I need more power Scotty!

[ntsqd]

To me a concern is that we put a lot of thought & effort into getting a 4 or 5 stage charge controller for the solar system and doing our best to get the max output of the panels to the controller, but simply accept the 'stupid' power coming from the alternator. Regular alternator regulators do not use a 4 or 5 stage charging algorithm, they simply set the charging voltage and pump the amps into the battery regardless of the SoC. I've mentioned before that I looked into marine alternator regulators as they employ multi-step charging algorithms, but those come at a real premium! Some sample links:
http://www.balmar.net/?product=regulator-ars-5-h (West Marine: http://www.westmarine.com/buy/balmar--ars-5-12-volt-regulator--7807969?recordNum=1 )
http://www.sterling-power-usa.com/ProReg-DW-waterproofalternatorregulator.aspx
An advantage would be that the starting battery(ies) would also benefit from multi-stage charging and should last longer.

I hadn't dug into the C-Tek Dual 250S enough to notice that it wasn't configurable. Assuming it would work out of the box with your batteries it can be connected to both solar and to the alternator charge wire. It uses the same 4 stage charging scheme with the strongest input of the two. Which means that it also will function in place of any truck/camper isolation methodology so it would replace that need as well as the solar charger controller need. Until this recent revelation about lack of setting ability it was looking like a clear winner, now I'm not so sure.

My admittedly limited understanding of the Smartpass is that it's basically a 120VAC driven battery charger designed to work in conjunction with the 250S, but their literature is less than clear about that.

With regard to a wind generator, there are telescoping aluminum poles made to be RV flag poles. 8' to 25', travels in an ABS tube mounted under the bed rail over-hang of the camper. I got it on clearance and use it for a radio antenna mast, but a wind generator could easily be mounted on top of it too. I would be tempted to look into disabling the built-in charge controller and use it with something mounted in the camper closer to the battery(ies). My extremely limited understanding of wind generators is that they don't work well with most (all?) solar charge controllers and need something specific.

 

[Zirdu]

Excellent summary. One place I am thinking you are overestimating your power usage would be in the Sure-Flo pump. You estimate use of 2 hours per day. Wouldn't two hours of continuous pumping drain your water tank several times over? In my Eagle, with a 11 gal tank, I think I might have averaged from 5 to 15 min per day use of the pump.

And it seems you are figuring for use in the winter in the Canadian Rockies, with no sun for two days at a time. Wow, that is an extreme situation. I mostly camp in US Southwest, so I get a LOT more sun, and I always get some sun every day, so I figure I can get solar charging every day. Of course some days better than others.

My theory is to plan for the average usage, knowing that some percentage of the time I will be draining the batteries. In those situations, I can run the truck engine, or drive around a bit, or turn the fridge up, or not use the heater, etc, to conserve power.

I am getting a new Grandby, and for convenience I just ordered it with dual factory batteries - total of 150 AH. I figure I will get by with this until the batteries go bad in 3 to 5 years. Then, hopefully the Li-ion batteries will be cheap enough I can replace with maybe 200 AH of Lithium! That would be equivalent to 400AH of lead acid AGM. In solar power, I am going with the super lightweight flexible panels, so i can get up to 480 Watts of panels on roof with little weight penalty.

Many here are not satisfied with the factory wiring for solar and alternator. To help with voltage drop in the supplied 10 AWG solar wiring, I am wiring some panels in series to increase voltage, and using an MPPT controller. I am not sure what to make of all the posts about need to increase size of wiring from truck alternator to house battery. If the wire size used by FWC is so inadequate, why do they use it? They seem so concerned with using only the best in all other aspects, why would they scrimp on this? How much more could it cost to use #6 AWG wiring here, rather than #10? Maybe people start having problems with alternator charging when they increase the house battery size beyond the factory supplied batteries? I don't know.

 

[ntsqd]

10 ga. is the largest wire that fits in most connectors used in the RV industry. To go larger means using a connector that is significantly larger itself, and not common within the RV industry.

 

[PaulT]

10 ga. is the largest wire that fits in most connectors used in the RV industry. To go larger means using a connector that is significantly larger itself, and not common within the RV industry.

Connectors are available with sufficient capacity such as the Anderson SB series.

