solar panel

[papab]

I'm pretty sure I'm going to eventually put a solar panel on my campervan, but I'm debating about whether to do it right away or put it off. We're planning a 2 or 3 month trip this summer to Ore, Wash, & BC, with most of the time in BC. I'm not sure what's up there, but we don't like commercial CG's, so we'll be in dispersed camping in the forest most of the time. I'm wondering if there will be large enough breaks in the trees to get enough sun to do any good? If I can get enough sun on the panels I'll make it a priority and get it done, if not, I have plenty of other work to do so I'll do it when I get back. Anybody been there with a roof (or portable) solar panel that can share their experience?

[stanw909]

What size battery bank do you have?.75 amp hours or 225 amp hours for examples. Are you travelling every day.Have you gone away for a weekend and camped without plugging in ? What are you running off battery? Solar is sexy but you may not need it unless you sit in one place a lot.

[papab]

150 amp hrs, AGM. novakool R4500 fridge which draws 5+ amps when running. I observed <30 Ah/day draw in cool weather, but up to 67 Ah/day in warm weather. I think I'm going to add some insulation around the fridge. Just got back from a 2 week trip & I had to start up the van a couple of times to charge up the battery. I won't be travelling every day. I won't be plugging in at all.
One issue I have is that I'm not getting as much charge current as I could. Right now I have a direct connection from van to aux, 220 amp alternator, lifeline says the battery can take 5C, but I need more volts to get that. I saw 100 amp briefly, but usually 13.6 - 13.8 V & 50 - 70 amps. It takes a good day drive to charge up from <40%. I'm thinking I need a DC-DC charger.
The van is a Ram Promaster, diesel.

[booster]

I think the DC to DC charger is a good idea. Even if you have the time, your voltage is too low to fully take care of your Lifeline batteries which want at least 14.4v and a fairly long absorption time to get totally full. The biggest charger I have found is 120 amps from Sterling. They list a 180 amp version, but don't have any yet and don't know when they will. Realistically, I don't think I would charge 150AH of batteries at over about 80 amps anyway as you need really good monitoring to go much higher for extended times. The 120 amp would be plenty, I think. Even with the charger you will be looking at a 6 hour drive every few days, if you want to take good care of the batteries.

[Lou]

It depends on which part of BC you are visiting. For example, in the provincial parks in the southwest, I'd say campsites shaded by tall trees, often evergreen, are the norm. In the south, central, part of BC, the Okanagan Valley has many bright, sunny campgrounds with little shade.

Go to the BC parks site http://www.env.gov.bc.ca/bcparks/
and in the top right hand corner, look up campgrounds "by location" and you will get a BC map with campsites marked. Click on a campsite in the area you intend to be and see photos of the sites. That will give you an idea of the type of vegetation to expect in that area.
If you do stay at a BC provincial park, don't expect electrical hookups or water at individual sites.

Recreational sites are even more primitive and some of the are free.
http://www.sitesandtrailsbc.ca/

I haven't heard of dispersed camping here, especially in an RV, but I guess you'd have to get caught for it to be a problem.

[papab]

Booster, why do you say it takes a fairly long absorption time to get totally full?
Lifeline manual:

Time to Reach Full Charge = [(DOD/100) x Rated Capacity (Ah) ÷ Rated Output of Charger
(Amp)] + 2 hours.

So even if it was close to dead (I don't plan to do that ) it would take less than 4 hrs with an 80 amp charger.

Another option would be an inverter/charger. When driving feed the power from the van system to the inverter/charger, then the aux batt. Are the xantrex units good?

Lou, Thanks for the links, they look very helpful. We're going to be mostly in the mountainous areas where there is good mtn biking & motorcycling. Once I get my head above water on the van build I need to start planning in more detail.

[booster]

Originally Posted by papab

Booster, why do you say it takes a fairly long absorption time to get totally full?
Lifeline manual:

So even if it was close to dead (I don't plan to do that ) it would take less than 4 hrs with an 80 amp charger.

Another option would be an inverter/charger. When driving feed the power from the van system to the inverter/charger, then the aux batt. Are the xantrex units good?

Lou, Thanks for the links, they look very helpful. We're going to be mostly in the mountainous areas where there is good mtn biking & motorcycling. Once I get my head above water on the van build I need to start planning in more detail.

