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Old 03-15-2014, 08:07 AM   #1
Western Traveler
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Charging batteries in dry camp

We are heading out on our first dry camping trip with this trailer (the tent it replaced was simpler).

Recent additions; LED interior lights, dual 6 volt batteries, and a 45 volt HF solar kit.

We have a Honda 2000, if the solar system doesn't keep up we will top off with the gen. We are sensitive to people running generators, a carryover from tent camping but now we are "them"...

Here is the question; can we top off faster plugging in the trailer shore power cord to the gen set or an external battery charger directly to the batteries?

I want to go as long without to check this current setup first, so I anticipate the batteries being down a good bit when we plug in.
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Old 03-15-2014, 08:31 AM   #2
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Your 45w solar panel will have "its work cut out" in keeping those 2-6v batteries fully charged. Don't forget that the 45w rating is under ideal conditions - full sun and any cloud cover will result in far less effectiveness and output. I'm not sure of the output in amps but I am guessing it might be around 4-5 amps ??? At this rate, the solar panel is only slightly better than a trickle charger.

I realize it is too late now, but you might want to consider a better solar panel with a minimum of 85w. We have one - regulated of course - and it is quite effective in keeping our 2 -6 volts fully charged. Again, using solar panels is very dependent upon cloud cover. Our panel is not permanently mounted as I've fashioned a "sandwich board" stand to hold it up when in use and it slides into a slot I made in the storage compartment when not in use.

As I see your situation, you can charge your batteries in the following ways:
1) using the solar panel
2) connect the 12v DC charge from the Honda generator - probably 8a charge
3) connect an external battery charger to the 110v AC output of the generator - amperage not known. Perhaps 10A ???
4) connect the generator directly to the RV and use the RV's converter to do the charging.

I would guess that method 3) and 4) would be the fastest way but not sure if one is any faster than the other. All methods except 1) involve using the generator.
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Old 03-15-2014, 09:00 AM   #3
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Festus,

Thanks for the response, the 45 volt panels are just a start as I hope to add to them by summer. I was thinking one more just like it and realize HF is a shorter lived and less than optimal panel but so many things to acquire for this new rig.
I will have no problem with running the generator just wasn't sure what would give me the fastest charge. Sounds like the 10a external charger will deliver in the shortest time.
Sedona and the South Rim Grand Canyon this trip so hopefully sun...or snow at the Canyon (wouldn't be surprised either way).

This is the kit we went with
http://www.harborfreight.com/solar-p...l#.UySHp_ldWSo
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Old 03-15-2014, 09:45 AM   #4
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OK, several things to consider:

12 volt battery charging
1. a 10 amp external battery charger will only charge at 10 amps. If you have a 30 or 40 amp external charger with an automatic monitoring feature, it will approximate the WFCO, but smaller chargers won't charge as fast as your converter/charger in the WFCO.
2. The WFCO 8955 power center produces 55 amps of power. It can charge your battery at SIGNIFICANTLY higher amperages than the 10 amp charger. To use such a small external charger will be counterproductive. It's better to use the automatic charge feature in the converter using shore power or generator power.
3. The maximum output of the WFCO is 55 amps, so any load will decrease the charging amperage to the battery, so don't run lights, the furnace, etc to keep all available amperage for battery charging.
4. You can NOT use both. If you connect an external battery charger, the WFCO circuitry will sense the 13.6 VDC from the external charger and go into "float mode" and not charge the battery at all.

Solar charging:
1. Not all solar panels are created equal !!! HF solar panels are "first generation" panels and do not produce much power. "Second and third generation panels produce significantly more power per square inch and operate much better under cloudy or off angle conditions. To purchase more of the "old style" to "upgrade a system" would be money wasted (to a great extent) as you won't get good performance or good power. Consider looking into the new technology for supplemental solar panels.
2. If you leave the solar panel connected to the battery while running your generator to charge your battery, you won't charge from the WFCO for the same reason as above.

I would suggest that you recharge your batteries when they reach about 70% charge condition. Here is the voltage/charge status reference:

100% 12.7+ VDC
75% 12.4 VDC
50% 12.2 VDC
25% 12.0 VDC
0 11.8 VDC

As you can see, lead acid batteries keep a fairly constant voltage and there' s not a ot of difference in a fully charged battery and a half discharged battery.

Most of the "push button/LED" battery status indicators with 4 red LED's will indicate 100-75-50-25% charged with each subsequent LED, but using a volt meter is really a much more accurate measure of battery status. Actually using a hydrometer, but that is sometimes difficult in the campground as it means taking the caps off the battery which can lead to splashing or spilling acid. The voltage test is "close enough" in the campground environment.

Good Luck
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Old 03-15-2014, 10:15 AM   #5
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John provided the technical side. I would say if you are going to run the generator I would connect it to the Shore power cable and have the converter charge the batteries. Connected this way, as you know, your entire trailer is powered up therefore everything available to you if needed (12VDC and 120VAC) But as John stated using any 12VDC devices will compete with the charging current to your batteries. Not sure what 120VAC lights you may have?

