Re: Electrical Upgrade Project Reply #50 – April 09, 2025, 12:58:26 pm I don't have a complete wiring diagram, but the attached shows everything attached to the house side of things with the exception of the alternator and secondary shunt. That portion is relatively easy to describe.Also, the attached Victron/lithium schematic contains a generator, transfer switch and DC-DC charger. I have none of those, but the rest of the wiring matches my installation exactly.The dual alternator/secondary shunt wiring is very straightforward.Secondary Alternator Positive (B+ post) --> 2/0 AWG --> Lynx Positive busbarSecondary Alternator Negative (mounting bolt directly on alternator) --> 2/0 AWG --> Lynx Negative busbarWhen installing the secondary alternator shunt for testing, it is inserted between the 2/0 cable and the Lynx bus bars. When on the positive bus bar, the current is high in the Alternator box and doesn't match the Battery box in the Cerbo display. When the shunt is on the negative, the current values match.
Re: Electrical Upgrade Project Reply #51 – April 09, 2025, 04:56:08 pm Cannot read any printing on this image, but the battery shunt seems to be correctly wired. Since the alternator case is grounded to chassis as is the Lynx negative bussbar, its shunt could not be wired similarly, so I am not sure what you have done to accomplish that?Steve
Re: Electrical Upgrade Project Reply #52 – April 09, 2025, 05:51:03 pm Hi Steve; The body of the Alternator should be grounded to the chassis, but there shouldn't be any connection to current flow. Only the output wire negative should go to the buss bar. Similarly the bussbar serves as a common tie point but does not connect current flow to the chassis. A connection point at the common bussbar should go to the current shunt, and then the 'not hot' side of the shunt should be connected to the chassis. Other items grounded that connect to the chassis should be connected to the chassis closeby. Iron isn't that good of a conductor, only surviving as a current carrier because of a large quantity of iron. Ground loops because of slight but still there, differences in potential, between grounding points can cause issues. (usually just small measurement errors). I couldn't read the notations on the diagram. I went to the internet source and I couldn't read it either. They really didn't mention much about the alternator at all. RonB
Re: Electrical Upgrade Project Reply #53 – April 09, 2025, 06:41:28 pm Quote from: RonB - April 09, 2025, 05:51:03 pmSimilarly the bussbar serves as a common tie point but does not connect current flow to the chassis.Ron, it is hard to read, but the diagram clearly shows a black cable connected from the negative bussbar to "chassis". The bussbar is also connected to the "low" side of the battery shunt. The "high" side of the shunt is connected to the battery negative. This is as it should be. This means the alternator body (negative) is equi-potential to the bussbar negative. Any small voltage drop due to chassis conductive imperfections would simply result in an error reading. So, it is still a puzzle to me where the alternator shunt fits into the picture...Steve
Re: Electrical Upgrade Project Reply #54 – April 09, 2025, 11:57:24 pm Here's a wiring diagram that I believe shows all electrical connections.RE the alternator shunt - the diagram shows it in the current location, the alternator negative feed to the Lynx. This location is reporting current consistent with the SmartShunt. The original location for the alternator shunt that displayed significantly higher current was in the alternator positive feed to the Lynx. 1 Likes
Re: Electrical Upgrade Project Reply #55 – April 10, 2025, 01:58:16 am Will, is the alternator body attachment somehow isolated from ground? If not, then this hookup should not work. Else, in effect, you show both sides of the alternator shunt connected to chassis ground.Steve
Re: Electrical Upgrade Project Reply #56 – April 10, 2025, 11:49:13 am Quote from: Steve - April 10, 2025, 01:58:16 amWill, is the alternator body attachment somehow isolated from ground?No. I verified there was excellent continuity from the alternator case to chassis ground right after it was installed. Reason being - when I first saw the wiring diagram from Nations Alternator, they showed a dedicated negative cable going to the negative bus bar for the house side of things. Knowing I had run a short, 4/0 cable to the chassis frame from the Lynx distributor negative bus bar, and knowing the alternator case was grounded to the chassis - I was hoping to get away with a single 2/0 feed from the alternator positive back to the positive bus bar on the Lynx distributor. It should be clear by now there are gaps in my electrical knowledge, but my assumption was the alternator chassis would already be grounded to the Lynx negative bus bar via that new frame connection I put in. The 4/0 cable I installed to the chassis frame from the Lynx is very short (about 18"), and I sanded the connection point down to bare, shiny metal.However, Nations got back to me and said their recommendation was always to run a dedicated 2/0 cable from the alternator body (via one of the mounting bolts) directly to the Lynx negative bus bar. They prefer not to trust chassis ground, for whatever reason. So, that's what I did.Quote from: Steve - April 10, 2025, 01:58:16 am If not, then this hookup should not work. Else, in effect, you show both sides of the alternator shunt connected to chassis ground.Well...I don't know what to tell you Steve. I'm not a huge believer in magic. But, here's what's showing now with the shunt on the alternator negative. Everything is hooked up just as shown in the diagram I uploaded. More details on the new alternator shunt, not that I can see how it matters - but I disconnected the 2/0 negative cable coming from the alternator case bolt where it attaches on the Lynx negative bus bar. I connected it to the shunt on one side, then ran a short, 10" piece of 2/0 cable to the Lynx negative bus bar on the other side. The two current sensing wires from the Wakespeed are attached to either side of the shunt as shown in the diagram.Excuse the ugliness, this is a temporary testing setup. And, when current was showing way high - the same setup shown below was in place, only the shunt was in the alternator positive feed going to the Lynx.
