I need tutorial on charging camper batteries from alternator

[DonC]

I know there are a number of threads about this general topic, but they often jump into the middle of specific issues. I have a 2012 Fleet and don't think I have ever gotten any charging from my truck. I now have a Trimetric and it confirms zero amp increase when the truck is running. I've checked this at 70, 80, 90% battery full. Pretty sure the Trimetric is working ok as amps coming in from solar match measurements of solar at roof, and amp measurement at the Trimetric for various things in the camper match some of the usage tables/info provided in the forum. And bottom line, I struggle with my camper batteries when I have many cloudy days in a row, even with my solar.

I'd really appreciate it if someone could describe in layman terms the components, how it is suppose to work, and how I can diagnose my problem.

What I know - alternator in truck, wiring added by FWC that goes to a plug that my camper plugs into, a Sure Power Battery Separator 1314A, and then 2 house batteries. I confirmed the camper is plugged in, and had a battery shop confirm that my batteries are ok. Alternator was replaced several years ago.

I have noticed a few times that my Separator gets really hot, to the point that the top of the battery compartment cover is warm.

Is there a step by step diagnosis I can do of my system? Again, something a laymen can understand??

 

[kmcintyre]

I had a similar issue although mine was installed by me. If you have a voltmeter what I'd do is disconnect the battery, turn the truck on and test to make sure you have amps flowing to the separator and then out of the separator. When I did that, I found that amps were coming in, but not out. Fuse blown. I had too small of a fuse installed. Easy for me and hopefully it's easy for you. The reason you disconnect the batter from the separator is that you'd be measuring amps from the battery and you want to make sure they are flowing from the separator.

 

[kmcintyre]

Oh, so I skipped part of your question. The separator keeps your camper batteries from draining the truck battery. At some certain level, the separator opens to allow current flow out. It's basically a one way switch. When some threshold is reached (charged batteries) it closes. It may be getting hot and blew a fuse.

 

[snuffy]

get yourself a good mutimeter and see first what your trucks alt. is putting out. most light duty trucks are not meant to charge two extra 12v. batteries. if they discharge to a certain level you can drive all day and they will never fully charge imo..

 

[DrJ]

Don,

There is a good chance that your battery separator has gone bad.
If you have a voltmeter,

First: confirm at your truck batteries (with truck running)with voltmeter that your alternator is working by testing voltage.
It should be around 14-14.6 volts.

Second: test the voltage before (or at) the battery separator (truck still running) it should be close to the first reading. Just test the connection points from the truck to your separator. If voltage is close to the first reading, you are getting power to the separator. I assume you are because it is so hot.

Third: check trimetric readings with truck still running. If you still see no charging after confirming steps one and two, I'd replace the separator. The part is something like $20-40 and FWC sells them or Amazon (probably).

Mine when out on my 2013 Hawk camper and it was a fairly easy fix.

One extra point - if your camper battery voltage is below 12.4 it may not charge it at all. It may seem strange that they will not charge when you need it the most but it's how these things were designed.

Hope that helps you.

 

[ntsqd]

I know some SurePower model(s) were subject to a recall. Is this one of them?

Along the lines of the other suggestions you need to know what the voltage is at the input to the SurePower unit after the truck has been driven for some distance and while the engine is still running. Also while the truck is still running measure the voltage at the output stud on the alternator. You're never going to have more voltage than that (w/o some tricky electronics anyway)
.
Voltage is easier to measure than current with most hand-held meters. Wires that are too small for the distance & current of the circuit will heat up resulting in greater resistance which causes a further drop in voltage. Voltage drop means that you may not have enough voltage available to charge the camper batteries.

Expanding on voltage drop a little, just in case this is all new to you. Voltage can be thought of as water pressure and current can be thought of as liquid flow. (All of the EE's out there are cringing, but it is a useful analogy for this situation.) A battery is a pressure vessel, you store energy in it by "pumping it up." If your pumping pressure (charging voltage) is the same as or only a little more than the pressure of the vessel (battery voltage) you aren't going to be able to flow much into it. If your pumping pressure is higher than the pressure in the vessel, then you'll be able to flow a lot more into the vessel.

