$250 Device for charging TM Batteries from TV *or* Solar

[rickst29]

Recent EBay prices for new units, from USA sellers, range from $190 to $260:
http://www.ctek.com/au/en/chargers/D250S%20DUAL
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Update 2/28/16: My own gently used unit is now for sale, $100, because I found a "slightly better" way to use my existing MPPT instead - and my new way allows easier switching between High-power Solar (330W max) and High-Power Bargman usage (at somewhat less power). I pay shipping.
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Maximum Output is 20A. It includes an MPPT charger (for low-voltage Solar, less than 24V) and claims to automatically uses both Solar and the Bargeman Supply from the TV to charge your batteries. If Solar is adequate for the current charging mode which it is using, it will use Solar alone. But in night time, or you don't have Solar at all - then it will run entirely from the Bargeman Connector. When running from the TV, TV Voltage is boosted for "Bulk" and "Absorb" charging stages. (I'm labelling the above-80% fixed Voltage Stage as "Absorb"). If your TV "float voltage" is really low, like the voltage supplied by my Toyota 4Runner - it might even do a small amount of voltage boost within "Float" mode. When you run the Fridge on the road, using 12VDC, "Float" stage will not be maintained when the Fridge power switches on - the draw will pull the battery voltage back down, and invoke restart of "Absorb". This device will pull all the current which the Fridge needs - and provide up to 6A "extra" for the batteries as well.

It's $100 - $150 less money than the competing Redarc, found by "ShrimpBurrito" in his research a few years ago: http://www.trailmanorowners.com/foru...ad.php?t=10587. But the Redarc doesn't have any simultaneous Solar capability - this appears to be a more complete product, using multiple sources at the same time.

[tentcamper]

Redarc does have the solar capability. Check out some of there other products. They operates with anything from 9 to 32V input and can operate with a different inputs for solar and change to TV start battery. Check out this product it operates off solar as an MPPT solutions, but then switch to TV start battery as a step up battery charger.

I have heard great things about this solution:
http://www.redarc.com.au/images/uplo...ger_130408.pdf

[rickst29]

Originally Posted by tentcamper

Check out this product it operates off solar as an MPPT solutions, but then switch to TV start battery as a step up battery charger.

I have heard great things about this solution:
http://www.redarc.com.au/images/uplo...ger_130408.pdf

Nicely done device, with twice as much Maximum Amps. But list price is almost twice the price I just paid for the Ctek D250S, so I suspect that it's unlikely be found for less than $325. The diagram (thanks for the link ) shows an external switch for the two input sources - that's a manual switch, unless you add their RK1260 as the switching relay device. (And the RK1260 only automates the switch, you're still not using Solar and TV power simultaneously.)

The MPPT Voltage limit causes the same limitation as Ctek - Panels must be wired in Series, not Parallel.

The BCDC1240 clearly "wins" is the situation of big TV wiring and alternator, capable of providing a lot more than 20A. But note that I don't insist on having big batteries in the TM to enjoy this Redarc advantage - even if the batteries shouldn't be charged at more than 10A, you'll be using the "extra" power into the Fridge. With a TV capable of 35A or more, and adequate TM wiring, the BCD1240 could run the Fridge and charge the batteries, while the D250S would be limited to only about 3A per battery while the DC Firdge is running its heater.
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New, 11/8/15: I found some measurements in other forums, by AU camper people, showing CTek performing very badly in Boondocking with Solar Panels alone. These measurements date from 2012, 2013, and one post talked about a firmware upgrade "solving the problem". But when one Ctek user upgraded to Redarc, he found that Redarc performed very well in both configurations (running from TV power, and running from Solar power).

So it's "Buyer Beware" with Ctek's Solar performance. I will be using it only with TV-supplied Bargeman power. I'd have to do a lot of ugly reconfiguration to even test the Solar functionality (using 2 of my 3 Solar Panels, rewired). My biggest panel is totally incompatible (with both Ctek and Redarc), so I will be staying with my separate Solar Controller.
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BTW, I might have been confused by the large number of smaller strands, but it looks to me as if the Bargeman cable "+12V" wire might be bigger than 10AWG. I don't need even 30A down that cable, so didn't actually measure it.

[BrucePerens]

Check out the West Mountain Radio PG40. Only $140 and it will charge a battery from an external supply, and feed your converter from the TV while it's plugged in. I use one to provide uninterruptible power for my ham station. I even have the desktop computer and the video monitor running on 12V.

[rickst29]

Originally Posted by BrucePerens

Check out the West Mountain Radio PG40. Only $140 and it will charge a battery from an external supply, and feed your converter from the TV while it's plugged in.

That offers really nice "smoothing" for the consumer devices (including the batteries), but it does not boost the Voltage provided form the Power Supply. Reference UG page 11. You need a separate boost device to do that - as we discussed in the Other Thread.

