Tom and Bex

Apologies about this long post, but just catching up and wanted to reply to a few points. Didn't realise when I started this post it would end up so long though! My Arduino based alternator controller handles thiis by operating in float if battery temp is 0c or below. Battery remains connected to boat loads, and alternator. In float mode, alternator supplies loads, but aims to keep amps in/out battery as close to 0A as possible. It does this by taking info from existing shunt. Just to clarify, I don't have a LA in parallel. Alternator controller and other charge sources are set so overcharge should not occur. High voltage disconnect is purely a last ditch safety system and has so far never activated. Wouldn't say it's overly complicated though. I haven't provided any protection to charge sources if disconnected due to HV event, but consider a fault would have already occurred by that point. Only difference really is my use of alternator controller to solve alternator charging problems Having read your later posts as well, I think you should just connect then up in parallel to your existing LA bank, set your max charge voltage to 13.9 (or 13.8 if you want ti be conservative) and just start using them and benefiting from your investment If you used an automatic switch such as motorised BEP switch already discussed, or even a simple relay, you could use the above device to set an over voltage protection of 13.9, and under voltage protection of 12.2. Then just use and forget about them. With the low charge currents you talk about you'd be extremely unlikely to overcharge them just charging to 13.9v and terminating at that voltage (which the over voltage protection would do if your charge sources didn't). You can over think these things sometimes (I know I did when installing mine!). Surely the ability to charge at high rates is one of the big advantages of Li over LA? Seems a shame not to be able to benefit fron thiis. The simple BMS @Dr Bob and I use (BMM8v2) activates low voltage disconnect at (from memory) 2.5v, and completely shuts itself down at 2.0v preventing any parasitic drain on completely flat battery. That's why we decided just to leave it permanently connected and let it do its own thing. If well balanced to start with, it really doesn't take very much to keep them balanced. Ours had drifted a bit after 3 months, but we often charged to 100%, and it's only in the top knee as you get above 95% that it really stays to show. We often charge our 320Ah bank at around 80-100A which is also higher than others here. Good to see it shouldn't be too difficult to modify. I thought most alternators could probably be modified without too much difficulty, our A127 certainly was (although we've already had to replace it due to burnt out rotor!). But surely comparing cell voltages at end of charge is all you need? As long as all cells reach the knee as closely as possible at your charging currents what more is needed? We probably charge at higher currents than others here, and haven't noticed any difference in which cell reaches the knee first whether charging at 90A via alternator, or 10-15A via solar (in summer!). I think the balancing is overplayed. If balancing every charge, it really should only be a very small amount so even with fast charge, time shouldn't be a problem. Our alternator controller had option of output to warning light, but I preferred to keep it as visual indication of excitation and controller actually working as it should. Have therefore kept ours wired to D+ (and one side of the brushes), with the reg connected to the other brush. Completely agree. On our 320Ah 20% just seemed to much capacity to waste. Having said that, we rarely seem to get above 70% at the moment, but that's through choice, at least we have the option to use the full amount. I'm also of the opinion charging to 100% doesn't do much harm, it's storing them at that long term that doesn't do them any good. Ours were up around 100% quite often in summer. As in my reply to Nick above, from reading around its time keept at 100% that does the long term damage vs charging to 100% as such. Agree you will get better life by only charging to 80%, but by how much? Even regular charging to 100% they should last many years. I tend to agree that cells seem to drift slightly quicker if pushed to 100% though, but that's not based on any actual evidence. Our alternator controller has CANbus interface for voltage, current, and SOC, but not having any CANbus devices no idea what information it would use or how it decides what data is relevant! Tom

I wish we had a fuel boat operating in our area?

Thanks for replies. Had to get one fron Cambrian house, Birmingham in the end! CRT customer service were useless, and just said they're aware of a backlog of cards and couldn't even give list of stockists. We do have a porta potty but prefer not to use it for various reasons. Thought we'd been organised by ordering cards in advance, and shop has always had them in when we've been there as well. We have used Copt Heath before when Lapworth is broken, but their pricing and the 5-6hr round trip puts us off, particularly in this weather. Anyway, all sorted now! And we're won't need to think about emptying our tanks for another 6 weeks or so..... Unfortunately it's just offices and they don't do pump out cards. That's what we were told when phoning them anyway! I believe 2 x 400L! Ex Black Prince boat. Only way we can do it at Lapworth is have an extension pipe screwed into offside fitting so we can quickly swap between tanks. Pumpout hose at Lapworth won't reach to far side otherwise. Only just enough time on one card, but certainly saves money! Best value is Hawne Basin though - £8 for both tanks, and thorough rinsing.

