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Old 01-12-2019, 09:24 PM   #1
Join Date: Aug 2018
Location: Bend, OR
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Electrical System Debacle

I've been living in my 1998 Ford E-250 Quigley 4x4 for the past few weeks now and am realizing the electrical homebuild I put together isn't quite going to cut it.

I have a 155ah battery (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1),
which is being charged by a Smart Battery Isolator (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1).
I think the issue is stemming from the fact that my alternator is only putting ~13.5 to the hotel battery and isn't getting it fully charged in my minimal day-to-day driving, since the battery wants at least 14.5v when charging.

I have fairly minimal power draws... a string of LED Christmas bulb lights that draw less than 1ah, an Espar D2 which we use for 2-12 hours at a time and a Maxxair fan that runs on settings 1-3 (<1ah). I have a wired propane detector and voltometer and a few 12v outlets I usually don't have anything plugged into.
The charge on the battery is getting down to 12.2v on a regular basis and I'm worried I'll start to damage the batteries ability to hold a charge if I push it much further.

Any thoughts on how I can deal with this issue in the short term? In the next few months I'm planning on adding a few hundred watt solar panel/system, but don't have any ability install it right now while I'm living in the van down in Bend.


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Old 01-12-2019, 11:19 PM   #2
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A good addition to any system is a battery charger. If you can plug into shore power than that would be the ticket. I have a Xantrex 40 Watt charger that has AGM settings as well as temp settings/sensor. I plug it in over night and my batter is good to go.

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Old 01-13-2019, 12:38 AM   #3
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13.5V is pretty low output for an alternator. Is it that low at the starting battery, too?

I know the isolator is supposed to be a "zero voltage drop" unit but I would check to see if you're losing some voltage there, or maybe in some of your wiring. A DVM is useful here. (I almost wrote "a good DVM," but even the cheap ones work fine for this sort of thing.)

If it's not being lost in the isolator, you may have an alternator problem, like a blown diode or bad voltage regulator. I've seen Bosch alternators in Volkswagens that were set at 13.75V, but the American cars I've seen were all 14+.
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Old 01-13-2019, 05:53 AM   #4
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The "normal" output for alternators should read 14.3 volts as an average. With engine running and all powered devices operating (headlights, blower motor(s) windshield wipers) that output should remain stable.

Anything less and you are definitely having issues with the alternator. That needs to be diagnosed and fixed first.
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Old 01-13-2019, 08:26 AM   #5
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Might be the diode bridge or voltage regulator, which now days is built into the alternator. It used to be easy to change on Delco alternators, at least back in the eighties, but I'm not sure how hard it is on Ford alternators. JWA is right, you first need to diagnose the problem. it shouldn't cost much, if anything to find out if it is the alternator. It may be a grounding problem, too.
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Old 01-13-2019, 10:24 AM   #6
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First, I would measure the voltage at your starting battery as a reference. And better yet disconnect the Aux Battery cable and measure the starter battery.

The link you supplied referenced a kit that came with the KeyLine dual battery isolator. The link says they supplied 20 ft of 7 AWG cable, or I suspect the metric equivalent. IMHO that would be undersized for the job at hand. It does not even cover the 140 Amp rating of the isolator itself. More important, there would be a significant amount of voltage drop. If you used all twenty feet, you could get almost 0.5 volts with 8 AWG wire at 40 Amps. Not sure how long your cable run is, but you will have some voltage drop, Any suspect connections will also add to your voltage drop.

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Old 01-13-2019, 11:44 AM   #7
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SOlar is not that difficult to install and is a short term solution imo. SOlar also doesn't need to be mounted and a portable solution could be of big help. A folding suitcase style 100-200w coupled with a Kodiak solar battery would be a good start. It's not an inexpensive solution, however. The Kodiak does allow you to plug in your van to the bank as if it was shore powered. You can also hook up the kodiak to you house battery to charge it. Check it out.
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Old 01-13-2019, 01:14 PM   #8
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Yeah that's kinda low voltage coming out of the alternator and agree with Greg that it seems like the bus wire is small. I've got a smart regulator on a high amp alternator and while on the road it puts out 3 times what Ford's high amp alternator does amperage wise. That has helped me a lot as I'm usually driving part of the day.

+1 on the shore charger if you visit places that have AC. Solar might be a solution but how much sun do you get up north? With full timing in places like that, some folks have to pack a generator especially if boon docking at one site for days at a time.

Just my opinion but I've always considered the bare min to be a 200 AH battery couple with at least (provided you have enough sun) a 100 watts of solar but I have a fridge and heater to contend with. I made sure I had enough room to add a second aux battery if I needed it and it didn't take long before I installed a second 4-D battery. It might be a little large but cold affects the discharge and as the batteries age they loose a bit of holding capability. Still even with a large battery bank, you have to be able to put back what you've used at a reasonable charge rate.
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Old 01-13-2019, 01:48 PM   #9
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I wonder if the alternator is sensing the voltage of just the start battery, and thinks it's fully charged, so it reduces the output? I would measure the voltage at the output of the alternator, at the start battery, and again at the house battery while the engine is running to check for voltage drop. Then add as much load as you can (lights, refer, heater etc) and you should see the voltage come up. There may also be high resistance between the alternator's output and the battery, so that the alternator see's a higher voltage than what's reaching the battery's, so it cut's back prematurely. In addition, it takes far longer to fully recharge the battery's than you may think. Simply driving around for a couple hours won't fully recharge the house battery, even with a high output alternator, because the absorption rate (the rate at which the battery will accept a charge) declines a lot as the battery nears about 80% of a full recharge. The final 20% can take twice as long as the first 90%

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Old 01-16-2019, 04:52 PM   #10
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Thanks for all of the info! At this point, I've resolved to driving the van whenever I go into town, instead of leaving it at the campsite, which has helped make the electrical system at least functional for our standards without damaging the battery (usually have the battery at 12.65 volts when we park at night and then it drains down to 12.25 volts by morning).

My tentative plan of action at this point is to:
1) Test voltage of alternator and see if I have issues with that
2) Then test to see if I have any voltage drop to the hotel battery (which as most of you've mentioned, I probably do)
3) Try and make friends with someone in Bend that'll let me plug in at their house and then buy a battery charger
4) Do the research and figure out what sort of solar setup I want. By moving to Bend from Seattle, I essentially doubled my days of sun, so I think this will be a viable option moving forward


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