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Monday, October 8, 2018

Charging FWC Camper’s LiFePo4 Battery From Tacoma

Note: Although this blog post talks about charging my FWC Camper’s LiFePo4 battery, the build below can be applied to any small dwelling vehicle that uses LiFePo4 technology for a house battery.  At the end of the post I will discuss the various ways to charge LiFePo4 house batteries and why I chose this particular design.


I traveled this past year (2018) in the Tacoma/Four Wheel Camper using just 175 watts of solar to charge my 50ah LiFePo4 Lithium battery.  I had wired my Tacoma to charge the LiFePo4 battery from the engine too, but never turned it on.  

I did not use this vehicle charging circuit!

Why you may ask?  The answer; I never needed to, as I had sufficient power using solar.  My solar is good but I figure after 3 days of no sun I would be low on power, so I need to plan for places other than the southwest where there is abundant solar.  I also did not like the lack of ability to control the rate of charge. I’ll discuss this later in my post.

This summer I decided to change how I charge the LiFePo4 battery.  My solar charging is through a Bioenno MPPT 20 amp solar charge controller.  My solar is designed to charge the LiFePo4 battery just under 10 amps.  I plan to charge from the truck at 10 amps, so my total charge rate will be 20 amps when in full sun and driving.

Now for my design/ build.  I contacted Bioenno and asked a number of technical questions, as I have a number of times, to verify the product specifications.  I have no affiliation with Bioenno beyond being a customer who designs using their products, but since I design using their products I do need to ask questions.

I share my design for vehicle dwellers interested in using the LiFePo4 battery technology.  Why I use Bioenno LiFePo4 batteries has been covered in my previous blog posts, when I first started using that technology in my Prius for its house battery.  I traveled for 3 years, 4 months at a time, living in my Prius.  I have posted in my blog extensively on how to live in a Prius in prior years blogs.

My initial design, last year, was to use a battery isolator that only sends power to the camper once the charging circuit reaches 13.7 volts.  This allows the vehicle battery to charge before charging the LiFePo4 house battery.  I continue to use this isolator in my current design.

Above is the isolator I used in my build.

I use waterproof breaker/switch to disconnect circuit when not in use. Isolators draw current low level current and if you don’t run your vehicle it will wear your battery down over time.

Above I have tucked the trolling motor outlet in the drivers side pocket hole in the Tacoma poly bed.

The engine power wire to the trolling motor outlet is routed under the body of the truck inside plastic loom and plastic cable tied.

I used 8 gauge cable to bring the power to the FWC camper through the Tacoma’s side-bed opening using a trolling motor power connector.

I bring in the power from the engine by inserting the trolling motor plug into the receptacle and then the engine voltage goes through another 10 amp breaker/switch, then on to a 12 volt to 24 volt step up transformer. Shown above.

From the recommendation from Bioenno, my LiFePo4 battery manufacturer, I purchased this bulk step down power supply.  They recommended a different model that only delivered 5 amps max charging, but I wanted 10 amps charging to get the 10 amps charging I needed to step up the voltage and then set this power supply to the desired voltage and amperage.  (The other charger uses the engine voltage and can only supply 5 amps.)

The power supply comes as a circuit board and display.  I mounted the circuit board in an aluminum project box, shown above.

Above I am testing the total charge circuit.  You can see I’m charging at 13.99 volts and .34 amps out of a total 8 amps max in my setting.  Bioenno has confirmed that I can charge at 14.2 to 14.4 and my setting will be at 14.2.  I have max amps set at 8 but will test my upper limit of 10 amps later.  Although the power supply will supply 15 amps I am limited by the 12 volt to 24 volt step up transformer of 10 amps.

Above top left is another 10 amp breaker/switch.  So I have one breaker switch before the isolator and one before the 12 volt to 24 volt step up transformer, located top center above.

The power supply in the aluminum box is located in the center.  To the right of the power supply is an inexpensive fuse box.

The switch, bottom left, is the original power switch to turn the power on from the original FWC lead acid battery.  I use the switch to feed the engine power into the FWC circuit to power items and charge LiFePo4 battery.