Up to 4/0 wire size and 350 amps
SB350 SB Series Loose Piece Contact

The 175 amp version might be suitable as it supports 6 to 1/0 gauge wire.
SB175/PP180 SB Series Powerpole Loose Piece Contact

Paul

 

[Vic Harder]

Ntsqd, thanks for joining in this conversation. I agree that the “stupid” alternator regulator is an issue. Regarding the CTWK 250s and Smartpass, I looked deeper for more documentation. Here is what I found:

Great writeup on a guy who is very happy with his total Ctek solution for Solar, Alternator and Shore power. - LINK

Ctek discussion at the Expedition Portal, with a recommendation to consider the BlueSea ML-ACR 7622 we already know about

One feature of the 250S I had not noticed before which is really interesting, is that it also functions as a DC-DC converter, and will UP the voltage output of the alternator to compensate for those that are regulated too low (Toyota Tundra comes to mind) or for excessive voltage drop. Very cool.

Here is another DC-DC converter I have seen recommended in the 4x4 community- LINK

I also found this awesome article talking about automotive alternators as “Battery Assassins” - LINK He is talking about boating applications, but those are very similar to what we are doing in our FWC/ATC/Campers. The same fellow also makes alternators ( LINK ) without regulators so you can use the external Balmar style regulators that ntsqd mentioned - LINK

And to clarify how the Smartpass works, and at the risk of being wrong, it does not appear to be 120AC driven. Instead, it bypasses the 250S during the bulk charging stage, and hands control back to the 250S when it detects that the charging current is dropping back to the levels the 250S can handle. That‘s 20A. Remember that number for a bit later....

And thanks to Zirdu, yeah, that pump usage was likely overstated... guess I was dreaming of long & hot showers ;-)... and yes, I am thinking cloudy/rainy days, something the folks in the PNW get too. When I was car camping this summer at Mt Rainier, I saw that most of the campsites had no sun... wonderful shade dappled campsites. So without a long portable cable and room to put the panels on the road (!) or other sunny spot, charging wasn’t happening without a drive. No generators were allowed.

And for sure, if we are only sizing our systems assuming NO days without charging, then it all gets much smaller/cheaper.

I am also starting to wonder if simply upgrading the wiring from the alternator to the camper batteries is just asking to blow my alternator by getting it way to hot. I suspect my alternator/ECU in the truck will protect it from overheating, but don’t know about that. Beware.

And if you need more “backstory” to why all this research and solution finding is necessary, this 2014 thread started by Ethergore is talking exactly about the problems we are uncovering and documenting here - LINK

Plus that thread has a reference to these really nice 300AH batteries that member DesertDave is using If you want to know why we are working so hard on protecting our investment, check the price on these bad boys... and you would need two of them..... GULP!

Speaking of smaller/cheaper, everything I am bringing forward so far seems to be leading towards spending more money and increasing the weight and complexity of the systems. I dislike this!

How to do it right, and do it economically are my questions now.

I for one am unlikely to buy a new alternator and external regulator. So I am stuck with the factory GMC alternator. Luckily, I get 15v+ out of mine. I understand the Tundra folks (post #14 from this thread says 13.5v) are not as lucky LINK & LINK

First,
Reduce how much power you need. Most of us are already doing LED lights, and the newer DC fridges are getting quite efficient.

Second,
Measure you power usage and battery health. Get that Trimetric TM2030!

Third,
Reduce the number of days between no – charging. Weather is unpredictable, but do what you can. Shore power/generator/driving can usually get your batteries up to 85%.

Fourth,
Figure out the “more power” option you are most likely to use. Will you drive every two days? Get sunlight? Get back home for a long time so the 120v is available for several days, ever via shore power or generator?

Fifth,
If you plan on driving every few days, maximize your charging potential. Consider getting the CTEK D205S and SmartPass, and upgrade to BIG wires. The CTEK will up your alternator output voltage (Tundra owners take note), and the SmartPass will dump up to 80A across those big wires. It MAY even compensate for the voltage drop, but I am not sure how, as it doesn't use a second set of wires for voltage sensing.

AT MINIMUM, if you get the D250S and size your wires for 20A, the D250S will pass your camper batteries a max of 14.4V less the voltage drop over your wires at the D250S maximum 20A of current.

