Voltage Regulator for DC Fuse Block

[foxontherun]

Good evening,
Looking to add a voltage regulator to limit DC voltage going to DC Fuse Block to no greater than 13.9V. Rather than having to put regulator on individual devices it just seems like it would be more efficient to just add a regulator to the DC Fuse block eliminating the need at individual locations, ie MaxxAire Fan.

The control board on my front fan burned up and I replaced with new board. Even though it's an upgraded control board for Lifepo4 it appears to only be rated for max 13.9 volts. The new board is already acting up (less than a month old).

Is this a good or bad idea? Thoughts, suggestions, recommendations on which regulator to use would be appreciated.

Hope everyone has a safe and happy Memorial Day weekend.
Harry

[featherliteCT1]

Have you seen the video linked first below which shows how to install a cheap buck converter to limit voltage spikes on a Maxxair? There the converter is mounted at the Maxxair rather than a DC distribution box.

https://www.youtube.com/watch?v=c9eLD1oBZVs/url

Note that the converter must be rated for the anticipated maximum amp draw. My Maxxair fan draws a maximum of about 3 Ah and uses a 5 Ah fuse. Consequently, I suspect that a 5 Ah converter would work fine.

Below is a link to a sample buck converter I bought that is rated for a maximum of 5 Ah.

https://www.amazon.com/dp/B081RG8XP5/re ... 8&th=1/url

If you wanted to install a converter at your DC distribution box, you would need to install a converter rated for the maximum Ah the Dc box is expected to carry. A quick google search discloses that there are several devices available.

[foxontherun]

Thanks for the feedback; I had not seen that video. The way my fans are wired I don't think I would have enough room to install it as my roof is well insulated all the way up to edge of fan. I had a lot of fun because of that when I installed the new circuit board on my front fan. The buck converter link you sent is one I have saved if I cannot find anything suitable for doing the whole fuse block. I also use a CPAP with humidifier and I definitely do not want that getting hit with too much voltage. I can run it off inverter but I do have a plug dedicated on the fuse block for just the CPAP to run on.

I have calculated what could potentially be used on what is currently installed on the trailer. If I calculated correctly if everything was on full blast at the same time would be around 50 amps. Not likely that would ever happen but I am attempting to build system to take it if it did happen.


I found a buck converter on Amazon as an example (not sure I am thrilled with some of the reviews I read) but would this be the appropriate type for what I am trying to accomplish? https://www.amazon.com/dp/B08THF63MQ/?c ... dp_it&th=1

Since I am just coming off 12v Lifepo4 batteries, I would assume the max voltage I could see would be 14.4 to 14.6 (based on some boost readings I saw when my charger was charging the batteries. I know when I first turn the breaker on for the charger that for a split second or two it goes from 13.6 to 14.4(6) then back down to 13.6 while at rest (no charging). Appreciate any advice or tips on how to safely accomplish this (assuming it can be done).

Thanks,
Harry

[featherliteCT1]

Harry,

The link you provided shows a 48V input so that will not work for you. The linked vendor menu shows a 12v-24v input device but maximum 20A rating.

Keep googling and report back.

[bdosborn]

Good evening,
Looking to add a voltage regulator to limit DC voltage going to DC Fuse Block to no greater than 13.9V. Rather than having to put regulator on individual devices it just seems like it would be more efficient to just add a regulator to the DC Fuse block eliminating the need at individual locations, ie MaxxAire Fan. <snip>

Voltage regulators aren't 100% efficient so your battery usage will go up 3-4% (depending on how efficient a regulator you buy) when you put every device on the regulator. The MaxxAire air fan is probably the only DC device in your trailer that needs regulation to prevent circuit board failure.
Bruce
P.S. The MaxxAire air fan has had the voltage limit problem for years and it's the reason I went with Fantastic fan....

[foxontherun]

Good afternoon Bruce,
I also have a CPAP with humidifier I am concerned most about. It is expensive to replace and is one of the other reasons I was looking the just protect the whole DC block. I found out after the fact this has been a problem for years on the fans. My fans have been working flawlessly up until now and the only thing that has changed was after the 2nd round of charging the pair of batteries back up to full from where the BMS cut them off (27.5%/13.02v to 14.1V/599.8AH).