Has anyone got a CRT pumpout card we can buy from them in Lapworth or surrounding area? Alternatively does anyone know where we can get one from? Shop on Lapworth locks has sold out and been waiting for a delivery for a while, and had ordered some ourselves online mid October, but still not here - is there a shortage? Really need to pumpout later today. Will ring CRT later but thought it worth asking on here just in case! Our alternative is to head up to Copt Heath Wharf, but as well as having to do Knowle locks (twice!) they charge £36 (£18 a side) whereas we can do both tanks with a single card usually. Tom

Which fits very well with my observations, that just having a set voltage cutoff for alternator charging would work very well. Like you, we were quite cautious with voltage settings initially, but increased both alternator and solar voltage to 14.0v based on observation and experience.

I can't see that it's been mentioned yet, but it looks like that bms requires a minimum of 7 cells connected to it? Fine for 24v system but not 12v. Not liked any closer at it though. One of the biggest individual component costs is the actual remote isolator itself (either motorised switch, or bi-stable relay and control circuit). Completely agree, particularly if putting the system together yourself. But does it actually matter that much if they are 80% or 90% charged when you hit the voltage set-point? It also depends how discharged they are before charging commences. On our system, they seem to hit 14.0v anywhere between 80-95% charged. Actual value depends on how discharged they were, engine speed, and if charging from one or both alternators. When charging from just engine start battery alternator, which only puts out 30-40a, they would hit nearly 95% if starting from low soc. That was the point voltage had climbed to 14.0v, by which time current had dropped to 25a or so. From my observation of charging at varying currents ranging from 100a down to 30a, I still believe charging to a set voltage of 14.0v will not overcharge them, and will give a finishing charge of around 80-90% - more than adequate for most users. And this was one of the main driving factors for us. We're not really high power consumers, but still managed to kill a set of LA's in just over 12 months. I do find us using more power now we don't have to think about conserving batteries as much though. You might find your solar gives more than 6 months. One of the big surprises for us was just how much better our solar was with lithiums. We've managed over 12 months and not managed to kill our lithiums yet! Our last set of LA's were down to under 50% capacity after just 12 months. Very similar to our setup. Unfortunately the regulator we paid around $80 for has now gone commercial and retails for around $500! Main difference is ours also monitors current, so intelligently switches to float based on voltage and tail current. Also monitors current in float mode to keep it as close to 0a as possible instead of relying on a fixed float voltage. Not sure what we'd do if ours ever packs up! As above, thiis is very similar to what we use. Does require alternator modification though. Very easy to DIY on an a127 alternator, not sure on others though. Not really that many wires needed. Very easy mod on a127 alternator! Multiple small cells in parallel are considered better for high current applications. That's why all major ev manufacturers use this setup. Multiple C discharge rates are possible like this. Most alternators fitted to canal boats will have internal regulators. Some are easy to modify. Basically to disable internal regulation you need to connect directly onto the brushes, and remove any other connection to brushes. (Technically only the regulated brush, the other can remain connected to ground or +12v). Regarding the Valence batteries currently on Ebay, I'm seriously considering getting one of the higher cycle ones and putting it in our camper. Not sure if 1500 cycles is a bit high though, and even then I'd have trouble justifying the £250! @peterboat what do you think? And does the internal bms create any problems with self discharge if not in use?