The previous owner moved the FWC battery from the rear to a cabinet built in the front truck cab wall.  I moved all power to the drivers side cabinet and upgraded to a LiFePo4 battery. (Below)

Above is my Bioenno 50 Ah LiFePo4 battery.  To the right of battery is a Bioenno 10 amp shore power charger. Top right is a 400 watt pure sine wave inverter.  To the top left is a blue seas fuse panel to distribute power to my power circuits in the camper.

Possible LiFePo4 vehicle charging designs.

1. 400 watt pure sine wave inverter tied to 12 volt vehicle battery powering the Bioenno 10 amp charger.

Comment 1: this is a straight forward design that I used in my Prius while driving or in Ready mode.  

There is a belief in the LiFePo4 world that although there are 2000+ charge cycles, that if you don’t fully charge the battery as often it may have up to double the charge cycles.  I don’t keep track of charge cycles so it’s not a big concern.

2. Direct charging LiFePo4 battery through a continuous duty solenoid.  

Comment 2:  I don’t care as much for a design that ties my house battery to the vehicle battery. (My goal is to keep my engine battery so it cannot be drained accidentally.)  Bioenno says it may be done as long as vehicle’s charge circuit is putting out at least 13.7 volts.  Note that voltage loss can exist the longer the wire run to the House battery.

3. Using solar charge controller- Isolator, 12 to 24 volt step up transformer, MPPT LiFePo4 solar charge controller to LiFePo4 battery.  

Comment 3:  I don’t care for the lack of current control of the MTTP LiFePo4 charge controller.  This does manage the voltage very well, although it will go into full battery charge more often.  This is the design I had installed last year in my FWC but never used.  I felt that I would have to be careful running bot solar and vehicle charge at same time.

4. The design I covered above - Isolator, 12 to 24 volt step up transformer, Voltage/amperage controlled power supply to LiFePo4 battery.  

Comment 4.  This is what is closest to what Bioenno recommends, other than step up transformer, but this only conditions the voltage to the power supply.  

This design gives me more control of voltage and current settings and I feel no risk in leaving both the solar charging and vehicle charging on at the same time.  It is also a very small footprint for space and weight considerations.  

For small vehicles the isolator is water resistant as is the step up transformer, so both can go under the hood.  But I recommend not doing this as you may want a good heavy duty 12 volt cigarette outlet for 12 volt cooking.  Therefore, keeping the step up transformer and the power supply close together in the vehicle gives you a high power 12 volt outlet and you LiFePo4 battery charge circuit together.


Tuesday, September 25, 2018

Camper (FWC) Side Window Curtain Modification

My long side window on my Fleet shell had a one-piece curtain 52” long.  

The problem is that there is too much curtain to bunch up in one direction to allow light in.  The right side as shown below is an escape window that is hinged in top.

The left side has two screened louvered windows, that take up about a third of the total window space.

The curtain isn’t insulated either

The solution is to use the reflective insulation material (InsulShine) I used for my home-made thermal pack to line the curtain.  See my blog post on my thermal pack build

My front window that faces the truck cab, and the rear door window has the InsulShine insulation from last year modification.  I ran out of time and didn’t get to modify the side window curtain.

After measuring where to make the split in the curtain, I wanted to have what I call a flap so the curtains overlap.  I sleep on the lower bunk often and when I move I don’t want the curtain to open or separate and allow cold air in.  So, it was important to integrate a flap into the design,

Abovevthe material was cut and Mylar insulation was added.  Last year I stuffed the InsulShine in the window cavity as it wasn’t yet sewn to the curtain.

In the picture above you will see the flap on the long side .  It has 2” Velcro on the other side of the flap.  On the smaller side I have a 1” opposite Velcro so the curtainand flap can stay positively closed if I want to.

Now the InsulShine instillation is in place.  Visible are the two pieces of the Velcro that keeps the flap together.

Now with curtain completed and installed with flap Velcro’ed together it looks like one curtain again, but now I can open the louvered windows and open just that side to let air to flow in.


Saturday, September 15, 2018

Speed Control For Endless Breeze Fan

The Endless Breeze portable 12 volt fan is made by Fan-Tastic Vent.  I use it in my Four Wheel Camper (FWC) to move air around the camper.  It also works good outside the camper on a 12 volt extension cord.  I have Fan-Tastic vents in the ceiling of my camper that I have a also modified with the PWM motor speed control.  Here is that modification post.