As a reminder, this voltage drop calculator will tell you that you need 4AWG wire to get 14.2v to your expensive AGM camper batteries. 2 AWG makes that 14.27V. Both of those will at least get your batteries above the float level, but sadly, below a full absorb charge level.

BEST CASE, get the SmartPass too, and upgrade your wires to 2/0 as well. Using my alternator at 15.2V output, through the SmartPass over 2/0 wire will deliver 14.95V during the bulk phase to my batteries. In all likelihood, that will get me to 85% battery capacity in less than an hour of driving/idling. Then the D250S will take over and at 20A give me 14.34V for as long as needed at the absorb level. Almost perfect.

I say almost perfect. I LIKE the CTEK because it combines a lot of functionality into one box. I just wish the voltages were adjustable. Because my alternator outputs higher than 14.4V, I could possibly be better off without the CTEK.

How? Since I will be upgrading to 2/0 AWG anyway, I could use the BlueSea ML-ACR 7622 to get 15V+ at 40A+ to my camper batteries. I would have to watch how that works though, because keeping that high a rate of charge going will kill the batteries and/or alternator. Hmmm... less than ideal with the Smartpass, but also maybe better than having to keep an eye on this and cook expensive bits.

Could be a win for the CTEK.

Let’s parse this out a bit more. With the CTEK, I don’t need the 7622 ACR That unit alone is $207 USD. IF I can live with only using 12V solar panels, then I also don’t need to get another charge controller for the solar system. That means not having to buy the Trimetric SC2030 at about $130. Total cost = $427. Cost of the CTEK combination is $470 on Amazon.com.

Simplicity + not perfect = happiness? Dunno.

Sixth,
Get more voltage from your solar panels. The cheapest/best solution for 12V and PWM style controllers seems to be the Trimetric SC2030. Unless you are putting more panels on the roof or using a portable with long cables.

Again, stock wiring to the roof is 10 or even 12g. Assuming 10g over 10’ of wire, and a single GrapeSolar 100W panel on the roof, that puts out 17.8V at 5.62A, the loss is an acceptable .62% getting you 17.69V to the controller and thus the batteries.

Up that to 300 panels and the loss is 1.91%. Upgrading the wiring to the roof to 6g gets us back down to a loss of .73%. Maybe this is a no-brainer, and the extra loss is OK?

Going to the portable setup, at single 100W panel 50’ away over the standard 12/2 cable (GoPower kit) we get a whopping 3.15% power loss. If I use two 100W panels at 50’, then my loss is 5.84%. Acceptable? I don’t know, as it still feeds 17.24v into the controller, and I should just think of it as having two 94W panels instead of 100W panels.

On the other hand, I can make my own much beefier cables and reduce the loss, and if I need more current capability at the controller, I can double up the number of SC2030 units – how to? Click here.

I can live with that.

Seventh,

More ideas???

 

[ski3pin]

Vic, again thank you for all the research and documentation.

 

[Vic Harder]

I'm sure I have read folks here saying that they have added solar panels to the roof/portable and used their existing charge controller for both panels. From what I have read, this isn't supposed to work, and you need a separate controller for each array? If the panels are identical, then it does work, but what are the odds of that, as we mix n' match and upgrade our systems?

Morningstar says you can't - LINK as do the folks here and here.

Given that folks here have done it, what am I missing?

And if it is true that we need multiple controllers, then .... well, I don't know what to think right now. Let me get an adult beverage and get back to y'all

 

[BFH4N]

Vic,

I read your post with great interest. It represents a lot of good work on your part. In fact, I was overwhelmed by it all. I don't think your usage projections match what I do very well, but that is to be expected, as everyone's case is different.

I have both CTEK 250S Dual and Smartpass units installed in my Fleet and it seems to work well for charging from the truck generator (I haven't hooked up solar panels yet). The CTEK (non-adjustable) maximum charging voltage of 14.4 Volts happens to match the optimum charging voltage for my batteries (2x Exide FWC OEMs). I set my TriMetric to the correct "fully charged" criteria for my batteries, and it shows that the CTEK easily gets the batteries back to 100% from an overnight drain down to about 75% after an hour or two of driving. I've seen it pumping significant Amps (up to 20) into the camper battery at 14.4 Volts from the truck battery at 13.6 Volts. It also allows a high rate of charge (up to 80 Amps in theory, and I've seen over 50) for a short time while the truck generator is charging the truck battery at a high rate. I have installed heavier wire (4 AWG) than the OEM from the truck battery to the CTEK, but the capability of the CTEK to boost voltage should give some degree of immunity to the voltage drop in undersized wire.

