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si-mon asked

Help with Cerbo GX and 48v Lead Acid battery system,

Hi

I've just had my third Cerbo GX delivered today with a serial number starting in 2215, I have a 48V lead acid battery system therefore, the system sits at around 53V normally.

I connected my first Cerbo GX before the batteries were at full charge, and it all went fine, then I had to swap the positions on the distribution bar as the cable lengths on my new Multiplus II were a little messy.

After switching the positions, the Cerbo GX never switched back on. I found out from another post here that there is an issue, and a 100V 100uf capacitor is a workaround as there are issues with Cerbo GX switching on, on 48v systems for a batch of them.

My 2nd Cerbo GX arrived along with the correct make and model of the capacitor suggested in the application note, so I set around connecting it all up. The good news is that I am an electronics engineer therefore, this all seemed simple. Connected it all up on my bench with a bench PSU, including the capacitor, and it all worked fine at 48v, programed it all up, then connected it up to my system, and after switching it on, the Cerbo GX never worked again. reconnecting it to my bench PSU, showed it didn't take any current. So number 2 was dead, and the capacitor didn't fix the issue.

NOW my third Cerbo GX has arrived and is in the "bad batch again", what to do??

  • Connect it directly to my "48v" DC rail with the capacitor, which is Lead Acid batteries so is around 53v (same as last time)?
  • Use something like a buck DC-DC converter from 48v to 12v?
  • Return it to the Amazon seller and ask for one in the "good batch"?
  • GIve up on the Cerbo GX, use a PI, and either a DC-DC converter or AC power, and lose the ability to have extra temperature sensing using Victron sensors?
  • Rip out what I've done up to now with a separate MPPT, Multiplus II, 2x Shunt's (one for each 48V bank), and swap to an EasySolar II GX, (I assume this won't pop the GX when connecting to the Battery Bank) But I think the Easy Solar II only has one Driect port??


My plan was to use a 48V (30v-72v) to 12v DC to DC buck converter, an additional fuse, and a switch, but considering this thing should be spec'd for up to 70V DC, it seems poorly designed.

I really liked the way this was going and the build quality seems good with the equipment so far except for the Cerbo GX which just feels like the onboard PSU isn't up for the job.


Regards

Simon

cerbo gx
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2 Answers
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kevgermany answered ·

I'd drop the input voltage to 24V with a buck converter. But the capacitor should work. Getting the later revisions is likely to be difficult. I'm just about to face the same issues, mine will be running on 12V, but only because there's 12V there already.

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si-mon answered ·

Hi Keygermnay, I have a 12v WaveShare screen from an old Rasberry pi Project, so changing to 12v DC seems sensible so I can see whats going on.

I do feel that the Cerbo GX should be more robust for a controller/remote management system priced at around £300, this thing controls higher power systems. It should take the voltage it's specification suggests.

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kevgermany avatar image kevgermany ♦♦ commented ·
From the other posts on this:

It seems to be a bug that occurs under rare, specific circumstances. Victron seem to have acted quickly, publicising the problem and workaround and also will replace affected systems without issue.

Problems do occur, looks to me as a user (I don't work for them, but am biased) as if they've done their best to to rectify, not trying to cover it up. What would have happened with a cheap no name brand? You'd probably have to buy another after fighting with zero support from China, as happened to me with an Android head unit.

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si-mon avatar image si-mon kevgermany ♦♦ commented ·
I'm not sure I can 100% agree with the statement above. A bug usually occurs in firmware and can be fixed in firmware. This is a hardware issue, it's not in any of the manuals that I can find or as part of the downloads section of the product.

I've been lucky where the issue for me occurred in the first 30 days, so returned them under the DOA terms.

It looks like the fixed units still aren't in the channel, I've purchased 3 now, all within the "bad batch". The "fix" didn't work on the 2nd unit I bought, and now I have the 3rd I'm worried about plugging it in, without adding some extra hardware to "save" the Cerbo GX.

If we are going to suggest all cheap brands wouldn't give support, that's not something I could comment on and suggest that a general statement like that isn't appropriate, what I would say is that a cheap unit from china is likely to be less than a third of the cost of the Cerbo GX, so I'd expect it to be robust and fit for purpose.


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kevgermany avatar image kevgermany ♦♦ si-mon commented ·

The definitive statement is here:

https://community.victronenergy.com/storage/attachments/42304-2022-08-cerbo-gx-power-supply-issue-in-48v-systems.pdf

I assumed before that you'd read it. My bad. Sorry.


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