Brands of AGM house batteries?

[GreyDawg]

Thanks, everyone!

Sorry I didn't reply sooner -- I am in Grand Teton National Park with very limited wifi access ( like .... Lurking at Jackson Lake Lodge among the Federal Reserve folks, snatching wifi in the lobby ... )

I have taken screenshots of all these answers, so give me a day or so to digest them. I am sure I will have lots more questions. But it is all becoming clearer ...

BTW, I never did any 12v work on my previous vans and am a complete 12v dimwit (dim watt?), as you may have gathered! ;-)

Cheers!

[VtSoundman]

The info posted by Greg is spot on...I prefer the victron controllers as they have a Bluetooth dongle Bluetooth and allow me to monitor the solar system (and battery voltage).

If you're buying new, ALWAYS get the MPPT controller...

The Duracell/East Penn batteries from Sam's club are an outstanding value and work great. Where they fall a bit short is in deep cycling (< 50% SOC or >50% DOD) ... but most folks never really deeply cycle their batteries... And most batteries calendar out before they cycle out.

[GreyDawg]

Thanks, VTSoundman.

(Starbucks is the road warrior's friend for wifi -- heading from Tetons to Moab, from cool to HOT)

This is starting to make a lot more sense. Later today I will try to draw out a schematic to run past y'all.

My present thinking is:
* 2 x. 105 AHr 12 v batteries, with room for a future third if needed
* MPPT controller per recommendations above
* 2 x. 100W 12 v solar panels, possibly adding a third later if needed
* Battery monitor & shunt
* Blue Sea ACR

..... And assorted fuses, circuit breakers, cut off switches and lots of cable ....


For the panels I can either go with the Renogy RGN-100D at Amazon referenced by Eric above, or with the Synthesis 100W SP100P panel at solarpanelstore.com for the same price: better warranty, but polycrystalline. (I will be driving by the solarpanelstore storefront later this week and could pick up, so no shipping). Thoughts about the two brands?

Finally -- for now ;-) -- is adding a third panel later just plug-n-play, or will additional ports need to be drilled, etc? I.e., for simplicity should I just do three panels now and bask in the luxury of 300W when in less than optimal conditions?

Again, thanks so much to everyone for taking the time to coach me in this rather daunthing topic!

[rallypanam]

This sure is sciency!

All I know is when I talked to Blue Sky tech/sales support and told them my intended install (3-100W panels, a 4D AGM battery), they told me not to waste my money on buying their much more expensive MPPT controller (if I recall it was twice the price or more), which I was willing to do.

They said the difference in real time gain was almost negligible on a small moving setup that would probably be partially shaded half the time.

[VtSoundman]

Originally Posted by rallypanam

This sure is sciency!

All I know is when I talked to Blue Sky tech/sales support and told them my intended install (3-100W panels, a 4D AGM battery), they told me not to waste my money on buying their much more expensive MPPT controller (if I recall it was twice the price or more), which I was willing to do.

They said the difference in real time gain was almost negligible on a small moving setup that would probably be partially shaded half the time.

Controllers (MPPT or PWM) are all over the place in terms of price. Since as vans and have challenging solar conditions with small systems, I prefer to optimize ... maximize harvest and minimze charge time.

I completely disagree with Bluesky about MPPT - it always yields more energy and in suboptimal situations, MPPT really shines.

I do not like battery chargers/controllers that do not allow me to set my own parameters - so that usually puts me into a higher cost category.

My system also supplies power for my mobile office - so my power demands are higher.

[Scalf77]

Originally Posted by VtSoundman

Controllers (MPPT or PWM) are all over the place in terms of price. Since as vans and have challenging solar conditions with small systems, I prefer to optimize ... maximize harvest and minimze charge time.

I completely disagree with Bluesky about MPPT - it always yields more energy and in suboptimal situations, MPPT really shines.

I do not like battery chargers/controllers that do not allow me to set my own parameters - so that usually puts me into a higher cost category.

My system also supplies power for my mobile office - so my power demands are higher.

I actually agree with both sides, I believe the reply given to rallypanam by Blue Sky was correct, given his configuration (3-100W panels, a 4D AGM battery), he had enough panel power to pretty much meet his needs, and the benefit of the extra power of an MPPT controller could be considered an extra cost. If you took that to (2x 100 watt panels) the answer might be different.

When I look at my single panel system here in the PNW, the extra that I can get out of the system is welcomed. So if you are challenged on panel space, a MPPT controller wood be worth it. I have plenty logged data, but generally in the peak spots,I am seeing a 30% increase in output.



a snapshot of my controller data this am.



Note: observant readers will wonder how my output in watts is higher then input (that is one remarkable MPPT design) . I have verified the output with two different sources The panel data is from the controller, they also provide a reading of the output, I also read the output with my Pentametric battery monitor. The two output methods track, so my assumption is the input data being reported low.

-greg

[Scalf77]

Originally Posted by GreyDawg

For the panels I can either go with the Renogy RGN-100D at Amazon referenced by Eric above, or with the Synthesis 100W SP100P panel at solarpanelstore.com for the same price: better warranty, but polycrystalline. (I will be driving by the solarpanelstore storefront later this week and could pick up, so no shipping). Thoughts about the two brands?

If you are going with a MPPT controller I would go with the Renogy, as the have a higner specified Vmpp 18.9 volts versus the 17.8 specified with the Synthesis 100W SP100P. The Renogy is also a more efficient panel output per space. The Renogy is 47 X 21.3 while the Synthesis 44.5 X 26.5.

