Question about Hooking up AC power in vehicle

I am hoping someone can give me a little advice. I recently purchased a nice power adapter..1500 watts and I would like to hook it up in my 98 Chevy truck. Be nice to always have power. My truck has a spot for an extra battery that I would dedicate to this adapter, but I am curious how one would link it up to the alternator so it would charge while driving. I would like to have both batteries charged from the same alternator, one for starting and car operation and one for AC power. Any thoughts?

I want to do the same thing and I think this is the right way.

Mount the extra battery and to charge it, just run it with the stock battery, in parallel. You can get a battery isolator from a travel trailer supply shop, that's what they use in an RV or trailer. That way the power inverter only drains the second battery, not the main one, unless you choose to.

I have a 1000 watt inverter to mount in my Liberty one day, hope this helps

http://www.surepower.com/
Look up battery isolators. You can go cheaper with a big relay to connect the two together but the electronic isolator is a bit nicer.

As everyone else has stated, use a battery isolator. You'll need some very heavy cabling as well, depending on where you run the 12VDC. Isolators usually come with a circuit breaker for over current protection, but if not, add one in-line between the isolator and the extra battery. It's all very straight forward and pretty easy to do.

There are three basic ways to go on the spare battery: Regular automotive battery, Deep cycle battery, and deep cycle battery that can handle starter motor loads (Sometimes called a Marine Deep Cycle battery). The later can also handle some high-current loads like running a winch intermitently. If you anticipate adding an electric winch in the near future, the last one is a good way to go. Otherwise, go with a deep-cycle battery for your invertor. Almost all automotive batterys get trashed if you deep cycle them (there are some expensive options that do it all, but why bother)

HTH,

Tom

Thanks for the advice! I appreciate it.

Be careful when using a diode type battery isolator. These are the "atomatic solid state" devices. I prefer the relay type.

The diode type have a small voltage drop (.6v) which does not sound like much, but the difference between a charged and discharged battery is not much more. Therefore you must increase the charging voltage when using the diode type. To do this, you move the voltage sensing circut from you regulator to the battery side of the isolator. Now the alternator puts out a bit of a higher voltage to compensate for the voltage drop.

If the diode fails open, the battery sense circuit will see no voltage and begin to increase the charge voltage. The result will be an explosion. Been there, done that.

The relay type is much cheaper, easier to install and gives you control over the charging conditions (with a switch if you want to),. Otherwise you wire it so your auxiliary battery is connected when ever your key switch is powered. Turn off the key and the relay opens. No chance of discharging the main battery.

Plus, should you somehow discharge the main battery, you can jump the relay and use the aux to charge the main. (or if there is enough voltage in the main to activate the relay).

I have been using aux batteries for 20 or more years and the relay system has been a consistant winner for me. I have seen (and experienced) many problems with the diode method. YMMV.

Only issue with deep cycle batteries is they require a lower charging apperage that what a normal battery isolated puts out. You'll need a battery charger/monitor for deep cycle batteries or they will ruin in no time flat.

That may be a good point. I use Marine deep cycle batteries (primary use for a winch & secondary use as a 12vdc power source) and have never had any issues. Those are not dedicated deep cycle batteries, rather, they are more like a modified automotive type battery. Back when I expected to regularly use a winch so continuously that it would get smoking hot, I used straight automotive batteries and lived with the inconvenience of limited run times for low amperage uses.

How do RVs and pick-up campers with on-board secondary batteries for power handle alternator based recharging?

Most RVs have starting batteries and Deep cycles. The generators often use the vehicle battery for starting. The deep cycles have their own battery charger/monitors for when the engine or generator is running. The two are on entirely different circuits.

Well, I'm certainly very interested in the subject!

Dedicated deep cycle batteries are customarily recharged differently from line power than automotive types, no question about it. I have been unable to find any information about special alternator-based charging systems that differentiate charging rates for deep cycle vs automotive batteries connected to the same alternator. There are dual-output alternators, but if I understand their purpose, it's more to function as an isolator than to control charging rates. I'm not sure what you meant about different circuits - I use battery isolators - is that what you mean?

All the info I've been able to locate so far goes back to the same system I use - a battery isolator. I have not yet found any alternator-supplied deep cycle chargers - can you point me to some information, please? I'm not interested in 120v AC chargers; I understand those. I am aware of (and somewtimes use) 12vdc logic controlled rechargers for NiCad hobby battery packs and there is at least one available for cordless tools (I have not used). But I haven't seen any such thing for LA batteries as would be used in an RV. Actually, I'm kind of skeptical that there is such a thing, but I'd be happy to wrong about that!

In a "typical" RV running off battery power (and there may be more than one deep cycle battery in some RVs), the recharging demands for the deep cycle battery vastly exceeds the recharging demands for the "starter" or automotive battery. Eh, I've got to dash off for now - will pick this back up tonight.

