Critique proposed solar battery upgrade

BFL13, too bad the powermax doesn't do temperature compensation.

The charging specs on those is 14.7v bulk and absorb with 13.6 float. PD9200s can't do that except perhaps the ones modified by Randy at bestconverters.

http://www.fullriverbattery.com/product/batteries/DC215-12

You will want a high amp charger to keep your gen time down doing 50-90s. The high amp PDs are not PF corrected so they take a lot of VA.

You would do much better IMO with one of these, which has high amps, PF correction, and best of all--adjustable voltage. eg if it is 35F out, your 14.7 will really be 15.26 ish temp comp, so you can set that. You can't do that with even a 14.8v modified PD.

http://www.boatandrvaccessories.com/products/powermax-pmbc-100adj-charger

So, to try and put a pin in this choice for me, I think i’ve settled on getting 3 or 4 Fullriver AGM 215 amp-hr 12v batteries (DC215-12). To support this, would I be ok with a Progressive Dynamics 9200 séries converter/charger and a Morningstar MPPT solar controller (say the TS-MPPT-60) with 750 or 1000 watts of solar? I would probably add a Tri Star monitor as well.

phemens wrote:
Ah, there’s nothing wrong with what I have, it works. The problem is, i’m moving to a ‘new’ rig and I just can’t resist adding some improvements while I’m up to my arms in alligators anyways ;) I’m always tinkering, trying to fix what ain’t broke I guess.

Makes sense to me! Every time I go camping I see a new way I could do things and have to try it out, so it never stops. Not many of us get it right the first time and can just leave it be. :)

Ah, there’s nothing wrong with what I have, it works. The problem is, i’m moving to a ‘new’ rig and I just can’t resist adding some improvements while I’m up to my arms in alligators anyways ;) I’m always tinkering, trying to fix what ain’t broke I guess.

I don't have the scenario for how often you would want fast charging off the gen and what the gen hours might be in the campground. Or how much gas you would need for the gen while it runs forever, and how far to get some more. Everything is about the scenario. EG with the Honda 3000 in the truck bed I just fill the gen when it needs some (not often) when I am filling the truck (often)

All I can say is that it will take "forever" to recharge any decent size bank with a typical RV converter. Also no converter seems to be adjustable voltage except the charger in an inverter/charger or else these PowerMax adjustables. There are some Meanwell or Megawatt adjustables but they are at lower amps--good for a smaller bank or lots of gen time on a bigger bank.

The battery specs these days seem to be anything other than what RV converters do, so you really need an adjustable voltage one. But then Mex says ignore most of that, because the battery specs are dubious anyway. Beats me! You can go to about 27% charging rate on an AGM like mine, so four of those 100Ah jobs would accept 108 Amps set to say 14.8 v.

How to do that with your 14.4v 55 amper? So out comes the PowerMax 100amp ADJ raring to go :) But now you need more than a 2000w gen to run it. So sad too bad. "They" don't make it easy for an RVer to assemble a proper set-up. :(

I also like having the portable extra charger in case the converter dies while on a trip. You can still operate by using the "spare" charger.

On the solar side, you have many choices and I can't say what would be best. EG, I don't know the roof space options on the trailer.

I have no problem with two solar controllers in parallel on the same battery bank. BTDT. One set up I ran for a while had my big inverter just on the two T-1275s and they had their own solar set, while the rest of the RV ran on its own set of batteries and they had their own solar. You can do just about anything and it all works.

I am just unclear what's so wrong with what you have now that you need to change anything for the new trailer. So you are the expert on that. :)

BFL13 wrote:
I really like my T-1275s. Four of those would be awesome. I think two would be enough in summer, with four being needed in winter.

I keep the 450AHish bank going all summer on solar using about 100AH a day. So they really only get down to about 85% most days, since the solar keeps filling them up faster than we use them. It is not easy to measure just what AH a day you really use. I do that with my 255w panel in the tilted twirler contraption.