Other than running fans on speed 2 or 3 and LED lights on occasion there was no other battery usage (charger still on to keep them topped off). Then a few days later I was checking the AiLi Voltmeter to check status of things and noticed some Boost charging was going on and saw it flash 14.4 then to 14.6 before it started going down. I unplugged the charger so I could try to figure out why the boost was happening when battery was full the night before. That is when I started having he erratic behavior with my front fan (rear was is fine as near as I can tell, both the same age).

I have replaced the control board with the "supposed" upgrade for Lifepo4 but that quit yesterday. Prior to installing the new control board I tested the fan motor just to make sure it was working; it worked no problems at all. Now, after installation of the new control board and running fan a few days it quits working again. I test the motor again and now it is burned out or at least not working where it was working before. It is not a power problem; there is power all the way to the fan (typically around 13.7v, same as the dc fuse block).

I did a random test out of curiosity; I unplugged the charger and attached the multi-meter to it just to see how much it shows when first plugged in...13.2 then 13.6 then 14.4 and back down to 13.6 all within a matter of a few seconds. I found this info online for the PD9260CV charger: "The Boost Mode rapidly charges the batteries at 14.4 volts till the batteries reach 90% charged. The Normal Mode finishes the charge cycle by reducing the voltage to 13.6 volts till the batteries are done charging. Once the battery is completely charged the unit switches to the Storage Mode and maintains the batteries at 13.2 volts. The Equalization Mode charges at 14.4 volts every 21 hours for 15 minutes to prevent battery stratification and sulfation."

The last sentence (every 21 hours...) is what I am wondering is affecting the fans. I leave my fans running 24/7 usually one doing intake the other exhaust. If I end up putting individual buck converters on do you have any recommendations on them or at least which ones to stay away from? Some of the reviews I have read on some are not so great. My apologies for this being so long.

Thank you for your input!
Harry

[bdosborn]

I did a random test out of curiosity; I unplugged the charger and attached the multi-meter to it just to see how much it shows when first plugged in...13.2 then 13.6 then 14.4 and back down to 13.6 all within a matter of a few seconds. I found this info online for the PD9260CV charger: "The Boost Mode rapidly charges the batteries at 14.4 volts till the batteries reach 90% charged. The Normal Mode finishes the charge cycle by reducing the voltage to 13.6 volts till the batteries are done charging. Once the battery is completely charged the unit switches to the Storage Mode and maintains the batteries at 13.2 volts. The Equalization Mode charges at 14.4 volts every 21 hours for 15 minutes to prevent battery stratification and sulfation."

"The Equalization Mode charges at 14.4 volts every 21 hours for 15 minutes to prevent battery stratification and sulfation" is a lead acid battery parameter, are you sure you have a charger set up for LiFePo4? I really think it's bad design from Maxxair that is causing the fan to fail and I'd add a voltage regulator to it no matter what version of the controller you use. The internet has tons of posts regarding Maxxair controller failures. Most automotive alternators run at 14.4V continuously so you can see that there is a problem with the Maxair input voltage limit. Finally, my wife has a CPAP that we run off the manufacturers 12V cigarette lighter plug without a regulator and no issues (so far)
Bruce
P.S. Here's a thread on the van forum about the Maxxair issue and a link to a regulator:https://www.fordtransitusaforum.com/threads/maxxair-fan-issue-voltage-too-high.69690/

[featherliteCT1]

Voltage regulators aren't 100% efficient so your battery usage will go up

Bruce,

Thanks for pointing that out.

The Drok buck converter depicted below is the converter many have used with the Maxxfan. It is rated at 5A , purportedly with a idle draw of less than 10mA. If that is true, 10mA x 24 hours = .24 Ah over 24 hours. That may or may not be significant depending upon the size of the electrical system.

I am going to install the Drok with a cutoff switch.

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[foxontherun]

"The Equalization Mode charges at 14.4 volts every 21 hours for 15 minutes to prevent battery stratification and sulfation" is a lead acid battery parameter, are you sure you have a charger set up for LiFePo4?

