Dre

THREE KILOWATT!!!!!! Is your Tesla parked on the stern?? Oh wait... you have 15s right?

I keep mine under the pillow!

The Sterling has a Lifepo4 setting plus I'm pretty sure it also has a custom setting if not happy with those parameters so it's fully automatic. I was getting 45/50 amps charge from the alternator to the LA bank originally so I went for the 60a b2b and it charges the lithiums at around 50 amps which is what I wanted. It also has the "half power" function that charges at around 30amps if I'm going on long cruises. Mine is similar to yours but it's dc to dc so you can hook it up directly to any battery. It's quite small and cheap but very good quality I only mentioned the low temp protection as many bmss and most cheaper drop in lithium batteries don't have this function. On my bms you can set it to whatever you want (I set mine to 5 degrees C) and it will shut down the charging side of ever it goes below this temperature. The load side fets will still be on. That's in case the ambient temperature will drop below 0c (very unlikely as my batteries are inside) and you can irreversibly damage lifepo4 by charging below 0c. My cheap Chinese Hall effect (or you can get one with a shunt if you prefer) battery monitor has two programmable relays. They can be set to come on and off by voltage or state of charge. Say come on above 80% soc and turn off below 50% or whatever. At the moment I turn the mcb on manually (240v element) for a couple of hours when I need the hot water but I'll be connecting a relay to a SSR when I have the chance. 14.2v is the charge limit on the mppt (epever) that translates to slightly less at the battery terminals. Also remember that unlike your power supply the mppt provides quite a lot of current and the batteries seem to reach a higher voltage than they really are. Always check what the actual voltage is at the battery terminals and adjust the mppt settings until you get the voltage you want Well I have about 1kw so I expect to be using the sterling quite regularly. This is a useful little table of average daily Amps for any given month in UK from a 100w panel. Jan 4.68 Feb 9.36 Mar 16.29 Apr 25.71 May 34.85 Jun 35.42 Jul 34.57 Aug 28.19 Sep 19.34 Oct 10.85 Nov 5.60 Dec 3.54 I still don't know how much I use daily (as I frankly don't really care) so I'll be turning the engine one when needed ?

Hi Ivan&Alice That's great stuff I have left a lead acid connected to the alternator to which I connected my sterling b2b to charge the Lifepo4 when needed. The sterling can autosense and start charging automatically but I have used the manual function via a little switch so I start it when I want. My model charges at about 50 amps with the option to go half power at the press of a button. It works just fine. For top balancing I used a cheap (but pretty nifty) power supply that works with anything up to 32V DC. Like you I got the bank charged with solar and stopped when the first cell got up to about 3.5v (that's when the out of balance increased quite dramatically). Then connected the power supply to the lead acid and top balanced the whole bank. I'm also full time liveaboard so no mains either! I also looked at the various options for battery protection/bms but went for the simplest. All my DC goes through a 120A bms that also has low temperature protect. The bms has a little Bluetooth dongle that allows me to monitor all cells and check and change all the parameters I could possibly need. It also has a good coulomb meter. But I've actually disconnected the Bluetooth now that I'm happy the setup is working as I want a fit and forget system and I didn't want to keep looking at the app! Luckily I got a 2kw victron inverter super cheap on ebay that works a treat and it has remote relay inputs. So the inverter is connected directly to the battery as I didn't want all those amps going through the bms and programmed the hall effect battery monitor's relay to turn off the inverter if ever the battery voltage dropped too low. I think the Bmv also has a relay for this function. To be honest that's just for failsafe as I have never gone low enough to worry. I've just installed a 1kw element in my calorifier and been getting free hot water (draws about 80amps) while we're getting a lot of solar. So my system is pretty simple. Top balancing and setting up the mppt was the main concern as with solar the biggest risk is overcharging. A good top balance allowed me to set the mppt to 14.2 and still be perfectly balanced. Undervoltage failsafe is there but as continuous cruisers we're always aware of where our batteries are at so not much of an issue. As for alternator charging the Sterling is plenty good. It probably doesn't have the best profile for Lifepo4s but unlike solar I wouldn't be leaving it charging all day so it probably will never reach full charge anyway. Infact I hope to use it the least possible even in winter. I'm about to order it all again for my friend's boat and at less than a grand for the whole of the above system (not including the solar and inverter of course) is crazy good value considering the capacity (300a) and the performance if lithium! I keep reading the inefficiencies boaters have to endure with lead acids and wonder WHY!? ?