But energy generated centrally on a large scale is much cleaner than lots individual ice cars, and much easier to monitor and reduce emissions from than millions of private cars. I know several people who get their cars out to drive half a mile to school! Why????? Our 4 year old had been walking 1.3 miles to pre school since just over 2. Children need and enjoy the exercise and fresh air. The unnecessary congestion and traffic as a result of short school runs really annoys me. I've been hearing that for ages. I would think with the amount of money and time invested in research something would have come to light by now. I'm not saying any of the Li technologies are perfect, far from it - I just can't see any other technology replacing it within the next 20-30 years at least. I'm not sure that's actually the case. I suspect in 5-10 years most (if not all) new boats will have Li batteries (at least from the top builders). The additional cost of an integrated Li solution when designing from scratch is relatively low compared to the cost of a completed boat from one of the top builders. I suspect the reason it's not common now is the reluctance of the boat building industry to adopt new technology. But that's likely to improve dramatically when large numbers of Li batteries need recycling. I know there's quite a few small Li batteries from phones etc, but they're on a different scale to the larger capacity ev batteries that will need recycling in 10-15 years or so. I'm sure automated processes will be developed as and when demand increases.

I was surprised how noisy our (ex-hire) boat was with an Isuzu 42 when we got it. Flexibly mounted with Aquadrive. At cruising speed difficulty to hold normal conversation on back deck, and very noisy inside. One of the first jobs was sound insulation (foil faced foam sandwich type with lead like layer in the middle), followed by hospital silencer. Whilst it's not silent by any means, you can easily hold normal conversation on back deck at cruising speeds without raising voices, and when idling can't hear it at all at front of boat (inside our out). There's been times I've accused the wife of turning it off, only to find it still running when I venture back there! Really surprised how much difference it made, and surprised all boats don't have this.

Totally agree. On the a127 thiis is very easy to do and easily reversible. Not so sure on other alternators though, so need a simple fits all solution.

We were only able to locate someone injured on a common the other day because a passing walker used what 3 words to pin point their location. Still needed local knowledge to get ambulance to nearest access point though!

Exactly something like that, but envisaged sensing voltage from alternator side of relay. That way when it opens voltage would rise so avoiding relay chatter. Power supply could be taken from ignition switch or alternator side of warning light, so relay was only powered when engine running. You also need to get out of the lead acid way of thinking. It really doesn't matter if the batteries are supplying boat loads after they are charged. You don't want to keep the batteries at 100% and leave the alternator supplying all loads. Unless you have a really small bank, and high usage, there should be no problem leaving the alternator disconnected after voltage hits set point. If it was really going to be a problem, then manually restarting charging wouldn't be too onerous. Remember this was looking for solutions for a cheap basic install. Your more complex and costly installation could involve modified alternators, external regulators, sterling a to b etc.

Wish I'd had that offer when doing my system! If you do make any of these, I'd be interested in at least 1 of them. For comparison, there's a commercial version here: https://www.solar4rvs.com.au/rec-bi-stable-relay-driver-bslrd-for-bottom-end-sw I'm sure I found the specs for this switch somewhere but can't now! Seem to remember it was in the region of 10-15ma but that might have been another component I was using!

I think that's the updated version of what me and Dr Bob are using. I think it's not quite as good as the earlier one we use - possibly something to do with configuring alarm functions. I'd also be very wary of using it to do any form of balancing. They're designed for small batteries as found in rc models, not the sort of sized banks found on boats!

