Convertor Questions

[surfib]

My grandfather is getting ready to head out on a trip from San Diego, CA to Oklahoma City, OK. He will be camping along the way but before he goes I need to style out the camper.

The most important thing on my list is a convertor with battery charger capability. I looked at the IOTA that comes with the FWCs but I havent found a price for them anywhere and when I get on their website I cant find a local dealer for them.

Another is inverter, I might just go a cheapy vector since I'm not gonna use any tvs or anything like that.

Last but not least is battery isolator/combiner so I can hook up my truck batteries to my camper. Any suggestions, I believe I have a 105 amp alt in the truck and a lot of the standard isolators I've seen at Kragen etc... are rated at like 90amps. Also, what guage wiring should I use between isolator to camper battery?

The setup:

1992 Ford F250 Diesel single cab long bed 4x4 with a 1978 FWC Keystone.

Thanks guys!

 

[benburnett]

wiring

We use a 10 guage stranded wire from the truck battery back to a battery separator, then from the separator to the battery.

Can't help you on a converter. We don't use those yet.

As to the inverter, I use one on my truck right now. It is 1500 watts and works great for me as long as I don't leave it on over a weekend when I am not using the truck. Have had to jump start the truck twice now due to that one.

 

[surfib]

Ben,

Thanks for the info! You have a plethory of knowledge and are always willing to help!

On the seperator, what brand do you prefer?

I might be making a trip up your way to check out Northern Californa. I would love to put in new top latches. Someone pushed the front up on mine and ripped a back one out. Its in there solid but would like some new ones none the less due to the set rusting.

 

[benburnett]

Separator

Surfib,

I don't know the brand of the separator just off hand. I will check on that tomorrow for you and post the info to you.

We can help you out on the clamps. Just let me know ahead of time when you would like to come in so that I can be sure we have enough in stock.

 

[Stan@FourWheel]

hello surfib


we are using the double insulated, stranded, 10 gague wire for the truck camper wiring (truck battery back to the camper battery). Works great, lasts a long, long time.

We have a couple of power converters over the past few years, but the best one we found was the IOTA 30 amp. version. Easy installation and very reliable.

http://www.iotaengineering.com/pplib/dlsmanl.pdf

If you want to find a local supplier or buy one on-line, just Yahoo or Google search ... "IOTA 30 amp power converter" -- you will get many companies selling them.

You can call Chicali in our service dept. @ (800-242-1442), if you want a price on one (we have them in stock) , just guessing here, but I think they are about $ 150.00 --- you can probably find them on-line for less $$.

Right now we are using the SurePower battery separator -- seems to be working fine. It has is quirks if the customer has a hugh power demand or a bad truck battery, but outside of that it has been working well.

On the older trucks like yours, I kind of favor the old battery isolator that hooked up to the firewall in the trucks engine compartment and has a "hot" wire hooked to the windsheild wiper motor. Those seemed to work great ! The only reason we stopped using these is due to the computers in the new trucks. The engine computers are too sensitive when you tap into wiring in the engine compartment -- it is telling the truck computer something is wrong with the electrical system.

Maybe Pevey will jump in, I know he had some good advice and experience on this subject

hope this helps ...



.

 

[benburnett]

Surfib,

The battery separator that we use is a Surepower 1314 CP. Cost is about $75.

The picture that Stan put up of the solenoid works great though. We used them for years and never had a problem with them.

The solenoid is easy to wire also. Come from your battery as shown in the picture to the large bolt on one side of the solenoid. The other large bolt side goes to the battery in your camper. One small post you use for ground to the truck and the other small post you wire to the hot wire on your wipers as shown in the picture.

We also used to put a 30 amp thermal fuse in line from the truck battery to the solenoid to protect the system if someone tried to jump your truck wrong.

Hope some of this helps.

 

[Pete D]

I have some comments gleaned from years of reading RV groups and from personal experience, however, I haven't owned a TC yet, so if I am wrong on something PLEASE correct me in the forum so the archives are right! I'd rather be right that wrong and I'd really rather be corrected than be 'permanently' wrong.

Re the battery isolator, the relay isolators constructed for the purpose are, IMHO, the best way to go -- Starting relays may not stand up to the 'normal on' service -- Electronic isolators may not be a good way to go if they use diodes to isolate because the diode may insert a one-half volt drop in the charge circuit and that, coupled with wiring loss, may result in a habitually undercharged TC battery, which will shorten its life. Below is the charge table for flooded lead-acid batteries (dunno if it applies to AGM or gel-cells, but there will be something similar) -- See what subtracting 0.5V does to the charge percentage.... Rather than mess with vehicle wiring per se, I always connect my RV battery charge wire to the battery (with an auto-reset circuit breaker on it).

