8 replies to this topic

[carld]

I am reasearching options for adding solar to my Ocelot next year.  I had the Ocelot pre-wired  so I won’t have to tare into it to add solar.  I’m looking at the following:

 

HQ 100 Watts 12 Volts Monocrystalline Semi-Flexible Solar Panel $190

CTEK D250S DUAL  $190

Bayite DC Digital Current Voltage Power Energy Meter Multimeter with 100A Shunt $18

Battery Tender Jr. 0.75 Amp 110V to 12 battery charger

 

The CTEK D250s has the following advantages:

Replaces the battery separator

DC to DC converter boosts aux battery charging voltage overcoming IR wiring losses from main battery system

Charges aux battery using optimized temperature and voltage sensing 

Dual input is  MPPT solar providing maximum power temperature compensated charging to to aux battery system

With engine on combines power from main and solar up to 20 amps max to aux

With engine off provides solar to aux with pulsed charging of main

 

 

The CTEK dual can be combined with the CTEK smart pass to provide maximum initial charging current > 20 amps if needed but for my case I don’t think its needed.

 

The Battery Tender Jr is a 5 stage battery trickle charger.  I connected between the 3-way fridge 110 V and 12 V inputs.  When I am at home I can plug it in and it keeps the batteries at full charge and cool down the fridge.  I’m not quite sure how it will react in parallel with the CTEK d250s.  I think without is plugged in to 110 it’s inactive.  When both are operating they both sense the aux battery voltage and try to adjust to the programmed set voltage.  I might need to add a 1  ohm resistor in line with the Battery Tender to help Isolate them.

 

I plan to glue the flex panel to the roof  to minimize weight and not have to drill holes in the roof.  I plan to using clear silicon because its water proof, last a long time and easy to remove if necessary. 

 

I was looking at the Trimetric battery monitor for $150 without shunt, but the Bayite monitor has similar functions and costs $18 with a shunt.  Currently I have a cigarette lighter type plugin volt meter with dual USP ports I use to monitor the battery. 

 

So far I haven’t had a problem with the battery.  My last trip I stayed 3 nights in the mountains of Tucson where the temperature dropped to around 30 F.  I ran the heater  and LED light and on the third night the voltage dropped to about 12.2 V.  The next day I drove about 4hr to Cochise Stronghold with the 3-way fridge on 12V (turned it off the last hour) and the battery voltage came up to  around 12.8V.  Then spent a day at Hueco Tanks, 3 nights at Big Bend and a night in Fredericksburg TX before going home.  Used the heater every night and the temperature was consistently around 30 F.   I refelled the propane tank in El Paso after 5 nights.  The refill was 3 gal and the gauge had just moved to empty.

 

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[ntsqd]

I installed a BatteryMinder 120VAC battery charger shortly before installing solar and have used it exactly once. Truck sits in the sun, so the 100W of solar has been more than up to keeping the camper batteries up. If still determined to have such a unit on-board I'd have a look at the C-tek offerings and see if there's one designed to work with the controller that you're looking at using.

 

It does sound like you *might* simply use a 18VDC output transformer with a inline diode that is wired in parallel with your solar's input to the controller. It would likely need to be a fairly 'clean' transformer, but I suspect that it might work. The controller already has multi-stage charging built-in, seems unnecessary and potentially conflicting to have another.

 

At that price differential I'm dubious of the Bayite part. In that rough price range I'd be more inclined to go with the "Watts-up" meter as several here have used it with good results.

Edited by ntsqd, 29 December 2015 - 02:25 PM.

[Old Crow]

I see the manual for the D250S shows how to connect a separate ac/dc charger to it on Installation Sheet 6 (page 21).  But it connects via a Smartpass so that would mean the additional expense and space of that other device.

 

http://smartercharge...50S-DUAL_EN.pdf

 

The problem statement says it's a solution for charging both the main and aux batteries with the ac/dc charger.  I believe your intent was only for the aux battery so perhaps the solution is unnecessarily complex.

 

How about this:  If you're concerned about the ac/dc charger being in the circuit at the same time as the D250S, install the wire loom for it on the aux battery and just unplug it at the SAE connector while you're using the D250S.   When you want to use the charger (presumably when you arrive home), disconnect the battery from the D250S (either via its thermal circuit breaker or by removing a cable) and plug in the charger.  Reverse the process when you're on your departure prep.

 

Also- I'd agree with ntsqd that a CTEK charger might be a better way to go. Perhaps it's vendor-bias but  I'd probably go for the 4.3 or 3300 model to get the 14.7v bulk charge capability of snowflake mode, the recovery-mode program, pulse-charging, and the faster charge speed (compared to the Battery Tender Jr.). 

 

-OC

 

PS- I don't have solar but the first thing that came to mind on your use of glued-down flexible panels is this thread:  http://www.wanderthe...going-vs-dead/. I'm also clueless on how the D250S compares to other options for adding solar.

