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Dr Bob

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Dr Bob last won the day on June 13

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  1. It does complicate things with your alternator/inverter/charger/Li charging. If I was doing it, I would try to get it so the Li's were paralleled with the LA's and connected together for normal use ie discharge and charging via the genny to charger to circuit. So in normal use, the charger can back off when the Li's get full....unlikely in winter.....and the Li's always above 12.8V so the LA's never discharge. So in the circuit you need a shunt on the -ve cable from the Li's (to measure A, Ahr and voltage in the Li's) and on the +ve from the Li's you need a fuse and then your auto disconnect switch. What switch are you using? The BEP or the Tyco. I have also added a belt and braces approach and put a manual battery isolation switch on the LA side of my BEP switch. Now the issue comes if you want to use the alternator. In the above config, you could run it but you might not have enough control over the alternator output ie too much current..or being able to terminate the charge if the Li's get full.....again unlikely in winter. It would be worth having this config available to try as in winter you will only run your engine a bit and never likely to get full or overstress the alternator as the ambient is cold. You can 'learn' the system doing this. If you go on a long cruise then just isolate the Li's after an hour or two. You may find this works fine for the next 3-4 months and then you can think of improving it. Maybe an alternator option will pop up in that time. Now, you could do the above with a slight mod to allow the alternator/inverter/charger/Li charging thing. Disconnect the charger 12V+ wire from where it connects into the current LA system and reconect to the terminal on the manual disconnect switch on the Li side. The charger is therefore feeding in between the manual switch and the auto switch. If you therefore wanted to charge this way rather than direct from the alternator, you just isolate the manual switch but your boat services will be drawing from the LA's only.....but your change over switch is going to have the same issue (I think) in isolating the Li's from the domestics. If you then want to charge just the LA's to fill them back up, you reconnect the LAs via the manual switch and trigger the auto disconnect to isolat the Li. Watch how discharged the LAs get in this system...if you are significantly discharged ie <70% then you will have to recharge at a decent voltage ie>14V. If you are only discharging by 5% or maybe 10% then the <14V regime of the Li system is likely ok....it is for me. Let us know how big your LA bank is, how big is you Li bank and what modules you are using for measuring voltage, A, Ahrs, cell voltage and how are you going to disconnect on high/low voltage, high/ low temperature and high/low cell voltage.
  2. When will it be? Do I need to get the time machine out?
  3. Maybe they serve fish in the Nelson? ......you have to read the thread!
  4. What's the Nelson like now? Been meaning to go in but always seem to go somewhere else. Is the food as good as last year?
  5. Cant see any mention of fish!
  6. I have the AtoB. They are not much use for charging speed if your domestic alternator is good. Yes, it puts the two alternators together but once you are over 80% full, your batteries will dictate the amount of current going in so likely two alternators will be no faster than one. Also if one alternator is giving a higher voltage than the other, the higher voltage one will provide all the current to the AtoB and the other will do nothing. In my system I have a 50A engine battery alternator that puts out 14.3V and the domestic 90A putting out 13.9V. When both are connected the 50A will be running full blast with the 90A giving nothing. I rang Sterling and they told me it would only work with 2 alternators the same!!! DUH!!! They dont say that in the advertising bulls**t. The main use for an AtoB is if your alternator doesnt put out over 14.0 volts as with some automotive type alternators . This is the second boat I have had with 13.9V max. The AtoB takes the voltage up to 14.4V so charges the batteries well. In that respect it works very very well. If you still have contact with the original owner, ask why the AtoB was fitted. If you get 14.4V without it then I wouldnt bother using it. HOWEVER, dont throw it away as it may be very useful if you get LiFePO4s in the future! I'll buy it for a tenner if you dont want it!
  7. Well the duck hasnt got any! ...not sure about the noodles as they still havent arrived.
  8. Yea, but at least you can laugh at The Walking Dead!
  9. We've just started watching it. Yea, it's interesting and not the normal stuff I watch. I do like the way all the telephone calls are listened to by a multitude of operators.......prolly just like they do now. 😃 Canal boats are more interesting but we've only got Zomboat to watch! Who the heck would have a bright red bote?
  10. We don't have any! Must be a reason? An ecofan? Naw, you have one of those already. I know. Get a duck! There! Way to go!
