Battery Isolator

[Semyers]

I have a 2014 Hawk, mounted on a 2013 Ford F150, air bags and E rated tires. I spent 3 ½ months driving from Tucson, Arizona to Alaska and back last summer. It was a bucket list trip and I had the time of my life. Great pictures of bears and a lot of fish.) My only concern was the inability to charge the camper batteries (I have two) while driving if the camper battery voltage was below a certain level. This required that I stop at a campground periodically where I had electrical service to top off the camper batteries. I understand the need to isolate the truck battery from the camper to ensure a start when needed, but there must be some way to isolate the truck battery, while still allowing the truck to charge the camper batteries while driving, no matter what their voltage. Any ideas or suggestions would be appreciated. I attempted to search the forum for any discussions regarding this issue but found nothing.

Thanks,
Scott

 

[PaulT]

I understand your concern as I ran into that problem on the first outing in my 2014 Hawk with factory 100 watt solar. Due to tall Doug firs in the campground over the 4 day trip, the solar panel was unable to keep up with the demand. There was no possibility of shore power.

Part of this was my lack of understanding on how everything electrical worked together and separately. Another part was the fact that a shadow over a single cell in the panel, essentially blocked charging. After the batteries dropped below the isolator cutoff point, starting the engine had no effect on battery charge. With the fridge consuming nearly 5 amps when running, there was insufficient solar power left over to replace charge in the battery even with full sun.

Another problem was my setting the fridge too cold causing it to run too frequently and too long. After the end of the 4 days, the battery voltage was as low as 11.9 volts when the fridge was running. Starting the truck resulted in battery isolator relay clunking on then off after a few seconds.

After leaving camp at noon, I stopped in full sunlight to check things in the camper and saw close to 6 amps on the Zamp controller. After 3 hours of driving home in full sunlight, the indicated voltage was high enough that the truck was apparently contributing to the battery charge. I plugged the camper into shore power on arrival at home and left it plugged in for several days to allow the Iota to fully charge the batteries.

I added a portable 100 watt solar panel that I aimed at the sun after first getting up and used until breakfast was done and it significantly improved the situation. I have since acquired and mounted a 160 watt panel on the roof. On a recent 2 week trip, it was very nice to see the batteries topped off by noon or so. Be aware that adding a second panel requires that you replace the factory provided 10 watt fuse in the output of the Zamp controller with a higher amp fuse. The Zamp manual recommends a 30 amp fuse. That fuse is in an in-line fuse holder and hidden (camouflaged?) in the wiring in the battery compartment.

Keep aware of your power use and battery voltage and if you see it falling too low, turn off the loads and watch the voltage on the display. When it recovers some, you can start your truck and the truck should start recharging the battery. Watch the battery voltage on the Zamp and allow it to charge your batteries for a while before turning on the loads again. The fridge temp should not get too warm in an hour of so of letting your truck run with the fridge turned off. The Zamp display will not show the charging current going to the batteries from the truck but you can infer that the truck is charging the battery by the voltage going higher than the resting voltage.

You could bypass the factory provided voltage sensing isolator and install a Blue Sea marine isolator under the hood. See their Add-A-Battery kit. There have been quite a few threads on this issue in the past few years.

Paul

 

[DannyB1954]

My solution is to install a relay that is powered by a circuit that only gets power when the key is on.
These let you add a second fuse to an existing fuse spot. You will also need to buy a small fuse, (2 amp).
http://www.amazon.com/TrendBox-Standard-Circuit-Adapter-No-WIRE-CUTTING/dp/B01BIDQ84O?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

The relay I use takes very little power, (like 1/2 amp), so the fuse box doesn't mind that a bit. The relay I use is one of these, they are commonly called Bosh relays. http://www.amazon.com/Pack-EPAuto-Relay-Harness-Bosch/dp/B017VDI0GY?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00
You may be able to purchase just one each of these if you look around.

How it works, When the key is turned on a circuit that gets power then, gives power to close the relay. This connects the vehicle battery to the house battery. The vehicles charging system charges both batteries. When the key is turned off, the relay loses power and disconnects the house battery from the vehicles electrical system.

Also it is a good idea to put an inline fuse between the vehicle battery and house battery. I use a 60 amp. Between the batteries I also used doubled up 10 gauge wire, (should be able to carry 60 amps). The heavier the wire, the less voltage drop there will be between the two points. http://www.amazon.com/Bussmann-HHX-Maxi--Line-Holder/dp/B000CZ2Z92/ref=sr_1_20?s=automotive&ie=UTF8&qid=1462909604&sr=1-20&keywords=inline+fuse+holder

 

[craig333]

Or just rip that isolator out. I've never used so much juice the truck fails to turn over and if I'm worried I might I just set my switch to camper only.

 

[ntsqd]

DannyB, do you have more than one of those relays in parallel? They're only rated for 30 amps normally.

I like the right Voltage Sensing Relay (VSR) or Automatic Charge Relay (ACR) because they won't close and connect the camper battery until the starting battery(ies) have been recharged. Searching either of those two names should pull up the many discussions that have been had here about them.