I think it is all about who you believe in the specs and recommendations, as you can find about any recommendation you want. As the battery goes through the bulk phase, the current usually is dropping some, even if they call it constant current phase, so it can take longer than the straight capacity/time thing by an amount. Batteries vary a bunch, so some will get closer to the formula, and some not as close. Our 375ah wet cells will take only about 100 amps, no matter how big the charger, when down to 20% left, agms will be better than that, though. The two hour absorption time is a one size fits all rule that doesn't apply all the time, or even much of the time, IMO. If your batteries are down only a little, you can get by on less absorption time, it they are down under 50% many folks recommend the 4 hours I quoted. That said, using time for absorption control is not the best way to do it, by a long ways. The best way is to monitor the amps going into the batteries, and stop charging when it hits a level that doesn't reduce any more with time. There have been lots of discussions here on that type of charging, so you may want to search "ending amps" or "return amps" as both are the same thing. It can be done manually with a battery monitor like the Trimetric, so you can even know when you have gotten fully charged whether you are on shore charger, driving, or solar. On our wet cells, I have seen our absorption time vary from about 1.0 hours to over 6 hours, depending on how far the batteries were pulled down, and how many charge cycles had been run since the last time they were taken totally full. You really need to get the batteries totally full at least every 7-10 charge cycles if you want them to last, and every 3-5 cylcles would be even better. If you don't get them full regularly, you will quickly start to lose capacity on them, which is mostly not recoverable if it has gone on very long.

[stanw909]

Diesel Promaster huh ! Can it be idled like the gas model(no egr to clog)? If it can be idled for long periods maybe the extra alternator would work for you. I would like to take a moment to hijack your thread and ask what model Promaster and what mpg figures are you experiencing?

[papab]

About 25 mpg (updated this), mixed driving. It does have an EGR, probably not a good idea to idle very much. I didn't realize there was a 2nd alternator option until I googled it and found the thread here. It's only for the gasser tho. Since it already has a 220A alternator and I'm not fully utilizing that I don't think it's necessary. A DC-Dc charger or inverter/charger would still be necessary.

One thing I'm wondering about is that the starter battery is AGM also, but they never turn down the voltage. Before I installed the 2nd batt I watched the voltage & it was always about 14.0 - 14.2. Seems like too much for float, and not enuf for bulk/absorption. Perhaps the AGM starter batteries are different that a deep cycle, or perhaps they figure it's 'good enuf'.

[booster]

Your right, that voltage is high for constant voltage on an agm. I think that you will be able to address that if you do the 12-12v charger. IIRC the Sterlings makes it so you can split the controlled charge to the house and starting batteries, but I would have to look to confirm. With a 220amp alternator, having the charger would be a good idea a it will limit the current to batteries to the charger rating to prevent heating, and also be a lot easier on the alternator because it will keep the load more reasonable compared to its capacity.

[papab]

Yea, I'm not worried about my aux batt so much. I had planned on switching it off when it got to 100% (if I didn't put in a dc-dc charger). But the van batt is always at 14+ & it's AGM also. Messing with the stock cabling to the van batt & connecting to the Sterling is not something I want to dive into.

[papab]

This is what I'm planning on:
https://lh4.googleusercontent.com/-dprl ... nElect.jpg
[I got an error when I tried to insert an image, let me know if the link to the picture doesn't work]
As I said, i think, I've been charging my aux battery direct from the van system, but not getting enough voltage to pump the amps in. The alternator is 220 amp. I'm going to add an inverter and a charger to get more amps. I looked hard at the Sterling B2B units, but the charge logic is not what Lifeline recommends.

I haven't shown everything here,
The charger will be a 60 or 80 amp, prob truecharge or samlex. Inverter not picked out yet. The VSR will be a BEP 140amp.
When the A/B is in A position the charger is disconected, the aux batt is connected to the inverter & ,if the van is running, connected to the van batt. If the switch is in B position, the charger is connected to the aux batt & the inverter is fed by the van battery (if running).
What do ya think?

[avanti]

Most such systems don't bother with the A/B switch. As I understand it, conventional wisdom is that there is no harm having multiple charging sources (charger/alternator/solar) connected in parallel. One of them ends up providing charge voltages, which the others see and shut down.

Also, depending on how large an inverter you are planning, you might want to consider a combination charger/inverter with an internal transfer switch.

[booster]

Xantrex makes a little 15 amp transfer switch that would probably work well for you. We use on in the more normal way to control outlets, but you could just go to the charger only and it would be automatic switching for shore or engine/inverter.