As with the Fantastic fan/vent in the ceiling of my FWC, the motor runs at a high speed for me on the low setting.  The Endless Breeze comes with a speed switch that gives 3 speed settings and my modification does not change the 3 speed settings if the PWM is fully on.  As with the roof units the fans can be noisy even on the low setting, thus adding the PWM speed control a nice change for noise when sleeping.

My problem:

When I just want the fan to provide a light breeze In my FWC camper, I want to be able to set the fan speed to what I want for air movement.  I also would like to conserve my solar power LiFePo4 battery system with lower my current draw when running the fan all night.

The answer:

Below is the PWM speed controller that I bought from Amazon.  What Pulse-Width Modulation does in this case is sends 12 v on and off.  The faster the 12 volt pulse the faster the motor spins.  When the pulse is off there is no power draw.  Therefore a 50/50 cycle the motor uses half the current.

Here is what WIKI has on PWM

I tested the current draw of the fan to ensure that the 2 amp PWM will work with it.  I did this by putting the PWM between the fan’s 12 plug and the battery.

Above is the open fan with the 3-position speed switch with a plastic cable tie holding wires from the PWM I added.  

With the PWM fully on the 3-position switch still functions as it was designed.

On the other side of the fan top from the 3-position switch I have installed the PWM

Above you can see the open space opposite the 3-position switch where the PWM fit nicely.

More of my wiring.  The added wiring is run along the fan edge like the wiring that comes with the fan.

Here is how the fan looks now with the PWM added to the top.

My test showed that the PWM would adjust the speed of the fan from full speed to off.  I set the speed to be a constant light breeze and  I was only drawing .49 amps.

Note the PWM has a light on the circuit board that shines through the white plastic so you can see that it is turned on.


Friday, September 14, 2018

Speed Control For Fantastic Fan in FWC

Most of the time my Fantastic fan is too high a speed on low setting.  The Fantastic fan comes with a speed switch that gives 3 speed settings.  I can just open the vent on the Fantastic Fan for natural airflow, but some mechanical draw helps.

Note: I had upgraded my Four Wheel Camper’s Fantastic vents because  the rear one was a vent only and this is where I cook.  The front one over the bed was powered.  Here is my modification on this conversation.

(Above is the upgraded vent only to power vent/fan with temperature control)

My problem:

When I just want some powered exhaust from the vent with my window cracked open below, I don’t need the fan on spinning very fast.  I also would like to conserve my solar power LiFePo4 battery system with lower current draw.  A side benefit of the slower speed is the fan runs much quieter for sleeping.

The answer:

Below is the PWM speed controller that I bought from Amazon.  What Pulse-Width Modulation does in this case is sends 12 v on and off.  The faster the pulse the faster the motor spins.  When the pulse is off there is no power draw.  Therefore a 50/50 cycle the motor uses half the current.

Here is what WIKI has on PWM

I needed to test the current draw to ensure that the 2 amp PWM will work on the Fantastic Fan. 

I dropped the cover of the Fantastic Fan and put my clamp meter on. The inspection showed 2 amp controller would work.

I then temporarily wired in the PWM and tested it.

My test showed that the PWM would adjust the speed of the fan from full speed to off.  I set the speed to be a constant light draw and I was only drawing .59 amps.

This low draw with lower window cracked will provide powered heat extraction cooling the inside of camper and making my Engel compressor fridge run easier.  Since I have the temperature control on the Fantastic Fan when the fan turns on my solar battery system will have no problem providing the power needed.

The spot I was able to fit the PWM was next to the speed switch.

This is the way it looks with PWM installed.  Note the PWM has a light on the circuit board that shines through the white plastic so you can see that it is turned on.

Above is the installed PWM controller ready to adjust the speed to what I want it to be.

It works in both exhaust venting or power fan pushing in air.  As stated I have it set to start on venting on low speed once it gets hot inside the camper by setting the temperature control in the upper right corner in the picture above.