If we put this machine between the "el-cheapo" Voltage Booster and the TM batteries, it would replace the need for "PWM Solar Controller", and it might also be a lot more friendly to the "boost device". That would solve the problem which seems to have occurred in my original build. But it's primary intent is to "smooth" on the output side (batteries and expensive equipment). The UG offers no information about the nature of impedence variations which will present to the PSU.

Even if it does turn out to be a "friendly" load, allowing el-cheapo "Voltage Booster" boards to be used, the total cost ( maybe $120-$140 for the PG40S, another $40 for the project-boxed "Booster") is getting close to cost of the Ctek device. Ctek is purpose-built for exactly the "charge from TV" problem, and it also provides the "combining" feature, and the built-in MPPT controller for Solar. The PG40S seems to be solving a different problem (PSU output noise reduction), and charging the battery if the input "PSU" Voltage is sufficient.

[BrucePerens]

Originally Posted by rickst29

The UG offers no information about the nature of impedence variations which will present to the PSU.

It doesn't matter. This is DC electronics feeding varying loads, they really only see a reactance when they start. And most of those boost regulators are current limiting, so they can handle a capacitive load which presents close to 0 Ohms when it starts, since that's the norm for electronic circuits. Your boost voltage regulator didn't die because of the load impedance.

Resistance would be a more accurate way to state this rather than impedance, since it's mostly DC. And if you want to talk about AC, you need to consider reactance rather than impedance, since it matters whether your load is inductive or capacitive and impedance doesn't say which.

If they say their device always presents a low AC impedance, that just means they have a capacitor across the input. A high AC impedance would indicate a choke in series with the input or you're feeding a transformer winding through some sort of oscillator. Other than that, the DC resistance will dominate, AC probably doesn't matter at all, and the resistance will range across whatever is required to provide the current as various devices turn on and off.

If you need to condition the load after your el cheapo voltage converter, you probably just need a capacitor in parallel.

[rickst29]

Originally Posted by rickst29

Recent EBay prices, from USA sellers, range from $190 to $260:
http://www.ctek.com/au/en/chargers/D250S%20DUAL
Maximum Output is 20A. It includes an MPPT charger (for low-voltage Solar, less than 24V) and automatically uses both Solar and the Bargeman Supply from the TV to charge your batteries.

In "early" firmware (2013 and earlier), Ctek was found (by users posting on other forums and boards) to do a bad job of delivering Solar Power to batteries, even when the TV is not connected. At least one person upgraded to the Redarc, and found the more expensive machine to work as expected (i.e., WAY better.) Although there is talk of a certain firmware release solving the problems, I didn't find any measurements of solar power delivery from one of these "later" devices.

With a lot time spent re-wiring panels into parallel, and deleting the high-voltage panel from my Solar Array, I could check out this possible problem on my "new" device, using just two panels in parallel. But my Solar is working great in its current configuration, with 3 panels at high voltage (~65V). I've decided to leave the Rogue MPPT and Solar Array unchanged. And there is already a switch to disconnect Solar from the Rogue MPPT when towing in non-optimal conditions.

Therefore, although it is an expensive machine, built and advertised for combining Solar and TV power sources, I'll be using it only for TV power. (I'll leave the Ctek Solar terminal unconnected.)
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Update 11/09/2015: The box arrived, and it has the newer firmware "B50". Unfortunately, the Temp Sensor is an insulation-wrapped "lump", and not a ring terminal for a "+" battery terminal. This will limit the accuracy of its measurements. There is no documentation about efficiency (i.e., heat generation by the device), but it probably doesn't generate much heat. (That's a SWAG). To prevent theft, I will mount inside the TM - next to the Rogue Controller. (The other "good looking spot", behind the Fridge, can't be used ,because the Temp Sensor Cable is too short to reach my front-mounted batteries.)
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Update 11/14/2015: I've installed it, it works pretty well. (With no connection on the "Solar Array" terminal).

[Bill]

Rick -

In my opinion, your decision is a good one. I always advocate making changing one at a time, so that you can see the effect of each. You can always make your solar panel changes later, but for now, you will get to see what the CTEK device does for you, without cluttering the situation.

I look forward to your reports on both the CTEK, and later (if you decide to do it) the solar array.

Bill

[rickst29]

In another example of my fixation on "optimizing" things which already work perfectly well , I'm putting the CTek up for Sale, and implementing my "other design" instead. That design, also providing excellent "Tow Vehicle charges the TM" capability, boosts the Voltage right under the hood, and goes into my existing MPPT.

The Ctek MPPT doesn't have my Rogue's programming options, and runs with their idea of "default" SLA battery charge management. My "other" design also creates only half as much current along the "+12V" TV and Bargman cable path, using energy more efficiently. And, I can make the switch between "Solar" versus "Tow Vehicle" automatic, if I want to do that. Therefore, See this Thread in "Parts and Accessories": http://www.trailmanorowners.com/foru...ad.php?t=16980