Subtract the input voltage to the SurePower unit from the warm & running truck voltage at the alternator, this is your voltage drop from the alternator to the camper. If this is not an exceedingly small number (3% or less of the alt's output voltage) you'll need to look into why it is so large. Bad/loose connections, too small of a wire used, corrosion, & no dedicated full length ground wire are some of the causes. If it is too small of a wire or you suspect that it might be then have a look at these tables: http://www.ancorproducts.com/en/resources/three-percent-voltage-drop
Be sure to include the ground wire length in the circuit length. You may have to make a WAG as to the Amps involved. Other than your pocketbook you can't be hurt by guessing a little high. I would say the upper absolute limit would half of your alternator's rated output and normal charging may only be 1/4 of it.

If that doesn't fix it next measure the voltage on the output side of the SurePower unit with any solar charging system disconnected. It should be very close to the same as on the input side. If it is not, talk to SurePower about why not.

Finally measure the voltage at the battery while the truck is still warm and running. This voltage should be pretty close to the output at the alternator less 3%. If it is not and checking everything else in the system hasn't turned up anything then check the wires between the SurePower unti and the battery.

 

[DonC]

thanks, this gives me a few places to start
re the recall, I think I checked previously and it was the 1314 that was recalled not the 1314A

 

[wuck]

Surepower recall info link

Affected Products Model S/N Start S/N Stop
1314 (-B, BP-D) 09004545 11002845
1315 (-B, NM) 09002323 11001573
1318 09000274 11000192
1319 09000058 11000013

 

[Wandering Sagebrush]

Surepower recall info link

Affected Products Model S/N Start S/N Stop
1314 (-B, BP-D) 09004545 11002845
1315 (-B, NM) 09002323 11001573
1318 09000274 11000192
1319 09000058 11000013

Wuck, thanks for posting the recall info. The site team is discussing a pinned recall thread for issues like this.

 

[DonC]

ok, my son who is an ASE tech helped me today. He denies any knowledge about electric systems but he knows 100% more than I do!

Alternator is charging the truck battery at 14+ v. There is 14+ v going into and out of the Separator. All fuses look good and nothing is loose.

So... could the Separator have an intermittent problem? There is also a 30 amp fuse next to the Separator - I forgot if it was into or out of the Separator. Should I just replace both? If so, is there an upgrade to the 1314A that I should get while I'm at it?

 

[pvstoy]

Fuses look good but could be bad, always check them or replace to confirm. Always check wire connections for looseness or bad. Check grounds also. Just because it looks good they need to be tuged and pulled to reveal shorts. You have 14+ volts going in and out of the separator then confirm the same at the battery. If not the your problem is between the separator output and the battery post.

 

[DrJ]

Don,
What was your trimetric reading when you measured 14 + volts into and out of your separator?

It appears your separator is working at least part of the time.

 

[hooptytank]

For the batteries to charge off the alternator they must also have a good chassis ground. Grounds are often overlooked. clean, tight, corrosion free. You can also measure volts on the ground side, should be close to 0v, if it reads over 0.5v theres a poor connection somewhere.

As far as positive side, measure V at alternator output, isolator in/out, truck and house batteries. Look for a problem where readings are inconsistent with alternator output V.

I ran all new 2/0 AWG poitive and negative wire to house batteries and a blue sea systems ACR-Si 120A auto isolator, works great! also after a few days the 60w solar panel will top off the house batteries enough to where the relay will energize and also keep the truck battery topped off

 

[wuck]

Don, A few things.

1) For another thread, I measured the current consumption of my 1314 separator when closed at about 3/4 amp. 3/4 amp x 12 volts is about 9 watts, enough to heat up a small sealed compartment. In that thread, I doubted any compartment on our FWC are sealed enough for something to get really hot, but haven't measured the actual temperature of mine when operating. 9 watts is a bit more than an old incandescent night light or christmas tree light, certainly uncomfortable to hold when lit.

2) 14 volts on both sides of your separator indicated it was working for that measurement, but if I was measuring I would have disconnected the solar charge controller to ensure it was not circumstantially putting about the same voltage on the house battery side of the separator.

3) I'm suspicious your trimetric shunt may be wired incorrectly, or more specifically the grounds wired incorrectly. Only the batteries negative terminals should be connected to one side of the shunt, everything else is connected to the other side of the shunt. If the truck negative or ground is connected directly to the battery then the alternator charge current doesn't flow through the shunt, the trimetric can't measure it.

Trimetric install instructions