-greg

[boywonder]

Originally Posted by Scalf77

Note: observant readers will wonder how my output in watts is higher then input (that is one remarkable MPPT design)

The two output methods track, so my assumption is the input data being reported low.

-greg

Amazing! Either that or we have a first law of thermodynamics issue....

I too think that for van applications PWM vs MPPT isn't much to sweat over. That being said if I bought an MPPT controller I'd seriously consider a single 300-320W house type panel.

Originally Posted by GreyDawg

(Starbucks is the road warrior's friend for wifi -- heading from Tetons to Moab, from cool to HOT)

This is starting to make a lot more sense. Later today I will try to draw out a schematic to run past y'all.

My present thinking is:
* 2 x. 105 AHr 12 v batteries, with room for a future third if needed

Finally -- for now ;-) -- is adding a third panel later just plug-n-play, or will additional ports need to be drilled, etc? I.e., for simplicity should I just do three panels now and bask in the luxury of 300W when in less than optimal conditions?

Moab has several nice coffee houses....and microbreweries!


FWIW one of my panels is polycrystalline and the other two are mono. Although some would say it's taboo to mix types, they are playing well together.

...The more battery AH the better........I have 350AH of AGMs and it's marginal after about 4 days, but thats with powering an electric 2.5 gal water heater for a few hours each day.

More panels with a given battery AH just means that they will top-up charge faster. More battery AH allows for longer runs times obviously...

If you run sufficient wire size into the van adding additional panels is straightforward, especially if you use the MC4 type connectors, which are readily available and cheap from Renogy and others.

[daveb]

For my needs the roof is valuable storage space. The space an extra panel takes up wouldn't do a lot more for my common loads. Each person will have different needs. My daytime usage is mainly to charge from the night before not to run things in my van all day long other than the fridge. Solar might not be worth it if you live/play in continuous overcast skies. But I'm always in a mix of sun and clouds or shade and want a reasonable charge rate in partially blocked sun. Same with light overcast or fog, so the more solar the better. A non scientific example is at one time I had 3 flat panels (total 180W), a PWM controller and a single 210AH battery. With my usual loads, I was back to fully charged between 10-11am (with an average morning SOC). Later I replaced the flat panels with two 135w Kyocera glass panels (now 270w total), an MPPT controller charging two 4D batteries (now 420AH). Now an average is fully charged by 9-10AM. But that's an average for me even though there are so many variables. Sometimes in overcast skies, I only get a couple amps worth of charging. My backup is that I generally drive daily & have a smart regulated high amp alternator that can throw some reasonable amps at the system even when just idling. It's also where the larger bank shines.

I think 200w worth of panels is a good average start. Go for an MPPT if it's in your budget but don't sweat it. Build to expand, so proper sized bus wire, & universal mounting so you can change panels (or add if the weight is reasonable) down the road. Batteries are a cost vs maintenance thing IMO. Cheap AGM deep cycle battery may not last as long but more often the true grit of a battery is how well it recovers from unintentional deep discharges and poor charging methods. Two 105's is a fairly good size bank but you might consider building to expand more. I've never looked at the cost of a single 210AH lifeline compared to two 105AH batteries of the same make but do feel the less connections the better. Still I've been real happy with the two 4D's I'm running... well until it's time to replace them

[GreyDawg]

Again, thanks everyone. I am learning quite a bit from this very civil and helpful discussion.

DaveB, thanks for describing your "in the field" experiences. You say that you want "want a reasonable charge rate in partially blocked sun" by which you mean cloudy -- but what happens if one panel is partially shaded? I've read that in this case, serial vs parallel wiring of the panels is important, so that one gets at least one panel working. I've also read a bit about "bypass diodes" but haven't got a clue about that. Should I be thinking about bypass diodes at this point, or is that worrying about the minor stuff?

It sounds like our usages are similar, though I can envision being parked for a couple of days without driving, relying on solar with the heaviest load being a fridge at about 3.5AH for, maybe, 12 hrs per day? That's a swag.

BoyWonder, DaveB: Thanks also for reminding me to size the wiring with future expansion in mind. I will put that on the list.

BoyWonder: Yes, Moab has excellent coffee houses (Red Rock Bakery is now 100% solar) -- it is one of my favorite places (though this is the first time I've been there in the height of summer...I prefer March and November! It is a bit toasty today). Moab Brewery for sure, but are there others?

Regarding 2 x 105 AH batteries vs a single 210AH, the decision is purely pragmatic: in the "real" SMB I had about 15 years ago, I had a 4D battery under the stepwell. When it started failing, the Lifeline folks told me to remove it and bring it to them. Two problems: I didn't have a lift or support for its awkward location, and I can't lift 125 lbs from a very awkward position. Hence I want two 65 lb batteries, right by each other, in a power distribution center box inside the van.

BTW, the controller will also be in the van, though not contained in the power distribution box. Perhaps on the wall about four feet away.

Scalf77, rallypanam: thanks for the MPPT/PWM observations. What I've read is conflicting, and the prices are all over the place (and I don't understand many of the bells and whilstles). I will be having a chat with tech support at AMSolar this week as well as stopping by Solar Panel Store; it will be interesting to see what those folks add to the mix.

Again, thanks to EVERYONE for taking the time and energy to lead me through these very murky waters.

Cheers,
-- Meredith