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Date Posted |
Forum
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RE: Where do I look for the high powered DC-AC inverters?
Kevin,
I guess we don't know what kind of RV you have.(?)
In case you have a Truck Camper, Class A, Class B/B+, or Class C/C+ RV - here's an excellent article published by an RV manufacturer that provides a guick education (before you buy an inverter) on how to heat and/or cool your RV when camping (near the end of the article):
http://www.sportsmobile.com/1_heating_ac.html
Here's a line of relatively inexpensive and excellent pure sine wave inverters with two year warranties. I have a 300 watt one of these that handles 500 watt peaks and so far has not let me down. You'll be interested in the higher power models:
http://www.samlexamerica.com/products/subcategory.asp?CategoryID=7&title=Pure%20Sine%20Wave%20Inverters%20Light%20Duty%20Commercial
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pnichols
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11/18/09 12:15am |
Tech Issues
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RE: Class C to A?
The DW and myself spent 10 weeks straight this past summer in our 24ft wide-body non-slide Class C and were ready to keep going right up to the day we returned home. No toad either, we just took the Class C everywhere except for trips to downtown Washington DC using public transportation.
Our rig has double queen beds, with one permanent, so the DW can lay down and rest on a moment's notice. Ours also has an unusual amount of exterior storage - four exterior compartments with one of these large, plus two more exterior accessible long compartments going across underneath the coach floor for shovels, fishing poles, etc.. We do not need any additional exterior storage on the ladder, the roof, or front/rear bumpers. We are able to bring along large items such as: Multiple chairs, including two full size lounge chairs. A portable generator to back up the built-in generator along with a gasoline container for it. A foldup picnic table. Three foldup lounge tables. A barbeque and fire wood. Etc..
The DW loves it's interior compactness combined with all the comforts of our stick house, including built-in extended range Internet broadband via a battery powered wireless modem so we can stay in contact from inside the coach or outside on the picnic table, with or without hookups. We use a large portable 12V-powered computer for TV, the Internet, and SD/HD movies so as to gain interior room by not having a built-in TV.
It depends on how much flexibility you want for camping, as most Class A's are longer and a bit taller than our Class C ... plus I don't think I'd ever try to jack up a Class A and change a rear tire out in the middle of nowhere. We like to be able to spontaneously cover the campsite spectrum from nicer private parks to remote and small boondock spots.
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pnichols
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11/17/09 11:54pm |
Class C Motorhomes
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RE: Using Electric Blanket while Boondocking
Danny,
I would not recommend messing with 110V AC powered electric blankets and the conversion losses you get with having to use inverters.
Go with a direct 12V electric blanket for most efficient use of your precious battery power. These blankets cycle on and off - especially if you use a lightweight standard blanket over them - so the amp hours they use from your batteries can be considerably less than what you get by merely multiplying their specified current draw times the number of hours they're used each night.
There are some links above posted by others on where to find 12V DC electric blankets.
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pnichols
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11/14/09 11:31pm |
Tech Issues
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RE: Fuel injected portable generators,,,,soon?
At the very least, you'd think Honda would add the simple twist knob altitude adjustment on their current portable 1000 and 2000 generators. My built-in Onan has this and it sure simplifies tweaking it for high altitude camping.
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pnichols
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11/13/09 12:35am |
Tech Issues
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RE: How many watts?
"I know some RV'ers can't run their A/C and Microwave at the same time, unless they have a much larger generator than a 4K."
Hmmmm....I don't quite understand what you mean. My Onan 4KW runs our 13.5K A/C and microwave at the same time with power to spare - no problem.
By the way, note for those of you that want two generators to back up each other and to reduce weight per lift - two Honda 1000's connected in parallel put out more steady state power than one Honda 2000. Twin 1000's output 1800 watts continuous.
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pnichols
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11/13/09 12:28am |
Tech Issues
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RE: Personal safety while boondocking
I installed a: Wilson Direct Connection Cellular/PCS Amplifier, an RV/Trucker Spring-Mounted Cellular Antenna, the specific little interconnect assemblies that go between the amplifier cable and into the external antenna connector on each of our two different model cell phones, and a Cradlepoint MBR1000 router.
The router is for high speed Internet access outside the RV through cell towers via a Verizon USB 760 air card we plug directly into the router. When doing this if more Internet access range is required, the amplifier can be plugged directly into an external antenna connector in the side of the USB 760 air card.
For extended range phone calls we plug the amplifier cable into the specific little interconnect cable which is plugged into the external antenna jack of whichever phone we want to use.