Well my 2 cents or in this case non technical 1 cent
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Old 03-15-2014, 11:35 AM   #6
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OK got it, charge though the shore power cord at 70% charge life. I know the HF are not the best but thought I would give them a go. Good advice to buy quality as upgrade as I know they will deteriorate over time as well.
@PARAPTOR
LED interior lights.
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Old 03-15-2014, 08:05 PM   #7
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Quote:
Originally Posted by Western Traveler View Post
We are heading out on our first dry camping trip with this trailer (the tent it replaced was simpler).

Recent additions; LED interior lights, dual 6 volt batteries, and a 45 volt HF solar kit.

We have a Honda 2000, if the solar system doesn't keep up we will top off with the gen. We are sensitive to people running generators, a carryover from tent camping but now we are "them"...

Here is the question; can we top off faster plugging in the trailer shore power cord to the gen set or an external battery charger directly to the batteries?

I want to go as long without to check this current setup first, so I anticipate the batteries being down a good bit when we plug in.
. Here is a good chart that might help.
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Old 03-27-2014, 11:54 PM   #8
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Back from our trip so here is an update. I took Festus and John's advice. Left the HF solar panels in their box and returned them when I got home. We definitely will need a quality solar panel in the future and I need to find a way to use less draw in dry camp. We did not disconnect alarms but were pretty frugal with our lights and eq. Most everything on the panel off, water pump etc. No hot water and fridge on propane only however it was down to 12 degrees at night so the furnace was certainly used. Once we started losing amps on the 6 volt batteries we just couldn't catch up with 3-4hours with the Honda 2000 each day. Ended up at a full hookup campsite on day 6. Batteries at about 30%.
I think I need to see if these new batteries are actually taking a full charge as well without any load...
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Old 03-28-2014, 06:49 AM   #9
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Western Traveler,

You might want to verify the size of the 12VDC wiring that feeds the batteries from the converter. It may only be 8ga or even smaller. If so, it won't carry the amperage that the converter is putting out so the wire might well be what's limiting your charge rate..... Just a thought.....
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Old 03-28-2014, 08:01 AM   #10
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Think you said 2k watt generator about 16 amps. You said could not catch up and being in that climate I assume your converter was supplying 12VdDC to run furnace, lights, etc. and charging your batteries at the same time. Very different to using converter output to solely charge the batteries. Without knowing the power being drawn by the tailer while charging the batteries, not sure if or how long it would take to get caught up? Maybe someone with expierence in this situation will chime in. I have no experience dry camping, when had to charge batteries just plugged rig into house and walked away. Did not time how long it took to recharge dead batteries (2 12V)

Replacing regular bulbs with Led would be a start
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Old 03-28-2014, 08:32 AM   #11
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In addition to having a look at the wires from the converter to the batteries, you might want to "experiment" with using the generator's 12v DC charger to charge up your batteries. It will produce 8A. This way, it will bypass the converter and the circuit leading to the batteries and the possible wire gauge problem won't be an issue. This won't solve the problem of not being able to bring the batteries up to charge but could be a temporary solution if you find yourself with no "juice" left in your batteries.
Just charge them up directly from the Honda.

If those 6volts have been run down to 30%, as you indicated, then it will take some time to bring them back up to a fully charged state.
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Old 03-31-2014, 11:05 PM   #12
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Thanks for all the feedback. I am back at work on the Pacific (Hawaii, nice to be here rather than home that has surpassed 100" snow and still falling today) but will start looking at things again on my return. I am thinking the wires running from the converter are the same as coming off the batteries? Guessing 8 ga. It is pretty stiff. I didn't look that close.
Again we are already running LED lights. While charging from the generator we had everything in the trailer off except a couple of LED lights and the alarms. I had anticipated compitition between usage and charge. The way Festus is suggesting would probably give me a quick answer. That and checking the wire guage. Plan on taking them off the rig and charging completely on my return. When I checked the individual cells with a hydrometer they were all very close so I am thinking it is not the batteries which are new.
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Old 04-01-2014, 04:57 AM   #13
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Battery Hook up

When you hook the Generator 12Volts or a solar panel directly to the battery to charge, ... do you/can you leave battery connected to the trailer? or do you need to disconnect the battery from the trailer? ... Thanks
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Old 04-01-2014, 06:13 AM   #14
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MIKEPATC -
There is no need to disconnect the battery - just leave it hooked up. If you are considering using a solar panel, a regulator may have to be used depending upon the size and output of the panel. An 80W solar panel, for example, would require a regulator to be placed between the solar panel and the battery in order to "regulate" the charge.
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Old 04-04-2014, 04:54 AM   #15
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Thanks

Quote:
Originally Posted by Festus2 View Post
MIKEPATC -
There is no need to disconnect the battery - just leave it hooked up. If you are considering using a solar panel, a regulator may have to be used depending upon the size and output of the panel. An 80W solar panel, for example, would require a regulator to be placed between the solar panel and the battery in order to "regulate" the charge.
THANKS Festus2 ! This forum is great !
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Old 07-13-2014, 12:49 PM   #16
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How big a solar panel would i need to to keep a 12 v battery charged while runing the fridge on gas? we made it 36 hours on a full charge before the fridge shut off, we bearly got the slid in, after a 2.5 hour hiway drive the fridge still wouldn't start,
were planning a four day dry camp and would love to know what panel would do the job

Thanks in advance
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Old 07-23-2014, 08:58 AM   #17
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Western Traveler,

You might want to verify the size of the 12VDC wiring that feeds the batteries from the converter. It may only be 8ga or even smaller. If so, it won't carry the amperage that the converter is putting out so the wire might well be what's limiting your charge rate..... Just a thought.....
John,
Thats just not true at all. If that were the case you wouldn't have to fuse any thing just let the wire limit the amperage.