I don't own one, yet, but this is my ideal battery charger: http://www.amazon.com/dp/B005LBCVL4/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1WJFO5EAJMISV&coliid=I1LW6VAW7Y7TI Takes the place of BOTH the isolator/relay and the solar charge controller. Treats the alternator's output as another charge source like a solar panel, picks the better power source, and applies the same charging logic to the camper battery(ies) regardless of the source.

 

[DrJ]

Here's what I did to address this exact problem. After months of trying it out, I still really like it.

What you are missing with the current system is control of charging. This allows you to have that.

http://www.wanderthewest.com/forum/topic/11861-automatic-charge-relay-how-to-improve-your-battery-isolator/?fromsearch=1

 

[DYNOBOB]

My solution is to install a relay that is powered by a circuit that only gets power when the key is on.
These let you add a second fuse to an existing fuse spot. You will also need to buy a small fuse, (2 amp).
http://www.amazon.com/TrendBox-Standard-Circuit-Adapter-No-WIRE-CUTTING/dp/B01BIDQ84O?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

The relay I use takes very little power, (like 1/2 amp), so the fuse box doesn't mind that a bit. The relay I use is one of these, they are commonly called Bosh relays. http://www.amazon.com/Pack-EPAuto-Relay-Harness-Bosch/dp/B017VDI0GY?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00
You may be able to purchase just one each of these if you look around.

How it works, When the key is turned on a circuit that gets power then, gives power to close the relay. This connects the vehicle battery to the house battery. The vehicles charging system charges both batteries. When the key is turned off, the relay loses power and disconnects the house battery from the vehicles electrical system.

Also it is a good idea to put an inline fuse between the vehicle battery and house battery. I use a 60 amp. Between the batteries I also used doubled up 10 gauge wire, (should be able to carry 60 amps). The heavier the wire, the less voltage drop there will be between the two points. http://www.amazon.com/Bussmann-HHX-Maxi--Line-Holder/dp/B000CZ2Z92/ref=sr_1_20?s=automotive&ie=UTF8&qid=1462909604&sr=1-20&keywords=inline+fuse+holder

I like this idea. There's an unused 80a relay under the hood of my truck now (intake heater grid delete) and an extra 10ga wire going from the engine compartment to the camper plug. Hook it straight to the house battery and that should fool the isolater into charging - now two 10ga wires are providing charging.

Thanks for bringing up the topic, this could bite you in the rear if you don't know about it...

.

 

[Ronanmd1]

DannyB - see below. I had the same problem. Sorted it out by increasing the gauge wire from the truck battery to the isolator. This prevented the voltage drop from disconnecting the isolator.

DavidO - You are bang on with your diagnosis and solution. I spent a few hours replacing the factory 10 gauge wire with 4 gauge (it was easier to find 4 gauge than 6 locally). Essentially I just replaced all the wires from the engine battery back to the isolator. I used an Anderson connector at the box to replace the smaller factory plug. It was a bit tight running the wires inside the camper but with a bit of filing I was able to make it work in its existing location. I left an extra foot of length at either end in case I ended up needing to move the isolator.

I don't have a trimetric monitor, so I decided to give it a 'real world' trial. I ran the camper batteries down to various voltages (as low as 11.6 V). Regardless of the voltage at the camper batteries the truck charging system (180 amp alternator) had no problems sending enough amps back to the camper through the 4 gauge. The voltage across the isolator generally stayed above 13.1 - 13.4 regardless of how drained the camper batteries were. This test was done with the fridge powered on since that is typically the case when I am on the road.

So far, It looks like the isolator works fine if left mounted in the camper. The 10 gauge wire is simply too small across that length (about 20 - 25ft) to provide enough amperage to avoid the associated voltage drop once the 2 deep cycle batteries start to charge and pull huge amperage. Dropping the resistance from the charging system by increasing the gauge of wire to 4 gauge (6 would likely work as well) seems to have fixed the problem.

Next up - add another 100W solar panel to the existing 85 W panel on the roof to help me stay charged when camping for a few days without driving.

Thanks for all the help guys. It is really appreciated.

 

[Ronanmd1]

This was the original thread:

http://www.wanderthe...harging-issues/

 

[camelracer]

If you're going to use a keyed relay instead of the battery isolator make sure the relay is activated from the accessory circuit and not the start/run circuit. If the start/run circuit is used you could be drawing starter current through this circuit when starting with a low truck battery. The relay and wiring probably won't handle that current.

 

[BFH4N]

The CTEK charging system theoretically solves all these problems. It consists of two units: "D250S Dual" and "Smartpass". I haven't used mine enough yet to know for sure, but I know that some folks are very happy with them. Check it out.

- Bernard

 

[DavidO]

Scott
You are not alone in thinking that you should be able to get better charging of your camper batteries from your truck. It seems that the group of people that have this problem. They are people who have compression refrigerators. I think that when FWC upgraded our campers to these refrigerators they did not upgrade the wiring from the truck to the camper, there is probably not one but several reasons. A few that I can think of: 1) not everybody needs it, if you have a shell or if you have a 3-way fridge the current 10 gauge wire should be fine. 2) All truck alternators are different some are more up to the task of supplying more amps than others. 3) thicker gauge wire is more expensive and more difficult to work with adding to the labor cost (good crimping is more difficult and more important, get a good tool) 4) if the camper has a great solar set up then charging from the truck is less important. These are only a few reasons I'm sure others can think of more.

