# DC/DC converter not charging



## Joker1 (Jul 5, 2015)

I have an Mean Well SP-480-12 DC/DC converter that is not charging my 12v battery even though LED lights up but their is no charging voltage. When I hook up the positive terminal of battery #1 and the negative terminal of battery #45 to the DC/DC converter corresponding terminal I get 13.5v coming out of the converter so is must work right. I run the converter through a contactor, the positive terminal of the contactor is connected the "L" terminal on the DC/DC converter, and the negative terminal on the contactor is connected to the "N" terminal of the DC/DC converter, this was done to control when the converter comes on and the LED comes on there but when I check the voltage at the terminals is doesn't have 144v on the input side like it should have and only 12v off the 12v battery on the output side.


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## Moltenmetal (Mar 20, 2014)

Sounds like you have the contactor wired wrong.

If you can post pics and other details of the contactor maybe we can help you.

Make sure any contactor you use to turn off the supply side of your DC/DC is rated for DC and capable of handling your full battery DC voltage- relays with AC contacts often cannot stop a DC arc even if the current of the DC load is small.


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## alvin (Jul 26, 2008)

I also used a contactor on the output , because without it the dc /dc would drain the battery to be charged.


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## Joker1 (Jul 5, 2015)

Moltenmetal said:


> Sounds like you have the contactor wired wrong.
> 
> If you can post pics and other details of the contactor maybe we can help you.
> 
> Make sure any contactor you use to turn off the supply side of your DC/DC is rated for DC and capable of handling your full battery DC voltage- relays with AC contacts often cannot stop a DC arc even if the current of the DC load is small.


I will take some pictures tomorrow, and get all the information I can on the contactor for you. I'm 95% done with the build and to knowledge the only two problems I have is the DC/DC convertor and the Solton Jr. controller keeps turning off and on when I draw about 300amps on my first road test.


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## pathrunner (Aug 30, 2016)

Joker1 said:


> I will take some pictures tomorrow, and get all the information I can on the contactor for you. I'm 95% done with the build and to knowledge the only two problems I have is the DC/DC convertor and the Solton Jr. controller keeps turning off and on when I draw about 300amps on my first road test.


Looking forward to the pictures. Any kind of fuzes or breakers tripping?


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## Joker1 (Jul 5, 2015)

pathrunner said:


> Looking forward to the pictures. Any kind of fuzes or breakers tripping?


As a matter of fact there was a fuse blown, but it after replacing the fuse it the DC/DC convertor still is not working.


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## pathrunner (Aug 30, 2016)

Possible then that you burned something else before the fuze went out. Sounds like it's time to grab a meter and start checking.


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## Joker1 (Jul 5, 2015)

Joker1 said:


> I have an Mean Well SP-480-12 DC/DC converter that is not charging my 12v battery even though LED lights up but their is no charging voltage. When I hook up the positive terminal of battery #1 and the negative terminal of battery #45 to the DC/DC converter corresponding terminal I get 13.5v coming out of the converter so is must work right. I run the converter through a contactor, the positive terminal of the contactor is connected the "L" terminal on the DC/DC converter, and the negative terminal on the contactor is connected to the "N" terminal of the DC/DC converter, this was done to control when the converter comes on and the LED comes on there but when I check the voltage at the terminals is doesn't have 144v on the input side like it should have and only 12v off the 12v battery on the output side.


To help everyone understand my problem I have taken some pictures of my wiring but I don't think I am much of a photographer so I am including a schematic of the wiring as well


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## Moltenmetal (Mar 20, 2014)

Take a look at the attached sketch- this is how I suspect you actually want to wire the DC/DC converter's input. Your schematic doesn't show a fuse in your high voltage DC system anywhere (which you should have, generally somewhere in the middle of the pack). I think you have a fuse in your DC/DC converter input line, which is a good idea (I didn't show it in my sketch).

Your low voltage side looks fine, though I'm not sure what the "relay" is doing or how it's wired since you just show it as a box.

Your high voltage side right now appears to have the DC/DC input wired in parallel to the contacts of the main contactor. When the contactor is energized and its contacts are closed, the DC/DC converter input is shorted out so it can't operate. When the contactor is de-energized and its contacts are open, the DC/DC converter is in series with the Soliton. That's not right- and likely not good for the Soliton. 

I don't know anything about the Soliton- its requirement for precharge, where it gets its KSI voltage etc., so can't comment on whether or not you have that wired right.

My DC/DC is actually wired so its input is always on unless I pull the fuse. That way, my 12V battery is always held at 13.5V, which means I don't have to pull my battery in winter and put it on a battery maintainer when my car is in storage. Instead, I just charge my HV pack a little about once a month in the winter to keep it at around 50% SOC where Li ion batteries like to be stored.


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## Joker1 (Jul 5, 2015)

Moltenmetal said:


> View attachment 67633
> 
> 
> Take a look at the attached sketch- this is how I suspect you actually want to wire the DC/DC converter's input. Your schematic doesn't show a fuse in your high voltage DC system anywhere (which you should have, generally somewhere in the middle of the pack). I think you have a fuse in your DC/DC converter input line, which is a good idea (I didn't show it in my sketch).
> ...


