oldguy
Solar Newcomer
Posts: 4
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Post by oldguy on Aug 31, 2018 23:11:39 GMT
Total newbie to solar.
I am interested in a camping/portable setup using a single 330watt panasonic 70v panel to charge a 12v battery.
At first blush, it appears that I should be able to use a Renogy Rover 40 amp Positive Ground MPPT Solar Charger to hook up to a 12v RV battery, since the max input voltage for the controller is 100v;
however:
I do not at all get the "positive ground" designator on the controller since US vehicle grounds and house neutrals have always been negative for a very long time.
Can someone please clarify if I can use this controller/panel combination and if so, indicate how to resolve the positive/negative ground issue?
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Post by bupkis on Aug 31, 2018 23:33:08 GMT
no need to ground a 12v solar install.
Positive ground controller has panel + battery + and load + all tied together internally.
Regulation is done on the negative side.
"If grounding is necessary, it must be completed on the positive line. If the controller is to be used on a vehicle which has battery negative on the chassis, loads connected to the controller must not have an electrical connection to the vehicle body."
simple solution is to not use the controller load terminals.
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oldguy
Solar Newcomer
Posts: 4
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Post by oldguy on Sept 1, 2018 0:11:19 GMT
Is it that simple? The trailer only has a single battery to accept the charge and the object of 330 watts is to immediately use the excess power above charging the batteries for utilities in the trailer. Is it ok to use the battery as a power buffer and run off the battery circuits in the trailer while hitting the controller with such high current rates on the battery charging side?
It is rated at 40 amps, but I'm a bit concerned about pushing any limits.
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Post by tattoo on Sept 1, 2018 0:17:52 GMT
Yes sir it's that simple....
Don't let your battery get below 12.0v and keep an eye on it to make sure it doesn't...
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oldguy
Solar Newcomer
Posts: 4
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Post by oldguy on Sept 1, 2018 0:49:19 GMT
very good. Thank you.
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Post by bupkis on Sept 1, 2018 13:35:24 GMT
The controller prevents overcharge, it limits power to the battery when it is not needed.
A typical RV install calls for hooking the controller to the battery then the panel to the controller and that's about it!
You should be advised on a portable panel with MPPT controller to always hook the controller to battery(ies) before connecting the panel to the controller and to disconnect the panel from the controller before disconnecting the controller from the battery.
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oldguy
Solar Newcomer
Posts: 4
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Post by oldguy on Sept 1, 2018 16:42:09 GMT
Just for completeness: What would I have to do to run something off of the controller load connections and what would I have to be careful of to avoid shocks or shorts?
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Post by tattoo on Sept 1, 2018 17:11:55 GMT
Just for completeness: What would I have to do to run something off of the controller load connections and what would I have to be careful of to avoid shocks or shorts? You don't have to do anything special to run off of the load side of the CC.... Just as long as it's a small load something like a light...... If you put to much of a load on the CC load side you will get error codes....
As far as shocks or shorts go just don't hook a ground to the hot side..... And you will be just fine...
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Post by bupkis on Sept 1, 2018 17:36:17 GMT
ya need to use both the + and the - terminals for any load on the load terminals, not chassis as a common/return path. Load terminals are for timed events like on at dusk and off at dawn with 15 or so different settings.
catastrophic fuse at the batt +, this is sized based on your wire size and/or max expected load.
Fuse between controller and batt, 40-50A and you'd be using short length of 8 gauge wire or bigger.
Technically you'd fuse the + coming off the load terminal based on wire size and load, same thing if using battery.
Vehicle 12v is fused and goes to fuse box where each circuit is fused.
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