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I previously used a pop up camping trailer. I acquired a few electronic items along the way, some of which I would like to transfer to my new PM Conversion.

I have an Exide Nautilus 1300EX Inverter/Charger. It is rated at 1300 Watts. It was designed for marine Applications. I acquired it about 15 years ago for $300 at a clearance markdown from $600. So far, I have only used its inverter function. But with more experience with battery charging, I want to try to use the charging function as well. It is designed for 3 stage charging with variable settings. The following settings can be adjusted:

Charge Voltage
Temperature Compensation
Maximum Charging Amps
Return Amps (Level of switching from Absorption to Float Stage)
Time (Maximum Time to stay in Absorption Stage)

The Charger function requires AC Input (i.e. Shore Power).

Since I rarely camp at sites with electrical hookups I would not have the necessary AC input.

So my question is: To charge while driving, can I use a second 1500W inverter wired to the vehicle battery to provide AC power to the charger? First, will the charger like Modified Sine Wave AC Input? And Second, will the Alternator to the second inverter be able to keep up with the load?

To make this worth it, I have a couple of other uses for the AC Power from the inverter connected to the vehicle battery/alternator. I can heat water using a 1000W bucket heater. And I can use a microwave more effectively than connecting it to the house battery. Just so there is no confusion about this, I would only be using this 2nd inverter with the engine running.

I saw a reference to adding a second alternator to a Promaster for $2000. I don't plan to do that, but the website mentioned that the Promaster operation uses about 120 Amps+/-. Since I have the 220A Alternator, theoretically I have about 100 Amps to work with without depleting the vehicle battery. So I have about 1200 Watts. Assuming 87% efficiency, maybe about 1050 Watts. So all of these uses are theoretically possible. What I don't know is if the 120 Amps necessary to run the PM is a max, min or average. How would one measure this?

Anyway, while I am sure there are those that will say don't do this, I would be interested in hearing if anybody has tried hooking up an inverter directly to the vehicle battery to run loads with the engine running. If so, how large a load have you been able to successfully run without discharging the vehicle battery?

I would also like to hear thoughts pro or con, even if you haven't tried this.
 

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Haven't done it.

The idea of an alternator running an inverter that has a charger built into it will technically work, but the efficiency numbers for the inverter and charger would make for some losses in the process. The shorter the wires between each of the pieces (bat1, invtr, chgr, bat2) the better.

Someone on the forum had discussed using an Arkpak and running an inverter to a charger to allow higher current charging. Hmmmm...

Ed
 

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I'm using a similar setup, alternator -> inverter -> charger.
http://www.promasterforum.com/forum/showthread.php?t=39913

I have an 1800 W inverter, a 60 amp charger, and a diesel PM. At idle, with the load, the inverter trips off due to low voltage. I haven't used it very much yet, that will change in a few weeks with a big trip planned. I think this will be workable, but I'm a little worried that I'll come to a town and have to stop and have to power cycle it to get it back on. I can reach my A/B switch, so I may have to switch it out when coming to a town, which will be a minor hassle. I have a 1/0 cable from the PM battery to the aux battery, then a short #2 to the inverter. I'm not sure the size of the stock cable from inverter to battery, that may be too small for this setup. I may need to add a cable from the alternator to the inverter or the aux battery.

I'd be surprised if the PM uses 120 amps under normal running conditions. That's a lot, many vehicles don't have an alternator that big.
 

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All this seems nuts to me. Let the vehicle alternator charge the batteries. Done. This idea of running an inverter to get some esoteric current and charge rate is just unnecessary IMHO. If any battery needs such a complex charging diet regularly junk it, get a flooded cell battery or AGM designed to charge from an alternator AND/OR install solar with an MPPT controller with adjustable float setting. These solutions are proven to work, don't require a wiring and switching nightmares or your faulty memory to monitor them. Inefficiencies introduced by this tangled web of inverters will make the situation worse. Really..... the alternator in your van is a powerful device and has a charging program to automate a task mastered by engineers 50 years ago. Are you all just trying to burn out a perfectly good van? Forgive the rant.... i'll seek counseling!
 
