Very Early Stages Wiring Build Questions/Help

eric780

New member
Hi everybody,

First time poster, long time listener...

I'm in the very early stages of camperizing my 2003 Ford E350 7.3L and I just wanted to share some of my ideas to see if anyone has done something similar, or if it's even realistic.

  • Is it possible to wire my house battery loop (solar panels, house batteries) in parallel with the engine/alternator loop?
My thought process was that if the house batteries get too depleted, I could run the engine to help recharge them. I've added the switches between both loops, but I'm not sure if only one or both would be necessary. The switch would need to be closed when the vehicle is not running, so that it doesn't drain the engine batteries. But I'm not sure what the criteria could be in order close the circuit and have the alternator charge all batteries when the engine is running.

  • The second aspect is that during longer periods where the vehicle is in storage, the circuit could be closed in order to keep the engine batteries charged via the solar panel.
I don't plan to run a lot of things off the house batteries. Just some LED lights for maybe a few hours, and recharging cell phones, bluetooth speakers. I don't believe that it would be a huge strain on the alternator, but maybe it could be controlled that only 5-10% of the output goes to the house battery loop?

If you've made it this far, please let me know your thoughts. Thanks in advance.

523511
 
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headingwest

New member
Hi Eric look up DC to DC chargers. They detect when your engine is running and charge your secondary battery. A 2 way version will also allow your second battery to charge your starter battery in an emergency.

Sent from my SM-G935F using Tapatalk
 

DiploStrat

Expedition Leader
Snarky answer out of the way, some news you may be able to use.

-- Post this in the 12v forum and do some reading there. All of your questions will be answered.
-- Most decent camper systems link the starter battery to the camper battery with some form of isolation.
-- Solar and shore power are typically linked to the camper battery.
-- You need to read up a bit on the charge characteristics of the battery you want to use for your camper battery - this will determine the desirability of using a relay based or a DC-DC charger based system.
-- You need to know the base charging voltage of your Ford. Along with the type of battery you want to use, this will tell you whether to use a relay or DC-DC system. If a relay, I recommend an intelligent or voltage sensing relay.

Lots of information on lead acid battery systems here: https://diplostrat.org/documents/

Good luck!
 

pappawheely

Autonomous4X4
In fact, I have a CTEK solar controller that senses a draw and sends power to whatever battery needs it. It can charge the house batteries from the alternator, or charge the starting battery from the solar panel. I lost my alternator in a remote area, and thought I was stuck, but my solar panel kept the starting battery charged. I was able to drive over 300 miles on solar with no alternator at all.
 

billiebob

Well-known member
Snarky answer out of the way, some news you may be able to use.

-- Post this in the 12v forum and do some reading there. All of your questions will be answered.
-- Most decent camper systems link the starter battery to the camper battery with some form of isolation.
-- Solar and shore power are typically linked to the camper battery.
-- You need to read up a bit on the charge characteristics of the battery you want to use for your camper battery - this will determine the desirability of using a relay based or a DC-DC charger based system.
-- You need to know the base charging voltage of your Ford. Along with the type of battery you want to use, this will tell you whether to use a relay or DC-DC system. If a relay, I recommend an intelligent or voltage sensing relay.

Lots of information on lead acid battery systems here: https://diplostrat.org/documents/

Good luck!
I like how quick a summary that link is !!
 

DiploStrat

Expedition Leader
There are several articles on the linked page:

-- One is a slightly dated white paper on the problems of charging a lead acid battery in a typical overland camper (as opposed to RV) situation: https://cookfb.files.wordpress.com/2015/04/electrical-power-for-the-overland-camper-the-problem.pdf

-- The next discusses real world experiences in upgrading the camper battery wiring from something on the order of 6 AWG to 1/0 AWG or larger: https://cookfb.files.wordpress.com/2015/04/enhanced-camper-battery-wiring-scheme.pdf

-- Watts Up? discusses planning and sizing a camper electrical system for overland, again, as opposed to RV park, use: https://cookfb.files.wordpress.com/2015/04/enhanced-camper-battery-wiring-scheme.pdf

-- Charging Up! is the white paper updated a bit and presented as slides: https://cookfb.files.wordpress.com/2016/09/battery-charge-slides.pdf

-- Finally, Doubling Up! discusses various ways to connect your camper battery bank to the vehicle's electrical system: https://cookfb.files.wordpress.com/2016/09/dual-battery-slides-2016.pdf

None of this applies directly to lithium batteries, primarily because my AGM's are paid for and still working well!

I hope you may find this useful.
 

headingwest

New member
One thing to keep in mind is that your starter battery charges differently to your house battery. Your alternator doesn't "fill" the start battery, it just tops up the little bit used to crank your engine, then runs the electrics. If your alternator is putting out 12.5 to 13.5v then this isn't high enough to pump the juice into your house battery. It might take your house battery 50 hours to charge and not charge it properly to keep the battery healthy.

One hack I used to bump the voltage, then charge properly was to buy a cheap laptop charger which goes into your cigarette socket, set it to 15v, then plug this into a cheap solar controller, then into my house batteries. It worked a treat and only charged when the engine was running. You do get a fair bit of heat loss through the system as these are cheap electrics, but you could invest in better components. It's very easy to wire and protects your electrics. I put the battery in a box, added some usb ports, and went camping.

Laptop charger - maybe get better than this, but it will do the job

Solar controller - again for a few more bucks get a better version

Keep in mind this 80 watts so a couple of hours driving will give you a few days worth of lights and a small fan, maybe a phone charge. But not run a fridge. If you need faster charging get a dc to dc charger connected to your alternator.
 
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