Parking my baby for 6 weeks

[wfscot]

Hey all,

I'm leaving the country for 6 weeks and have to park my baby ('05 Ram 2500 diesel + '14 FWC Hawk) in storage for that time.

The FWC has aux batteries, but the solar system should keep those topped off.

Do I need to worry about the truck batteries at all? Would it be possible to somehow rig things so that the solar also kept the truck batteries topped off (bridge the isolator??)? Any other ideas?

Thanks!

-Scot

 

[PaulT]

A quick and dirty solution:
With a small AC inverter plugged into your camper batteries, attach a lightweight extension cord to the inverter, run the cord out the turnbuckle door, under the truck and come up under the hood. Plug one of the smaller Battery Tenders into the extension cord and attach the leads to your truck battery.

Perhaps not the cheapest or most ideal but quick and dirty for short notice.

Paul

 

[wfscot]

Thanks Paul! That's not a bad idea!

I'm not sure my inverter is up to 6 weeks continuous operation, but it's worth a shot if I can't figure anything else out.

 

[Beach]

6 weeks should not be a problem if your batteries are healthy, but you could disconnect them if your worried about parasitic draw and don't need the alarm active.

 

[ntsqd]

6 weeks shouldn't be a problem for an older rig. New rigs can have a lot of parasitic draws just sitting there with everything supposedly turned off. Each is tiny, but cumulatively and over some time they become a problem.

Some solar controller's have the option to charge a second battery bank. Our SunSaver Duo will do this, but I don't have it wired that way.

In theory a dual sensing VSR or ACR will close and allow the solar to charge the truck batteries once the camper battery(ies) are at 100% SoC and the truck batteries have dropped some voltage.

Assuming that your solar system can overcome all of the conversion inefficiencies and still provide enough power to charge the truck batteries and restore the camper battery(ies) from the previous night's drain Paul's suggestion looks like a winner to me. May want to see about a timer so that the inverter is only live when the sun is up. Otherwise it will be a constant drain on the camper batteries.

 

[wfscot]

Yeah, I was wondering about the dual VSR. Someone brought up concern over starting the truck with the VSR closed and thus a possible current spike. This thread also seems to suggest it's not a great idea, though:
http://www.thehulltruth.com/boating-forum/635616-charging-dual-batts-through-vsr.html

Anyone had success with dual VSRs? Even while traveling we tend to park for a week or more and it would be nice to have a permanent solution if this works.

Otherwise, inverter + battery tender it is.

This also gets me thinking again about a 12V-12V charger. Prior to solar, I really wanted one to improve the efficiency and battery-friendliness of charging while the truck is running (vs the standard VSR). It would be super cool to have one permanently installed where you could switch the direction. One switch position would charge the camper from the truck, the other would charge the truck from the camper. Interesting...

 

[ntsqd]

If the solar system and the VSR/ACR are both doing their jobs then you shouldn't see much current thru the ACR/VSR during starting because the starting batteries will be able to do the job on their own. Not something that I'm inclined to worry about. The bigger issue would be if the two sets of batteries are different types, enough different that their charging regimen is different. Then the controller's setting(s) can only be ideal for one set of batteries. Perhaps something from these folks: http://www.pulsetech.net/
On further look I think that this is the unit that I'd go with for my own use: http://www.pulsetech.net/SP5-SolarPulse-12V-Solar-Charger-Maintainer-5Watt-7298.aspx


Since our rig sits a lot between trips I've given some thought to a small solar system to keep the starting batteries fully charged. We get enough sun on this Coastal Desert to make that a viable option.

I've spent a bunch of time researching better alternator regulators in a quest for better charging of both sets of batteries. There are some really good ones out there (Sterling Power and Balmar) but they aren't very price competitive. I can replace a battery set for that price.

So then I read up on the solar charger. I've yet to find one that is rated OK with power sources other than solar. I figured that if I could apply alternator power or even crude battery charger power to the controller's input then I would get the benefit of all of the intelligence designed into the controller. Ideally I'd connect every charge source to the solar controller and let it do it's thing. Unfortunately every one that I looked at specifically stated in the owner's manual to only connect it to solar panels and no other source.

 

[wfscot]

ntsqd, I agree on the dual VSR. The more I think about it, the spike seems a non issue. The bigger concern is the mixed battery bank that the solar controller is trying to charge while the VSR is closed. That said, it can't possible be any worse than the dumb regulator on the truck alternator charging both batteries through the VSR while the truck is running. It probably would work just fine. Sometimes I worry that I worry too much .

The PulseTech approach is certainly interesting. That said, I can't help but think that it could screw up the charger logic, especially if that logic involves any sort of state related to the battery over time. It should work great with basic stateless smart chargers, though.

And don't get me started again on the whole using-a-solar-controller-with-the-alternator discussion. I initially thought that as well and have been similarly stymied. The only unit I've found that actually supports it is the CTEK D250S, but I'm not convinced that's the greatest product. There's a whole discussion about it on an earlier thread of mine here: http://www.wanderthewest.com/forum/topic/8898-dc-dc-battery-charger/

Ultimately I think I'm going with PaulT's solution this time around (thanks!). I don't plan on doing this very often, so it doesn't make much sense to invest in a better solution. I've got more important pits to pour my money into .

 

[PaulT]

That is the reason that this type of charger exists, CTEK D250s Dual

I have not used one but someone else on the forum has one and posted a note about it. Perhaps, it can be found and an update made. I do know that their CTEK 7002 charger has a good reputation.

Paul

 

[ntsqd]

Just now sitting here it occurs to me that perhaps the reason that other charge sources aren't allowable by most solar charge controllers is that the input voltage is too low. If I could tweak the alt's regulator to output ~18 VDC then maybe the controller would perform and behave as expected. It's not like the panel output is magically or intrinsically different power, it's still just DC power. Of course a second such controller would also be needed for the starting bank.

Unless! Could use my existing SunSaver Duo (in single bank mode) in the engine bay for the starting bank and let the VSR switch it's connection to the camper bank as it does now. Then install another charge controller in the camper (might go MPPT this time around) for solar system charge control. hum....... time to talk to my local starter/generator/alternator guy about adjustable voltage alt regulators. The alt used on our CTD is externally regulated, so that part of the swap would be easy.

For those with different chemistry starting and camper banks it probably would be better to send the ~18 VDC power to the camper and let the solar charge controller do the transmorgrafacation (thank you, Calvin!) there.

This all assumes that I've hit on the reason.

 

[simimike]

Six weeks should not be a problem. I've let my truck and camper sit for months in the winter(mild SoCal). Also keep in mind that cars sit on dealers lots for far longer. And there's always jumper cables.