Please, if you have some specific links to the gadgets, I'm very interested in learning more. Again, not interested in 120v AC chargers - plain old alternator based chargers.

Regards,

Tom

IIRC they are bettery equalizers http://www.surepower.com/conv.html

The reason you don't find much on them is they are very $, something like 10times a simple isolator so most people just find it cheaper to replace their battery every couple years.

Thanks - but that's not what equalizers and convertors are for. Those are for OUTPUTS. I've used equalizers before (military applications). I'm asking about the INPUT side - the 12vdc charging side. AFAIK, there is nothing other than battery isolators.

I am eager to hear otherwise.

That's a company with some great products, BTW - thanks for the link.

Tom

EDIT: I found some neat DC input 2 and 3 stage chargers. Although the majority are NOT for 12 vdc batteries, there are a few models. The maximum charging amperages are fairly modest and are in any event linked to the ratio between input and output voltages. It would take hours and hours to recharge a deep cycle battery discharged to 50% level (common) and worse for 80% discharge level (feasible with true deep cycle batteries). A battery isolator would still have to be in the circuit ahead of it, I think - maybe not. It looks like these are pretty specialized and I would be surprised to find one in an RV, although I suppose you could get one if you really wanted. Maybe other companies make these in larger capacities...?

I'm going to stick with battery isolators and not worry about getting maximum life from a semi-deep cycle battery. I've got 10 years on one that's holding up fine and three years on another, ditto. END EDIT

Oops, wrong product page then. Its been a while but I e-mailed a reseller of their stuff and asked that question and was quoted a price of well over $1000. So I decided I would just buy a new battery every couple years also and run from an isolator <img src="/images/graemlins/smile.gif" alt="" />

This may be an option. http://www.batterystuff.com/battery-chargers/12-volt/marine-chargers/ you could easily put an inverter in your vehicle with a switch to tun on the charger when the engine is running.

To Tom. I am not sure what you are trying to do. I have been playing with rv and solar stuff for years and perhaps I can help. but I don't understand the issue.

Basically I use a Trace regulator to control charging to my RV batteries. It is a 3 stage regulator. I run everything thru it, solar, generatory, alternator and A/c battery charger. I use AGM batteries which are pretty picky about overcharging.

Sorry I missed you in Fla. (wilma). I was at one of the kitchens you were at, but I had other things on my mind and did not think to hunt for you. Can't remember the name of it now, but it was SE of the lake.

So try to explain your need again and keep it simple for my simple mind.

Ron - I think you just answered my question - I can look up TRACE on Google or if you have a link...? My setups are perfectly OK for my current uses - this had more to do with getting a complete answer to the original question. And it's useful to me to know more about the subject.

Yeah, I asked around for you when I had a moment. Was running K5 most of the time (LaBelle) and helped with some difficulties at K15 (Belle Glade) the last few days I was deployed. Need to save up some more vacation time, so not sure if I'll be able to deploy this year. Hopefully none of us will need to...

Thanks for the info!

Tom

The particular model I use is the trace c-40, which is of course a 40 amp unit. It took a direct lightning hit (along with everything else in my camper) and did not fail. YMMV.

Don't have a link, but google trace. They have the manual online.

I use a Radio Shack digital meter with RS-232 to monitor its operation and it has stayed just as I have set it for many years now. Forgot when I bought it, probably 9 years ago.

For the AGMS's I use it in 3 stage mode. Bulk charge at up to 14.4v, then about an hour at 14.1, then drop to a float of 13.1-13.3. It just sits there and does what it is supposed to. Oh, I use their thermal monitor mounted to the side of one of the batteries. I have 4, 105ah Lifeline AGM's in the camper.

Just bought a Kipor 2000w generator ($545 delivered). It is a honda clone 59db, What with the satellite internet system, ham radios and all, the solar is having a hard time keeping up when all the toys are running.

Eventually I hope to have the camper set-up so it can support something like a kitchen or similar with VOIP, Internet and ham radio. Because the internet will be outside of the Red Cross firewall, it will be available for regular e-mail. As you know, the ECRV internet is not for personal use.

Ron

Ron - Those things are VERY cool - inverter + 3 stage charger in one unit - THANKS! These really interest me now that I know they are readily available.

Looks like Trace Engineering is part of Xantrex and they have some awesome products (not cheap, of course): http://www.xantrex.com

Please let us know how you like the Kipor after you've used it for a month or two. That's right in the KW range I've been interested in for an on-board genset.

>>As you know, the ECRV internet is not for personal use<<

Heh - I found out that staff people get freaked if you have a stand-alone personal laptop within 50 ft of a cabled ARC network - VERY paranoid about ingesting anything into the network - good.

Tom