[carld]

So far my setup now is working fine.  The battery tender jr keeps the both truck and camper batteries charged between trips and the plug-in voltmeter/usb gives me a good indication of the battery state. After my last trip the camper was sitting in the driveway for 3 weeks.  I looked at the voltage and it was around 12.4 V on both the truck and camper.  After plugging in the battery tender the voltage came up to about 12.5 V on both and after 3 days the battery tender green led was on and both batteries were at 13.1 V.  I want to add solar to maintain the camper battery while camping and reducing the load on the alternator while driving and running the fridge on 12V. The CTEK Dual only it should keep both truck and camper batteries charged and I can just unplug the battery tender.  In any case I'll put a current meter on it just to see how it reacts in parallel with the CTEK Dual.  

 

After doing some more research the Bayite Monitor only measures and accumulates aux battery current in one direction.  I guess this is a limitation of having a single polarization +Vbb supply.  So for now I'll stick with my plug-in voltmeter and maybe someday upgrade to the Trimetric monitor.

 

I think some of the failure problems with the flex panels have been fixed.  These panels are only semi-flexible which might make them more reliable.  They are light weight about 4lbs and will conform to the mounting surface.  The HQST panels don't have a warranty but for $50 more other brands  on amazon (Kingsolar 50, 100 and 120 W and Allpowers 50 and 100 W) have 100 W flex panels with a 1 yr warranty for $200. 

 

 

The total cost should be around $350 ($200 for 100W solar panel and $150 for CTEK 250s dual).

 

I updated my schematic.

 

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[ntsqd]

I'm not seeing how the truck's alternator can charge the camper battery(ies), does it?

If so, there needs to be a high current fuse or breaker at each end of the + wire connecting them. I use a high current manual reset breaker at both ends with the one in the camper also functioning as the camper's main breaker. Only a battery cable into it, all other connections are on the 'switched/breakered' stud.

 

The BatteryMinder that I installed connects to the Main breaker and to the camper side of the shunt in the - so that the TriMetric 'sees' it's input too. As has been said, nothing on the battery side of the shunt except for the cable to the camper's battery(ies).

 

My TriMetric has no wire or cable going to anything solar, only to several locations on the shunt and the battery +

 

 

[carld]

ATC installed a AOPEC R12140B battery isolator between the aux battery and truck battery.  They ran a 2 10 gauge wires directly between the truck battery battery isolator. I think I should install a 40 amp fuze at the truck battery connection.  The way it is currently the aux battery can assist the truck battery which is hopefully unnecessary.  

 

The way I understand it the CTEK dual, it is a DC to DC converter with two main supplies, the truck battery and a solar panel.  I suppose the supplies are somehow combined by synchronized switching across an output transformer then rectified and filtered to the aux battery.  The switching is controlled to provide maximum power point tracking (MPPT) for the solar input and deliver a temperature compensated charge to the aux battery.  Across the transformer they can step up the voltage so that if the truck battery is at 12.6 volts it will can deliver up to 15V to charge to the aux battery depending on temperature.  The output is limited to a maximum of 20 amps to the aux battery and camper load. I suppose if the truck battery voltage drops below some level, the CTEK will only draw power from the solar and it will intermittently switch a trickle charging voltage back to the truck battery and continue to keep the aux battery charged from solar.  This is what it sounds like to me there is not a lot of information about it.  There should probably be 30 or 40 amp fuse between the batteries and the CTEK as well as a  fuse to the solar panel.

 

The Trimetric has two voltage inputs.  The main one is used for the aux battery voltage and current to monitor the state of the batter.  You can choose to connected the other to whatever you want.  Connecting it to the solar panel would help you know how they are working. 

 

I found another battery monitor on Amazon, the DC 0-120V 0-25A Voltage Current Capacity Power Combo Meter Battery Monitor Forward Reverse Current by AiLi, $16.5.   I'm trying to find out more information about it, like does it have a remote current shunt.

 

[carld]

I'll change the cables from the AOPEC isolator to the CTEK but keep the AOPEC installed as a backup incase there ever is a problem with the CTEK.

[ntsqd]

There is a battery on both ends of the wire(s) from the truck battery, I feel that there should be a fuse or breaker at both ends of that wire too. This is a point that I initially over-looked and only had a breaker at the truck battery end. Sometimes the wire isn't live at the camper end due to the ACR, but not always. I don't know if the C-Tek controller will allow power backwards out of it or not. If any doubt put in a fuse or breaker.

 

In my install I monitor both the truck and the camper battery voltages with the Tri-Metric. I don't care what the solar panel voltage is, I only care about the controller's output and what my starting battery voltage is. I can always use the on-board DVOM for solar panel voltage if I need to troubleshoot.

[carld]

Im sure the CTEK completely isolates between the batteries.  I have a question to Amazon and contacting CTEK manufacture to see if the outputs of the D250s have current limiting.  I assume it limits to the output 20 amp limit.  Im adding 40 amp auto-resetting breakers to both battery lines and a 20 amp inline fuse to the solar panel.  Its January 1 and the price for the CTEK and solar panel are up 5 to 10%.  I think I might opt for the Kingsolar 120W panel with a 1 year warranty.   Supposedly the efficiency on the MPPT converter is around 95%, so in good sun the 120W panel should almost match the Dometic 12V current.  I updated my schematic.

 

258.89 Kingsolar 120 W panel

203.12 CTEK D250s

  12.00 2 40 amp breakers

   7.00 MC4 connector tool

  10.00 pack of 5 MC4 connectors

491.00 Total  

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