lifepo4 and maxxfan

[mdkelley]

Hello,

I am new here. I didn't see a new member introduction so I will do that quickly before posting my question.

Matt from Michigan. I have a 1989 pop top 8' skamper on a 2004 2500 duramax. So far I have installed a MaxxAir fan, one LiFePO4 battleborn with a power dynamics Li single stage converter/charger, and removed the non-functioning 3 way fridge and am putting a 5000btu AC unit in that space. I also purchased a 2200 honda generator to use for off-grid battery charging and running the tiny AC unit. This camper follows a van conversion camper the wife and I used for about 4 years. Also installing a WiFi ranger and have a wilson cell booster. That pretty much rounds out my rig introduction.

My question: Will my power dynamics 45 amp LiFePO4 controller burn out my MaxxAir fan? I ask because I think it did! So, on to question2. If that is true (too much voltage to run a fan) what regulator do other use to get around this issue? I wired the converter in to my system to act as shore power and have a quick disconnect to put the battery into the system when not on shore power or if I need to charge the battery. I figured there is no reason to constantly charge the battery if I am on shore power. I am not sure if I need to get a 12v regulator that is rated at 45 or more amps since that is the output of the converter, or if the regulator's amperage rating is more for amp draw and not really an amp input rating. I would think maybe a regulator from a truck may work since an alternator usually puts out more than 45 amps but looking for some guidance from someone who has done this already so I can avoid any implementation headaches (learning curve).

Thanks,

Matt Kelley
Michigan

[mdkelley]

From another forum
MaxxFan top voltage = 13.5V per Airxcel, Inc.

Once that fan gets to 13.5 is when its starts to cause concern.

Derek Hicks
Technical Assistance Coordinator
RV Products, a division of Airxcel, Inc.
3050 N. St. Francis
Wichita, Kansas 67219
Office: 316.832.4357
Fax: 316.832.3417
www.Airxcel.com

[BFL13]

Try the fan again on battery voltage of 12.x and see if it runs.

It would be silly for the fan to not work at 14.x because on a hot day when you want it, your solar could be at 14.x.

You want a normal converter that does 13.6 most of the time installed in the RV. You could keep the one you have as a portable charger using jumper cable ends for the output to clamp onto a battery. Float the LFP at 13.6 and haul out your portable charger to do the 14.x thing as required.

You can unscrew the bottom of the fan housing ( also the lid crank handle) and see the wiring to the various parts including the CB and wires up to the top of the motor. You can trace the voltage with your meter in different spots to see where there might be a problem.

One I installed had voltage except up to the motor. I happened to tap one of those connections and suddenly the fan started! That is also when I learned about the fan direction rocker switch trick mentioned earlier.

[mdkelley]

No wall switch, I wired it in directly and also tested it after installing and it worked fine. It just hasn't worked since installing the new high voltage converter and knowing the converter puts out higher voltage I did a web search about voltage and the MaxxFan. What I found was that there were some online who had issues with their fans burning out the circuit board, and MaxxAir told them their fan CB could handle somewhere around 13.6v but any more would fry the CB.

@otrfun - So, it sounds like maybe a voltage regulator would be a good idea between the converter and the camper (not between converter/charger and battery though) due to the higher voltage the single stage PD unit puts out?

I do disconnect the battery when running on shore power/converter because I agree with what you are saying about constantly subjecting the battery to the high voltage bulk charge (since I read on the BB site they say not to leave their battery subjected to the bulk rate for extended periods). I did a lot of reading up on the subject before finally deciding to go with a converter that the battery maker recommended. I am planning to only use this converter to charge the battery when it gets low. I am installing two battery monitors also, one to monitor discharge and one to monitor charge rate and levels. I am honestly brand new to LiFePO4 technology and there is so much conflicting info out there it gets confusing. Thank you all for the help and info.

[scbwr]

Re the fan not working: By any chance is there a switch for the fan on the wall? If there is and you simply hooked up all the wires, than the wall switch will still be functioning. I thought of this because I installed a MaxxFan in our bathroom, and didn't bypass the wall switch, so it's easy to try to turn on the fan and have it not work because the wall switch is in the off position.

And yes....I really should take a few minutes and redo the wiring to avoid this problem! It's on the list.......

[otrfun]

BFL13 wrote:
. . . If it is not too late you might want to return that one for their two-stage version. The original one-stage like you got was a mistake, where they thought an LFP could float on 14.x for an extended time, or else they expected you to not float the LFP at all . . .

Agree.