Regarding converters and battery charging, keep in mind that the converter's primary reason for existing is to power RV accessories using 12VDC from shore power when available. Until recently, battery charging has been a distant second goal. From what I read at the IOTA site, these seem to be in that class, charging a battery to a pre-set voltage, without regard to battery condition or ambient temperatures, just like a battery charger from several decades ago.

When the battery needs a hefty input, esp AGMs which reportedly can take it, the system puts out only 8-10 Amps and in the float stage, where the charge should be small, the system is still trying to pump 8-10 Amps.

If left connected for long periods of time, like winter storage, it is easily possible to overcharge a battery and ruin it.

BTW, much the same applies to the 12VDC outlet on some generators, except that they have no voltage cutoff, preset or otherwise.

The best way to charge a battery is with a multi-stage, temperature compensated so-call 'smart' or 'intelligent' charger. These are somewhat costly when integrated into a converter (Marine and RV markets tend to have premium prices) and less expensive when in a dedicated battery charger.

My *personal preference*, in large part because I usually camp where there is no shore power, has been to ditch the converter entirely (as excess weight, but my converters were the heavy transformer kind, not much lighter electronic kind) after pulling out the 12VDC fuse block and use a Vector battery charger when I have 120VAC and when the truck charging system hasn't been used much. If I had a generator, I would still use the Vector because it would charge faster and better than the generator's 12VDC outlet.

If one has a lot of RV 12VDC appliances and is used to having 120VAC available, then they may regard a converter is being more useful than I presently do, of course.

Another reason for a battery charger over a better converter besides the cost is that the charger can be used on other batteries and, if big enough, for starting vehicles. If needed, I can also run a battery charger off an inverter, presuming they are matched.

 

[S.C.M.O.D.S.]

Hey Pete,

I just bought an Interstate AGM battery for my Ranger II FWC (just got it and I'm trying to get it ready for my 6 month trip to Alaska this December). I know that AGM batteries (and it seems all batteries for that matter) are best charged in 3 stages. I took the old battery isolator setup off the truck that my camper was on previously, but from what I understand this isn't ideal. I've read that if your truck battery begins to not hold a full charge, then your camper battery won't get fully charged b/c the isolator hasn't sensed that the truck battery is fully charged. So this seems lame and I would also really prefer to have something like a 3 stage charger type of unit between my started battery in my truck and the AGM in my camper to optimize battery charge and life of the AGM. Do you know of a unit that can be installed like an isolator to do this? Otherwise you said that you run your charger off an inverter. Does this mean I could plug an inverter into the cigarette lighter of my truck and use an extension cord run back into my camper to a 3 stage charger that is hooked up to my AGM while I'm driving to get a proper charge? If this will work, it may seem cumbersome but I would rather have a proper charge and longer battery life as I will be out in BFE a lot in Alaska between May and June. Also do you know of a good fairly small 3 stage charger? I apologize for the bombardment, I just want to have a good setup so my furnace doesn't quit working on me when I'm hell and gone from the nearest town in piss freezing weather. Any advice would be great!!!

 

[pvstoy]

Battery Separator they are good for some applications, but not for all. PLEASE read the attached PDFs on the dual battery isolator and the battery separator from SurePower.

http://www.surepower.com/pdf/separatorinterconnect.pdf
http://www.surepower.com/pdf/isolator1.pdf

It clearly states on the dual battery separator PDF about that if your starting battery is going south or needs more of a charge because you left the dome light on, then your camper battery is not going to get ANY charge until the starting battery reaches a certain voltage.

I prefer, in my opinion, the dual battery isolator as the better choice. It will charge both batteries at the same time and will give each battery what it needs. And either battery will NEVER see each other (unless the diode goes belly up).

You can up size your battery in the camper, or add two together to have more storage capacity for longer run time between charging.

You can get you a decent efficient gas generator small in size and a dedicated automatic battery charger and run that set up to top things off. That is also a good way of doing it if you have solar panels and not enough sun or duration of daytime in the winter months.

 

[Sev3en]

I'm still in the learning phase as far as 12v systems go and that being said will not even try to offer advice regarding what you chould do, but, I am reading a book right now titled:

"Managing 12 volts" "How to Upgrade, Operate, and Troubleshoot 12 volt Electrical Systems".
By Harold Barre.

Search on Amozon.com or I bought mine at Camping World

This book is awesome! I have learned so much about batteries, charging, and creating and managing a 12v system that I am almost understanding some of it


I would totally recomend you check out this book. Good luck.