Thursday, September 13, 2018

White Perforated Window Coverings for FWC Camper

I first became aware of perforated vinyl window coverings as Fire Chief, when our ambulance vendor suggested it on a new ambulance purchase.

My first exposure to the use of perforated vinyl for RV’s was when I saw my friends Dan and Brenda’s RV mini bus conversion, with the windows covered.  At this time, a couple years ago, I was on my travels with my Prius. 

When I traveled in my Four Wheel Camper / Tacoma this year, I didn’t like that I had to put up and take down curtains only for privacy.  I decided I wanted to try putting the white perforated vinyl on my camper.

Above is my Amazon purchase for Perforated vinyl.  I bought more than I needed and will share the extra with my friends.

I started with the side window area.  The right side is fixed glass and my starting point.

I tape the vinyl sheet at the top and peal the paper backing down from the top.  As I do I press and deal the vinyl to the glass dealing with wrinkles first and then pull the vinyl back off window and press to the sides and corners.

I use a credit card to move the wrinkles as I can.  Care needs to be taken not to tear the perforated.  I trim with a sharp utility knife blade.

Above is an example of the left and right top window now has the perforated vinyl applied and the bottom right doesn’t.  This shows the visibility you have and how much is reduced when you apply the vinyl.

Above the side windows are all covered including the smaller crank windows.

Here is the final look with all windows on the side covered.

I also covered the rear door window.  This still allows me to view out the back through my Tacoma’s rear view mirror.  

I did not apply the perforated vinyl on the window that needs the rear cab window so I would not reduce my visibility.

The issue of security and privacy is not as much of an issue on this cab window as there is a lot of glass over a distance to try to peer through.  I will use the curtain here as needed.

It’s amazing how well this product works, but if it is lighter inside than outside the camper, you can see in the camper a bit.  There is an advantage not covered above using the perforated vinyl.  That is I get ambient light in and at night in a lit area.  You don’t need to use the flashlight for all nighttime activities.


Saturday, August 11, 2018

Prius Brakes Do Last 100,000 Miles

I had a coupon for a reduced cost oil change at the dealer I use.

I wanted the oil changed and tire rotation.

While waiting for them to finish, the service representative came over and said he wanted to show me something in my car.

He andvthe mechanic slowed me that my brakes were getting thin.  3-4 mm of pad was left.  Nothing that required immediate attention, but good to know.  He said I’ll save you some money by turning the discs.  I said thanks.

I asked what the cost was knowing that I do my own brakes.

He came back saying that the front brakes would be $333 and the rear $364.  (They are disc brakes all around).  Then he said the engine air filter needed to be replaced for $48 and the cabin air filter too for 58.

I just smiled and said I wouldn’t be able to spend the additional $800 today.  I explained that Toyota was right that Prius brakes last 100,000 miles as my Prius has 98,500 miles.

They were right that in the near future I would need new brakes.  I decided to just do it this pm since it was going to rain and I could do it in the garage.

PS: (8/13/18) My friend David, who has much more knowledge about Prius maintenance than I do, wrote to me after my original post.

He cautions that some people who have changed their own brake pads have had problems doing it.  I checked online and did find some postings about getting error codes and one where the brake system activated pressure from sensing the fob.  Although I didn’t remove the 12 volt battery power before performing my work and I have not seen any codes or problems, it is good practice to remove 12 v power as the Prius is a sophisticated computer system and we know not what it all does.

End of PS

The rotors were in very good shape withvery little rust and heat disapating vanes are clear.  Turning wouldn’t hurt the but it wasn’t necessary.

I bought the disc pads for all 4 brakes.  It cost $120.
I took the calipers apart and checked the pins to make sure they moved freely.  I then replaced the front pads.

I then moved to the rear brakes.  I use a “C” clamp to push in the caliper piston on all other disc changes in the past, but in the rear this didn’t work.

I went to YouTube for direction to find that the rear pistons need to to turned back into themselves.  Below is the tool that is needed to put in my 3/8” drive socket wrench.

This tool cost $13.00 (below)

The tool is designed to adjust 6 different type of calipers as each side has a set of different placement and type of pins.

I used the tool and finishedvthecrear brakes.