After doing at least 15-20 heavy discharge cycles with our LifePo4 battery pack using a standard, 3-stage, lead-cell 13.2v/13.6v/14.4v converter, I'm come to the conclusion there's very little to no advantage to using a one or two stage 14.6v dedicated lithium converter (we sold ours). Yes, a 14.6v charge voltage will charge a LifePo4 to 100%. 14.4v will only charge a LifePo4 to ~99% SOC. However . . . lifePo4's don't do well being floated at (or stored with) a high state of charge for long periods of time like a lead-cell battery. IMO there's little to be gained jumping through hoops (purchasing a 14.6v lithium converter) to get that last 1% SOC. If ah capacity is a concern, why not simply discharge 1% lower.

IMO, a single-stage 14.6v lithium converter is far from an ideal choice. It subjects the LifePo4 and all the DC components in the camper to a 14.6v (bulk charge) 24/7/365. IMO a 2-stage or 3-stage converter/charger (of any kind) is a better choice. It will spend the majority of its time in a lower voltage 13.2v/13.6v float/absorption mode---a good thing. Zero chance of overcharging a LifePo4, plus the DC components in your camper won't be forced to operate on the upper end of their voltage range 24/7.

[mdkelley]

ok. I will check the fuse maybe tomorrow or Monday. Almost done with the AC install and want to knock that out first due to the heat here right now!

[pianotuna]

.

[wa8yxm]

The specifications for charging a BB Battery Bulk/absorb = 14.2 – 14.6 Volt, with 14.4 Volt ideal. That is the same as the Progressive lead Acid bulk charge voltage That is the highest voltage the system should produce at any time.

Most converters output between 14.4 and 14.6 in Boost/Bulk mode.

[BFL13]

Those fans have their own fuse up in the fan area you might have blown. (one version has a pop-out glass fuse)

One version has a rocker switch for fan direction. If that is in the middle with no direction selected the fan will not run.

You only need a converter, forget the regulator idea. If it is not too late you might want to return that one for their two-stage version. The original one-stage like you got was a mistake, where they thought an LFP could float on 14.x for an extended time, or else they expected you to not float the LFP at all.

Your plan to disconnect the battery when on shore power should be ok though. Just remember to do that if you will be on shore power for a long time. If you got the two-stage it would drop to 13.6 and float the LFP safely so you would not need to disconnect it.

[mdkelley]

Yeah, I pulled that light and wiring and checked voltage at the fan connector and tested the fan before I stuffed the wiring back into the ceiling, it still didn't work.I can check the voltage at the circuit board as well but doubt there is any issue with the wiring.

[wopachop]

mdkelley wrote:
Also, the lights all work fine, even the one on the circuit that feeds the fan.

Ah then something came loose with the fan wiring. You definitely have 12v feeding the fan?

[mdkelley]

Yes progressive dynamics from Marshall mi. Getting older and my memory is slipping ??.The voltage at the fan connector was 14.2 if I remember correctly, I will recheck when I get home. I read online some said maxx air told them anything over 13.6 would fry the circuit board. I emailed maxx air today and am awaiting a response.

Just thought maybe it was the higher voltage since the fan worked with a regular lead battery when it was installed in a few weeks ago. I will connect it directly to that FLA battery to see it it works with that. I tried it with just the BB lifepo4 battery and then just the converter and neither worked. If no one runs a voltage regulator with the high volt output lifepo4 charger/converter and a maxxfan then it must be something else going on. Also, the lights all work fine, even the one on the circuit that feeds the fan.

[wopachop]

2 Matts from Michigan!! You guys should be at redbud right now!!!! (making jokes)

What voltage did your fan get? Just like cars and dirt bikes all the 12v stuff is able to get 14v and not burn out. No need for a regulator. But you can find them cheap on ebay. I use them for other stuff. Many have a little potentiometer that you turn with a screwdriver to adjust the output voltage to whatever you want.

[Grit_dog]

Welcome and yes thank you for the detailed explanation.
Refreshing in a forum that a lot of “Wut iS wRoNg??” type questions are asked.
Short answer is have you measured voltage output to your DC fuse panel and at the fan? What is it?

The battery isn’t the issue. With normal fla batts at a nominal 12.6V output fully charged and lifrpo4 at 12.8, this is a nonissue. IMO
Pulling off shore power through the converter, voltage may be/is higher, assuming here but haven’t tested, but again this is a normal scenario.
Could the fan just be defective?
What leads you to believe it’s too high of voltage?

[Matt_Colie]

Matt,

Welcome and thank you for trying to supply enough information.

You called the converter "power dynamics". Did you mean "Progressive Dynamics" from Marshall MI?

If it is a PD unit, it did not burn out your fan.

If it is a PD unit, just set the connections to the battery and forget the rest. Those guys do their homework.

If this is not the case all bets are off.

Matt - another from SE Mi