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cheesegas

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  1. Best to get a buck-boost converter - more efficient than a linear regulator and can cope with the supply voltage being less than the output. Plenty of pre made modules on Amazon for not much money: https://www.amazon.co.uk/Converter-DC5-30V-1-25-30V-Automatic-Regulator/dp/B07WP5KDR5/
  2. Update on this - the mount with the most weight on it eventually failed resulting in an awful racket, unsurprising as to get the engine level it was at the end of its deflection. Called R&D and their shear mounts are low enough to fit between engine and bearers, but the deflection is very small, only 3mm allowed! They didn't offer any advice, just referred me to the spec sheets again and again. Ordered some more AV Mounts, this time two 90kg (75kg fitted before) for the heavy side and two softer ones. These have marginally higher deflection at 4mm. edit: Another update - got a call back from a chap at R&D who was very very helpful and recommended I order four compression mounts of the same 86kg rating, he said not to mix mounts of different capacities. Going to order them and return the AV Mounts I think!
  3. What's your setup? Inverter/shunt/system controller? You may be able to do it in software already.
  4. As above, how do you use the boat? CC'er liveaboard year round with no shore power? CC'er liveaboard who spends the winter in a marina with shore power? Holiday boat used in summer only? Liveaboard in a marina with shore power? Plenty of different use cases.
  5. Unfortunately it's not as simple as that - if there is field drive and the engine is running, there is always output current. You can't have the field on and no current flowing in the stator. This is the problem; to maintain float voltage, almost zero current must flow out the alternator (well ok, maybe 100ma...) which means the field must be sufficiently low for this to happen. This level of field current is not enough for the tacho to work. Your logic system would work fine when in bulk or absorption, but in float with no loads switched on in the boat there's the situation of the field being very low and the output current of the alternator being next to zero; the tolerance of a shunt is probably less than the current needed to maintain a lithium battery in float. Lithium systems are even more difficult as there's a situation which could last 10 minutes or so when the regulator drops the voltage from say 14.2v to 13.4v; the battery must actually discharge a little in order for the regulator to achieve target voltage. For this to happen, the field must be zero and the output current and thus tacho will be zero also. This looks the same to the regulator as the engine being switched off. A crude alternative would be to force the alternator to always output current by switching in a ballast resistor when in float, but that's wasting energy... Another, better, workaround for the tacho issue is on dual alternator installations, to connect the regulator's tacho wire to the starter alternator so it always gets signal. I'm frankly surprised this isn't recommended in the manual. I agree that documentation is not very good and they seem to rely heavily on the brief blurbs in the app rather than having a detailed manual. There's no explanation of how various settings interact, for example the minimum field. Some descriptions are bad too - the voltage at which the regulator drops the field under a high voltage fault condition is called Maximum Voltage. This sounds like the maximum allowable charge voltage under normal conditions, and the blurb in the dialog box doesn't do much to explain. High Voltage Cutout would be more descriptive.
  6. Speculating here but maybe coming out of the lock they got wedged sideways on the motorcycle, so they tried to raise the level in the lower pound to lift them off the motorcycle. Turned out they were wedged so tightly that the rising water didn't lift them and ended up downflooding the boat through a vent etc.
  7. No need for a tacho at all - it's never worked for the 4 years I've had the boat and I've never felt the need for one. This is mainly a vanity exercise as I have a week off work when I should be derusting and painting bits on the boat but it's weeing it down every day... With most external regs which can switch to float mode, alternator driven tachos are effectively disabled when it's in float, especially if there's solar. It's just fortunate my boat happened to come with a non alternator sensed tacho. This isn't a cheap way of doing it - that would be hybrid, which ironically doesn't suffer from this issue! As I'm sure you've read in my other thread, an alternator sensed tacho is unreliable with any regulator like this - Wakespeed, Balmar etc. The Zeus doesn't need a tacho input to operate but it does rely on tacho input for one of the optional features. It's worth noting too that a 'marine' alternator would suffer from exactly the same issue as this. Balmar regulators have a similar tacho keep-alive function which needs to be used with their alternators; it's less configurable than the competitors and works poorly. Many high output installations do not suffer from this issue though as there's a separate alternator for the starter battery, which the tacho and regulator takes its signal from. If the field of the domestic alternator is dropped, it doesn't matter. However, I don't have the room in my installation to fit a second alternator, hence doing it all from one. Basic technology and lead batteries are fine if you have shore power and/or don't live aboard, but lithium batteries in the winter for a liveaboard without shore power are literally life changing. I've tried marina life and I hated it, I'm happy to pay for the technology and do the research needed to fit lithium batteries etc - it's definitely at the forefront of things so there's still shortcomings people are unaware of! My job includes a lot of getting various things speaking various protocols to talk together and electrics too, so this keeps me on the edge.