Some math--at that place in May no clouds a few years back with a 130w panel I ran tests and measured daily AH from solar as:
Flat-56 AH
Tilted up aimed South all day-70 AH
Tilted and twirled toward sun during the day-90AH

So my 255w would do
Flat- 110AH
Tilted South-137AH
Aimed- 176AH (so the 255 in the contraption easily handles our 100AH daily usage even with mixed sun and clouds nice summer days)

However, to do that test I had to keep the battery voltage from getting up during the day (ran loads) and choking off the incoming AH, so it is hard to get an accurate idea of how it all works, which depends on how much the RV is using during daylight.

If you do all your AH use at night, then your solar can only do the batts and will have excess AH in the afternoon that go to waste. That is a good time to recharge your laptop or whatever chores you can invent, instead of doing it at night.

It is not always worth it to have more solar, once you have enough. On overcast days it doesn't matter how much solar you have, you get very little. It is worth some over-panelling of the MPPT controller like Morningstar recommends because although you can't use it all at noon, you do get more in the early morning and later afternoon, so overall you get more AH in the day. But just adding panels as such is a different thing.

I can't say how many watts would be good lying flat on your RV roof because that would depend on the time of year and your latitude. I can tell from my figures that my 255 would do us as a roof- mount flat with that 110AH, but I would rather have more to be sure. I would be happy with two 255s flat, which would get us about the same as the one does now in the contraption.

So about 500w would be more than adequate in my case. Total waste of money and effort to get more than that. (For us !!!---could be worth it for somebody else doing things differently)

EDIT I forgot you asked about a converter. IMO just use the RV converter, whatever it comes with, for when on shore power. On shore power you don't need solar either. For battery charging using the generator, use a variable voltage (to meet any battery spec) high amp charger as big in amps and VA draw as your generator can run, and which the battery bank will accept at 50% SOC. the object is to have the shortest gen time to restore the most AH.

Eg, I use the old single voltage 13.8v Parallax 7355 converter that came in the RV as the converter, but use PowerMax variable voltage chargers (modified converters, so they could be your converter too if set-up that way instead of using them as portable chargers.) I normally do 50-90s starting at about 155 amps with a two hour gen time window at the provincial park. I have to cheat a bit and go about 15 minutes over, but the rangers can't hear me anyway what with their chain saws being so loud! :)

When on generator, I just plug in the shore power cable and charge batteries using the RV converter (which on the new 5er I think would be a 3 stage, but will check, I had replaced the legacy one in my Jayco) - are you suggesting it would be better with a separate charger? I've seen threads on this, but that's probably overkill for what I would occasionally need to top off with. I was primarily asking about the converter if going to AGM, but I think by switching to the 4 T1275's I will manage temporary heavy loads on the inverter nicely. For the solar, I already use a Rogue 30 amp MPPT controller for the single 250W 24v panel, plus another separate 30 amp controller for the legacy 290W 12v array. My thinking was to consolidate to a single 24v array (say 3 or 4 x 250w) or keep the single 250w 24v panel, and replace the old 12v array with a new 36 or 48v one (2-3 x 300w).

Mex wrote, "I use two ammeters. Or you can use a single and manifold the main cable away from the battery post with the shunt or pickup between the manifold and post. Either way will display actual amperage going into the battery."

That is how it works between solar controller and Trimetric too. Two ammeters really.

The controller amps is what the solar is supplying and the Tri shows what the battery is getting. Subtract Tri from solar and that is your load but only when it is all inside the solar amount. The charger always does loads first then battery, solar or converter same thing. Once loads equal solar intake, the battery gets nothing. Over that and the battery has to chip in too. With no loads, the battery gets it all up to what the battery will accept.

Mr Wiz has meters all over the place AFAIK, so he can tell what amps are going where. I am still working on how that might play in my truck camper set-up with its AGMs, but I know Mr Wiz is right. You do have to be sure there is no way for any RV load to by-pass the Tri shunt on the way to the battery.