Re: Electrical Upgrade Project Reply #57 – April 10, 2025, 12:46:19 pm Hi Steve and Will; In the olden days, particularly GM chassis, the Alternator case was the conductor to ground, hence the 'one cable (+) was possible. But that flexible woven link from the engine to the chassis had to conduct all of that current. That connection just isn't up to the high powered 'non engine' requirements today, especially considering the charging of house batteries and other auxiliary items like hydraulic levelers, winches, lighting and equipment not actually involved in running the engine itself. In more higher powered alternators the negative connection may not be related to ground even. The ground is still necessary for the voltage and current regulator to control rotor current and field strength. But the stator where the actual power is generated, needs it's own conductor. That cable properly should go to the shunt, that proceeds to chassis ground through the Lynx distribution box (4/0 cable). In the diagram, that voltage goes to the Wakespeed WS500 controller. That, I'm sure isn't that controllers only information about current. The smart shunt information goes to the Cerbo unit as expected for display. The Wakespeed controller also has a data input to the Cerbo. Will, your MB has similar equipment to Tim (T & F)'s rig, also a MB ('08). (no second alternator, and with S.O.K. batteries). He used aluminum Unistrut rails on his roof to mount 800 watts of solar, with provision for expansion to 1200W. Do you intend to expand your solar? RonB
Re: Electrical Upgrade Project Reply #58 – April 10, 2025, 04:07:00 pm So, the current from the alternator takes two parallel paths to the ground point the shunt is connected to - one path being through the chassis, the other through two lengths of 2/0 cable and the shunt. The cable has a resistance over 20' of less than 3/100 ohm, and the shunt probably 0.0001 ohm. The chassis path is probably 1/2 ohm or more. That means that over 99% of the current flow from the alternator passes through the cable and the shunt, yielding an accurate measurement. Just keep those connections tight!Steve
Re: Electrical Upgrade Project Reply #59 – April 10, 2025, 06:03:16 pm Quote from: Steve - April 10, 2025, 04:07:00 pmSo, the current from the alternator takes two parallel paths to the ground point the shunt is connected to - one path being through the chassis, the other through two lengths of 2/0 cable and the shunt. The cable has a resistance over 20' of less than 3/100 ohm, and the shunt probably 0.0001 ohm. The chassis path is probably 1/2 ohm or more. That means that over 99% of the current flow from the alternator passes through the cable and the shunt, yielding an accurate measurement. Just keep those connections tight!Chassis grounds have been known as electrical problem spots since the beginning of automotive electrical when some genius figured a car's metal frame could replace the ground wire in an electrical circuit. Today, cars are still wired this way, and they still have ground problems.Poor or multiple ground pathways are a reason why high-power radio gear and other voltage-sensitive devices suggest or require that each device have both positive and negative fused wires running directly to the battery's terminals or bus bars. Reducing induced electrical interference is another reason.Through the years, I have spent hundreds of hours chasing down electrical issues that were traced to poor grounds and/or multiple ground pathways.. Strange things happen when poor, multiple, or missing grounds are encountered.Steve's advice applies to all of us with an upgraded electrical system to often check the hardware securing the cables and periodically check for voltage drop over each cable when the system is under load, both when charging or discharging. It can be surprising to find an otherwise good-looking cable has a bad crimp and high resistance. In high amperage systems, a small amount of resistance can waste a lot of power and potentially burn things up.Larry
Re: Electrical Upgrade Project Reply #60 – April 10, 2025, 06:50:15 pm Quote from: RonB - April 10, 2025, 12:46:19 pmDo you intend to expand your solar?I'm on the fence, but am leaning that way. Currently I have 3x100W panels, wired in parallel.There's some agreement from those who know more than me that mixing and matching panels is not ideal. So, were I to bump to 500-600W I'd likely get all new panels just to be sure and repurpose the existing panels to another smaller installation. Panels aren't that expensive these days, and the additional labor would be minimal. I don't do panels - I'd farm that out on my next trip south through Oregon.I'm on the fence, as there's a school of thought that utilizes no solar, or very limited amounts. Rather, a substantial battery bank combined with direct and rapid charging from the alternator. This philosophy was shared with me by AM Solar when I did my recently sold van, and it worked very well - I had no solar on the van and never needed it. With 800AH of lithiums, that was typically plenty of power for 3-4 days - and our usage typically had us staying somewhere less than that, then driving several hours to the next stop. The batteries would easily top off during the drive.The difference between the van and the current installation was a shared alternator vs. dedicated auxilliary. The van charged via a Victron relay. Not quite as fast as what I have now, but we never needed more.With the setup I have now, should I find myself staying somewhere longer than a few days or the drive between stops is short - I can always let the engine idle for a couple hours to top things off adequately. However...adding 500-600W of solar isn't that expensive compared to what is in there now, and I've already installed the MPPT to handle that many panels. I'll probably do it, mostly for peace of mind.
Re: Electrical Upgrade Project Reply #61 – April 10, 2025, 10:55:28 pm "I can always let the engine idle for a couple hours to top things off adequately."That may not be the best idea, for a couple of reasons. First, alternators don't generally put out their full rated power at idle speed, so this can be a slow way to charge batteries. And second, my understanding has always been that it's not good for an engine to idle for hours at a time. (Auto mechanics, please correct me if I'm wrong.)
Re: Electrical Upgrade Project Reply #62 – April 11, 2025, 12:43:27 am There's plenty of debate on extended idling, but my research on the V10 in particular has me feeling quite comfortable with it. Other may feel differently.The alternator output issue though, is a non-issue in my case. Yes, standard alternators may not put out significant amps at idle. The Nations 280XP is designed for very high output at idle - check a few posts back for details. While the output varies depending on many factors (temp, battery SOC, etc.), I've seen it put out more amps at idle than my Multiplus does on shore power.
Topic: Electrical Upgrade Project (Read 3620 times)
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Topic: Electrical Upgrade Project (Read 3620 times)
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