  8. True, on a modern installation with dual alternators it doesn’t matter except for when you have ‘wait for tacho’ enabled. That requires a minimum field current. I think it should also have a warning in the app… There should either be an enable/disable option for minimum field with a warning when you enable it, or it defaults to zero and then when you enter in a number it pops up with the warning. There’s a half page dedicated to this very pitfall in the Wakespeed manual for example, and you’re also less likely to use minimum field on the Wakespeed as it doesn’t have a wait for tacho option. My 35 year old Isuzu originally had a sender on the camshaft for the tacho, but newer engines don’t, pretty much all mechanically injected engines of the sort we see on inland craft have an alternator driven tacho. The Wakespeed can take engine RPM from CANBUS but I don’t know if the Zeus can. I was going to try connecting the Zeus’s tacho input to my Isuzu’s sender, but it doesn’t allow for a tacho ratio below 1 - it needs to be 0.5 as the camshaft is half engine speed. I could knock together something to output a second pulse, but at that point you may as well install a sender on the crank pulley or something!
  9. It would only need a software update (I expect!) to be able to add the feature to create a map. You’d fully charge the batteries, allow the reg to drop into float mode, disconnect all other charge sources and then slowly increase RPMs whilst the regulator hunts for and then sets the minimum field for each RPM setpoint. Once the map is created everything would be automatic. I don’t remember the peak-peak voltages when I had the oscilloscope on it, and neither did I put a multimeter on it to get the RMS voltage…but I did have a spare tacho dial attached to the W terminal. I noticed that the dial would jump around at roughly the same point the Zeus begins to lose signal, which suggests it’s an alternator output issue. Further refining the input signal processing on the Zeus may help though.
  10. The problem is just that. The Zeus can apply a minimum field current, no matter the RPM. If you set it to something like 5%, there isn't enough magnetism in the rotor to induce a large enough current in the stator for a meaningful signal to be present on the W terminal, so the tacho reads zero. In my setup, 24% was just enough at idle to get a tacho signal; 23% meant it jumped between zero and 700rpm. This is the threshold of the tiny bit of excitation you mentioned. However, at higher RPMs when the rotor is moving faster past the stator, that same 24% field drive induces a greater current in the stator than at idle. It's not only enough to drive the tacho but it's also enough to push the output of the alternator above the target voltage when the load is low. A user configurable map of minimum field % against RPM would solve this, so it's dynamic and reduces the minimum field as RPMs increase.
  11. Have a read above, I think I was a bit rambly here and there but the reason why it doesn't come on is that unless the minimum field % is configured, the Zeus has no idea if the engine is running or not when the batteries are full and Zeus is in float mode. The inputs in the above scenario are in the exact same state as when the engine is not running but the ignition is off. All *edit* off the shelf external regulators have the same issue, it's about how it's dealt with. I agree that perhaps like Balmars, the first time the ignition wire is turned on the ignition light should come on though. Once the regulator drops to float mode it would then only come on if there's recognised fault state. Interesting, I didn't know this was doable in an off the shelf chip! I mentioned that this is one of the potential fixes, a dynamic minimum field current depending on RPM, good it's already been done! Wakespeed and Zeus apply a fixed but configurable minimum field current, Balmar as far as I know apply a fixed but unconfigurable minimum field which in my experience isn't enough. I don't know how Mastervolt handle it.
  12. Yep, tacho dial's getting +-12v and the wire from dial to sender and from sender to negative are all intact and tested with <1ohm resistance. Looks like it's possibly a bad dial or misadjusted sender unit.
