Victron DC-DC charger questions

[AJMike]

I just bought the Victron 12/12/30 Isolated Victron DC-DC charger to use to charge the 2 BattleBorn batteries in our Fuse. It will be replacing the Renogy DC-DC charger which has been an issue since I bought it 6 months ago. If anyone has this charger, or the non-isolated which I assume is mostly the same, I have a couple of questions about its installation.

The instructions for the charger say that it should be fused with a 60 amp fuse, but I don't understand why they would recommend such a high amp fuse when the charger is only 30 amps. The Renogy 20 amp charger recommended the input be fused at 30 amps and the output at 25 amps, which makes sense to me, but Victron is suggesting 60 amps for both the input and the output. Why?

The second question has to do with the automatic on/off switch. Victron says that it can sense the increase in the voltage of the starter battery when the engine starts and use that to turn on the charger, but it also says that this may not work if the voltage drop is too large due to a long wiring distance from the starter battery to the charger. Does this work for those who have installed it? Or did you need to run an auxiliary wire from the ignition to the charger to turn it on?

Thanks for any help here.

[Morich]

On theory, it sounds like quite easy for the increase in voltage to be sensed and I would not expect a reasonable length like an RV to have enough voltage drop to cause problems.
At float a battery will be in the range of 12.5 or so and when the engine alternator start, that will often be a around 14 volts. So to cause trouble on sensing the wiring would have to lose in the range of 1.5 volts and that is either way small wire or way longer than we get in RV.
On the fuse size, I could only guess that it would be to cover for any inrush on starting, possibly to fully charge a big set of capacitors?
But do know this is theory and not backed by user experience. I would have to go with their recommendations as I certainly do not know much about what peaks of current they might be expecting. One would have to get way deep into the design part to figure the why of that one. Possibly as simple as some want to engineer much more conservative and avoid any possible complaints on fuses blowing?
I have run across times when things have been down due to a 2 amp fuse when a 5 amp would have been just as safe and I have wondered just who decided to cut it so close as the difference in 2 and 5 amp as either one was not going to heat the wire enough to cause a fire but a 2 would blow every thunderstorm!
Just one of those middle of the night callouts that leave you shaking your head!

[BobC]

I'm curious as to what problems you had with the Renogy. I just installed the 20A Renogy.

[AJMike]

Originally Posted by BobC

I'm curious as to what problems you had with the Renogy. I just installed the 20A Renogy.

This is a bit of a long story and it has been going on since I first bought the 40 amp charger last April and has still not been resolved.

1) Ordered the charger through Amazon last April and had it installed by a recommended professional. He used 4 gauge wire, as recommended in the installation instructions and fused it at 60 amps input and 50 amps output as recommended.

2) The unit started to fail very quickly with the current dropping from 40 amps back to 0 and then back to 40 amps. When I did a long time check using the Victron battery monitor I found that the up and down spikes were very regular and decided that it might just be running too hot. There is a built-in fan but perhaps it was not doing its job properly. See the screen shot at the end of this post.

3) I contacted Renogy support and sent them the screen shot of the current output from the Victron smart app but I might as well have been talking to the wall. They told me that they had no idea what that was, and that turned out to be an interesting comment considering what they told me later.

4) I moved the charger to another compartment and installed a cooling fan. I should not have had to do that because of the built-in fan, but I figured that I was already deep enough into it to spend some more time. That stopped the up and down spikes, but now the unit output began to become very jagged and constantly decreasing. The current display on the Victron. smart app started at 40 amps, then dropped slowly to 35 amps, then 30 amps, then 25 amps, all the time that the solar was increasing, which implied that the charger output was even lower since the current display should have been the combination of both.

5) Contacted Renogy support again, and again got no help although someone said that perhaps the unit was over heating. I don't see how that is possible since the fan output was directly on the unit and it felt just fine, but still. Renogy support said that they would send me a shipping label. This was now 3 months after my first contact, but I figured later is better than never and there is a 12 month warranty.

