DerpsyDoodler
Solar Addict
- Joined
- Jan 10, 2021
- Messages
- 2,247
yeah, that’s how I have it installed...the current reading on my chargery BMS is flaky and all over the place. jason told me its because the shunt has to be installed on the positive side. when i swap the BMS with my other one, the current doesnt jump around. it’s a problem with the BMS and i feel like he’s trying to avoid taking care of it.The Shunt is ALWAYS on the Negative Side.
does it seem absurd to you that jason says the shunt should be on the positive side of the curcuit for the bms16?The readings were quite "bouncy" and firmware fixes were added to address that to a point. Then using Batt Terminal Lugs to power the BMS as opposed to using the lead harness also improved that (note the power adapter with filter) that came out of that. Of course the DCC with ISO board made the other difference to address issues.
Now I was using Deltec 500A/50mv shunts so I had to calibrate those (I have a box of them) and I quickly learned that the connections (wires etc) have to be extremely good as in "perfect" so cleaning & scrubbing and making sure it's bang on to make it work right... and they did BUT twas a PITA to recalibrate every time I flashed the firmware. So I switched over to the latest 300A/75mv Shunt offered by Chargery (with the base etc) so I don't have to futs with it... Geez those 500A shunts weren't cheap, $ lesson learned. BUT another lesson learned, you really have to clean the contact points GOOD ! I dunno what kind of oil or wax or whatever is on them but man what a PITA and it does throw the reading out by a bit...
Now I use the BMS8T-300's (two versions of it) and so have not suffered some quirks BUT to be honest when all of that circus was going and the complainers were at full throttle, it turned out that about 75% of the problems were user to component errors... NOT reading the manuals/docs, making assumptions and doing whatever "because they were smarter than the engineers who designed it" and worst of all was not frickin cleaning the contact points properly and then blaming.
Hence why I unwatched all those threads and stepped back from it all because there is only so much nonsense that I am willing to handle and I refuse to be the target for people who cannot RTFM or use common sense that they should have. I tried to help people & the company to improve their products to all of our benefits and I get accused and attacked (those posts were deleted) with all sorts of crud so tough nuggets, I help with some thig ONLY if the mood strikes me now. Im no fricken Commie or Agent for any company or org, none of that malarkey.
How many times does someone have to get their hands burnt before they just walk away from it ?
Rule of 3 applied, never ever more than 3 times. Applies across the board as a Sanity Safety Protocol.
Also works amazingly well for raising children (says the dad of 5).
Humans use the Rule of 3 all the time without realizing it and sadly not realizing the power t has when used properly & effectively.
3 strikes, your out, do it in triplicate, 3rd time is a charm... ad infinitum.
I tend to think the same way. Shunt on the positive side just hurts my head. However, the Thornwave Labs Powermon-5s shunt (somewhat of a competitor to the Victron Smart Shunt) has to be put on the positive side.I know some do it and it works, apparently, it's not supposed to be a problem. But my Geezerhood is flashing as I was always taught to shunt on NEG only. One reason, a shunt is a huge "open contact point" and a Hot Shunt - well, you know.... could make baked human quickly !
can anyone explain this? all a shunt does is provide resistance to measure for a voltage drop. 2 sense leads one on each side, to measure voltage at those 2 points and compare. what difference does it make? is it a firmware difference? measuring from 0 volts as opposed to measuring from battery voltage?I tend to think the same way. Shunt on the positive side just hurts my head. However, the Thornwave Labs Powermon-5s shunt (somewhat of a competitor to the Victron Smart Shunt) has to be put on the positive side.
Did you read my entire post? i thought my understanding of how a shunt operates was clear with my explanation, “a shunt measures voltage drop.”How is current measured using shunts?
The use of shunts for measuring current is a simpler and more cost-effective alternative to the use of sensors for current measurement. However, they are precision measuring devices, and a few things need to be considered to achieve measurements of the necessary precision.www.rutronik.com
For a regular dumb shunt, it really could be on either the positive side or the negative side. The standard is to put it on the negative side, primarily because many systems may have lots of paths out from the battery, but a common ground back to the battery. Think for example about a car. Most of us old timers only knew of shunts on the negative side.can anyone explain this? all a shunt does is provide resistance to measure for a voltage drop. 2 sense leads one on each side, to measure voltage at those 2 points and compare. what difference does it make? is it a firmware difference? measuring from 0 volts as opposed to measuring from battery voltage?
Right. These aren’t smart shunts. regular old dumb shunts.For a regular dumb shunt, it really could be on either the positive side or the negative side. The standard is to put it on the negative side, primarily because many systems may have lots of paths out from the battery, but a common ground back to the battery. Think for example about a car. Most of us old timers only knew of shunts on the negative side.
Shunts that have some electronics / smarts to them MUST be wired as specified by the manufacturer because the electronics pull the power they need from the expected positive and negative points connecting to the smart shunt. So the Victron Smart Shunt has to be connected in the negative path, and the Thornwave Labs smart shunt has to be connected in in the positive path. Either may have some protections, but I would assume that if you put them on the wrong side you will fry the smarts, and $100+ will be down the drain.
I should add: I was giving you a general answer about shunts. I know nothing about the Chargery shunt, but I would assume the sense leads to the shunt (for measuring the very small voltage across the shunt) would have to be in the right polarity, which would change between the two places you might put the shunt. Wiring it backwards may cause a problem or maybe even damage with the Chargery BMS.With the above said, jason really has some explaining to do. seems to me like he may be using this as an excuse not to stand behind this *ahem* product.
Correct. The sense wires are installed accurately.I should add: I was giving you a general answer about shunts. I know nothing about the Chargery shunt, but I would assume the sense leads to the shunt (for measuring the very small voltage across the shunt) would have to be in the right polarity, which would change between the two places you might put the shunt. Wiring it backwards may cause a problem or maybe even damage with the Chargery BMS.
This was the diagram i used from the website, but jason sent me a different diagram that showed it on the positive lead.