I haven't tried the solar charging capability of the CTEK yet, but I can say that it is seems to be a viable alternative to the automatic battery isolator and the FWC approach of "hook the batteries together and hope for the best", which probably leads to less-that-satisfactory results in most cases.

- Bernard

 

[Vic Harder]

Bernard,

This is great data! So are you saying that you see 14.4 at the camper batteries when your truck batteries/alternator are only putting out 13.6? That would be amazing, and shows off the DC-DC converter function of the D250S, and that's over 4g wire, about 20' long? That implies the CTEK is upping the voltage to 14.6 before sending it to your batteries. Neat.

 

[Captm]

Thank you for your research!
Just a quick question and maybe you addressed it but I missed it. When you say a "20ft" wire run is it 10ft each way or 20ft each way for a total of 40ft ?
Cheers!

 

[BFH4N]

The CTEK in my Fleet is installed near the batteries, so the size of those wires is not important. To some (unknown) degree, the capacity of the CTEK to boost voltage makes concerns about voltage drop in the wires from the truck battery to the CTEK unimportant. The same goes for truck generator output voltage.

The CTEK works similarly with solar input. (I guess all MPPT charge controllers do.) The voltage and current from the collector are not the same as what is applied to the battery. My brother has confirmed this with his single-collector solar CTEK installation.

By the way: The CTEK output is not a steady current, because it is constantly testing conditions (finding the Max Power Point, presumably) and adjusting accordingly. My brother reports that attempting to monitor the instantaneous output (voltage or current) gives confusing readings, especially with a digital meter. Averaging over about 10 seconds smooths it out. The TriMetric seems to do a good job of this, giving steady readings.

I used a 120-Amp Anderson Powerpole connector in my 4 AWG wires. It's very robust and a great waterproof hood is available. I had to buy a big special crimper, though.

- Bernard

 

[ntsqd]

Thanks for the SmartPass clarification.

I do not trust that voltage drop calculator link as it does not agree with the ABYC compliant chart that I've used for years. Nor do I trust most of the charts out there on the net because they are geared towards NEC applications employing AC and not DC. My Ancor Marine catalog has a chart for 3% Voltage Drop that I use. It can also be found here: http://www.ancorproducts.com/en/resources/three-percent-voltage-drop Note that on this chart that the circuit length is the total length, not the one-way length specified in the linked calculator. For a 3% V.D. at 20A it calls for 6 gauge up to a 40 foot total circuit length. 4 gauge is listed for 20A out to 60 feet, so that would be appropriate for less voltage drop on a shorter circuit length without going too far overkill or too deep into the wallet unnecessarily. Note the ripple effect that excessively large cables have on the wallet and on your inner peace from working with them in tight confines.

Given that the CTEK is a DC-DC converter the supplied voltage isn't too critical since it will trade amps for volts to deliver the programmed charging voltage. It may take a little longer to get to 100% SoC if the V.D. is excessive, but I doubt that a minor drop would even be noticed except by the most anal-retentive.

I am of the opinion that all camper battery controlling/charging devices should be mounted in the camper. This keeps the cables/wires between them and the battery(ies) as short as possible so they can be smaller. Mounting the device(s) outside the camper does not negate the need for large cables in the slightest, I see no gain and now when the camper is moved to a different truck none of it's support hardware came with it. That's what works for me anyway, I'm sure it's different for others.

Simply upgrading the charge wire should have no negative effect on the alternator. If anything it now has to work less hard to charge the battery(ies). I once read an article claiming that some resistance in the charge wire is desirable, but the argument made no sense. Flip side is that I see no reason for a 1/0 charge cable 18 inches long. Use the Voltage Drop tables to size the cable for the alt's max output over the length of the circuit. That being the length from the alternator to the truck's battery(ies) and back only.

 

[DrJ]

Vic,
I've been gone for days and just catching up on your outstanding posts.
Great work on educating our group on electrical power.