Bruce, it was my understanding that my charger would work for Lifepo4; but tonight I found some info that indicates it may not be. Hope I haven't damaged my new batteries. I will be contacting PD on Tuesday when they are back in office. THANK YOU for bringing that to my attention!

The batteries have built in BMS that is supposed to protect from overcharging. The batteries each came with a 10 amp charger which I will use in the meantime to charge the batteries.

From the thread you gave me I selected this buck converter: https://www.amazon.com/gp/product/B018W ... 0DER&psc=1 Do you think this would work out?

I appreciate the input both you and featherlite are sharing with me.
Harry

[bdosborn]

I'm pretty sure the BMS will protect the batteries from the equalization mode but you might check to see if PD has a LiFePo4 charge wizard pendant. They didn't when I checked several years ago for the trailer so I went with an Iota charger that did have one.

I used a DROK converter to boost 12V to 24V when I experimented with a 24V air conditioner. It worked fine for the weekend I used it. I also used a DROK converter to buck 12V to 5V for the LED color changing lights in the van and it's been working for a year now. We use the LEDs as a night light when we camp so the DROK gets more use than you'd first guess.

Bruce
P.S. The 24V air conditioner sucked and I sent it back...

[foxontherun]

Thanks Bruce; good to know the DROK worked out for you.

Will order a couple of them; my color changing lights already have the 5v adapter on the plug. I just cut the plug off and wired it in to the terminal block. Seems to work ok; only issue we have is when using remote controls, ha! You never know which button on another remote is going to mess with the lights. I have tried hiding the lights remote sensor but the other remotes seem to always be able to mess with them, ha!

I have a window shaker A/C that I haven't tried on the DC yet; planning to do that this week or next as it is getting quite sticky here in TN. Want to slide it out and check it before starting it up for this season. Paid $200 for it new and this will be fourth season for it no issues, yet....ha! It does a great job and is also quiet.

Have a great and safe Memorial Day!
Harry

[featherliteCT1]

Harry,

What kind of inverter do you have and what is the watt rating, continuous and surge?

Also, how many btu is your air conditioner?

[foxontherun]

Good afternoon, the Inverter is a Gowise PS1002 I bought on Amazon. It seems to work pretty good so far. When I was doing my 1st test drain on the batteries I had a 100 watt incandescent light plugged in, my refrigerator, and at one point just to see if it would work had my Vornado 1500 watt space heater on it (on low setting which I think is 750 watts which is what it is always set on). It seemed to handle everything just fine, never got hot.



The window shaker is a Frigidaire 6000 BTU. I haven't tried it on the inverter yet; I just put my batteries in this year but I plan to test it out here in the next few days. Want to pull it out and clean it up and make sure everything is in working order so I know it works before trying it out with the batteries. We have been camping in the southeast so if we don't have shore power we can't use it. If we go somewhere when it is hot we either have hookups where we go or it has to be shady, ha! It can run you out if you let it; nice and cold. If it will work on batteries it will just be ran long enough to cool the trailer down. My trailer is stealth (no windows). Air flow is when the back ramp is down and side door open and both ceiling fans going. I do have windows in the rear wall once you have the ramp down.



Harry

[featherliteCT1]

Harry,

I suspect that the air conditioner will draw about 500-700 watts per hour, ignoring start up surge. Your inverter should work fine.

After you test your air conditioner, let us know how may watts the air conditioner draws.

Good luck!

[foxontherun]

Below is a snip from when I did an initial test using shore power; you are pretty much on the money if I did my calc correctly. I thought I had some data from where it ran for long periods but can't find it at the moment.

Harry

Re: Window Air Conditioner Intake/Exhaust
Post by foxontherun » Tue Jul 07, 2020 9:42 pm
I have completed the construction of the AC test and ran the initial 6 hour test today. Temp in trailer at start was 93 degrees with 48% humidity; west side of trailer in the sun all afternoon. AC is temporarily built into the side door on the east side of trailer which receives sun until early afternoon. Test was from 2 PM to 8 PM. AC used 3.35 KWH, startup was 4.3 amps if I read meter correctly. The interior temperature was 64 degrees 45% humidity at the end of the test. I was impressed with how cold it was in the trailer. I didn't think it would get that cold in such a short time with the trailer in the sun all afternoon.