The amplifier and router plug into 12V receptacles - so 110V inverters are not required so as to eliminate any power conversion loss when dry camping. Also to save power when dry camping we try getting in/out first by powering up only what we need in this system. Sometimes for Internet access we can plug the air card directly into the computer and leave the amplifier and router off. Of course for phone use we first try the phones without the amplifier, then turn on the amplifier and connect it to phones for extended range when needed. So we have several different setup combinations we can use for cellular phone and Internet service, depending upon how far out in the middle of nowhere we are camping.
With this setup, you can even receive Internet television channels if you can't get the reqular OTA channels or don't have a satelite TV setup. This setup did cost a few $$$, but we find it be priceless for staying connected and for convenience by being able to surf the Internet out at the picnic table or for allowing friends we dry camp with to connect up to the Internet from their rig or get out for emergency phone calls.
If this setup can't get you out to a cell tower, there is one more way to get extended cell tower access even further away by using the specialized multi-element "yagi" cellular antenna type that this person uses:
http://www.boxcarcabin.com/ruralcell.htm
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pnichols
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11/09/09 07:23pm |
Public Lands, Boondocking and Dry Camping
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RE: Solar Charging
"Panels are as low as $2 a watt, maybe lower."
smkettner,
Please provide one or more links showing where one can purchase a, say, 120W panel for around $250.
Also, if you can, provide a link or two where I can instead purchase a foldable or roll-up 80-100 watt panel for under $300.
Foldable or roll-up is what I would really prefer, so I can store it in a compartment and place it out in the sun while our MH is in the shade .... but I will also consider a solid 120W panel for $250.
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pnichols
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11/09/09 11:04am |
Public Lands, Boondocking and Dry Camping
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RE: Tv
I'd look on the specifications page of the owner's manual first. It you don't have a hardcopy of the owner's manual, plug the TV's Model No. into Google on the Internet and find a link to either it's owners manual or a description/discussion of it's specifications.
By the way, what makes you think your TV isn't capable of 1080 P? Many late model ones are capable of this "ultimate" resolution .... I wouldn't ever replace mine with anything less. (Mine current TV is 1080 I.)
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pnichols
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11/08/09 11:34pm |
Tech Issues
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RE: Personal safety while boondocking
".. cell phone reception is non existant where we camp"
Deputy Chief P.O.,
(unless you have satellite phones - the ultimate) In addition to personal safety emergencies .... no cell phone service at remote camping locations could present a much worse danger - a medical emergency. ..... Or mechancial breakdowns out in the middle of nowhere, too
Have you ever considered for your motorhome a roof top cellular antenna direct wired to an inside cell phone transceiver ("amplifier/enhanced receiver") with the transceiver then direct wired to the external antenna connector on your cell phone(s)?
We have this setup in our Class C MH and it works as advertised. Both our cell phone and cellular Internet access are greatly improved - at way less cost than a satellite phone. We used this on an extended 9000 mile trip this summer and found it very rare to not have our cell phones connect and Internet access in all sorts of situations and locations.
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pnichols
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11/08/09 05:45pm |
Public Lands, Boondocking and Dry Camping
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RE: Onan 4000 Vs. V10 ?
0.7 gal/per hour is what another reported here quite some ago on V10 consumption at idle and it's the figure I use.
I believe many Ford V10 powered emergency vehicles, shuttle buses, etc. are run long periods at idle speeds so the engine can probably take it fairly well, by design. For added care, I use Mobil 1 synthetic oil in my V10. You can even use better oil, like Mobil 1 Extended Service synthetic in it, and I plan to start using ES soon, myself. If you're concerned with engine wear when idling, I'd recommend contacting Ford Customer Service to get their official position on this.
Since my Onan 4KW Microquiet consumes about 1/5 to 1/4 of it's power when fully powering and only powering my RV battery charger, it's consumption is probably around 0.30 to 0.35 gallons per hour when charging the batteries. Since the V10 is so quiet when idling - even quieter than the little Hondas - I use it in "highly noise sensitive" camping situations when other campers are close by. In other situations I start out idling the V10 for maybe 30 minutes (quietest), and then finish up using either a Honda EX650 I carry along (louder but still very quiet), or our built-in Onan 4KW (loudest but quite tolerable as installed by Winnebago).
Your idling V10 is the quietest and most expensive way to charge your batteries, but your Onan is the loudest and a less expensive way to charge your batteries. It will help when using your Onan if you use a very good multi-stage charger with large gauge cabling to help minimize run time of the Onan. Of course the cabling from your V10's alternator to your RV batteries should also be large gauge (Winnebago installed 6 AWG gauge cabling for this in my rig).