Most travel trailers have small low power inverters / chargers. My 2014 333MKS comes with a charger that will do Max 20A charge rate @ 14v.

Your best bet for charging those batteries is to run the generator and use the built in charger. It will do the job in a few hours. Sure you could go out and get a 80A "rapid charger" that will boil off the water from your system.
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Old 07-23-2014, 10:11 AM   #18
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[QUOTE=b.d.m;136977]

Most travel trailers have small low power inverters / chargers. My 2014 333MKS comes with a charger that will do Max 20A charge rate @ 14v.

QUOTE]

b.d.m.
Do you mean a converter rather than a power inverter/charger? My '08 Cougar has a converter which has the capability of charging the batteries but doesn't come with a "small, low-power inverter/charger". As far as I know, any inverter would have to be an owner supplied add-on and RV's do not normally come equipped with a stand alone inverter or inverter/charger.
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Old 07-23-2014, 10:48 AM   #19
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My 2014 333MKS comes with a charger that will do Max 20A charge rate @ 14v.
From a previous post .....
" (my Cougar has a 5 Amp charger)."

Which one do you have???? ... Mine has a 55amp converter/charger. Have they reduced the output on the converters since '07????
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Old 07-23-2014, 12:44 PM   #20
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John,
Thats just not true at all. If that were the case you wouldn't have to fuse any thing just let the wire limit the amperage.

Most travel trailers have small low power inverters / chargers. My 2014 333MKS comes with a charger that will do Max 20A charge rate @ 14v.

Your best bet for charging those batteries is to run the generator and use the built in charger. It will do the job in a few hours. Sure you could go out and get a 80A "rapid charger" that will boil off the water from your system.
I really don't know where to begin, so I suppose at the beginning is probably the best.

What makes you believe that my comments are "really not true at all" ???

If you don't fuse a wire and happen to apply greater than the current carrying capability the wire will overheat and potentially cause a fire. Anyone would be foolhardy to take your comment literally. Could you possibly be thinking about a fusible link when you make your statement? Figuratively, a fusible link is a wire of "lesser capacity" used as a fuse to protect the remainder of the wire from damage from being overloaded. It will "melt down" before the main wiring harness is damaged.

Most trailers DO NOT have "small power inverter/chargers" in fact no Keystone products come with a "standard inverter" of any kind. They all have WFCO power centers ("CONVERTER/charger} installed as standard factory equipment. The size ranges from 45 amp up to 75 amps WFCO 8945, WFCO 8955, WFCO 8965 or WFCO 8975. Some "select large" Keystone products come with the WFCO 8990, but the are very rare.

According to WFCO technical services, when connected to an appropriately sized shore power (or generator) supply, the total rated output (let's use 55 amps since that is the normal size power center) is available for use. That means if the "other RV power requirements are 15 amps, the batteries will charge at "up to" 40 amps. Of course this depends on the discharge state of the batteries and may be substantially less depending on the charging sequence "sensed" by the WFCO and the resulting voltage/amperage requirements.

Anyone who has installed a "high load" DC device in their RV is well aware of the significantly large gage wire required to provide adequate DC power to the device. In fact, for a 20' run with a 10% voltage drop, at 20 amps, 8 gage wire is required. Using 8 gage wire, the resulting voltage drop will significantly degrade the battery charge capability of the WFCO. it will drop the "nominal BOOST" voltage of 14.4 VDC by 10%, down to about 13.4 VDC. That is below the "absorption mode" voltage of 13.6 VDC. So battery charging time will be significantly lengthened.

What that means in "layman's terms" is that when your WFCO is sensing a need to "rapidly charge" your 50% discharged battery, it will supply 14.4 VDC, but the battery will only sense about 13.4 VDC and the charge time to recharge your battery will be significantly longer than if you had 6 gage wire in the circuit. Even 6 gage wire has a "nominal voltage drop of about 0.5VDC in a 20' run.

Unless you've changed out your Keystone installed WFCO charger for something else, you're mistaken when you say, "My 2014 333MKS comes with a charger that will do Max 20A charge rate @ 14v" According to WFCO, the maximum charge rate is dependent upon the "electrical load requirement" of the RV, and all remaining amperage is directed to battery charging. (That's why it's rated at a specific output). So if you turn on all your lights and run the furnace and water pump, you may only have 20 amps available for charging the battery, but normally, the available amperage will be significantly higher than 20 amps.

I will agree with your statement that the best way to charge the batteries is to run the generator and use the built in charger. That's what Keystone intended when they designed the electrical system and installed the WFCO power center.
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