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hhaley avatar image
hhaley asked

Maximum battery charging current of a SmartSolar 100/50 charge controller

What is the maximum battery charging current that I can expect from a SmartSolar 100/50 charge controller?


I very recently installed this charge controller and placed a 50A circuit breaker between the charge controller and the battery bank.

I'm discovering that my 50A circuit breaker is tripping between 11AM and 1 PM now that the sun is getting higher in the sky. When I check the state of the charge controller, I am getting over 550W of solar production and the current is around 45A. So far I have never seen a current reading over 45A.

I'm thinking my circuit breaker amperage rating is too low.

The wire size from the charge controller through the circuit breaker to the battery bank buss bar is 6AWG. 6 gauge was chosen because it was the maximum wire size specified in the Victron user manual.

All the battery cables within the battery bank and smartshunt are 2 gauge.

The maximum current specified for a 6 gauge wire is specified to be 72Amp.

I'm thinking about using a 60A fuse but would like to know what is the maximum current the smartsolar 100/50 controller can provide before making a final decision.

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3 Answers
seb71 avatar image
seb71 answered ·

Maximum 50A to the battery (if you have enough PV panels). It's in the name (100/50).

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hhaley avatar image hhaley commented ·

What you stated is also what I thought and is the reason I went with the 50A breaker. However, my charge controller is definitely tripping the 50A circuit breaker.

The Victron spec for the 100/50, states maximum charge current is 60A.

In searching this forum for similar questions, I found information that the maximum circuit breaker rating should be 150% of 50A rating or 75A providing wiring can handle current

I’m going to go with a 70A breaker because I’m using 16 awg wire that is rated for 72A and it’s close to the 75A maximum.

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seb71 avatar image seb71 hhaley commented ·

The breaker/fuse should be rated for some higher current than the current you normally have. It also depends on how the wires are placed (in conduits or in air), environment temperature, etc. And the wire should be rated for higher current than the breaker/fuse.

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seb71 avatar image seb71 hhaley commented ·

Another thing to consider:


Can your battery handle 50A charging current?

If not, you can limit the charging current from the solar charger settings to a value lower than its maximum 50A.

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klim8skeptic avatar image klim8skeptic ♦ hhaley commented ·

The Victron spec for the 100/50, states maximum charge current is 60A.

Rated charge current is 50a.

mppt-100-50.png

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mppt-100-50.png (116.7 KiB)
offroadflow avatar image offroadflow klim8skeptic ♦ commented ·

You confuse "rated current" with "Max PV short current".

Plus it does not answer the actual question about the breaker issue... :)

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klim8skeptic avatar image klim8skeptic ♦ offroadflow commented ·

The heading of the post reads "Maximum battery charging current of a SmartSolar 100/50 charge controller"

Pretty sure the answer to the post is 50a.

OP seems to have worked out that the breaker should be proportioned to protect the output wiring.

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offroadflow avatar image
offroadflow answered ·

Depending on the type of breaker a 50A is too small.

As an example: Victron specifies to use a 120-150A breaker for a 100A controller...

Leave some headroom since the controller is limiting the max charge current anyway.

Cooling the breaker with a fan might help too, but is rather unprofessional.

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alan avatar image
alan answered ·

What sort of breaker is it? if its one of the thermal only ones, like this https://www.bluesea.com/products/category/14/32/Circuit_Breakers/285-Series?Mounting=Surface_Mount, then its bound to be problematic near its rated current. Especially if its not a brand name unit.

You should really be looking at a Magnetic hydraulic unit

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hhaley avatar image hhaley commented ·

Thanks Alan, You are correct. I was using one of the cheaper audio circuit breakers that I bought on Amazon for around $12 or so. Last night, I bought the a 70A from the same manufacturer in your link.

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alan avatar image alan hhaley commented ·

Hmm, I would have bought a Magnetic Hydraulic type. But the bluesea Thermal ones will at least be of higher quality but it will still be thermal only.
It may still be soon enough to cancel, if you can I would.

I only linked that so you could see the type I was talking about.

I would only buy something like this, https://sbpe.com.au/products/beny-battery-breaker-80a?variant=31698984337450&utm_medium=cpc&utm_source=google&utm_campaign=Google%20Shopping&utm_term=&utm_campaign=Victron&utm_source=adwords&utm_medium=ppc&hsa_acc=5005704043&hsa_cam=11092236948&hsa_grp=111479144569&hsa_ad=463396354207&hsa_src=g&hsa_tgt=pla-950619218531&hsa_kw=&hsa_mt=&hsa_net=adwords&hsa_ver=3&gclid=Cj0KCQiAgomBBhDXARIsAFNyUqPZCkso_8WTxkU3F5-vBlifoswSxjKkZXWOZceQqUBY3qUB-EYNmnQaAp4FEALw_wcB

or this

https://www.bluesea.com/products/7583/C-Series_Raised_Rocker_Circuit_Breaker_-_Double_Pole_80A_AC


I have looked at systems that had 200A cheap thermal units that were breaking In our hot climate on the back side of a wall that gets the afternoon sun. The units were tripping at about 30A and couldn’t handle anything.


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offroadflow avatar image offroadflow alan commented ·

Just put a 70A fuse in line and forget about it.

They will never trip anyways in normal day to day life...

Less is more folks! ;)

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seb71 avatar image seb71 hhaley commented ·

Good quality DC circuit breakers are expensive.

Fuses are safe and relatively cheap.

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alan avatar image alan seb71 commented ·

Well they have come down a lot, the 80A zjbenny is $120 AUD.

This noark 100A is about the same.

https://www.tro-pacific.com/collections/dc-circuit-protection/products/100a-2p-dc-mccb-9md1b-tm-noark


A fuse holder from victron RRP AUD is $15-20 and a pack of fuses is $19-25. And 48V fuses are $50 each so it can make a lot of sense.

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seb71 avatar image seb71 alan commented ·

I am using HRC fuses type NH (size 000/00C and 00). Big, but not that expensive.

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alan avatar image alan seb71 commented ·

They are still about $10-20 (granted for a pack of 3) and a disconnect holder is about the price of the breaker.

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seb71 avatar image seb71 alan commented ·

I got a NH fuse extractor for 6-7 euro.

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alan avatar image alan seb71 commented ·

I was talking about a Disconnect like one of these.

https://www.swe-check.com.au/product/oez-3-pole-disconnect-switches-for-nh-fuses

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