Here's a good link (ignoring the actual RV manufacturer who published it) that talks about various ways to get electrical power into your RV that applies to any type RV. Note that they openly advocate idling of the engine as part of your power mix:
http://www.sportsmobile.com/1_heating_ac.html
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pnichols
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11/07/09 07:40pm |
Class C Motorhomes
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RE: What's the difference in a Heat Pump and an A/C?
"..but the ones I have are actually electric furnaces that completely heat the house when the temperature gets cold enough"
That's exactly the way my 30 year old Carrier HP works and why I want to replace it with a new one with a very high efficiency heat pump section -> so that an expensive electric heat boost section of the new heat pump doesn't have to run anywhere near as much at any given cold temperature.
Air conditioner/heat pump combination units for RVs could be built the same way: Very high efficiency compressor machinery supplemented with a 1500 watt boost heat coil. As an added benefit, a high efficiency compressor section in 13.5K combination RV models would make it possible to run them with the Honda 2000 inverter generator in far more situations - of course with the 1500 watt boost heat coil locked out when using the Honda so as to run just the heat pump part of the unit for heating in moderate cold temperatures.
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pnichols
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11/07/09 09:13am |
Tech Issues
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RE: Personal safety while boondocking
Browning four-round semiauto BAR in 300 Winchester Magnum (30-06 on steroids) ... but don't carry it in the MH ... would put us over the rig's CCC limit. ;)
(Instead, we have an extended range cell phone system and an axe in our rig.)
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pnichols
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11/06/09 11:48am |
Public Lands, Boondocking and Dry Camping
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RE: The true costs of running a generator?
This entire discussion thread has been very interesting and educational.
Here's an excellent article on some RV electrical power options and when/how to use them. It's a little off-topic, but is related and very infomative for the curious. Even though it's from a specific Class B manufactuer the principles and methods talked about apply to all RV types:
http://www.sportsmobile.com/1_heating_ac.html
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pnichols
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11/05/09 11:27pm |
Tech Issues
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RE: What's the difference in a Heat Pump and an A/C?
"The efficiency of the heat-pump in these "new-systems" still have a limit at around 40 degrees."
Well, not necessarily so any longer. As I said in other posts above, the 40 degree outside temperature heat pump efficiency limitation is becoming an old rule of thumb.
Here's what's possible in modern state-of-the-art air heat pumps:
http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12620
Especially notice the advanced technologies sections near the end of this article.
Also note that old or new technology air heat pumps do not suddenly drop off as outside temperatures get below 40 degrees - their efficiency declines in a smooth fashion. This means the electric or gas heat booster units built into air heat pumps merely have to come on more and more as the heat pump section operates at less and less efficiency.
The new advanced techonology heat pumps in cold climates may still require supplemental boost gas or electric heating sections for low outside temperature extremes, but their boost sections will not be needed as much at any given low temperature as the boost sections in older air pump systems .... hence the new heat pumps with their sophisticated decision-making controls can miminmize the cost of heating at any given time and outside temperature. In moderate outside temperatures, of course the new air heat pumps will use less electricity than earlier ones.
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pnichols
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11/05/09 10:18pm |
Tech Issues
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RE: How long will it take to charge my battery?
"These would be my suggestions for a complete test."
Sal,
I did several tests similar to what you list a couple of years ago and the data is in the rig and unavailable right now. Our Class C rig is in the shop getting the overhead forward facing bunk window replaced after being shattered by a rock this summer. :(
All my testing at this time indicated "pretty good" current replacement by the 7345 (~8 feet of 8 AWG cabling and frame ground) into my 200 AH AGM coach battery set. The batteries reached 90%-95% SOC, if my memory serves me right, in around 3 hours from around 55% SOC (30 amps discharge rate for 3 hours). Alternatively, this time was shortened a bit as indicated by comparison data I took using the V10's alternator (~8 feet of 6 AWG cabling and frame ground). I estimated reaching 90%-95% SOC by watching the ammeter sink to under 5 amps charge acceptance rate and then cross-checking terminal voltage after 24 hours of settling - however I can't recall if my batteries's performance curves showed under 5 amps as being above 90% SOC, but the curves in my last link below definitely show 90%-95% as being about right in this amount of time.
My batteries may be the reason for my thinking the 7345 was doing well, as they are somewhat unusual for use in an RV. They're a couple of Interstate labeled but C&D Technologies manufactured "motive power" 100 AH-each 12V AGM batteries intended for use in wheelchairs, residential solar systems, etc.
