Can you have 2 24v to 12v converters?

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Texas710
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Can you have 2 24v to 12v converters?

Post by Texas710 »

I had a 24 to 12v converter take a dump on me and I thought I might want to split the ignition (SSI) from the accessories (HAM/CB, a few lights etc).

I purchased an Eaton, sealed converter and have it wired up to the batteries/disconnect. This unit is solely for my 12v ignition needs. This is wired up and working well.

I also purchased a Victron converter but am having issues with where to get the 24v and ground. I am wanting to use this for the accessories but I seem to be getting, or creating, unwanted current paths which are not ideal.
The output on this converter feeds a fuse block, that then powers 2 radios, a few cabin lights and a couple gauges. I have not traces all wires in this system, but I know it runs my trucks RPM gauge and I am wondering if this tie in somehow is creating the problems. I don't think my 12v system is totally isolated from the 24v system, just not sure where it would connect, or be able to cause issues.


Is it possible to have 2 system running at the same time, or I am seriously over thinking the need to separate my two systems?

Thank you for any help or thoughts.
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rmel
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Re: Can you have 2 24v to 12v converters?

Post by rmel »

There is really no problem with multiple 12V sources derived from 24V.

Just don't have a sneak path connecting their Power outputs together, which
does not sound like your situation. Your Eaton source is direct to the Battery
and fused, powering the PinzSSI. Make sure Ground is common and robust
between these two power sources and all devices connected to each power
source are well grounded -- Chassis is your friend here. I would also suggest
connecting the Victron to the battery with it's own fuse. You could go direct
into the Battery box or use the 24V accessory plug behind the passengers seat.

Since you mentioned the RPM gauge, powered by the Victron -and- I presume you
are using the Tach output from the PinzSSI to drive that gauge. That is fine. The
Tach output is a signal into the gauge, with a very high input impedance -- no
worries here. I have my 712 configured exactly this way with a VDO Tach.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
Texas710
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Re: Can you have 2 24v to 12v converters?

Post by Texas710 »

Okay, so if I am hearing you correctly, I should be able to connect both converters to the same 24V source and ground (Say battery bank, fused of course) and they would work fine.


Having done that, and it not working, leads me to believe I need to dig a little more into how the 12v system is wired. This is the system I bought and it has worked fine with 1 converter in the past, I think a little more investigation is needed into the 12v wiring as it's not functioning as I would expect. I will definitely be looking at grounding points on the accessories and trying to find the issue.

Thanks!
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rmel
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Re: Can you have 2 24v to 12v converters?

Post by rmel »

Yes, correct. Two, even more converters should work just fine.
Which Victron model are you using? If the "Isolated" version BOTH
Negative terminals must go to Chassis ground.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
Texas710
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Re: Can you have 2 24v to 12v converters?

Post by Texas710 »

I believe its the Orion 24/12-25, no issue doing that but I was under the impression both grounds were internally connected.
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rmel
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Re: Can you have 2 24v to 12v converters?

Post by rmel »

For the non-isolating version YES, both "-" terminals are tied together internally.

But for the isolating version they are NOT. This then allows for a Negative output
and the "+" is chassis grounded. A somewhat rare application but there are times
when a negative voltage supply is needed.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

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Mr Zero
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Re: Can you have 2 24v to 12v converters?

Post by Mr Zero »

Texas710 wrote: Wed Oct 05, 2022 11:20 am...but I seem to be getting, or creating, unwanted current paths which are not ideal. ...somehow is creating the problems.
Can you further describe the unwanted current paths and problems that you're experiencing in the system? Are you running any 12V directly from battery? Let me throw out a scenario that I recently experienced while troubleshooting that caused me a bit of confusion until I got it sorted...

I also was running a Victron 12/24 converter and it failed. It's 12V out also fed a small fuse block. After the converter failure I went direct to the positive post of the truck's grounded battery to provide 12V to the fuse block. With the main battery switch OFF/disconnected I now had 12V in my 24V system, that should be 0V (as far as I could see at the time) with the main battery switch OFF. It took me a bit to realize that the 12V from the grounded battery to the fuse block was acting as ground (because fuse block) to the truck's second/positive battery when the main battery switch was OFF, allowing 12V current from the second battery in the 24V system. I don't know if that scenario is anything like you're experiencing, but maybe there is some similar weirdness there that may be of help in your troubleshooting.
Texas710
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Re: Can you have 2 24v to 12v converters?

Post by Texas710 »

Mr. Zero. I think we may have similar issues. My converter that run the ignition only has no problems. But once I hook up the second converter to the fuse block, I get problems. With the battery key off, there is power to my ignition switch, which is not normal. I am figuring there is some sort of shared wire in the dash between the 24v and 12v systems (possibly through a gauge?) and just have not traced everything back yet. At least that is the theory for now.

Curious what you did to sort the problem?
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rmel
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Re: Can you have 2 24v to 12v converters?

Post by rmel »

If your converters are connecting to the Top battery 24V, and NOT
the midpoint 12V, then with the Battery ground switch OPEN there
no possible way for any power to be present anywhere -UNLESS- your
Battery Ground Relay is stuck closed or power is getting to it from
a sneaky path then then when the Ground switch closes it "latches"
it ON. Power for that relay is sourced from the D+ output of the
Alternator -- and thus the engine stays running when the Ground
switch is opened.

Mr Zero's problem, as I understand it, was tapping power off the
mid-point 12V, thus creating a leakage path to ground for the top
battery.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712MK

Driver: Ron // KO0Q
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