  11. You say your voltage went from fully charged to 11v ish in 2hrs? First of replace your batteries. The AtoB will do all sorts of stuff like sound alarms on the ignition panel ( I have one) if the voltages are low, which they would have been on start up. How good was your engineer - did he know about these AtoBs? I've had an engineer say mine was bad when investigating an alternator problem last year when it clearly was fine. Get new batteries first and then you can see if the are problems with the rest of the Sterling kit. You start by saying the alternator alarm went off and that was the reason for calling out the engineer. What alarm was it?
  12. Nick, remember that if your bank is top balanced which is likely, there will be more of an inbalance at the bottom so if the cells are not well matched this could be a significant inbalance. Under normal operation this is fine and not a problem. Its only an issue when your SoC drops and you get one cell to the bottom knee ahead of the rest. So as MP says, you need a cell level disconnect. Mine is set at 2.8V (but that is what the BMM8 sets it to). Not my choice.
  13. Yes, but my victron IP22 30A has a LiFePO4 setting but doesnt cut the current and voltage as it gets to 100%. Best have a charger that will go to float (ie set to low 13V's) at whatever termination voltage you put in and one where you can set the current. I think Richard's Sterling does this. My IP22 would be no good to shut down itself but would work if you terminated via a auto disconnect ie BEP or tyco but the relay cutting the charger rather than isolating the batteries. I would wire all 4 into the Li as it will be the battery to use when not charging via the engine. See response above on shutting off the charger. Yes you do then need to think about how you isolate your Li's from the LAs and I am not sure what the optimum is as I have not thought it through. (Acute brain drop occurs if you try and think too much!) Maybe Richard can explain his proposed system? -it sounds like worth trying but there is a lot of detail to iron out. What you dont want is two BEPs as they are £150 squid each. The Tyco's are much cheaper but then your going to have to talk to MP for his circuit. If you are thinking of trying Li's then it is worth experimenting a bit. If you buy them now and get them installed, say before Christmas, then you will get b**ger all solar but you can charge for an hour in the morning and an hour in the afternoon and not burn out your alternator as it is cold and you will never be near 100% SoC. By Spring, by the time it warms up and you need to control your alternator temp there will be more sun and you will be moving to a more automated system. When I put mine in, I was planning to manually isolate the alternator each day and just use solar when I didnt have time. Within a month I had worked out a solution and so spend no time at all (apart from the word I am not allowed to say but it what you do when you spin lots of plates). Nick will have his alternator controller out by Chrismas!
  14. The big pro has to be that you dont overstress you alternator. Say your Li's are half full, you alternator will be working flat out so may burn itself out if you do this for any length of time and it wont turn off when your Li's get full. If you use the Alt/LA/inverter, then the Li will take the power from the inverter/charger at the rate it wants, the LA's will power the inverter and the alternator will charge the LA's as if they are in bulk. When the Li's get to full, the inverter/charger will back off - IF you can set it to the voltage you need - Richard can as he has a programmable Sterling - so then the alternator will cut back in current as the LA's demand....but still 14.4V to keep the LA's topped up. Negatives? There could be an issue if the inverter/charger puts a lot more current into the Li bank than the alternator is putting into the LA's. In that case the LAs will drop in SoC as the Li's increase in SoC. The beauty of using LAs with Li's is that the LAs are alway near full as you dont drop the voltage below 12.7V. If they drop to 50% then you are going to need 14.4V to get the LAs back to full which you may not have if you then stop the engine. Yes, the Li's will charge the LAs back up to full but only at 13.3V or less. The thing is though that most(?) inverter/chargers are programmable so you should be able to set the charge current similar to the LA charge current. A lot here will depend on the capacity of the LA vs capacity of the Li. This is going to open up a huge can of worms - as Nick criticised my system back in March - saying I needed 14.4V to keep the LA's in good shape. 6 months on, my LAs are in the same shape as life before Li's despite only being charged at 13.7V max - as I doubt they were ever discharged below 95%. There is a logical argument for this which is outside your rules for a response 🙃 so I wont bother outlining it.....but you will need 14.4V to charge LAs if they go down to 50% SoC. What I am not sure about is what happens if your LA bank is 90% charged and you take 50A out with the inverter, what current is you alternator controller give? I've been using an AtoB with my LAs so cant talk about 'normal'charging of LAs. Maybe sulphation is the big downside if the LAs go down to 50% or another downside is lower charging rates from the alternator than if the alternator was directly connected to the Li bank. Need also to think about the wiring so you isolate the Li's from the alternator yet want to have your domestics are fed from the Li's. Someone needs to try it and keep a close eye on SoC of the LA's.
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