  13. Finally got mine fitted! Notes below, the way it handles minimum field to keep the tacho alive is very poor. Minimum field is not a problem unique to this unit though. The alternator light, much like @dmr experienced, does not act like a normal light which at first appears like a simple oversight. When you turn the ignition on and the engine isn't running, it doesn't come on. I have forced it into a fault condition to see if it works though and it does flash out fault codes nicely... I wouldn't expect the light to work if the batteries are full and the minimum field % is below what is needed to excite the stator though. The error here is not having an option in the config to enable/disable minimum field % drive - you just set the percentage. With the minimum field at say 5% and the batteries full, the Zeus doesn't actually know if the alternator is spinning or not as nothing comes out the W terminal since the field current is so low! I believe that to avoid the light coming on in error (a full battery/low field state looks the same to the Zeus as when the ignition is on and engine is not running), they've just disabled it under those conditions. The way to 'fix' it as mentioned is to have an option to enable or disable the minimum field percentage option; if it's enabled, the light works like a regular alternator light, if disabled it acts like it does now. The 'enabled' state would allow the Zeus to assume that if it's applying minimum field and it's not getting anything out the alternator, it's not spinning. I had the minimum field set to 24%, just enough to keep the tacho output alive at idle. Any lower and it becomes intermittent, I've verified this with an oscilloscope to ensure it's not just the Zeus being insensitive/too low an input impedance. This is fine for charging at low RPMs when the battery SoC is low. However, if the battery is fully charged, the regulator is in float and the engine RPMs are high, it's still maintaining the same minimum field %. This means that the voltage will continue to rise unchecked as it can't drop the field current low enough to achieve the target voltage - 13.35v in my case. It'll rise until the lithium BMS does a high voltage disconnect or the Zeus trips on its own high voltage protection. I highly recommend setting the Zeus's high voltage protection lower than the BMS's high voltage disconnect to ensure it stops trying to charge the batteries with an ever increasing voltage BEFORE the BMS disconnects. It does not have any runaway detection like competing regulators do. To summarise... Given the target market for the Zeus, I think the minimum field % urgently needs an enable/disable option, along with a big big red warning in the app if you enable it. If you don't change the factory high voltage trip from 16.0v to something lower, setting a minimum field too high will fry your alternator if your lithiums do a high voltage disconnect, or if you have lead batteries it will boil them. As an experiment, with 24% minimum field on my 90a Prestolite, I connected an old lead battery to the lithium (hybrid eat your heart out...) and brought the engine up to 2500rpm / alternator 4500rpm. The BMS did a high voltage disconnect at 14.6v, the voltage on the lead battery quickly rose to 16v and the Zeus tripped. However, there is little hysteresis built in to this, and it appears to go into a loop of enabling itself, voltage rising and then tripping over and over again! In my test setup, the lead voltage sat around 15-16v. One fix for this is a dynamically changing minimum field, mapped by the installer against engine RPM, and a big fat warning in the app if you enable that not-present minimum field option. The other way around it is to take the engine speed from a different source so it doesn't matter if the tacho output of the alternator drops to zero. However... This overall problem is not unique to the Zeus, it's something we have to deal with in all external regulators which are capable of reducing the alternator voltage to float. Even with the first fix mentioned above, an MPPT in float with a voltage set to slightly above the alternator's float voltage will disable the tacho output. Communication with all components in the system is really important here - all charge sources need to take battery voltage from not just the same physical place in the circuit but ideally it's got to be one 'thing' (SmartShunt etc) measuring the voltage and sharing that data; it's a shame DVCC isn't supported yet. Small voltage differences can cause havoc. The issue unique to the Zeus is the option to 'wait for tacho'. Bafflingly, if enabled, the regulator will first apply the minimum field current % and then when it sees a tacho reading, it will then ramp up the field. If disabled, it appears to apply (almost!) full field first, then ramp it down like most other regulators. I can see no reason for the 'wait for tacho' option other than avoiding overheating the field winding if you leave the ignition on and engine not running. Another option for engine running detection could be a simple accelerometer you'd bolt to the engine. It's worth noting that not all alternators are the same; some may not have this problem - with bigger alternators it's possible to set the field current low enough for the tacho to work but not for the voltage to run away. The Wakespeed handles the minimum field drive in exactly the same way and is prone to the same problem; however, minimum field % is disabled from factory, and requires going into the advanced config and sending Putty commands to set up which the average user will not do. Before firmware 2.5, if it detects a voltage runaway condition, it will drop the field to zero to avoid a BMS trip. However, as of 2.5.1, it will behave like the Zeus and not drop the field % below minimum until it trips on high voltage. The difference is that the Wakespeed has a big fat warning in red in the manual about this very situation. The Zeus does not! It's also possible for the Wakespeed to take engine RPMs from J1939 CAN registers, whereas it appears the Zeus is read only.
  14. Thanks, I'll try unscrewing it a little. Currently it's around 1mm away from the cam lobe. As mentioned, I've measured it with an oscilloscope - think of it like a fancy AC multimeter where you can see changing voltages mapped out on a live graph!
  15. ...I'm about to update my Zeus thread as to why this isn't possible, hence the long route to get a working tacho! Have a look in half an hour or so.
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