question

dubhdubh1 avatar image
dubhdubh1 asked

Victron SmartSolar MPPT 75/15 regularly changing batteries - can profiles be used?

I am using the controller with one 12V panel and several 12V batteries. The batteries are all solar system or camper dedicated lead-acid batteries, but they are different ages, makes and capacities so I can not connect them at the same time (right?). So I connect one, when it is full, disconnect it and connect the other - and so on. Can I do this and still benefit from the battery charging profile learning capabilities of the controller? Or can I save a profile for each battery and switch them manually? Do I need to do either?

MPPT Controllersbattery charging
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JohnC avatar image
JohnC answered ·

Hi Dubh. No, it won't remember charge history once disconnected from the batt. Some models may, but it's unimportant anyway.

Your mismatched collection could probably be safely charged all at once with a soft profile like say 14.0/13.5V. A smidgen slower to get em up to full, but safe enough.

Once the charge day is done, separate them. And don't discharge them together into a common load, that's a different animal.

Run your hand over em under charge. If you can detect a warmer one, it's likely a goner.

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dubhdubh1 avatar image dubhdubh1 commented ·

Hello JohnC, and thank you for the response! Well - I have all the time I'd ever need for the charging process. The location is used only on weekends and the system can charge the battery for the whole week. BUT - during the week I am not there or even close to check or disconnect the batteris - this is why I do not connect more than one. I'd consider trying the multiple batteries approach you suggested while I am there to monitor the lot, but I'd probably not like to mess with changing the profile every time for that.

I gathered the best compromise would be to connect just one battery and leave it for the week to charge. Then when I arrive there is a choice - if it is cloudy I'd leave the same battery and use the power from it, if sunny, I'd connect another and charge and use it at the same time.

What made me ask was the controller manual saying something like the controller evaluates the battery at first and then chooses the best parameters for charging. I thought that changing the battery would defeat the purpose of this function and so wondered whether the was a way to tell the controller that it has already seen and evaluated the battery currently connected - ie profiles. But you say that it is unimportant anyway. Is that because the evaluation is (for such a low end system) just a gimmick? Or because it happens so fast it can be done every time and I'd not lose any benefits? Or because for just one panel and one battery the difference is so small there's no point? Or all of the above? :)

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JohnC avatar image JohnC ♦ dubhdubh1 commented ·

Yeh, sometimes you gotta step back and ask if you really need all these features. The manual is really referring to a daily-cycler situation, and for a weekly 'maintenance' charge might be better set up at a much lower Float V. In that situation, just one batt connected at a time.

No reason you couldn't click on a more aggressive profile whilst you're onsite, but it won't remember what you did last weekend in terms of setting a charge programme, and nor should it.


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