Main Problem Dead Truck Batteries While on 34 Hour Rest Break

If you spend any time over the road trucking and try to save fuel and engine wear by reducing idle time then you have surely experience dead batteries due to running your power inverter and electronics while the truck engine is off.

This winter, spring and fall I have hardly idled my truck at all without any APU system.

Secondary Problem Shortened Truck Battery Life Due To Over-discharge, Truck Sitting Too Long Unplugged

Another problem I’ve been having is premature truck battery failure.

I had to replace my three house batteries twice in less than a year. This is due to running them down to low while the truck was left sitting – parked on normal home-time and extended vacations.

With a new fully charged set of lead acid batteries my truck needs to be started or plugged in to a charger every 4-5 days, after 3-6 months I was only getting a few days before the batteries would not start the truck due to over discharging while the truck sits unused. Shortly after this I would have to replace them due to one having a dead cell or not testing good.

This problem is caused by parasitic draw when the truck sits unused. On my truck it’s about 1 amp measured with a multi-meter between the negative battery terminal and the negative battery post, connecting the multi-meter between the two with everything in the truck turned off.

Solution to secondary problem portable solar kit

Amazingly the solution to the secondary problem was pretty simple – a portable 200 watt semi flexible solar panel kit. The kit I purchased from Amazon is not the best quality but once I extended the wires from the panel to the charge controller it has completely solved my dead battery during time off problem.

I am confident I could  leave the truck parked indefinitely and when I returned the batteries would be fully charged and able to start the truck.

A portable system is inexpensive and convenient however it does require you to set it up and secure it to the hood of the truck.  It could blow away and become damaged or get stolen if you do not park in a secured lot.

The solution to the main problem of keeping the trucks house batteries charged for extended rest breaks while using several electronics is a little more difficult.

The solution for this main problem could be …

Hooking the portable solar up before the batteries are discharged. My testing with a normal house load after running the batteries down to 12.4 volts the system could not add a charge on top of the power I was using inside the truck.

I have not proven this yet from my own personal experience but based on quite a bit of research I think I could get a full 34 hour reset without starting the truck if I connected the solar up as soon as the truck was shut off.

The key here is to use less than or close to 5 amps which is what the 200 watt solar is practically capable of putting back into the trucks batteries while getting good sunlight.

A much simpler solution and the one I am working towards is to mount a larger semi flexible solar panel to the roof of the truck. Exactly like MVT has been doing with their trucks for quite a while now. I am sure you have seen their trucks wondered what the deal with those panels were, me too.

I finally decided to take the time to do more research.

Their solar system supplier is eNow, who has also been testing with US Express trucks.

I posted my notes and links below so you can do some in depth research into eNow’s case studies as well.

There are also links to several articles written about the carriers who have been using the 300 watt MPPT solar systems in conjunction with battery powered APU systems which run off of 4 additional Deep cycle AGM batteries.

Unlike RV’s and Boats Using solar to power big truck sleepers is much more challenging because without using the trailer’s roof the is very limited space to mount the solar panels.

There is another Canadian carrier that I found Macgyver’ed their own truck solar system together with what I assume were off the shelf parts designed for the Marine and RV industry. Here is the link to the article I found on Groupe Robert solar setup.

It looks like they used six 100 watt panels to make a 600 watt system.  Based on numbers from eNow’s research with US Express 600 watts could supply around 19 amps to your trucks batteries.

Solar panels for truck drivers links, research notes and questions

full recharge in 8-10 hours of daylight –

how many watts?

CCJ Innovator: Groupe Robert cuts idle time, extends hotel load time with solar panels

3.5 year return on investment vs fuels savings cost –

idling or diesel APU? they had diesel APU’s previously now battery powered APU’s

eNow’s system

https://enowenergy.com/wp-content/uploads/2017/09/eNow_Battery_APU_200W_and_300W_Case_Study.pdf is 300 watts

US express / e now

https://enowenergy.com/wp-content/uploads/2017/09/eNow_U.S.-Xpress-Case-Study_-HVAC-_Solar.pdf

during 10 hr sleeper break 47 amp hour of solar charge in addition to keeping truck batteries topped off with a full charge- this equates to about one extra hour of AC runtime –

one large panel?

how big – 6 ft by 3 ft ~

MPPT charge controler – 300 watt panel 9.4 amps per hour

PWM system 200w avg 2.95 amps per hour

I am assuming the avarges are during 10 hrs~ sunlight and not 24 hours per day

Battery APU system uses 4 agm deep cycle batteries – weight? cost? – easy to find out

Build your own 300w MPPT system

https://www.walmart.com/ip/Elfeland-300W-42V-Semi-Flexible-A-Class-Sunpower-Chip-Solar-Panel-Solar-Cell-Module-Battery-Charger-with-1-5m-Cable-For-Home-Boat/511529003?

size – 61.8″x36.2″x0.078

use a 24volt battery apu ac system for more efficiency vs 12 volts

battery seperator (contactor) between truck batteries ( starting and house) and aux apu batteries 4 agm

, how many batteries – 4 additional – how many in total 8 with 4 house batteries

, how many amp hours etc

excellent article about state of charge and quality battery recommendations https://deepcyclebatterystore.com/how-to-maintain-batteries/ 

Sleep during the day to maximize solar with battery apu setup

http://m-v-t-s.com/certified-technologies/engine-related/enow/ – The  youtube video only had 261 views I am surprised there is not more interest