Mex, an example of sales vs engineering is the Chev truck sales brochure, where they say the truck can handle an enormous trailer, but the combined weight rating set by the engineers means a normal truck can only handle a much lighter trailer. In very small print, the sales brochure says they used a "base truck" with one driver in it. Apparently they make that base truck out of balsa wood just for this sales claim. (I don't know why they say just one driver. They must mean that DW is a back seat driver so normally you would have two drivers? ) Anyway your pal, Herb, is still out there. :)

Gelled electrolyte construction has one specific point of superiority and that point has absolutely no relevance for the average consumer.

Management to Telecomm battery engineering dept.

User manual recommendations for cycle life...

"Do whatever it takes to make OUR AGM batteries achieve maximum cycle life short of making it look *completely* ridiculous".

Telecom battery charging recommendations are predicated on 90+% of outage cycling being restored with PUBLIC POWER not generator power. Dual function of generator recharging. Assume 100% hotel load. Recharge the battery. By utilizing a multi-stage load shed protocol a telecom tower would shed least important loads first and life support (911) calls, last.

I really like my T-1275s. Four of those would be awesome. I think two would be enough in summer, with four being needed in winter.

I keep the 450AHish bank going all summer on solar using about 100AH a day. So they really only get down to about 85% most days, since the solar keeps filling them up faster than we use them. It is not easy to measure just what AH a day you really use. I do that with my 255w panel in the tilted twirler contraption.

Some math--at that place in May no clouds a few years back with a 130w panel I ran tests and measured daily AH from solar as:
Flat-56 AH
Tilted up aimed South all day-70 AH
Tilted and twirled toward sun during the day-90AH

So my 255w would do
Flat- 110AH
Tilted South-137AH
Aimed- 176AH (so the 255 in the contraption easily handles our 100AH daily usage even with mixed sun and clouds nice summer days)

However, to do that test I had to keep the battery voltage from getting up during the day (ran loads) and choking off the incoming AH, so it is hard to get an accurate idea of how it all works, which depends on how much the RV is using during daylight.

If you do all your AH use at night, then your solar can only do the batts and will have excess AH in the afternoon that go to waste. That is a good time to recharge your laptop or whatever chores you can invent, instead of doing it at night.

It is not always worth it to have more solar, once you have enough. On overcast days it doesn't matter how much solar you have, you get very little. It is worth some over-panelling of the MPPT controller like Morningstar recommends because although you can't use it all at noon, you do get more in the early morning and later afternoon, so overall you get more AH in the day. But just adding panels as such is a different thing.

I can't say how many watts would be good lying flat on your RV roof because that would depend on the time of year and your latitude. I can tell from my figures that my 255 would do us as a roof- mount flat with that 110AH, but I would rather have more to be sure. I would be happy with two 255s flat, which would get us about the same as the one does now in the contraption.

So about 500w would be more than adequate in my case. Total waste of money and effort to get more than that. (For us !!!---could be worth it for somebody else doing things differently)

EDIT I forgot you asked about a converter. IMO just use the RV converter, whatever it comes with, for when on shore power. On shore power you don't need solar either. For battery charging using the generator, use a variable voltage (to meet any battery spec) high amp charger as big in amps and VA draw as your generator can run, and which the battery bank will accept at 50% SOC. the object is to have the shortest gen time to restore the most AH.

Eg, I use the old single voltage 13.8v Parallax 7355 converter that came in the RV as the converter, but use PowerMax variable voltage chargers (modified converters, so they could be your converter too if set-up that way instead of using them as portable chargers.) I normally do 50-90s starting at about 155 amps with a two hour gen time window at the provincial park. I have to cheat a bit and go about 15 minutes over, but the rangers can't hear me anyway what with their chain saws being so loud! :)