6) Finally the unit quit completely. It would not do anything. I had been waiting for the shipping label but after 2 months it still had not arrived so I contacted them again. This time they immediately sent the shipping label and I returned it to them yesterday and will see what, if anything, they find.

We were heading out on a trip and I knew I was going to need a new charger and I tried to buy a Victron, but could not find any so I ended up buying the Renogy 20 amp as a stop-gap measure. It was relatively inexpensive and I needed something until I could get a better charger and I guess hope is stronger than experience ...

Just as we started on our last trip I found an available Victron 3 amp charger and committed to ordering it since I did not expect much from the Renogy 20 amp. However the 20 amp charger has worked properly ever since I got it. It produces 20 amps regularly, it is steady at 20 amps and there is no frequent down and up changes and as the solar picks up I can see it added to the 20 amp output. Started at 20 amps, then 25, then 30 and so on as the solar added output. This is how I expected the 40 amp model to work, but it did not; however the 20 amp charger is doing just fine and I am not sure I need the Victron charger.

A comment. The people at Renogy support seem anxious to help and one person has been very helpful, but they do seem at times to be disorganized and perhaps there is poor communication between different parts of support. There was one period when I did not hear back from them for 3 weeks and then the 2 month wait, but now they seem to be better organized. I will see what happens when the 40 amp charger arrives and is examined.

Hope this helps.

[AJMike]

Originally Posted by Morich

On theory, it sounds like quite easy for the increase in voltage to be sensed and I would not expect a reasonable length like an RV to have enough voltage drop to cause problems.

The idea of how it should work seems perfectly reasonable. The alternator produces an increase in voltage and so that should be reflected at the charger and be noticeable. Added to that, I suppose, is the fact that cranking the starter should further drop the starter battery voltage and make the increase when the alternator starts even more noticeable. I was just curious as to whether anyone had experience with the Victron charger actually doing what seemed so logical in theory.

Originally Posted by Morich

On the fuse size, I could only guess that it would be to cover for any inrush on starting, possibly to fully charge a big set of capacitors?
But do know this is theory and not backed by user experience. I would have to go with their recommendations

I suppose so. It just seems odd to be putting a 60 amp fuse on an output line that is not supposed to carry more than 30 amps. I would feel better about this if there was some way to question the Victron techs, but there does not seem to be any way to contact them to ask as there is with BattleBorn or Zamp. If I install the Victron charger I will follow their recommendations, but I can't help but feel that it is a bit dangerous.

It would be nice to have some digital device I could hook into the output to measure what the line was actually carrying and store that information so I could see it after driving but I don't have anything like that and buying it would probably be too expensive. Still, it would be nice to know.

[Winterbagoal]

Just a curiosity question...
If the Renogy 20A charger seems to be doing the job, why are you replacing it with the Victron 12/12/30 unit? Couldn't you just sell the Victron unit on Craigslist or eBay? Or, is it trying to match component brands, which I sort of get. You have a Victron fuel gauge or something?

[AJMike]

Originally Posted by Winterbagoal

Just a curiosity question...
If the Renogy 20A charger seems to be doing the job, why are you replacing it with the Victron 12/12/30 unit? Couldn't you just sell the Victron unit on Craigslist or eBay? Or, is it trying to match component brands, which I sort of get. You have a Victron fuel gauge or something?

I have a Victron Battery Monitor, but that is not the reason.

I ordered the 20 amp Renogy charger some time ago when I realized that the 40 amp charger was not going to work and I was never going to hear back from Renogy support about warranty work, and installed it for our trip to South Padre Island some weeks ago. However since it was really hot we ended up using regular campsites with electricity for the entire trip and I did not use the Renogy charger at all. In fact it was turned off for the entire trip.