You mentioned before about using a 300 amp hour plus battery system. Do you have room for that big of a battery?

I went with 225 amp hours because that's all I could get to fit in my front dinette grandby battery compartment.

One thing I would recommend would be to have a portable and fixed panels to reach your solar goal.
I have 250 fixed 24 volt panel and a flexible 135 watt panel that I move wherever the sun is. Most times I get by without needing the portable panel.

Well done on putting together the most interesting post I've read in months!

 

[Vic Harder]

Thanks for the SmartPass clarification.

I do not trust that voltage drop calculator link as it does not agree with the ABYC compliant chart that I've used for years. Nor do I trust most of the charts out there on the net because they are geared towards NEC applications employing AC and not DC. My Ancor Marine catalog has a chart for 3% Voltage Drop that I use. It can also be found here: http://www.ancorproducts.com/en/resources/three-percent-voltage-drop Note that on this chart that the circuit length is the total length, not the one-way length specified in the linked calculator. For a 3% V.D. at 20A it calls for 6 gauge up to a 40 foot total circuit length. 4 gauge is listed for 20A out to 60 feet, so that would be appropriate for less voltage drop on a shorter circuit length without going too far overkill or too deep into the wallet unnecessarily. Note the ripple effect that excessively large cables have on the wallet and on your inner peace from working with them in tight confines.

Total length, doh. Yes, I suppose there and back is more like 40' vs the 20' I was thinking. And it is interesting that they recommend a max of 3% drop. I suppose this is an industry accepted value? I love your reasoning on inner peace, $$$ and wire gauge .

I'm wondering if there is still value in reducing the voltage drop more than the 3% ABYC recommends, given that the battery manufacturer wants to see around 15v for the bulk charge phase. It isn't just about the current. That's also my concern about the CTEK, as the voltages are not adjustable. They are OK, just not great. And given that the batteries are the heaviest and most expensive part of my power system, AND that they will fail eventually, I want to maximize their life expectancy. I'm just not sure if the way to do that is to use the CTEK to avoid pushing high levels of both volts and amps at the batteries when they no longer need it, or to suffer from insufficiently charged batteries because the CTEK is factory configured to not supply enough volts to the batteries.

I think i need more documentation, not more power!

Simply upgrading the charge wire should have no negative effect on the alternator. If anything it now has to work less hard to charge the battery(ies). I once read an article claiming that some resistance in the charge wire is desirable, but the argument made no sense. Flip side is that I see no reason for a 1/0 charge cable 18 inches long. Use the Voltage Drop tables to size the cable for the alt's max output over the length of the circuit. That being the length from the alternator to the truck's battery(ies) and back only.

Thom, I'm not following you here. Why only to the truck's batteries vs all the way back to the camper batteries/CTEK/ACR?

 

[Vic Harder]

Vic,
I've been gone for days and just catching up on your outstanding posts.
Great work on educating our group on electrical power.

You mentioned before about using a 300 amp hour plus battery system. Do you have room for that big of a battery?

I'm building up a shell, so I can decide now how big my battery box needs to be. The L16 (400+ AH) size is a bit too big for my tastes, but the 330 AH size is only an inch or so taller than the 220AH batteries. I can work with that


One thing I would recommend would be to have a portable and fixed panels to reach your solar goal.
I have 250 fixed 24 volt panel and a flexible 135 watt panel that I move wherever the sun is. Most times I get by without needing the portable panel.

That's what I was thinking too... 265w on the roof and 160w portable. Are you feeding both into the same mppt controller? You have a Tracer A mppt, right? How is that working for you?

Well done on putting together the most interesting post I've read in months!

Thanks! I know I'm interested because I am trying to understand all this before I spend big $$ on it. It is gratifying to see others getting value from this discussion too.

 

[ntsqd]

The Ancor Marine page has a 10% V.D. (Voltage Drop) chart for motors etc., and a 3% V.D. chart for electronics. I use the 3% chart as my jumping-off point for everything. It builds in some Factor of Safety and things generally work better when the voltage is on the high end of the normal range.

DC-DC converters more or less consume Current to make Voltage when the output voltage desired is above the input voltage. So the CTEK will output whatever voltage it is programmed to output, it will just use some of the current to do so and not pass all of it on to the battery(ies).