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All this seems nuts to me. Let the vehicle alternator charge the batteries. Done. This idea of running an inverter to get some esoteric current and charge rate is just unnecessary IMHO. If any battery needs such a complex charging diet regularly junk it, get a flooded cell battery or AGM designed to charge from an alternator AND/OR install solar with an MPPT controller with adjustable float setting. These solutions are proven to work, don't require a wiring and switching nightmares or your faulty memory to monitor them. Inefficiencies introduced by this tangled web of inverters will make the situation worse. Really..... the alternator in your van is a powerful device and has a charging program to automate a task mastered by engineers 50 years ago. Are you all just trying to burn out a perfectly good van? Forgive the rant.... i'll seek counseling!
RD,

Well said.... I'm doing what you said... so far works well....Aux AGM battery designed to charge off alternator... Wirthco 150A Battery Doctor relay... short fat wires!

No smoke.... yet >:D

Ed

ps. I could have sworn I saw a Sandstone Promaster go by my house today, maybe headed for NH? ... (sorry, just kidding!)... soon, soon,
 

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Quote
Ed

ps. I could have sworn I saw a Sandstone Promaster go by my house today, maybe headed for NH? ... (sorry, just kidding!)... soon, soon,"

Agggh! A week at least! Thanks for thinking of me in my time of need. (did it have the aluminum wheels- could be!)
 

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RD, What you're saying is all good, but I tried direct from van. It doesn't charge up quick enuf for my needs. The voltage is too low. When loaded down it's less than 14V. The only thing more complex about my setup is needing an inverter and a charger instead of an inverter/charger. Adding solar is not simple either. I'd like to use the flex panels, but not sure they're mature enuf yet, so I'm holding off for now. The battery will last longer and have more capacity with a proper charge also.
 

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RD, What you're saying is all good, but I tried direct from van. It doesn't charge up quick enuf for my needs. The voltage is too low. When loaded down it's less than 14V. The only thing more complex about my setup is needing an inverter and a charger instead of an inverter/charger. Adding solar is not simple either. I'd like to use the flex panels, but not sure they're mature enuf yet, so I'm holding off for now. The battery will last longer and have more capacity with a proper charge also.
There is ABSOLUTELY, no way that scenario would be or could be more efficient than charging the batteries off the alternator. It would deny the laws of physics. If you get that to work, you should start immediately working on a perpetual motion machine. :)

-t
 

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I'm all charged up reading this!

RD is correct, why bother with a needlessly complexed system? BTW, my alternator has no problem charging the house batteries up @ over 14v in short time if I wish to do it that way, but I do have 2/0 cable connecting them all together.
 

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RD, What you're saying is all good, but I tried direct from van. It doesn't charge up quick enuf for my needs. The voltage is too low. When loaded down it's less than 14V. The only thing more complex about my setup is needing an inverter and a charger instead of an inverter/charger. Adding solar is not simple either. I'd like to use the flex panels, but not sure they're mature enuf yet, so I'm holding off for now. The battery will last longer and have more capacity with a proper charge also.
I get that and I read that into what you said before. The battery does not need to be fully charged everyday so your best hope at this time may be to buy the correct charger which it sounds like you will do and stop or camp where you can plug it in once a week or so to top the battery and preserve it. Look at Grape Solar for a thicker perhaps more rugged flex panel. All those panels suffer from the same problem, they are a plastic surface and need to be treated well. No jamming through brush, and care in cleaning. Think of them as the lenses of your sunglasses, they will be fine if treated well. I think there are MPPT controllers which might take the van's voltage and output a higher voltage to finish the battery but I have no experience there.
The solar solution may be cheaper than the arrangement you are thinking of and it is mature enough technology to give you years and years of service. By the time you find the solar has improved enough to adopt, your old set will have paid for itself i bet. Go for the solar.
 