 I do have a fuse in between the battery packs I just omitted it by accident my fault (and I tried so hard to get it diagram right). I studied your sketch and read your explanation three or four times. Here is what I get from all this, but mostly from your sketch (I am trying to make this fix as simple as possible for me so as not to have to pull out a lot of wiring and maybe just reroute some wires) on my sketch I have the (+) positive terminal of the contactor going to the (N) terminal of the DC/DC converter, if I disconnect the wire (in this case blue wire) from the (+) positive terminal of the contactor and connect it to the (-) negative terminal of the contactor and run to the N terminal (which it is right now) of the DC/DC converter that will fix one leg of the circuit right? Now this is where I get a little fuzzy, because again I am trying not to make it overly complicated to rewire, would it be all right to come off the front side of the shunt in other words the side that is coming from the last battery (-) negative post and go to the L terminal of the DC/DC converter or do I need to be in between the shunt and the Soliton controller? Once again I do appreciate all your time and help in resolving this problem thanks.


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## Moltenmetal (Mar 20, 2014)

> I have the (+) positive terminal of the contactor going to the (N) terminal of the DC/DC converter, if I disconnect the wire (in this case blue wire) from the (+) positive terminal of the contactor and connect it to the (-) negative terminal of the contactor and run to the N terminal (which it is right now) of the DC/DC converter that will fix one leg of the circuit right?


Right.



> Now this is where I get a little fuzzy, because again I am trying not to make it overly complicated to rewire, would it be all right to come off the front side of the shunt in other words the side that is coming from the last battery (-) negative post and go to the L terminal of the DC/DC converter or do I need to be in between the shunt and the Soliton controller? Once again I do appreciate all your time and help in resolving this problem thanks.


If you are using an amp-hour meter, you need to tie your L terminal to the side of your shunt which is connected to the Soliton, i.e. the + terminal of the shunt. That's what my wiring diagram shows. You should use that terminal as the B- connection for all loads coming off your high voltage pack, so the shunt measures the total current running back to the battery B-.

If you connect directly to the - terminal of your battery (or the - terminal of your shunt, which is the same thing), your shunt and hence your Ah meter will miss the current drawn by the DC/DC converter. You will think your battery pack has more Ah left in it than it actually has- that can get you into trouble.

It's not very hard to buy a ring terminal, crimp it onto your wire headed to the L terminal of the DC/DC converter, and put it on the + side post of your shunt. Just make sure that the big wire going between the shunt and the Soliton is on the bottom of that stack, and the low current ring terminal going to your DC/DC is on top.

Make sure you put a fuse in the line running from your - terminal of your contactor to the N terminal on the DC/DC. In fact, it's good practice to put fuses in both wires headed to the DC/DC input, though not absolutely necessary (I didn't). And make sure those fuses are good for high voltage- don't use modern spade-type automotive fuses for any connection to your high voltage battery pack, irrespective of current, as the gap in the automotive fuse may not be wide enough to stop a high voltage DC arc. Glass fuses are fine.


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## Joker1 (Jul 5, 2015)

Moltenmetal said:


> Right.
> 
> 
> If you are using an amp-hour meter, you need to tie your L terminal to the side of your shunt which is connected to the Soliton, i.e. the + terminal of the shunt. That's what my wiring diagram shows. You should use that terminal as the B- connection for all loads coming off your high voltage pack, so the shunt measures the total current running back to the battery B-.
> ...


 I did exactly as you instructed me to do and it worked perfectly the DC/DC converter is putting out 13.5v as it should. I already had an in line fuse (the kind you suggested) from the contactor to the “N” terminal of the DC/DC converter so it only took me about half hour or so to rewire my screw up. I think you’re a genius and can’t thank you enough for all your invaluable help I couldn’t have fixed it without your help. I test drove the truck as soon as I was done with the rewiring in hopes that would also fix the Soliton Jr. controller, but no luck it still shuts down when I draw around 300amps then comes right back on that is the last problem I have to resolve. Thanks again


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## Moltenmetal (Mar 20, 2014)

Glad to help- I got a lot of help here so I'm happy to give back. Your DC/DC circuit was simple enough that even I could figure it out...Sorry I can't help with the Soliton Jr. as I have no experience with them at all. Hopefully someone else will chime in and walk you through the diagnosis. Has whoever you bought it from tried to help yet?


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## Joker1 (Jul 5, 2015)

Moltenmetal said:


> Glad to help- I got a lot of help here so I'm happy to give back. Your DC/DC circuit was simple enough that even I could figure it out...Sorry I can't help with the Soliton Jr. as I have no experience with them at all. Hopefully someone else will chime in and walk you through the diagnosis. Has whoever you bought it from tried to help yet?


I really am very grateful for all your help. I have talked to the manufacturer of the Soliton Jr. about a week ago and have not heard back from him yet hopefully he can come up with something. The guy I bought it from has been no help what so ever the whole build.


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## Moltenmetal (Mar 20, 2014)

No problem at all- happy to help.

Suggest you post a new thread with your Soliton problem under motors and controllers. Lay out exactly what problem you're experiencing, and make sure to give them all the info they need: battery configuration and size (looks like you have 45 LiFe cells in series), motor type and size etc.


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## Joker1 (Jul 5, 2015)

Moltenmetal said:


> No problem at all- happy to help.
> 
> Suggest you post a new thread with your Soliton problem under motors and controllers. Lay out exactly what problem you're experiencing, and make sure to give them all the info they need: battery configuration and size (looks like you have 45 LiFe cells in series), motor type and size etc.


I will do that right now thanks for the advice.


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