Charging Lithium and Lead Acid Batteries on a Catamaran
Transcript is auto-generated.
[Music] Jeff Cote here with boatingtechtalk.com we've got a question from a fellow boater Manny asks Jeff do you have any advice on how to design a charging system for a catamaran specifically Manny continues to ask combining two alternators to charge three battery Banks while sailing and charging using Shore power at the Merino and Manny keeps on and goes on and says Jeff I've got two lead acid starter batteries and one lithium house battery Bank okay all right there's a lot of information here to consider right first of all with a catamaran a little bit similar to power boats that have dual engines right you're gonna have basically debt you should have dedicated starter batteries for each engine which Manny does good now they're lead acid and that's in contrast to the lithium so there's going to be complications here on how do you recharge using an alternator something that is lead acid and something that is lithium so that's going to be an issue that we're going to resolve and then also questions about how do you have three battery banks with only a single let's say inverter charger and how do you charge three battery Banks offshore power okay well let's start with first things first let's start off with Shore power Shore power in a boat like a catamaran or actually again this would apply to other power boats that have got dual propulsion system right which is not uncommon for many power boulders the first thing you want to do is you'll probably want to have because inverter charger is only most of them only have a single connection to the battery bank and some of them have maybe an auxiliary but it's quite hard nowadays they used to in the past like sand tracks for example but nowadays you're not going to be able to use an inverter charger to recharge three battery Banks it doesn't quite work like that so one suggestion is to install onboard and most likely a lot of you if you're going to have a boat of that size with dual propulsion you might have an inverter charger so if you've got an inverter charger I would have my inverter charger and especially the charger profile of my inverter charger just charged my house battery bank which is lithium so again dedicated inverter charger to Dedicated lithium that makes sense but what about my auxiliaries what about the starter batteries well the starter batteries going to be charged from Shore power via a small little dedicated charger so it could be a 20 amp 30 amp 40 amp that small little sort of auxiliary charger and we see that on some boats you might have even a generator on a catamaran and so it would recharge both the engine port engine starboard and generator battery and generally those batteries are not going to be lithium they're probably going to be lead acid now it could be flooded could be AGM but you know so install a secondary a dedicated small charger that is meant to recharge your starter batteries so again the port and starboard engine batteries and maybe even a generator battery so so far we've got an inverter charger for your lithium because the battery is lithium and you can configure your inverter charger for lithium and then we're going to have a small auxiliary charger for your charging batteries for starting all right so far so good but now the question might be well okay Jeff great so we've got this sorted out when we're connected to shore power or running a generator but what about under propulsion what about how do I get my alternators which are most likely connected to my engine batteries and how do I have my engine battery and my alternator on either side recharge my lithium battery well the way to do that especially when you have different battery Banks chemistry in this case Manny has lithium and also lithium and lead acid well then okay so then maybe what you want to consider doing is installing what are called DC to DC smart converting devices right so these devices and victron creates them and we have a whole section on our website check the links what it does is it says okay well I'm seeing a what I consider being a charge voltage at this battery so a charge voltage assuming that your starters are 12 volts could be 24 but let's assume it's 12 volts if ever we Sense on the anywhere on the engine battery a charging voltage meaning that somehow maybe the alternators are working and charging the batteries above let's say 13 4 13 3 then maybe you want to share that charge and have it go to the lithium but the lithium won't want the same charge profile as your lead acid battery so you need a device that is going to basically be a DC to DC device but also has some intelligence so it needs to be a device that actually looks and says okay well what does the lithium battery need and should it have what the lead acid battery does and most of the cases it's no so there's going to be some adaptations there's going to have to do something from what the lead acid battery is getting which has its own alternator with its either external regulator or internal regulator and then take that and convert that to the right voltage that the lithium battery wants to recharge now the limitation with that is that these DC to DC charging converters are generally not we're not able to install them or procure them with high amperage so you know some instances where let's say for example it's a small alternator you only have a 50 amp alternator well you might only put a 30 amp and that's basically now in 2023 is basically the max size is about 30 amps and so on some boats where we want to share more alternative power let's say you have two 100 amp Alternators on either side you're like well why would I limit myself to only 30 30 when my engine batteries don't need more power and I want to take all that extra power and I want to redirect it to my lithium well in some instances we've installed two three so we'll actually put stack them one on top of another not literally but like effectively have maybe even three of those devices go from starboard to lithium and then from Port to lithium and so we'll have three to three DC smart charging Converters on either side to be able to utilize the power from the alternator especially once the engine battery is full to have that power go back to that house lithium battery and general Strokes that's basically how we solve multiple engines or charging sources for alternator to go back to lithium and that's also how we charge having different chemistries on a boat is to have different types of chargers for different types of batteries so if you've got further questions about this topic put post your comments below and see if the community can help out a little bit we're curious to see what kind of challenges you're facing and we've also have different write-ups on this on our website so let's geek out and make our boats better and more reliable thanks for all of you for watching we appreciate it so if you're curious again go on our website and find out more answers and solutions with this sort of setup and thanks for asking and thanks for all of you for listening and tuning in English (auto-generated) Videolytics Tools
