tkmbe avatar image
tkmbe asked

Can I use Victron Smart 100/15 with other battery charger in parallel ?


I've just received my fist Victron MPPT charrger Victron Smart 100/15.

I've connected a Amerisolar 280W Panel and 2 car batteries 75Ah in seriel to get 24V.

This will be changed to a 340W Panel and 2 150ah 12V Trojan batteries in the near future...

I use this for my communication tower at home. I know the car batteries are not the optimum....

Before the MPPT charger I used a Mean Well 24V/6A charger with 28.V bulk and 26.8 fload Voltage (ENC 180).

Because the battery is not fully loaded over the day (at least today) with MPPT and I want the battery have normally full loaded my question:

Can I use in parallel my Mean Well charger putting to battery port, without damaging MPPT charger?

Or to I have to disable with sw the charger which is "only" for maintence?

If it will not damage the MPPT charger I could put an timer, so that in night battery would be charged my Mean Well and in the day by MPPT charger...

Any other idea?

Thanks a lot, I'm very new to the whole solar stuff....

battery charging
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3 Answers
JohnC avatar image
JohnC answered ·

Hi T. Yes you could do that. They can't hurt each other, as the only interaction they have is via Vbat.

The timer idea is fair enough, but if your batts are kept charged you may not want/need them doing an Absorb charge every day. Certainly not from both chargers.

Maybe set your Mean Well to a constant 'storage' V of (say) 26.4V, and your mppt to a little higher, maybe 27.0V. Even without a timer, and both together 24hrs, the MW will back off with sun as the Victron takes over.

Car batts would be suitable to do that with, and extract some life from them as you need.

Depends on your loads of course, as to where you go with the charge algorithm(s).

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tkmbe avatar image
tkmbe answered ·

Thanks a lot for the info. Will try this.

My load is about 1.5-1.7A at 24V i.e. 40W...

Now testing two days battery goes down over night to 24.32V i.e. 12.16V each battery so guess I have the battery 60% discharged, which is not very nice for a lead/acid I guess...

(I have read that state of charge is: 12.2V/50% and 12.0/25%, 11.9V/0%)

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JohnC avatar image JohnC ♦ commented ·

Yeh. Those V's you mention aren't too bad really, and if that 40W load was removed, maybe even bounce back a little.

Those 'calcs' can be a little rough too, and as batts age, etc. can be a guide, but not necessarily gospel. Nice if you could get a bit back into em each day, especially if you cycle.

Have a go, get a 'feel' for them. Never forget though that they are inherently evil devices, so treat accordingly. :)

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tkmbe avatar image
tkmbe answered ·

Some more questions:

If I connect Mean Well battery charger the Voltage will be min. 28.2V at battery but with MPPT Charger not?

MPPT charger will raise battery voltage from current level of battery slowly to absorption level...

Why is this? Is the MPPT chargers a current supply instead a voltage supply?

The battery voltage of my mean well is fix 28.4V names Vboost and Vfloat 26.8

Diagram of Mean Well charger

What should I set for absorption tension of MPPT ? 28.6V

In fact my Mean Well charger never reaches float state, don't know why...

meanwell.png (23.0 KiB)
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JohnC avatar image JohnC ♦ commented ·

Edited my first post for 24V equiv V's, sorry.

If your MW isn't configurable, that's a shame. If it's never reaching Float, maybe it's spending too much time in Abs? I'd be reluctant to do that, especially if you're not cycling the batts.

You could even consider setting it up on a $5 power-point-timer to charge in 'shots' for (say) 30min every 90 min to avoid Abs stage, or at least from spending too much time there. Maybe off in daylight hours.

Both chargers will simply attempt to reach their own V targets independently with the power each has available. The mppt will wind up slowly as the sun rises, just by virtue of the sun available.

That 'constant current' thing is much the same as what Victron call 'bulk'. Technically different, but your 100/20 may have an option aboard called 'battery safe', much the same..

With both running together becomes meaningless because each isn't really aware of the other, just the Vbat it's chasing. And the V rise will happen much faster with two running. Maybe too fast?

The Victron may arrive defaulted to 28.8 and 27.6V set. That would be typically ok for pb's, and if you see an 'adaptive' option, that's some smarts to check your batt history and fool with it's behavior.

Too hard from here to tell you exactly what to do. Try to learn what your batts want, however way you decide to treat them. And have a go meeting that need.

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