That said I think it would be nice if when we ordered our campers with a compression refrigerator FWC would be more straight forward about our charging needs. If it is over 90 it is likely that the refrigerator will be running almost full time and that takes a lot of amps. I'd like to see FWC offer an option of upgraded wiring from the truck to the camper.

Many people have addressed this issue differently by changing the way the truck charges the camper batteries by adding different isolators, separators or solenoids or even in some cases direct connection with or without a switch. In most all cases they also changed out the wire to a larger gauge sometimes people just added a second 10 gauge wire (I don't recommend this). Everybody who post here about their upgrade is happy about how it works for them (I'd be interested to read any post about what didn't work).

There were so many ways to go with this improvement that I didn't know which way was the best way to go. When reviewing the Sure Power Separator which was already in my camper I discovered two important things. 1) it is rated for 100 amps and 2) the installation said to use 6 gauge wire for wire lengths from 10 to 20 feet. I then decided to change out the wires from the truck to the camper and see if this alone fixed my charging. What a difference it made now if the batteries are down to 75% and I start the truck after 10 minutes of running at idle my voltage at the camper batteries is 14.1 or 14.2 volts and my camper batteries are being charged at a rate of 30amps/hour. Problem fixed, this seems to be as fast as my batteries will take this charge if the fridge starts running the charge rate doesn't decline so the wires are caring 4 or 5 more amps.
Hope this helps.
DavidO

 

[Vic Harder]

The CTEK charging system theoretically solves all these problems. It consists of two units: "D250S Dual" and "Smartpass". I haven't used mine enough yet to know for sure, but I know that some folks are very happy with them. Check it out.

- Bernard

That D250S Dual seems like a slick unit. I notice that the max charging current is only 20 amps, and DavidO says in his post that he is getting 30+ amps to his camper batteries from the alternator. I looked at the CTEK site, and that the biggest controller they carry. Am I missing something? How can this work well in the scenarios CTEK designed this for?

 

[billharr]

One time having a problem with the isolater was it for me. I already had the old selonoid from my 2002 Hawk under the hood of the truck. Removed the new isolater from the camper, changed to 6 gage wire. Everything works great.

I under stand why FWC uses the isolaters they are plug and play, no need to do more that run a wire to the camper.

 

[Happyjax]

I also read the instructions for the installation of the Surefire relay and the smallest wire recommended is 8 gauge for installations up to 10 feet when start assist is not being used. 6 gauge as David said for 10-20 feet.

Installing the wiring per manufacturers specs should not be dependent on what kind of fridge you use or heater or anything else. The directions say 8 gauge minimum and that is what should be used.

When you don't follow specs plug and play becomes plug and pray.....

 

[Ronanmd1]

Hi guys - edited the link in my earlier post for anyone who wishes to follow that thread.

Thanks DavidO

 

[buckland]

Just a fast question to anyone out there. New truck, so have to put in new cable to camper. The 2 posts on battery separator under the hood... one post copper one aluminum ... the line from Camper goes to the aluminum and the line out to battery is the copper? attached old and new...can't be 100% sure which wire goes where.

 

[K7MDL]

The device in your picture is a breaker, not an isolator. Battery does go to one side, load the other. It should be located close to the battery as you can make it. Its job is to protect the wire, which means you need large enough wire that if shorted, the breaker will trip before the wire melts its insulation.

As to which side goes to the battery, look for a BAT label imprinted in the plastic near the copper color post. The other side likely has AUX imprinted. The light color post should be steel. Check out the picture of a similar Busman breaker here. Zoom in on the pics and you can see the labels.

 

[ntsqd]

BTW, there should be another such breaker in the charge wire at the camper battery too. If the wire shorts and the truck battery breaker pops you still would have a problem without a camper battery breaker.

That D250S Dual seems like a slick unit. I notice that the max charging current is only 20 amps, and DavidO says in his post that he is getting 30+ amps to his camper batteries from the alternator. I looked at the CTEK site, and that the biggest controller they carry. Am I missing something? How can this work well in the scenarios CTEK designed this for?

Batteries have a max current that they will charge at. That rate is dependent on the State of Charge. It's tempting to think of batteries as "buckets" that you can dump amps into, but they really don't work like that. MPPT charge controllers can vary both the charge current and the charge voltage to optimize the charging. I'd rather have that than a bulk 30A dump into the battery.

 

[buckland]

Thanks I have it all installed ... though I have to say...the breaker sent from FWC came and after the install I noticed it was askew so I reached in and low and behold the small plate was screwed in to the truck but the breaker was separated from the plate...swell.... must be a cheap 'weld' so I should go get another.... I suppose they are sold at auto stores. ... Tomorrow I gets some gumption up and drill through the bed to install the eyebolts ... New truck...don't want to mess up. I have the measurements from the set up on the Taco.
I guess when you're walking on thin ice ya might as well dance!