[markopolo]

Quick question - are you getting the charger & inverter so you can charge the batteries when you plug in or when you are driving or both?

[booster]

Another thought, if you don't like the charging parameters of the battery to battery charger, you will probably be able find a smart regulator for the alternator that would be setable for parameters. I haven't looked at them, but it would be a lot easier if you can find one. All you would lose over the b to b charger would be current limiting.

On edit-it looks like this one would run at the recommended Lifeline charge profile

http://www.xantrex.com/documents/Acc...xx_RevB%29.pdf

[avanti]

Have you looked at the CTEK dual (alternator/solar) DC charger? It seems to be getting some attention.

[papab]

Originally Posted by avanti

Most such systems don't bother with the A/B switch. As I understand it, conventional wisdom is that there is no harm having multiple charging sources (charger/alternator/solar) connected in parallel. One of them ends up providing charge voltages, which the others see and shut down.

Also, depending on how large an inverter you are planning, you might want to consider a combination charger/inverter with an internal transfer switch.

If I don't have the A/B switch, then I have a feedback loop, from charger output to inverter input. Seems like a bad idea.
A combination inverter charger couldn't be used to charge up the battery from the van battery. Everyone I've seen either inverts, or charges from 115V input.

Originally Posted by booster

Xantrex makes a little 15 amp transfer switch that would probably work well for you. We use on in the more normal way to control outlets, but you could just go to the charger only and it would be automatic switching for shore or engine/inverter.

I'm not sure what that would do for me, but I'll take a look at it. I'm getting a 60 amps charger.

Originally Posted by markopolo

Quick question - are you getting the charger & inverter so you can charge the batteries when you plug in or when you are driving or both?

Both

Originally Posted by booster

Another thought, if you don't like the charging parameters of the battery to battery charger, you will probably be able find a smart regulator for the alternator that would be setable for parameters. I haven't looked at them, but it would be a lot easier if you can find one. All you would lose over the b to b charger would be current limiting.

On edit-it looks like this one would run at the recommended Lifeline charge profile

http://www.xantrex.com/documents/Acc...xx_RevB%29.pdf

I think I'd risk overcharging the van battery. Perhaps I could put an isolator somewhere, but it would be more complicated & there isn't much room. Maybe I'm just afraid of messing with the van side.

Originally Posted by avanti

Have you looked at the CTEK dual (alternator/solar) DC charger? It seems to be getting some attention.

Not available for the diesel.

Thanks, keep it coming.

[markopolo]

Some tough challenges to work through ..........

The DC fridge needs power. It's not high amperage but it sure adds up over time.

Ram warns against prolonged idling in the diesel supplement manual - http://www.ramtrucks.com/download/pdf/m ... SU-3rd.pdf - page 37.

You need time plus voltage in addition to amperage. A fast charge high voltage for the Lifeline could be too much for the engine battery and maybe some things in the coach.

It doesn't sound like you'll be plugging in often.

I think I'd focus on solar. Get the bulk charge from the alternator and get the top off from solar. A small quiet generator would also be an option in conjunction with good charger. Plugging in every 2nd or third day might do it.

[booster]

Your original idea of the bat to bat charger may be worth revisiting, now that I look at it again.

I say that mainly because of the rather "fluid" recommendations that have come out from lifeline over the last couple of years on charging their batteries. Over a few phone call and email sessions with them I have been told no more that .4C max rate to 1C and the there is always the 5C they list in the spec sheets. Lifeline, and quite a few of the other manufacturers are also starting to like higher charge voltages, especially in short shots to prevent heating and overgassing, to work like mini equallizations. It might pay to give Lifeline a call and talk to them about it. My guess is that they would not have any problem at all with charge profiles that Sterling uses. Personally, I think the idea of doing a higher voltage at the beginning of the absorption cycle is a good idea, as it gets your capacity back faster at a time when all the power is going to recharging, not gassing. Lifeline also shows low float voltages recommended, I think 13.3v, but all float situations are not created equally. Having 13.5 or 13.6 on the batteries for a 5 hour drive every couple of days (and float will only be a little of the time) is a whole lot different that a 3 month storage at that voltage. I think Lifeline would have absolutely no issue with it.

The B to B charger is such a good solution for what you are trying to do, and would be very simple and reliable, another shot at it may be a good idea. The 120 amp one would be just right for you.