Trust but verify

s.

 

[craig333]

If you're going to use a solenoid make sure its a continuous duty model.

http://www.westmarine.com/webapp/wcs/stores/servlet/SiteSearchView?jspStoreDir=wm51&catalogId=10001&Nao=10&Ntx=mode%20matchallpartial&keyword=solenoid&Ntt=solenoid&N=377%20710&y=0&x=0&storeId=10001&Ntk=Primary%20Search

 

[surfib]

Thanks for all the info guys, below is what I have come up with after reading all the stuff!

I have a old style isolator, continious duty, marine grade form West Marine sitting in my garage, I think I'll go with that. So it has for posts, do the two small posts matter? As in, can ground/power be on either side or are they specific. I don't have a wiring diagram for it. Also, am I going to have any problem with the truck having two batteries already, as required by a diesel?

As for the IOTA, it does have a separate add-on, about $28.00 that turns in into a "smart" charger/3 stage charger. I found it in Arizona on the net for $160 shipped.

This part is more for Stan:

Do I need a seperate circuit breaker on at my 110 box?

Do I hook up my 12v output to the box?

The box to the battery?

If I use the setup to charge my battery with my truck as well, is their any reason is should disconnect when charging my battery with the convertor?

One last one, if i switched my truck on, without it running, to activate the solenoid, could I use the convertor to charge my truck batteries without screwing something up?!

 

[Pete D]

One drawback to most systems where the house battery is being charged by the engine system is that the engine starting battery is in parallel with the house battery. Most 12VDC experts recommend that batteries being used, esp charged, in parallel should be as much alike as possible, even down to date of manufacture because large dissimilarities cause problems. That's one reason why the double-6V golf cart batteries in series are preferred by the serious folks over double-12V batteries in parallel (in addition to the additional energy and the superior number of charge/discharge cycles).

IMHO, one reason we get away with it in the typical RV setup is the voltage drop in the wiring between the house battery and the engine system, but of course the wire is shorter in TC than in TTs. I could easily be wrong about this.

The suggestion of the dual isolators to 'hide' the batteries from each other looks like a good answer with the following caveats (BTW, notice that the dual isolator is relay based, with no apparent diodes, whereas the single is diode based and doesn't seem to have voltage specs...):

1. If the dual isolator has a major failure so neither battery is on-line, likely the alternator will be damaged. Unlikely, but possible. BTW, this is also a potential problem using a battery switch while the engine is running.

2. It will give priority to whichever battery is lowest, which is not a good thing if the house battery has a bad cell or internal short. Also, IMHO, I would prefer my relatively delicate starting battery to always be recharged first (not as robust as a deep cycle when it comes to time delay to recharge) and I also consider the starting batty to be more important than the house batty.

3. PDF says that if starter falls below certain voltage, the house battery will be brought on-line to assist. If you don't have adequate wiring and fuse in place, this may be a problem (Found this out when I had a down starter and blew the 30A house fuse by cranking without disconnecting -- Brought house battery up and used it to jump truck).

A more perfect, but very costly, solution is a marine dual-output alternator installed on the truck, with two completely separated charging systems.

Solar panels are a good way to go, even in shade, because they are constantly working. Summer in Alaska has a LOT of sunshine, esp if you are north! Honda used to make a 600W inverter generator that looked ideal for running a battery charger.

With regard to using an inverter to power a battery charger, that works (keeping H gas in mind) but the typical cigarette lighter wiring isn't adequate and the inverter will shut itself down for low voltage. I recall small home color TVs shutting down the inverter because the deGaussing circuit at TV startup sucked too much current. The solution is to mount the inverter in the engine compartment and either wire it directly to the battery or use one of those 12VDC outlets with battery clamps.

The rule of thumb for inverters is to always keep the 12VDC wiring as short as possible, which means mount it near the battery and use a 120VAC extension cord; the wiring losses mean less at the higher voltage.

 

[craig333]

As for your solenoid, it doesn't matter which post you use.

 

[flinchlock]

Pete, I have been reading Introduction to Batteries and Charging Systems on the Sure Power web site, and I am not sure the following is true...Electronic isolators may not be a good way to go if they use diodes to isolate because the diode may insert a one-half volt drop in the charge circuit and that, coupled with wiring loss, may result in a habitually undercharged TC battery, which will shorten its life.
I am not trying to be a jerk (just trying to learn), but do you have any proof regarding the one-half volt drop?