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There is ABSOLUTELY, no way that scenario would be or could be more efficient than charging the batteries off the alternator. It would deny the laws of physics. If you get that to work, you should start immediately working on a perpetual motion machine. :)

-t
Nobody said it was more efficient
 

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Discussion Starter #13
All this seems nuts to me. Let the vehicle alternator charge the batteries. Done. This idea of running an inverter to get some esoteric current and charge rate is just unnecessary IMHO. If any battery needs such a complex charging diet regularly junk it, get a flooded cell battery or AGM designed to charge from an alternator AND/OR install solar with an MPPT controller with adjustable float setting. These solutions are proven to work, don't require a wiring and switching nightmares or your faulty memory to monitor them. Inefficiencies introduced by this tangled web of inverters will make the situation worse. Really..... the alternator in your van is a powerful device and has a charging program to automate a task mastered by engineers 50 years ago. Are you all just trying to burn out a perfectly good van? Forgive the rant.... i'll seek counseling!
I probably would not be considering this if I didn't already have most of the equipment I need. My experience with charging batteries from the alternator has been less than I expected. The batteries seem to die off within 1-3 years. Probably not getting enough off a charge. So I thought I would give this a try. If it works, great. If not, it will not have cost me much. I have seen others report trying similar systems, and they have been satisfied with the results. My main concern was how much of a load I can expect to successfully use.

Another issue is battery location. I have other plans for the area behind the driver's seat. I want the battery to go in the back on the driver's side behind the wheel well. I would need some massive cables for the length from the battery to the back. With the system I envision I will put my 1500W vehicle inverter under the driver's seat which is within 2-3 feet of the vehicle battery. According to the inverter instructions, runs of less than 6 feet can use 5 AWG Cables. I will use 2 AWG. I plan to put the 1300W Inverter/Charger in the area in front of the driver's side wheel well about 7-8 feet from my vehicle inverter. This will be an AC connection. I plan to use 12/3 Wire for this. From the Inverter/Charger to the house battery in the back is about 5-6 feet. I already have the 2 AWG cable for this connection. My existing connection wiring for this uses a 250A Fuse. Not sure if that is correct but I believe I was following the advice I received when I first installed it 15 years ago. I Plan to use the same now unless someone thinks it should be different.

I admit there will be some efficiency losses due to the 2 inverter system, but I believe the charging choices will mitigate that somewhat. I don't see it as being overly complex, just a few extra connections to multiple pieces of equipment which I already own.
 

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Discussion Starter #14
I'm using a similar setup, alternator -> inverter -> charger.
http://www.promasterforum.com/forum/showthread.php?t=39913

I have an 1800 W inverter, a 60 amp charger, and a diesel PM. At idle, with the load, the inverter trips off due to low voltage. I haven't used it very much yet, that will change in a few weeks with a big trip planned. I think this will be workable, but I'm a little worried that I'll come to a town and have to stop and have to power cycle it to get it back on. I can reach my A/B switch, so I may have to switch it out when coming to a town, which will be a minor hassle. I have a 1/0 cable from the PM battery to the aux battery, then a short #2 to the inverter. I'm not sure the size of the stock cable from inverter to battery, that may be too small for this setup. I may need to add a cable from the alternator to the inverter or the aux battery.

I'd be surprised if the PM uses 120 amps under normal running conditions. That's a lot, many vehicles don't have an alternator that big.
I figured idling amps could be an issue so may have to manually switch system on/off when running a high load until RPM's are up. Also may have to turn off other unneeded loads when running high loads from the inverter. I assume your 60A charger refers to output. Any idea how many watts your charger draws?
 

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what OP is describing is similar to Orton DIY (check out this on sprinter forum) - Dave Orton ran this successfully for many years - now, the major reason I think he went from alt to inverter to charger was because of the elaborate, expensive, and sensitive Sprinter sensor system and didn't want to mess up voltages between house and veh battery - I don't think Promaster has that same issue. He had solar and shore connection but used veh inverter to charge as necessary. Those who take extended and off-grid trips are wise to have multiple sources of charging. Dave also used the veh inverter to run some high wattage stuff like a heater element for hot water showers and microwave. We are using this veh inverter concept as a temp measure until solar is installed and resolve the AGM charging via PAC-2000 relay question (which I think we are going ahead with without a special charger - if it blows up ....). The veh inverter is less efficient (12 -> 120 -> 12) but simple and inexpensive and sometimes simple and inexpensive wins.
 