I was told that the Victron charger was available just as we were leaving for our latest trip (for which we needed a charger) and, assuming that the 20 amp Renogy charger was going to work as poorly as the 40 amp, I ordered it. However on the trip we found that the 20 amp charger was working perfectly and as long as it kept working that well I was not going to need the Victron charger after all. It was delivered when we returned and now I have to figure out what to do with it. I can probably return it since it has not been used, or I can swap out the Rengoy 20 amp for the Victron 30 amp. Or I can sell it as a used but like new charger. I just have to figure out what is best.

I thought about advertising it on the For Sale part of this forum but that seems like a lot of trouble. Returning it would probably be easiest although it was not ordered through Amazon and thus I am not sure of the return policy of the selling company.

I tried to plan ahead, assuming I was going to have to replace the Renogy 20 amp so I might as well order the Victron 30 amp, and now I have ended up with both. On top of that I also assumed that I would never hear back from Renogy support about the 40 amp model that was not working (it had been 2 months since I last heard from them) and now that has been sent in for repair so I might end up with 3 chargers.

I was told as a Cub Scout to be prepared, but this seems a bit overkill in the "be prepared" department.

[Winterbagoal]

Originally Posted by AJMike

I have a Victron Battery Monitor, but that is not the reason.

I ordered the 20 amp Renogy charger some time ago when I realized that the 40 amp charger was not going to work and I was never going to hear back from Renogy support about warranty work, and installed it for our trip to South Padre Island some weeks ago. However since it was really hot we ended up using regular campsites with electricity for the entire trip and I did not use the Renogy charger at all. In fact it was turned off for the entire trip.

I was told that the Victron charger was available just as we were leaving for our latest trip (for which we needed a charger) and, assuming that the 20 amp Renogy charger was going to work as poorly as the 40 amp, I ordered it. However on the trip we found that the 20 amp charger was working perfectly and as long as it kept working that well I was not going to need the Victron charger after all. It was delivered when we returned and now I have to figure out what to do with it. I can probably return it since it has not been used, or I can swap out the Rengoy 20 amp for the Victron 30 amp. Or I can sell it as a used but like new charger. I just have to figure out what is best.

I thought about advertising it on the For Sale part of this forum but that seems like a lot of trouble. Returning it would probably be easiest although it was not ordered through Amazon and thus I am not sure of the return policy of the selling company.

I tried to plan ahead, assuming I was going to have to replace the Renogy 20 amp so I might as well order the Victron 30 amp, and now I have ended up with both. On top of that I also assumed that I would never hear back from Renogy support about the 40 amp model that was not working (it had been 2 months since I last heard from them) and now that has been sent in for repair so I might end up with 3 chargers.

I was told as a Cub Scout to be prepared, but this seems a bit overkill in the "be prepared" department.

Got kids? Grand kids? You should print off all the related posts and threads from here, and put together a "How To" (or Not To?) book on "Fun with Lithium Batteries, Solar Charging, Electronics Add Ons, and Other Tales of Mystery and Imagination".
It might make the Best Seller list somewhere (maybe on here?).
Name dropper. South Padre Island. So near, and yet, so far for us.....
Good luck with it, sounds like there's light at the tunnel's end.

[Morich]

So the bigger question might be? Did you get over to the "spaceport" down by Brownsville while in the area. We think it interesting to see how much high tech is going on and being right next to folks who do not have full blown running water if they don't haul it home on a truck!
Texas politics is always an eyeopener when we look very close. Who would have thought a guy could blow into town, buy up most of the houses and then shut down the whole area including a state park on the days they want to test spaceships????
But I know I'm confused because I thought rocket science was a high security thing that required very precise technical work. We didn't see much of either!

[AJMike]

Originally Posted by Morich

Did you get over to the "spaceport" down by Brownsville while in the area.

No. I did not see anything about that until I saw your post. I did look it up on Google and guess it is the SpaceX site. That is a bit puzzling because I thought that was somewhere in the middle of Nowhere, New Mexico, not too far off of I-25 from Las Cruces to Albuquerque.

We are heading back down there again in a week or so and it sounds like it would be interesting to see.