Two Charge Controllers Connected to One Battery Question

Converting Cargo Trailers into TTTs

Two Charge Controllers Connected to One Battery Question

Postby featherliteCT1 » Thu Jun 27, 2019 6:52 pm

Is there any problem with charging one battery using a PWM controller from a first solar panel and an MPPT controller from a second solar panel, where the first solar panel is not connected to the second solar panel, where both controllers are connected to the single battery, and where the PWM controller is connected to a battery monitor that controls the PWM charge parameters?

I tried to research this question but found conflicting opinions. Some say that the MPPT controller could be confused (e.g., by the pulsing from the PWM controller) or be confused for some other reasons.

Specifically, the PWM controller would be a Bogart SC 2030, the battery monitor would be a Bogart Trimetric, and the MPPT controller would be a CTEK D250S

Thanks in advance.
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Re: Two Charge Controllers Connected to One Battery Question

Postby troubleScottie » Thu Jun 27, 2019 7:53 pm

Not have installed either, the Battery bank meter does not care about what else is connect to the battery. One, two or no controllers will not affect its operation.

To detect the charging, the controllers need to be connected to the ground before the battery bank meter .

The question than is (1) whether one or the other or both controllers will care if the other controller is in the circuit but not charging and (2) does leaving a controller in the circuit that is not charging affect anything else.

I believe the controllers are not bad as your solar panels and thus your controller will go to zero occasionally. Some controllers do list that they have a draw when not charging. Definitely not the draw of a non-loaded inverter. That said, I would be more concerned that some other device might affect the controllers.

I saw on an RV site someone had 3 controllers connected together, 1 for each set of panels, to maximize the output. The sets of panels got different amounts of light due to fixed location on the RV. If I recall, the controllers were the same brand and type (mppt) but not the same output.

I would add a switch or switchable fuse between the battery and each controller and disconnect the controllers when not in use. You could go crazy and have two switches -- one for plus and one for negative. Obviously that would be dependent on being able to reach these switches easily.
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Re: Two Charge Controllers Connected to One Battery Question

Postby John61CT » Thu Jun 27, 2019 8:15 pm

No problem, any number of disparate charge sources can connect to one target bank.

Forget all those braying about them "confusing each other".

Ideally similar setpoints, but NP if not, all works out in the end.
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Re: Two Charge Controllers Connected to One Battery Question

Postby MtnDon » Thu Jun 27, 2019 8:45 pm

As John stated, no problem. Our 100% off grid home has one large battery bank, 4 charge controllers being fed by their own arrays of panels facing different directions. Everything works together well.
Our 6x12 deep vee nose cargo trailer camper conversion... viewtopic.php?f=42&t=58336

We have a small off grid cabin we built ourselves in the NM mountains; small PV solar system; 624 watts PV, Outback CC & inverter/charger ... http://countryplans.com/smf/index.php?topic=2335.0
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Re: Two Charge Controllers Connected to One Battery Question

Postby featherliteCT1 » Thu Jun 27, 2019 8:53 pm

Don, are you saying that you have a mix of PWM and MPPT controllers?
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