Newbie here...want to make a "simple" upgrade...

Hi all, first time poster.

I've got a Sprinter 2500 cargo van that my dad did a nice conversion job on, building out cabinets and beds, etc., and putting in a rudimentary electrical distribution system (mostly extension cords and power strips for AC, and a DC run to the cooler and FanTastic).  The system includes a Xantrex Powerback 1500 as a "house battery" solution. The Xantrex is charged off the 25 amp power outlet in the front of the Sprinter (or by shore charger), and contains an inverter rated at 1350 watts continuous.

At 51 amp hrs, it's a pretty lean boondocking setup.

What I'd like to do is simply replace it with larger batteries and component parts, but leave the system design intact. Meaning, I'd like to buy two kick-ass AGM batteries, find a spot where they can live (where the Xantrex is now, I suspect), and have the same DC charging/small to medium inverter features I currently have. Imagine taking out the three Panasonic batteries that are in the Xantrex now, and hooking up the leads from the larger batts...that's what I'm after.

I'm pretty clear about the inverter, but it's the DC charging that's got me confused...is it as simple as hooking a socket up to the batteries and plugging in the existing DC cable from the front power outlet? If that's a resounding NO, then what do I need?

And, I'd like some sort of digital readout as to the condition/voltage of the batteries, so I'd have a visual reference as to how run-down they were...how would one go about wiring in something like that?

Thanks!

Forget those expensive batteries and buy yourself a pair of 6V golf cart batteries.
As for the wiring system?  It sounds rather amateurish.  You really need to redo it to bring it up to some sort of standards.  Fuse panel, 12V wiring to everything, plus a select couple of 120V outlets.  A small converter/charger will allow you to charge the batteries when connected to shore power.

You will need to replace a lot of the wires with heavier wires to carry the larger load.

I would also recommend that you put a catastrophic fuse in the larger positive cable that you will use to connect your batteries to your invertor.

The Xantrex Powerpack is a combined converter/charger, inverter, and battery package, so you will need to replace it with three components. Or maybe just two if you get a combo inverter/charger plus some batteries.

The converter/charger hooks to 120vac power from shore or genset and provides 12vdc power out to the batteries. Actually more like 13.6v to the batteries, but we call it 12v. The inverter hooks to the batteries and draws 12v power out to produce 120vac.  The batteries are whatever type, size and quantity you choose.  Ideally you want to use shore power directly when available and only employ the inverter when there is no alternative. Some inverter/charger combos have a built in transfer switch to accomplish this. However, you can always draw power from the inverter if you like, but with some loss of efficiency. 

It would be helpful if you could sketch out a schematic for the existing wiring, so we had some idea of what you have.

I'm not clear on what you expect to do with a larger inverter, since batteries are going to be the practical limit anyway. I doubt if you can utilize more than the 1350 watt inverter you now have. It may be possible to remove the battery(s) from the Powerpack and simply wire new one(s) to the existing terminals. A single Group 27 12v battery will store about 105 Amp-Hours, double what you now have. AGM or flooded, 12v or 6v, deep cycle or marin is your choice for cost and longevity.  I have an article in the RVForum Library on battery choices - see http://www.rvforum.net/miscfiles/Choosing_right_battery.pdf

Well I will admit AGM's are a good size Kick in the rear.. if that is that's where you carry your wallet.

If you ONLY upgrade the batteries.. Then you can go longer between re-charges, and it will take longer to recharge... You need make no other changes.

With a converter that is roughly 30% of the battery C/20 (20 hour capacity) amp hour rate you need about six hours for a FULL recharge, if recharging from half full. about 2-3 if you are willinjg to settle for 90% charge.

Capacity  NOTE AGM (With one exception), Maintenence Free and Flooded wet.. All the same capacity wise

Group 24, about 75AH
Group 27 and 29 just under/over 100 (use 100 for estmate)
Group 31  130
Generally these are MARINE/Deep cycle (Keep fairly full 75% or more)

GC-2 (the good old six volt Gold Car battery) Pairs (You need 2 in series)  220 Amp Hour give or take 10 and you can safely use HALF that. and they are cheaper too.

THe exception in AGM is OPTIMA.. Multiple capacity by 0.6 (60%) because of all that air space.

Thanks, everyone, for your responses. Let me explain further, clarify what I know, and ask for help with what I don?t.

Let?s start by describing what I?m powering with the house battery:
-FanTastic 12v fan
-Koolatron P85 12V cooler
-Inverter (currently 1350 watts), used to power fluorescent and LED lighting

I?m not looking to add items and draw more current, I?m looking to add capacity so I can power these few ?essentials? for a longer period.

?donn? and Gary RV_Wizard? both commented about wiring. As I said, it?s rudimentary, but it?s serviceable.