Not sure why you would need protection based on total voltage in addition to cell voltage? Just seems to add extra complexity. We're happy our last line of defence protection is provided by the aus bms that monitors cell voltages only. We do have alarms based on total voltage though and low soc (and high/low cell voltage, and cell differential voltage). The alarms are mainly for our information though - particularly low total voltage and low soc. Cell differential voltage alarm can be useful to know if/when balancing might be required. I sort of agree. I think for a budget install, protection based on total voltage would be cheaper and perfectly adequate providing you stay conservative with charge and discharge. If staying in the range of 20-80% (possibly pushing up to 90%) easiest and cheapest method would be just parallel with existing LA bank, add some form of auto disconnect based purely on total voltage, and you have a complete system. Coupled with £25 cell monitor/alarm then you have a workable system with very little modification and cost. For complete protection and peace of mind however, and particularly if charging to 100% regularly, then a bms based on monitoring cell voltages gives the best protection. Ideally coupled with all charge sources being configured to not overcharge in the first place (however that is done!). I do think it's a case of needing one or the other though, not both! As I wrote above for a simple install, that cell monitor is very useful, and even gives a rough soc based on voltage, as well as very loud alarms! Overall I'm happy we spent the money on the cell monitoring and protection board we did though. For us this was a one off chance to install lithiums, and very unlikely to be able to afford the chance again in the foreseeable future! Because of this, maximum protection was paramount for us, even more so as there was very little information and experience to draw on of using these batteries on narrow boats at the time we were planning (other than the very expensive victron system that was way outside our budget)! Had we listened to some of the nay sayers on here, about how they were so fragile they were likely to set fire and burn a hole through the boat at the slightest chance, how impossible it would be to charge then, how the slightest thing would render them completely useless, and how the alternator would pack up every week etc etc we may never have installed them in the first place! After a year's experience I'd be happier now to consider using slightly less belt and braces protection. I don't know if it's the Valence bms keeping them in balance, the fact that Valence chose very well matched cells, or the design of your batteries which use hundreds of much smaller cells - either way they do appear to stay well balanced for you which is what matters. I did initially look at using those Valence batteries myself when I first saw then advertised, but was very wary of the lack of information available, and how reliably they would work without the propriety bms connected. Seems my concerns were unfounded in the end! I do notice the price is very much higher than when I first saw then come on the market 2nd hand though! As to the battery equaliser I posted a link to, in the description, it states suitable for a range of battery types, including lead acid and lifepo4. I guess it doesn't really matter on type, it just works to equalise the voltage across all inputs regardless of voltage level or battery type. It certainly seems to work well for us, and has solved the slight imbalance issues we were having when approaching 100% soc (which we do occasionally to sync the bmv). Well a127 alternators are very easy to either change the regulator for one like discussed earlier, or disable it to use an alternative external reg. I do think alternators pose one of the biggest hurdles for the average boat looking to change to lithiums though. The 2 suggestions you make appear to be the only easy option for most people if not wanting to modify existing alternator. Cheapest and potentially easiest, is to use a simple voltage control board (available from Ebay/Amazon for around £10), to control a standard relay, making sure to keep a lead acid connected to alternator output to prevent damage. Standard high power relay not a problem for this as would only be energised when charging so power consumption not relevant. We've had problems with our a127 alternator as well. Diode pack and rotor on ours! Ours is usually charging at max output when engine running though. Luckily we have a 2nd unmodified (starter battery) alternator that is connected during bulk charging that also provides a backup when main alternator fails. Sounds similar to us, although we do see 70a out of our 70a alternator when just above tickover! Thinking we should consider dialing back the max output slightly, or reducing the max alternator temp settings in our controller. As you mention though, at around £55 it's not break the bank money if (when!) it fails. Depending how long this one lasts now we're back in winter again, depends if and how much we change the settings in the controller. It's a case of cost vs convenience, fast charging vs alternator change! Just need to make sure we've got the right balance. Luckily changing the alternator only takes around 10 mins! Tom

But you can set the parameters that determine when it resets to 100% based on voltage and tail current, and set the alarm relay for 100% soc? Might have to tweak cef to make sure it didn't hit 100% based on returned AH before the voltage and tail current parameters were met, but should be possible with some experimenting and testing. But you can set the parameters that determine when it resets to 100% based on voltage and tail current, and set the alarm relay for 100% soc? Might have to tweak cef to make sure it didn't hit 100% based on returned AH before the voltage and tail current parameters were met, but should be possible with some experimenting and testing.

That switch was very high on my list when researching what components to use to provide the protection. Ultimately went with the BEP motorised battery switch in the end which has similar control (i.e. single on off wire). Mainly due to price and UK availability. This is exactly what I planned for a friend's camper, even using the same type of voltage control devices. Unfortunately he's decided not to proceed at present but good to here that it works for you! I've always thought this could be a relatively easy and cheap option for a basic install. Thanks for your detailed explanation in the alternator mods you've done. Interesting read, even if some of it is beyond my understanding! We currently use an arduno based external regulator, programmed with specific LiFePo4 settings, and using a current shunt as one of the parameters to determine end of charge (and to hold charge current to effectively 0a once charged, yet still support loads), Tom

I've seen cycle life widely quoted as 10,000 if kept within 20-80% soc. If avoiding the extremes, there doesn't really seem to be much of a mechanism for degradation from my reading of the papers. Couldn't agree more.

