything on my list.
While there is no power, I'll check the transfer switch to make sure all the lugs are tight.

 

[Old-RV'er]

Well, now I know "the rest of the story". Call Lifeline Batteries, Southern, CA. See if he will give you the alpine discount, or a veterans, old age, something kind of discount. When I changed my in the other MH, I took pictures of how they were wired, as they will take out the old ones and put in the new ones, but will NOT wire them up. That may have changed (at factory shop). They have distributor network, and I was very pleased with mine. Other folks make them as well, but cannot say who, as have not researched them. Let us know what you end up with please and how happy you are with whom did it for you, if you don't do it yourself. You can take all the jumper wires/bars and dump them in a baking soda/water solution and that will clean them off the corrosion I think. Then use NO-OX-ID-Special A dielectric grease on all the connection points and any corrosion won't be issue.

 

[Webz]

Replaced the batteries, copper bars and cables. I did install AGMs. Got so tired of the corrosion the flooded lead acid batteries caused. Used 1/4 inch thick copper bars instead of the 1/8 or 3/16. You can see in the pic how much corrosion ate away the old bar. Also used 4/0 cables instead of 2/0 and 3/0. The old cables had 3 to 6 inches of corrosion under the insulation.
I would strongly recommend using welding cables instead of battery cables.
Welding cables are made up with thinner strands making them more flexible. It's not too noticeable unless it is on the long wires going from the batteries to the coach.
First time in a long time the batteries showed having over 14 volts.
This was a two day job due to cleaning the battery tray.
Going to call Magnum today to change inverter/charger from lead acid to AGM.

 

[Neal]

Nice job @Webz. I'd love to see a dedicated write-up on this job including what you bought, where to get it from, etc. as others are soon to follow including self. I know @Chuggs recently replaced his, would love to get detailed stories of the job for others to learn from if you have time at some point.

 

[Webz]

Bought the batteries and cable at O'Reilly's. Got the terminal ends on Amazon.
Used dielectric grease on all connections including in the lugs prior to crimping.
Before I started, I put the wife in a hotel since we are full-time and it is hot here.
My biggest concern (worry) was damaging the inverter. Turned off every breaker I could find plus salesman switch, chassis batteries and unplugged from shore power. I did disconnect the positive cables first. It took longer to clean the battery tray and paint it than anything else. Originally I hadn't planned on replacing the long cables. Thought I could cut the ends off and replace the lugs. But the corrosion ran too far up the cables.
I'm so glad I took pictures but what also helped the most was numbering the old and new batteries. I put labels on each end of every cable that had the battery number as well as positive or negative. Then I did at drawing showing how many cables are on each terminal. This saved me. Thought I was finished until I looked at my drawing and saw one terminal was missing a cable. At first I didn't see any other terminal that was missing a cable. Looked at it a third time and found another terminal short one cable. Went through the old cables and found the one I missed making.
I guess the important thing is to take your time.
If anyone has any questions about what I did, I'll do my best to answer them.