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07-29-2021, 10:44 AM
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#1
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Winnebago Camper
Join Date: Oct 2019
Posts: 47
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Equalizing batteries blew Norcold fuse???
I have a 2019 Class A gasser and decided it was time to equalize my house batteries. The Magnum unit I have has a nice 5 stage charger and you manually request an equalization cycle. I have 800Ah worth of wet cell batteries. About 2 or so hours into the process, I went to check on it and noticed my fridge was dead as a doornail. Checked the breakers (ac and dc), nothing tripped. Read up on the Norcold and discovered there is a 5A fuse on the controller board. Checked that and sure enough it was open. I replaced it and all was well. But I have to correlate the equalization cycle to the blown fuse, too much of a coincidence. I don't know why raising the DC to 15 volts would increase the amperage to the board, but in the future I plan to shut down the fridge before any equalization request. Just an FYI.
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2019 Sunstar LX 35F
2000 Jeep Wrangler TJ toad
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07-29-2021, 10:53 AM
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#2
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Winnebago Master
Join Date: Nov 2018
Location: Pflugerville/Austin, Tx
Posts: 8,359
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Ohm's law?
Current it voltage divided by resistance, so if you increase the voltage while resistance stays the same, current will increase.
One of the points folks don't think far enough on when making changes to their electric.
__________________
Richard
Why no RV year, make and floorplan on MY signature as we suggest for others?
I currently DO NOT have one!
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07-29-2021, 10:54 AM
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#3
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Winnebago Master
Join Date: Feb 2020
Posts: 887
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Quote:
Originally Posted by steved28
I don't know why raising the DC to 15 volts would increase the amperage to the board, but in the future I plan to shut down the fridge before any equalization request. Just an FYI.
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E=I*R or I=E/R, E being volts, I is current and R is resistance. So when the voltage goes up, so does the current.
But it does seem that the rating on the fuse is pretty tight if going up a few volts from normal is enough to blow it. But maybe the circuitry can't stand more voltage and the rating is tight to protect it.
David
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07-29-2021, 11:19 AM
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#4
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Winnebago Camper
Join Date: Oct 2019
Posts: 47
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Quote:
Originally Posted by Morich
Ohm's law?
Current it voltage divided by resistance, so if you increase the voltage while resistance stays the same, current will increase.
One of the points folks don't think far enough on when making changes to their electric.
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Yes, thanks. I just thought that the board would not "accept" any more current, i.e. resistance would be increased.
__________________
2019 Sunstar LX 35F
2000 Jeep Wrangler TJ toad
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07-29-2021, 01:23 PM
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#5
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Winnebago Master
Join Date: Nov 2018
Location: Pflugerville/Austin, Tx
Posts: 8,359
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But on the other hand, it DID NOT accept it and the fuse did blow to show that!
I do not see resistance as a moving target but something that we can measure and set as a known quantity if we do not change some of the components, etc.
But on the good side, the fuse did blow and save the rest of the circuit, so the design was right for the normal voltages of cars which rarely go above 14 volts.
So if the norm we think of is 12V and we can get away with pressing it a bit to go with 14 for quicker charge, going to 15 may just be a bit too far if the frig is designed to work on 12 and a bit more for safety.
Folks who sell things do not always go into the hazards involved in some of the "added benefits" they sell!
I'm not a designer, so no real idea but it does sound like the "equalization" may not be a well proven item. Voltage increased by 25% over speced voltage sounds a bit too much to me.
Is there a good explanation of what equalization is supposed to do for the batteries? I've never heard it used before.
__________________
Richard
Why no RV year, make and floorplan on MY signature as we suggest for others?
I currently DO NOT have one!
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07-29-2021, 02:44 PM
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#6
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Winnebago Master
Join Date: Feb 2020
Posts: 887
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Quote:
Originally Posted by Morich
Is there a good explanation of what equalization is supposed to do for the batteries? I've never heard it used before.
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Aha, I get to spout off again!
Equalization is well known in the boating world that I come from. Standard, flooded cell lead acid batteries- the ones with the filler caps, tend to let the lead sulfate that is produced when they discharge, slough off of the plates and settle out at the bottom of the battery instead of staying on the plates, particularly if they sit discharged for several days at a time.
Equalization raises the charging voltage to 15+ volts and causes electrolyte disassociation or "boiling" which off gasses H2 and O2 on opposing plates. This off gassing stirs up the electrolyte and puts the lead sulfate back in suspension where it can be converted to sulfuric acid and lead which increases the state of charge.
I am not a fan of it and have rarely used it, but most FLA manufacturers agree it helps return a battery to full capacity. A moderate size solar panel like the 100 watt I have on my MH can easily charge up a partially charged battery in a few days and keep it topped up.
David
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08-04-2021, 06:54 PM
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#7
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2002 Journey WPK36GD
Join Date: Dec 2017
Location: NE, Indiana
Posts: 209
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Equalization
Indeed, as DavidM said " Equalization is well know in the boating Flooded Lead Acid world, and as he said it take the batteries up to ≈15VDC and "stirs the pot" to try and unsulfate the batteries.It is usually a manual process and should be use sparingly and then only for 2 - 4 hours in a 3 or 4 battery FLA bank.
Take my rig for example, while on shore power and in the "float" mode my batter voltage is 13.25VDC. This will sulfate the batteries over time so I try to equalize once at the end of the winter season and once at the end of the summer season. We are mostly on shore power or generator - one measly 60 W solar panel. I equalize for 3 hours AND MAKE SURE THE BATTERY IS WATERED. If the water gets low enough to show the plates that battery(S) are finished.
It cost several thousands of $ to come to this conclusion in my big boat battery banks. Properly maintained a battery will last 10 years±. I was a hard head!
Remember this when you think of Lithium and the long term costs. Personally, I think if you expect to boondock and plan a 7 year or more RV adventure and bite the bullet and scream. Install Lithium, solar panels to charge them, change the Inverter/Charger to the 4 or 5 stage charger and full sinewave, get the top quality solar mppt solar charger and a 2KW Inverter sinewave. This will cost a lot of money so plan it in your budget right away. BTW - all cruising (boondockers) sailors have changed to Lithium & assoc system or are thinking about it and how to get the $ to do it.
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