You don't want to float charge them. All the talk about float settings is purely to trick LA based charges to effectively switch off and not put any more charge in. This is best done by terminating charge completely, but as LA charge sources don't usually offer that option, the best alternative is set float value low enough that it has the same effect. With float at 13.2 or 13.3 no charge will enter the Li bank, and they will discharge until approx 80% and stay there. This can clearly be seen on monitoring.

I have a 40a sterling charger, and (from memory) have set it to 14.0v bulk, 13.4v absorption, and 13.4v float. Basically so it charges up to 14.0v then cuts off and maintains voltage at 13 4v. Only every used it to test the settings though, why bother running noisy generator to put 40a in when our quieter engine puts 90a+ and gives hot water!

Victron BMV?

Now our system has settled down and performing as we like, we don't bother with ours either. They just sit there and work! No interventions needed from us at all (other than remembering to charge them occasionally in winter!).

@Craig Shelley Very interesting. I'd be interested to read more about your system, particularly the alternator mods and what cells you're using. Interesting you've not experienced the need to do further balancing, I know we have and @Dr Bob has had problems with cells going our of balance towards end of charge. I wonder if it's down to different charging regimes or that we're using used cells?

I di really like MP's setup. Bit too complicated for me to design and install myself though, although if my design and programming skills were better, it's certainly a system I'd seriously consider. One of the problems is that of liability. If the BMS you designed or spec'd was to wreck an alternator, or worse, a set of (new) lifepo4 batteries at a cost of several thousands who would bear the cost? And having seen the state of some boats electrics I wouldn't want any system I designed anywhere near them! Our boats electrics were bad enough, and that was an ex-hire with recent BSS. Even assuming a new build so no previous LA batteries to use, I'm sure if you can afford a victron setup you can afford to add a small LA battery! You also need to add your own charging sources, fuses, distribution system etc, where do you draw the line?

My system is probably more complicated than it needs to be as I use a external alternator controller to control charging. The problem with using relays, is the continuous current draw - particularly high power relays as would be needed for main boat services. As to useable capacity, we generally use between 30-90%, but that's just convenience. They're so reliable that we got caught out the other day. We've got used to solar keeping up with our needs, together with an hours charge or so when filling with water. Couple nights ago we had an alarm going off during the evening as batteries had dropped to 20%! No worries though, silence alarm, and charge back up next morning when they'd dropped to 10%. We also occasionally charge to 100% which resets BMV, often when cruising or going for pumpout. Charging to 100% doesn't necessarily cause damage, provided cells are well balanced and voltages are kept within limits, it's storing them at 100% that they don't like. See comments above re cheap bms you mentioned. Most similar types have totally inappropriate voltage limits, which is the main problem using them. If I was to install another system, I'd probably use this together with a couple of bi-stable relays such as thiis (often available cheaper 2nd hand on Ebay - try searching for bds-a, Ford battery disconnect, v23130, or 6C1T10B728). For monitoring, I use Victron BMV to give SOC readings, and alarms. If paralleled with lead acid start battery during alternator charging, that would take care of alternator damage if disconnected, and other charge sources could then be set with appropriate voltages and you have a working system. Only extras you might want is balancing and cheap cell voltage monitor with alarms, but that's not strictly necessary. I did find cells tended to drift a bit (probably due to not being very conservative with using available capacity) so now have this installed which seems to keep cells very well balanced. I didn't bother with temperature protection - if batteries are less than 0c then I've other problems to worry about such as burst pipes, calorifier etc. Mine are installed just inside back doors in bedroom, opposite side to calorifier with central heating pipes running underneath, and skin tank at the back. I don't intend to let bedroom drop below freezing! If away for few days then they won't be charged anyway, but as above, bigger problems than batteries to think about if boat ever gets that cold!

Something often stated on here and I don't necessarily disagree, but is there actually any evidence or personal experience of this? Particularly in regard to 3rd party claims? My gut feeling is they probably wouldn't bother to invest the time and effort needed to investigate. I can understand for drunk driving etc, and claims for your own vehicle, but suspect for 3rd party only claims, with no obviously suspicious circumstances they would just pay out. As in fact they do for nearly all 3rd party claims, even if alcohol or drugs were involved, and I can't imagine they'd have much success trying to recover losses from the driver. In regards to a claim for damage to your own vehicle or property, that's entirely different, and yes I agree, they would try to look for excuses not to pay out!