Note from this .pdf spec, that since they are to be floated at 13.5V to 13.8V, the 7345 does not damage them. However, since they are AGM ("VRLA") batteries, the 7345 applied voltages also happen to charge them quite fast. As for needing to "sock" them with 14+V periodically, the V10's engine alternator serves this purpose:
http://www.cdstandbypower.com/product/battery/vrla/pdf/dcs_100it.pdf
Notice below in this C&D Technologies technical paper on their VRLA ("AGM") batteries in Figure 1 & Figure 10 that charging voltages right in the range of what the 7345 is capable of (2.25 V/cell = 13.5V and 2.30 V/cell = 13.8V) for outputs of 20 to 30 amps gives times of 2 to 4 hours for recharging from around 50%-55% SOC to around 95% SOC. Note also the "0.1C" shown in the curves. This is 20 amps for my 200 AH battery set:
http://www.cdtechno.com/custserv/pdf/2130.pdf
The subtle learning for me after studying these curves was that the terminal voltage versus energy replacement time for charging of AGM/VRLA batteries is VERY CRITICAL ... especially so in my situation of achieving terminal voltage in the high end of the 7345's 13.5V to 13.8V heavy loading range. Hence my constant emphasis that charge cable size is VERY CRITICAL and that one should strive for every tenth of a volt improvement they can make in applying the highest voltage possible on the terminals of the battery being charged - depending of course on how fast you want to charge plus maximum currents recommended by the battery manufacturer.
As I talked about above, my batteries may be OK with the single stage 7345 assuming I'm OK with around 3 hours charge time. However this degree of terminal voltage sensitivity may not be present with wet cell lead acid battereis, so maybe the use of brute force 14.X higher charge voltages is what's required with them for anywhere near reasonable charging times.
My thinking at this point is that it's not all battery and cable resistance issues, but also may depend upon the chemistry, materials, and construction of the battery as to how well the 73XX single stage converter family does with RV deep cycle batteries.
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pnichols
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11/05/09 09:03pm |
Tech Issues
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RE: How long will it take to charge my battery?
What Sal did could be a great - but tricky - feature addition to any high end multi-stage charger to remove cable size effects. However so far I've seen none with remote voltage sensing.
This may be because remote voltage sensing has potentially serious downsides:
First the charger must be internally protected from over-voltage and over-current damage which is not difficult to include, and is often included, in designs - some of which Sal's modification takes into account with regards to his 7345 converter. The second danger could be much greater and a possible product liability issue for a charger manufacturer. Remote voltage sensing improperly installed could easily "fool" many users into thinking their high power charger could now be used with long runs of 10 or 12 or even 14 awg charge cabling (not talking about the separate sensing wire) because they might try it and initially see that -"Gee, look at that ... 14.6 volts on the battery terminals 25 feet from the charger and the charger is pumping 60 amps into the battery".
This is because the charger would now be maintaining the 14.6 volts on the battery terminals no matter what and normal battery acceptance rates would allow the battery to draw the 60 amps. In a few minutes or seconds the too-small charge cabling would begin to get really hot - maybe in some hidden place or at some connector along it's length - and start a fire in their rig. The charge cabling awg size would have to be chosen carefully/properly so as to be able to carry the charger's maximum current without the cabling or it's connectors heating past safe limits. Charge cabling would also now have to definitely be fused properly based on it's awg size, it's length, any corroded connectors along it's length, and the charger's maximum current.
Without remote voltage sensing, manufacturers and us users can now pay little attention to the above heating hazards since voltage drop in too-small charge cabling is keeping us safe because battery acceptance is getting "automatically" depressed enough such that charger current maximums are not getting pumped through too-small cabling due to the physics. We are OK on safety - but not OK on getting all the current from our chargers and into our batteries that we paid for.
My vote is for chargers to be as close to batteries as possible (just like with large inverters) and to use very large cabling/connector sizes so as to both maximize charger current delivery plus therefore wind up with cabling/connector sizes so beefy that heating is not an issue with most converters or chargers that are commonly used in RVs.
i.e. Many, many Parallax 7345 converters are in the field. Other than the problem of their fixed voltage float boiling some lead acid batteries, how many of us are using 2 awg cabling on their 7345 outputs? Their output terminal lugs are sized for this and they would do much better charging batteries starting at low SOC values.
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pnichols
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11/04/09 05:38pm |
Tech Issues
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RE: How long will it take to charge my battery?
"Why not invest in a nice 100A panel meter? Here's one for $20."