That PDF on the top of page 10 says...Most of the switches on the market are far underrated for today’s high output alternators, with the exception of the solenoid type. The solenoid used in this charging application has its own set of problems. They are not designed for a continuous charging current to be flowing through their copper to copper contacts. As a result of this misapplication, a high resistance builds up within the switch that does not allow the auxiliary battery to fully charge.

That PDF on the bottom of page 11 says...The Sure Power Isolator System will assure a safety margin equal to or exceeding that of the alternator; it is an automatic guardian of all batteries; it will assure proper charge to each battery with minimum water consumption; it provides absolute isolation so that the cranking battery is always at full charge; and it will provide peace of mind while battery power is being used.

That PDF on the top of page 12 says...Never mix battery types in a parallel bank. All batteries in the bank should be identical in type, size, age, and voltage charge requirements.

My '07 Tundra has a group 27 (710 cold cranking amps at 0 F), and I would think it would be impossible for ATC/FWC to provide an exact battery type for every camper they sell.

So, I *think* the diode isolator is the more modern way to go.

That PDF also has a great chart on page 12 called "Recommended Wire & Cable Sizes For Charging Systems". My alternator has an 130 amp output, and assuming it is only 12 feet from the alternator to the camper battery, it will need 4 AWG!

So, lets keep this discussion friendly and we will all learn!

Mike

 

[Mark W. Ingalls]

Dear Mike--

Friendly is good.

Electricity is mysterious.

Pete is correct. More precisely stated, a Silicon diode requires about a 0.7 volt electromotive force in order for it to "turn on." Refer to this illustration from the Wikipedia article:

Switches do indeed need to be matched to their intended power application, as do all components ... even lug bolts. The article you cite may or may not be technically correct that switching resistance would prevent a battery from (eventually) becoming fully charged, but whatever theoretical quibbles one might have, one must agree with its point-- the contact area and spark gap of the switch should be appropriate for the intended current and voltage. By the way, a solenoid is simply an electromagnetically controlled switch, so too small a solenoid will have the same problem as too a small a switch.

In terms of mixing batteries in parallel banks, I am pretty certain they are referring to subsystem banks, e.g. two six volt camper batteries, and not the starting battery in parallel with the camper battery. You can convince yourself of this when you realize that there are other intervening series elements between the starting battery and the RV battery, making them not truly parallel.

Finally, I imagine myself to be a pretty modern person. However, I prefer a relay properly sized relay over and against a battery isolator for my simple camper battery set up.

Your mysterious friend,

Mark

 

[flinchlock]

Dear Mark,

"Friendly is good." YES

"Electricity is mysterious." YES

Pete is correct. More precisely stated, a Silicon diode requires about a 0.7 volt electromotive force in order for it to "turn on."
ok and ok

In terms of mixing batteries in parallel banks, I am pretty certain they are referring to subsystem banks...
ok

I prefer a relay properly sized relay over and against a battery isolator for my simple camper battery set up.
Any suggestions? What about the 4 AWG from alternator to camper battery (based on 130A at 12ft)?

Your mysterious friend
Which kind of mysterious...
1) exciting wonder, curiosity, or surprise while baffling efforts to comprehend or identify?
2) stirred by or attracted to the inexplicable?

Mike

 

[flinchlock]

Hmmm... http://www.ase-supply.com/product_p/31922.htm

The model 31922 Surepower dual battery isolator is a heavy duty type rated at 240 amps. This is a Schottky type isolator, which means that you have no voltage drop through the rectifiers. This is the unit for those of you with high output needs.

http://www.surepower.com/pdf/180031c.pdf

Checkmate?

Mike

 

[flinchlock]

Minimun wire is 8 AWG, not 10 AWG?

We use a 10 guage stranded wire from the truck battery back to a battery separator, then from the separator to the battery.

we are using the double insulated, stranded, 10 gague wire for the truck camper wiring (truck battery back to the camper battery).

But, BATTERY SEPARATOR on the Sure Power web site says...

Mike

 

[Mark W. Ingalls]

http://www.surepower.com/pdf/180031c.pdf

Checkmate?

Mike

From the surepower website: "The Schottky diode multi-battery isolator is required for federal KKK-A-1822A specifications because it offers a lower voltage drop than conventional battery isolators ."

(...a lower voltage drop...)

If we are playing chess, then I resign.

People who sell electrical equipment to consumers seem to want to over specify wire gauge. I'm not sure why that is. I think 10 is big enough. It's your money, spend it on what you want. I would also use the relay that works for Ben and Stan. (I tapped into the trailer package wiring on my '98 F150, so I use the factory supplied relay that came with the tow package.)