Hi, how did the balancing go? To add to what's been said... If the cells are still a long way to being charged, say below 3.3/3.2v you can turn the voltage on your power supply all the way up until you reach the max current that it can supply thus using the full capacity of your power supply and cutting down charging time. Your supply will be at the Constant Current stage and voltage is irrelevant (always monitor the voltage at the battery terminals). When you start reaching full capacity you will see that the voltage (at the battery) will rise more quickly and you now need to turn the supply down to 3.6v as it will soon be entering the Constant Voltage phase, where the current will start diminishing (think of filling bottles... You start at full flow and then slow the flow down to the top). You will soon reach 3.6v or just under at the terminals and the current supplied will go down to zero. It pays to reach 3.6v and then leave all cells in parallel for a few hours (or days) and then re top balance to 3.6v one last time. I initially didn't balance my cells properly as I didn't have a power supply and while they were all exactly the same voltage at up to 3.3v they started showing up to 0.3 to 0.5v difference at full charge. After top balancing they haven't gone over 0.01v difference..... Which is very satisfying PS What BMS do you use?

This is the power supply which I supply with 12v from the boat https://www.ebay.com/itm/253685854842 https://www.ebay.com/itm/253795258270 And this is the bms https://www.ebay.com/itm/323971537785

Hey clever people I'm back! Little update. I've now installed 3x 340w panels via a 100a MPPT (I thought I'd go big as I might want to add another panel later on. The Sterling B2B has been working fine but it's been unused since the solar install. I still haven't got to high charge with the B2B and the cells stayed balanced within 0.05v but now with solar I get to 100% charge easily and past the 14v mark they go out of balance by 0.3v so I decided to build myself a nice power supply to top balance the pack which I never did. At the moment I'm running 4 cells as I have lots of solar and I have the other 4 in parallel on the power supply set at 3.6v and 6a (about 20w. I guess it will take a while from 3.34v! Out of curiosity what do you guys use to top balance? Also the bms has been working flawlessly and the Bluetooth app gives access to more parameters and monitoring than I need. Of course the balancing turns on as set but as expected it can't keep up with this kind of power. So far I've only stretched to a 1kw chop saw (bms is rated at 120a continuous) via the 2kw inverter and don't plan to run much more than that. If I ever need to run more power I have another exact bms which I might try and run in parallel. This setup has been a joy to build and a joy to use so far and I'm hoping the balancing will work and last for a while. Dre

Mind you, they also gave me far too much oil for the engine.....

Yes good point but I'm fully aware of the danger. I have a rubber mat that I put on them and they are in the wiring cupboard where everything is well fixed. I really wouldn't like to test lifepo4 max short circuit current ??☠️? I went to Beta Marine to get the right spares and they gave me the alternator sizes..... And a black and white print of the engine ready to leave the factory ?

If by that you mean a "load dump" (great name ?) Sterling sell an alternator protector though the b2b has protection from a load dump, when say the bms cuts out while the lithiums are being charged

That's good to hear! I will gladly make my alternator the guinea pig but I first need to know that if I need to change the alternator, my Beta can take a bigger one without modifications.

That could very well be the way we measured the temperature. I reckon this alternator has been charging at around 40a for almost 15 years so I'm not gonna worry about its normal temp. If I really find that I need to charge faster I'll look into fans and cooling and bodging something up but the moral is.... The alternator is the limiting factor!

So the alternator temperature is the same when charging the lead acid bank or the lithiums at half power (around 28A) The hottest i could find with the ir thermometer was 115C. Yesterday it was almost 150C charging at about 52A. Also it seems that the alternator is not giving me much more than 30A as the lead acids are discharging at the same time. The old shunt monitor for the lead acids says by 25A but that monitor is crap and probably out by quite a few amps. Still, my impression is that for my 90A alternator a more realistic B2B would be a 40A max!