Sal,
I've installed these quite some time ago to monitor my coach batteries:
http://www.ecovantageenergy.com/catalog/items/item204.htm
http://store.solar-electric.com/mka-100-100.html
http://www.bestconverter.com/Voltminder_p_178.html
The meters are mounted right on the dash so I can also keep an eye on things while driving. The ammeter shows me when the alternator has the batteries topped up. The voltmeter tells me that A) I didn't forget to switch ON the coach battery switch so the refrig is operating, and B) that the boost relay that connects the coach and chassis batteries together is operating reliably. I recently had to change this to a silver alloy contact relay because Winnebago's stock relay was getting intermittent (probably corrosion on the contacts).
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pnichols
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11/03/09 11:42pm |
Tech Issues
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RE: What's the difference in a Heat Pump and an A/C?
There are also new state of the art air-to-air heat pumps for home installations that are effective under 30 degrees. Some of these can have electric heat strip boost or propane boost. At low outside temperatures their computerized controls choose pure heat pump mode, or pure propane mode, or pure electric heat strip mode, or a combination of two of the three - depending upon which mode is the most energy efficient.
They're probably using variable speed rotary compressors with perhaps two stages in series to accomplish this and their efficiency rating numbers are way superior to my 30 year old Carrier's. There's no reason other than "money" that RV air-to-air roof top heat pumps couldn't be offered in scaled down versions of these very efficient home units - with either heat strip or propane boost to deal with outside temperatures below 30 degrees.
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pnichols
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11/03/09 05:48pm |
Tech Issues
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RE: How long will it take to charge my battery?
"I have about 23 feet of 8 awg cable going from converter to the battery."
Sal,
As you probably know, the Parallax 7345 output lugs are specified to fit up to and including 2 awg cable. I'm really curious as to what current my 7345 would pump into my 200 AH AGM coach battery bank with the batteries down to 50% SOC and 8 feet of 2 awg cable between the 7345 and the batteries. I think I have it written down somewhere what cable drop I measured with the Winnebago stock 8 awg cable in place (about 8 feet) in parallel with a large battery jumper cable strand I ran in parallel to the stock 8 awg. I'll have to look it up. I'd prefer to have real data along with the equation's prediction.
I'm on somewhat of a mission to force/show/prove my 7345 to be "just fine" with my 200 AH AGM batteries. I'm reluctant to modify it's output feedback so as to rule out cable resistance cuz I prefer not to mess with the 7345 internals. Currently, with about 30 minutes of V10 idling alternator charging time through 7 feet of 6 awg cabling plus 2 hours of converter charging through 8 feet of 8 awg cabling I think I'm getting up to 90% SOC from around 50% SOC with the fast AGMs.
I can of course pick up another expensive 3-stage charger it I ever need it - but I want proof it's cost effective to do so. I have a sophisticated and pricey solid state switching 3-stage trolling motor charger but it's only 15 amps, but I can't really see any way of using it along with the 7345 to emulate a 60 amp 3-stage charger.
P.S. Don't be so hard on your 7345. After all, don't they set one back $150 to $180 new? I think it's notorious "charging problem" is merely one of speed (charge time) with dinosaur-technology wet cell LA batteries and too-small cable sizes. I'll bet the 7345 would have a different reputation if manufacturers had been installing them with 2 awg cabling all along. ;)
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pnichols
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11/03/09 05:37pm |
Tech Issues
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RE: What's the difference in a Heat Pump and an A/C?
".. there is NO REASON to have a Heat Strip on a Heat Pump since they all have either Hydronic or Furnace system on board for sub freezing temps."
If you have hookups or have a dry camp generator running .... why use either your own propane or excessive generator fuel? If temperatures are 40 degrees on up, an RV heat pump is the least expensive electrical way to heat since you are not making new heat. If for some unfortunate/emergency reason when dry camping in 40 degrees on up temperatures you are forced to get some heat into your RV for awhile using a generator, it will use less fuel powering a heat pump then it would by creating new heat from only a standard electric heater to get the same BTU's.
For marginally lower temperatures - say 35 to 40 degrees - getting some heat out of an RV's heat pump plus installed heat strips in it will STILL take less hookup or generator power than through only use of standard electrical heaters.
"The reason for a Electric heat coil on Home heat Pump systems is for Heat when it stays below freezing and the Heat Pump cannot get the BTU's of heat out of the air."
As I said, my home system has two heat strip stages. On the first stage the home is getting heated some by the heat pump and some by the first stage electrical heating elements. This is less expensive than no heat pump at all.
This reasoning also applies to an RV heat pump being supplemented/helped in the 35 to 40 degree range by 5000+ BTU's coming from it's heat strip.
"The Heat Pump mode puts out more heat."
Not in the 35 to 40 degree range - in heat pump mode you would get SOME BTU"s but not enough. Heat strips would provide 5000+ BTU's additional.
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pnichols
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11/03/09 02:38pm |
Tech Issues
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