As to the battery charge wire from the alternator, consider that if the camper were not present then the length from the alt. to the starting battery and back is the total length of the charging circuit. It is likely to be a fairly short length circuit, so a reasonable wire gauge will result in a low V.D. No need to use 1/0 there.
Add on the camper and that doesn't change, V.D. to the starting battery(ies) will be the same. Size the cables from the starting battery(ies) to the camper battery(ies) to have the minimum acceptable V.D., the alternator to starting battery charge wire will still have the designed V.D.
Said differently, the charge wire will be relatively short, so it can be large-ish without being near as big as the starting battery to camper battery wiring, and still have a very small V.D.

 

[Vic Harder]

More CTEK info. There shore power battery chargers are way smarter than the D250s Dual, with settings for Wet/AGM/Cold weather charging. The Dual doesn't have those settings, unfortunately. Their generic voltages may work for some batteries, but not all.

Right now I'm leaning away from the CTEK, and ONLY because the battery type/voltage is not customizable.

 

[craig333]

My recent trip allowed some decent experience with my upgrades. 250 watts of solar into 225ah of batteries monitored with the trimetric. Most days I'd awake in the morning with 2.9 volts or more still showing. I ran the heater, used the microwave and made no attempts at conserving power. My last day we came off the trail in the afternoon. Oops, taking something out of the fridge I'd accidentally turned it off. Seems they have little insulation as it was completely warm. Turned it back on. Next day after returning from Randsburg it was overcast. Trimetic showed 80% SOC and 12.6 volts.

So overall I'm pretty happy. With good weather I should never have a problem. Now I'll have to do some more testing with just the alternator simulating poor weather conditions.

 

[Vic Harder]

More on Solar Charge Controllers

Fascinating. I’ve been reading manuals. (And they say men don’t read instructions!!) Lots of manuals, from the manufacturers of charge controllers, both PWM and MPPT types.

Short conclusion: SolarBob is onto something when he says the Trimetric SC2030 is one of the best/smartest controllers out there.

Long conclusion:

1) Most of the manufacturers of less expensive units have unchangeable presets for the various battery types. This is not ideal
2) Even the more expensive and reputable manufacturers (Morningstar/BlueSky/Midnite) use a charging algorithm that assumes your solar panels are sized such that you WILL get a full charge every day, not the actual state of the batteries
a. A “Big enough” solar array is usually 1.5 to 2x watts in your solar array as AH in your batteries. And IDEAL charging conditions.
b. So for 200 AH battery array you would need 300W of solar panels
c. The algorithm is TIME based. As in, charge at this voltage/current for xxx minutes
d. The algorithm should check the voltage and current characteristics of the battery bank to determine if the charging is done, not assume the weather is good
e. Ideally, it would do both C & D.
f. The more expensive units do this: OutBackPower
3) The Trimetric does this, and it is inexpensive to boot

Oh, the other surprise was that you should not mix different solar panels feeding into the same controller.

“Only solar panels of exact or similar current should be wired together in series. When you connect a 3A panel to a 3.5A panel, the overall current will be dragged down to 3A. Such a reduction in current will by all means lead to a reduction in power output and therefore loss in system performance.
Similarly only solar panels of exact or similar voltage should be wired together in parallel. When you connect a 15V panel to a 24 V panel, the overall voltage will be dragged down to 15 Volts. Such a reduction in voltage will lead to a reduction in power output and therefore loss in system performance.” http://solarpanelsvenue.com/mixing-solar-panels/

This means that if you have different types of panels (for your portable and rooftop, or panels added later to an existing array) then you need to have multiple controllers, one for each type.

I know DrJ has had good luck with the EPEVER Tracer A, but those are among the controllers that only charge in the Absorb and Float phases for set amounts of time, not by when the batteries are actually charged.

So I am leaning very strongly towards the Trimetric SC2030 and upgrading my wire sizes if needed.

 

[craig333]

Unfortunately some people don't read this correctly. "Similarly only solar panels of exact or similar voltage should be wired together in parallel". I've seen some people think you can't add panels of dissimilar "wattage" but how would a controller know? It just sees the total. Fortunately my rooftop panels and my portable panel are the same or close enough in voltage. 17v seems pretty common in the panels most of us are looking at.