Can I use something like this DORK buck ?I am thinking in the event if my converter fails and voltage goes high of I don't isolate batteries before I equalize them.

I would experiment with one somehow... The BUCK BOOST type regulators are known to emit alot of RFI SIGNALS in the VHF/UHF radio/TV signals... The low wattage ones used with some of the power regulators for some of my LED LIGHTING has caused me alot of problems with my HDTV, WX RADIO, Ham Radios, etc...The higher DC CURRENT BUCK BOOST circuits may be an even bigger RFI SIGNAL problem... This is my experience using the BUCK BOOST circuits at any rate... Using high current INVERTERs also gives me similar RFI problems with their built-in buck boost circuits.Roy Ken

Just how high are you equalizing? Anything that runs on "12v" should be good at 15v, especially "automotive" stuff like an RV uses. 12v nominal is more like 13.2+ most of the time, 14.4v some of the time, and well, like you equalizing, a bit higher tooI wouldn't go putting buck regulators on all your dc loads, despite what ebay / amazon claims, a buck regulator is seldom a one size fits all power supply. they generally need to be matched to the load. DROK's el-cheapo multi-turn trim pots does not count as matching the smps to the load.If you're truly concerned about your converter failing, replace it with a quality unit, one that has integrated over-voltage protection.just my 5 cents as an armchair electrical engineer

If your thinking of the fridge control boardYes..you could use a DROK buckJust pay closer attention to the control limitsThere are minimum and maximum limitIt seems to be in the 2v rangeMeaning you can't make 13v down to 12v or 20v down to 12vin other words there is minimum voltage drop and a max voltage drop Depending on which one you getgetting the buck/boost board might be the best betput the board in the fridge compartmentWith no other loadsI would not try it with the furnace and A/C controls

My solar equalizes at 15.5 out of the controller. I see 15.3 at a 12 volt outlet near the distribution panel. The refer is farther away so it would probably be 15.1 or 15.2. I never neasured at this point. The service manual says never exceed voltage for refer is 15.4 and I recently had a control board failure. I always use the disconnect when I equalize but I may have forgotten when I equalized in November. I had a Board failure in mid December.

I equalized today and while I didn't use the disconnect switch, I did pull the fuses for the heater and refer and turned off all lighting.

How can I protect control boards from over DC voltage

15 Replies

landyacht318
Explorer
Jan 19, 2016
I use a Drok voltage bucker on a 1.3 amp 180MM computer fan. The hub got too hot and stinky at full speed when fed voltages over 13.

I limit it to 11 volts and it has been working well for a long time now.
RJsfishin
Explorer
Jan 19, 2016
Been RV'n over 40 years,....never needed any voltage regulation then, don't need any now, and I'd bet I won't never need any.
But then, I don't cremate my batteries either. Batteries don't ever need over 15 volts, and mine don't need over 14.4. But I know, ya gotta do what ya "think" ya gotta do.
CJW8
Explorer
Jan 19, 2016
smkettner wrote:
How about a sticker next to the equalize button.
"Isolate Battery Before Equalizing"

Never read a post where a random bad converter went over 14.4 volts.

That's no fun but you are probably right.

Noted on the failure but a rare alternator failure could go high.
CJW8
Explorer
Jan 19, 2016
After this discussion, I started thinking a relay that was voltage sensitive with an adjustable setpoint. A quick search didn't turn up anything but I did find this It is a Morningstar relay driver with 4 outputs and is programmable via RS232. This, with inexpensive automotive relays in the right places would do the trick I think.
CJW8
Explorer
Jan 19, 2016
If the never exceed voltage on the refer board is 15.4V, I suspect I would not be doing it any good over time to be sending it 15V.

Easiest is to pull fuses on the furnace and refer as mentioned and as I did yesterday. The refer board failed for unknown reasons and I am now fairly certain I equalized while it was on. Failure wasn't at that time but within 2 weeks of equalizing. (I really should keep a log book). We'll never know the cause of failure.

I equalized because I like to occasionally shut off my converter and check my battery capacity. A boondock test if you will. I have 3 each group 24 batteries, new in July. I shut off the converter and let the batteries stabilize at 12.7. I used some lighting (all LED). After two furnace cycles voltage holding 12.4 just before the third furnace cycle. I felt it wouldn't take very many cycles before the voltage was at 12 volts. It certainly wouldn't get me through the night. My battery tools (hydrometer and battery capacitance tester) are home in AZ and I am working out of my toy hauler in NM. I felt it wouldn't hurt to equalize while the sun was high.
time2roll
Nomad
Jan 18, 2016
How about a sticker next to the equalize button.
"Isolate Battery Before Equalizing"

Never read a post where a random bad converter went over 14.4 volts.
wa8yxm
Explorer III
Jan 18, 2016
It has been a LONG time since I saw the article but basically it was a Progressive Industries "Surge Guard" for DC.. I can describe the cirtuit, or rather it's elements, but I can not build it from memory

You have two voltage comparators(SP?) these are devices which compare the voltage on the "Sense" lead to a standard (usualy 5 volts) on board. They output HIGHER or LOWER (1 or zero depending on the input voltage

One is set to like 11 or 12 volts (low voltage cut off, in your case this one is optional) the other is set to like 15 (high voltage cut off.

The output of these drive a RELAY.. Since one should be high and one low when the voltage is right the relay pulls in and power is sent on to the loads.

If the voltage goes HIGH or LOW then both of them will have "Same State" this results in the voltage across the relay coil being zero (EIthe 12 and 12 relative to ground or 0/0 but either way ZERO refernce to the other terminal)

Any decent electronics technician can make such a device.
gatorcq
Explorer
Jan 18, 2016
IF your RV chassis engine alternator charges your coach batteries, what happens when your alternator fails? Can go as high as 18 volts? How many known failures have you had and this does not mean someone told you about someone. How many of you have really experience a failure due to an over voltage. Once we have a realistic number then we can do a MTBF due to a high voltage
Old-Biscuit
Explorer III
Jan 18, 2016
Why the frequent equalization?

Last Nov and now.....

I equalize twice a year.

And when I do I pull DC fuses for water heater, fridge and furnace
GordonThree
Explorer
Jan 18, 2016
Ask your solar vendor if they can program the aux output on the charge controller to power a solenoid. put the solenoid between your batteries and low-current DC load panel. program the solar controller to turn off the solenoid during equalize periods.

many of the solar controllers have programmable aux outputs, just a matter of pressing the right buttons, jumpers, etc.