My alternator is 90A already. How fast I charge the batteries with the engine is not too much of a priority to me as I'll have quite a bit of solar to help with that but remember that like any battery, Lifepo4s life cycles will be reduced if charged (or discharged) too quickly.

My Sterling came with jumper connected on terminals 2 and 3. This means that it will sense the higher voltage from the alternator and basically start and stop automatically when engine is on or off (there's also a delay that can be used) . I've removed this and connected a 12v feed instead to terminal 3 which allows me to switch it on and off as I please (I just used a spade connector but I will wire a switch in) . With this option not only am I able to start and stop when I want but it also allows me to charge from my lead acid bank directly as the Sterling is capable of Boost (it can charge from a lower voltage). I did this last night and it was taking 30A from the lead acid bank! Engine off. I am not sure why and when it decides to reduce the charging current... Possibly dependant on things like its internal heat dissipation and/or how much it can boost from a certain voltage. The Sterling also has a half power function which is easily accessible by holding the Setup button for 5-9 seconds. Today I'm gonna measure the alternator temps by charging just the lead acid bank and by charging the Lifepo4 at half power but it seems the Sterling has enough options for me to be able to use it one way or another. Infact I think it's an amazing piece of kit!

Great news.... It's all connected and running! At the moment the battery is getting 13.5v and around 50A Ive just checked the alternator and it's pretty hot. I have an infrared temp gun and the hottest I can measure pointing into the windings is 150 degrees C. I've just turned the engine off as I'm not sure about the alternator... Need to check temps when charging lead acid bank only. Happy so far though

I was about to link up the marinehowto page. In the end I think it's a question of suck it and see. I thought I had a 170a alternator but Beta told me it's a 90a so I'll just have to see and hope that it works with my 60a sterling. I think there's a degree of luck also between 30 and 50% ???

Also if anybody is interested the bank voltage is 13.20V as they were delivered. On the Lifepo4 chart that's over 70% state of charge

I agree! I was thinking of getting those Valences on ebay but I wanted to learn a bit more and also be able to get more matching ones later on. Valences at that price might not always be available and I'd end up mixing very different types of batteries. Also these perfectly fit in the cavity behind the 12v distribition panels where all the cables I need are. I think I might actually get away with just reterminating the existing cables with no new cables to buy or run ?

So it looks like prices have gone up... I only paid 600 gbp (no other costs and including postage tracked with UPS) for 8x 3.2v 150Ah. I would think that after the covid stall there's a lot of demand plus they'll be trying to recover some losses. I ordered directly with their website (after a couple of emails with the sales guy in China) because aliexpress wasn't working for me. Ordered on 3rd of February so China was already shutting down but still only took 3 months, two of which they were stuck in Germany! As I said the packaging and the voltages seem to indicate the cells are new or at least as advertised. Also being able to email them and get a reply during the height of a pandemic is pretty exceptional on their part and to be able to actually have them delivered puts most European /uk sellers to shame.

Sorry I thjnk that link didn't work. It's post #773 on page 31 I put the links for most bits

Great to hear that. That's exactly what my plan is... Bit of fun researching and setting up and then forgetting about it! But I would also like to show that lithiums are easy and cheap!

Hey, I received the cells yesterday... YAY! UPS, all individually wrapped and boxed and all perfectly matched in voltage. And they are tiny!! That whole thing is 400mm by 180 by 180 at about 24kg (replacing 5x 110ah acid lumps of 350x190x180 @ 23kg.... EACH) That's 300ah on a dinette TABLE! ? All I've DONE so far is checked the individual voltages which all match to two decimal points. Connected up into one bank of 12v with the supplied copper busbars (not the thickest copper but they gave me 16 of them so I doubled up on the series connections) Terminated and connected the balance and BMS leads and tested the Bluetooth app. App is great and has more parameters that I care for which all seem to work OK. Bluetooth worked straight away. BMS is 120A so I'm planning to add a second one as I would like at least a safely usable 150a for when I need it (my inverter is 2kva) BTW the BMS came with those cables already soldered on the board all I had to do is crimp some lugs on. Cables are 6mm each so you get a nice 18sqmm on each side. Can't wait to cut into my system and install this pretty little thing! Will keep you posted ???

Why won't it?

Perfect, thank you very much, papa!