I then checked the filters and both were in good shape and nothing that my airhose couldn’t address to clean them.

In the end I paid.

$120 for brake parts
  $13 for brake tool
$133 totalnpaid for about a $800 quote

The tools used are 
- lug wrench
- jack
- jack stand
- 14mm socket for 3/8” wrench below
- torque wrench
- bladed screwdriver (remove / replace brake pad guides)
- caliper piston adjuster
- 3/8” socket wrench and 3” extension 
- large “C” clamp
- possibly a hammer to loosen bolts

Prius dwellers have a choice in maintaining their vehicles.  Even if a small show was 1/2 the price you can save by learning g how to do it yourself.

Although, I have done brakes manybtime in many vehicles I have had my Prius since 8,000 miles and I knew that around 100,000 miles I would need to do them.

Always consult proper technical information before attempting repairs on your vehicle.  Ensure you have and use appropriate safety equipment.  When in doubt bring your vehicle to a trained mechanic.


Wednesday, August 1, 2018

Vehicle Comparison including RAV4 & Highlander

Hi folks,

Since getting home from this year’s travels I have been very busy around the house getting many things done. My thoughts have been with vandwellers having linked up with two couples in MA.  I took a short trip for a long weekend getaway in ME too.

Some time ago, I was asked to include the RAV4 and Highlander in my blog.  The following is a reader of this blog’s question.

“I am interested in buying Rav4 or Highlander. Could you please compare these cars totally grade with your 3 cars ?
thanks a lot”

Below is the Toyota RAV4 I caught at an event.

Although I have never owned a RAV4 I have gone to the showroom many times to look at them.  Why?

Answer: For all the things I love about the Prius and all the things I don’t like about the Prius.  If I hadn’t my Tacoma or found a Fleet shell model I suspect I would be in a RAV4 today for my travels.  

First, is ground clearance and the RAV4 gives me better ground clearance over my 2011 Prius and the newer Prius that is yet again a bit closer to the ground.  

Look up Ruby, AZ on Google and see that I drive the road from Nogales to Ruby only to get there and couldn’t get over s cattle guard that had too large of a drop off on the other side.  My Prius would have hung and gotten stuck on top of the guard.  

Ruby Road is leftbto right at top of picture.  The cattle guard is on Ruby Access Rd.  (Brown rectangle) can only go over guard crossing.

So, follow the map from Ruby to Arivarca.  A few miles north of Ruby the road crosses a wash.  The water wasn’t high, but the ridges left in the road from moving water made it impassable for the Prius to continue to Arivarca 

Above this is the section of Ruby Road on way to Arivarca with pin drops in both sides of the road Prius couldn’t get through without hanging on sandbars.

Fail!  But the Prius does well in so many other ways but so does the RAV4.  For me it has to be the hybrid RAV4 to fill in for the Prius and it does.  Drawbacks of the RAV4?  Yes.  The current RAV4 hybrid has a battery bump to design around, but I can design compensat for that.  Any other issues? Yes. The RAV4 hybrid is not true all wheel drive.  After reviewing the design of the AWD it does not matter to me that the front wheels are powered by the engine and back are powered by the electric motor.  Heck the Prius doesn’t have AWD

Now to the Highlander and yes the hybrid version.

Below is a Toyota Highlander picture I took from a Google search.

I owned an older non- hybrid highlander and although nice and more room, I don’t care.  I’m good in my Prius for room and don’t need more at the cost of lower mpg that doesn’t make sense.

So, as you can tell.  I have an opiolnion.

This year at the RTR I met up with my friend Susan from Oklahoma and her new RAV4 and installed a solar panel that I would be proud to have on my RAV4.

You can’t tell it’s there and you passively charge lithium battery so you don’t have to run the engine.  Susan’s RAV4 is not hybrid and she gets all the solar she needs from 80 watts and can set up to charge her lithium battery when she drives if she wishes.

An additional testimony is directly from me as Susan followed me and my Tacoma with FWC camper up and down roads that were challenging.  Yes this is true and I was sold on the RAV4 since I left Utah at the end of March.

Am I still a Prius guy.  Yes I love my Prius but one day it will need replacing.  The RAV4 is the only vehicle I would replace it with right now