Shore power is distributed through a ?main? power strip and two heavy extension cords which feed either side of the vehicle. The cords are well-dressed and I?ve used plastic ?conduit? to further neaten and protect the runs. DC is sent via a 12? cable which plugs into a small Coleman converter, powering the cooler and FanTastic vent. The cable is run next to the port-side AC cord, again bundled and dressed. It may sound ?amateurish? (it is), but it?s not at all dangerous (I say this having worked on many a television/video set, where we?re using hundreds of feet of extension cords, quad boxes, and lamps drawing between 8-15 amps each.)

While in transit, I take the DC lead out of the Coleman converter and hook it into the power outlet which I have under the driver?s seat. (This outlet is not switched via the ignition, it?s always hot.)  AC, of course, is n/a. Additionally, I have a 12V DC run from the power outlet at the front of the cabin (ignition-switched) to a Xantrex 1500, which charges the Xantrex while we drive. (Xantrex claims full charge for the batteries is 6-8 hours using DC - I also have the Xantrex AC charger for the unit, but have never used it. Is there an advantage to charging my house battery using the AC charger, over DC?)

Currently, boondocking needs are met by the Xantrex 1500. 51 amp/hrs, a 1350 watt inverter with two AC outlets. I plug the 12V line into the 12V receptacle on the Xantrex (after disconnecting the charging cable), and the ?main? power strip (mentioned above) to one of the AC outlets.

?SeilerBird? suggests: ?You will need to replace a lot of the wires with heavier wires to carry the larger load.?  I?ve no plans to increase my current draw (for instance, by trying to use the microwave and hotpot while boondocking).  What sort of ?larger load? are we talking about?

?Gary?, you?re description of basic system function is appreciated, and I understand. I see no reason to use the Xantrex/boondocking system while hooked to shore power (and, as I charge the thing while in transit, see almost no need to even charge the system with shore power - please correct me if I?m missing something here.)  I?ve also reviewed your battery article, thank you.

?John From Detroit?, I think you get what I?m going for here. I?d really like to simply be able to pull the current batteries (Panasonic LC-X1220Ps) out of the Xantrex and run the wires from the Xantrex shell to a couple of deep-cycle 6v AGM batteries. I?m leaning towards spending money for the AGM deep cycles - the batteries would be located inside, and I don?t want to deal with adding water, possible (if improbable) liquid leaks, etc. Beyond making sure those wires are plenty beefy, what else is there to worry about? I assume that the Xantrex is fused between the battery and inverter (as suggested by ?HueyPilotVN?). Essentially, all I?m doing it taking 51 amp-hours of battery capacity and replacing it with a (possible) 200-300 amp-hours of capacity. There?s quite a bit of wiring inside the Xantrex, and I?d definitely get someone with DC experience to lead me through the replacement. Am i naive in thinking this is something that could be reasonably accomplished?

If it is the case that this is a dumb idea, then the next step would be to piece a system together. But I?ll wait on those questions until you all digest this. Again, thanks.

As an FYI, that Koolatron unit will draw 6-7 amps 24/7 (84 watts), it does not switch on and off like a conventional fridge, it has no thermostat....  I used a similar one on my sailboat for years but it was a relatively power hungry beast....

The Koolatron and the inverter are both fairly high draw devices. If you ever actually pulled 1350 watts from the battery, that's well over 100 amps @ 12v. Lights alone probably won't ever get anywhere near that, but people tend to plug stuff in when outlets are there to use. Maybe a electric coffeemaker or a toaster...

How well the Xantrex 1500 Pack charges depends on the vehicle socket that is providing the power. The Xantrex does nothing other than accept what is there. If that outlet has 13.6-14.4v and can supply a steady 10-20 amps, it probably does charge fairly well in 8 hours, perhaps to 85-90%. If lower voltage or more limited amps, not so much. Personally I would hook up to 120v power for charging when available so that I knew the battery would reach 100%.

There?s quite a bit of wiring inside the Xantrex, and I?d definitely get someone with DC experience to lead me through the replacement. Am i naive in thinking this is something that could be reasonably accomplished?

Click to expand...

Maybe. I'm not familiar with the 1500, so have no clue whether it is simple or easy. Conceptually it's a no-brainer, but that's means little until you open up the Xantrex box.

I see nothing wrong or unsafe with your lash-up power system, even though it's is a far cry from typical RV. Whether it is adequate for needs, however, will depend on how you use it, i.e. what sort of power you use, drive time power, camping with shore power vs boondock, etc. I know you think your needs are modest, but inexperienced people often badly underestimate.

It occurs to me that you might be able to simply wire additional battery(s) to a 12 type outlet and plug the 1500 into that via ists DC power cord. Based on the slim info provided in the 1500 op manual, it appears that would basically supply 12v to the internal battery. Xantrex says there is no power regulation in-between. Crude, but probably effective.

Reading further in the 1500 manual, I see that Xantrax already provides for a supplemental external battery. Why not do that? It has terminals for an external battery connection and says to just run 2 gauge battery cable from the external to the 1500's terminals. "When all else fails, read the directions!".

http://www.xantrex.com/documents/Backup-Power/powerpack-1500/445-0127-01-01_Rev-A(artwork).pdf

Thank you. You truly earned your moniker with these posts!