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Nobody said it was more efficient
Yea, you said it right here.
RD, What you're saying is all good, but I tried direct from van. It doesn't charge up quick enuf for my needs. The voltage is too low. When loaded down it's less than 14V...
You of course are free to set up your charging system however you wish, but I am telling you that what you're suggesting is neither the most efficient way to charge your system, nor is it a recommended practice.

If this scenario is charging your batteries more efficiently than the alternator of your vehicle, then you have some issues with the charging system on your van. My Promaster has in the ballpark of 100 amps available for recharging the rears. I can guarantee you that NO AC charger that can be run off of an inverter, will remotely approach that.

Couple that with the fact that you are causing loss with two extra units in the chain, that is going to cause wear and tear on your vehicles charging system. Not to mention the grounding issues that you are creating with an unneeded inverter to convert the 12 volt to 110, and an unnecessary charger to convert the 110 back to 12 volt.

I can't see any scenario where this would be advantageous, or produce any desireable results.

Another point. I have heard some mention of running heavy gauge wire for your charging cable. That is really not necessary, unless you plan to put your rears under a VERY heavy load while charging. Yes, the heavier the gauge the better when running from your battery bank to your inverter, and short as possible runs. However your charging cable is not going to be under such a heavy load.

For years, I have run a 10 gauge cable from the front to the back, with a fuse or breaker to protect in case of too much current being drawn. Never a problem. Never even popped a fuse. And this is extensive daily use, many times running the rears down to an unuseable voltage, starting the engine to recharge, and even continuing to use the inverter while charging.

Not that heavier cable is not better. It is. It just isn't a necessity.

-t
 

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what OP is describing is similar to Orton DIY (check out this on sprinter forum) - Dave Orton ran this successfully for many years - now, the major reason I think he went from alt to inverter to charger was because of the elaborate, expensive, and sensitive Sprinter sensor system and didn't want to mess up voltages between house and veh battery - I don't think Promaster has that same issue. He had solar and shore connection but used veh inverter to charge as necessary. Those who take extended and off-grid trips are wise to have multiple sources of charging. Dave also used the veh inverter to run some high wattage stuff like a heater element for hot water showers and microwave. We are using this veh inverter concept as a temp measure until solar is installed and resolve the AGM charging via PAC-2000 relay question (which I think we are going ahead with without a special charger - if it blows up ....). The veh inverter is less efficient (12 -> 120 -> 12) but simple and inexpensive and sometimes simple and inexpensive wins.
I by no means am I an expert but a noobie at this. But the house battery and or main
battery is a giant capacitor (did I get that right?) In other words they protect the spikes of the sensitive electrical system. So doing the above way is just being
paranoid .But I don't blame him as the cost to fix a Sprinter is out of this world.
 

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I get that and I read that into what you said before. The battery does not need to be fully charged everyday so your best hope at this time may be to buy the correct charger which it sounds like you will do and stop or camp where you can plug it in once a week or so to top the battery and preserve it. Look at Grape Solar for a thicker perhaps more rugged flex panel. All those panels suffer from the same problem, they are a plastic surface and need to be treated well. No jamming through brush, and care in cleaning. Think of them as the lenses of your sunglasses, they will be fine if treated well. I think there are MPPT controllers which might take the van's voltage and output a higher voltage to finish the battery but I have no experience there.
The solar solution may be cheaper than the arrangement you are thinking of and it is mature enough technology to give you years and years of service. By the time you find the solar has improved enough to adopt, your old set will have paid for itself i bet. Go for the solar.

If a lead acid battery sits in an uncharged state it will start sulfating. This causes a permanent loss of capacity. The more often this happens the sooner the battery fails. One will not necessarily notice it right away, but when a battery can only be utilized to 80% of its original capacity it is considered failed.


This is true for all Lead Acid batteries but not for Lithium. Trojan has recently come out with a battery where they have added Carbon to the lead which they say gives a 15% improvement in capacity when the battery is not fully charged after each use. I believe these are just FLA batteries and thus may not be acceptable in a conversion van unless they are stored in an outside compartment.
 
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