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hi everyone we've got a question from Adam fellow border who's got a 900 amp hour lithium battery Bank boater goes on Adam goes on to saying I've got 200 amp Alternators on my crusader 454s both engines are started by a single lead acid starter battery one alternator is connected to a battery isolator which is also attached to my house is this setup safe for my alternators I heard lithium can overheat alternators but so far they don't seem to draw any power whatsoever from the alternator lots of questions to unpacked there's a lot going on here so first of all when you're talking about lithium batteries and alternators the reality is in the past flooded lead acid batteries and AGM lead acid batteries their acceptance of their car so charge acceptance rate over time would diminish dramatically that even though the battery was drained its ability to take a high rate of charge would diminish greatly over time as the battery heated and as you would be recharging the battery more and more it's a little bit similar to when I'm thinking about my own appetite really as I eat more I feel less hungry and I eat less and a battery a lead acid battery and uh AGM battery would do it you know you start your meal you're starving you're going to eat a lot down but eventually you're going to slow down a lithium battery doesn't do that a lithium battery can pretty much take for most of us pretty much everything you can throw at it all at once all the time till it's full and then suddenly full then it stops the reason that's hard on the alternators is the alternators are going to be working now with lithium for not necessarily a longer time but they're going to be working intense the whole time until it's charged and that intensity creates Heat and heat on an alternator can get transferred depending on the side loads on the alternate can be transferred to your water pump via the pulleys there's a lot in the alternator if it's working really hot there's not a lot of ventilation alternators do die on boats it's one of the most common items to fail is a alternator that's worked really hard but when it comes to lithium you've got to make sure that your alternators are basically ramped and overspeced for what you expect them to do because otherwise an AGM and a lithium battery don't sound the same thing not at all and they're not so what worked for an AGM or lead acid battery is unfortunately not going to work always when we switch to lithium so sizing your alternator or limiting your alternator by putting an external regulator and limiting the field voltage so you say hey you know what I only want my alternator to Output Max 70 or 50 percent of its rated capacity so I don't ever it's like running your car with a Redline 6000 RPM all the time you can do it until your engine blows up but that's basically what you're doing with an alternator if you're running your alternator basically a Full Throttle all the time when you're running it eventually something that's going to happen and your alternator is going to die so that's a reality with lithium and that's a good question by Adam um it gets even more complicated and then he says well can what happens are my batteries safe with this setup so the setup that Adam describes is it he has one starter battery connected to two starters so that's the way their setup is one alternator sounds like it's recharging it's the engine battery already and then he has a second engine that alternator connected to a battery isolator and that battery isolator connected back to the engine battery and back to the house already there only one of the engine can obviously recharge the house battery and that would be the engine that connected to battery isolator which in turn is connected to the engine and house pretty odd pretty odd that uh when that engine is running the alternator output would not affect the battery capacity of the lithium battery that's not normal so there might be an issue in the wiring and the battery isolator or in the alternator but certainly what I would advise Adam to do is just run one engine the one that's connected to this battery isolator and Adam needs to see a charging voltage go into the house battery if Adam doesn't see one then it's not working the charging voltage has to go up and so remove all charging sources solar panels battery chargers whatever it is that you have on your boat that's a source of power and then basically start the engine monitor the house voltage and that house voltage has to go up after a period of time let's say 60 seconds once you're at 1200 RPM or 1600 RPM rev up the engine a little bit and then once you're going to see whatever it is you want to make sure that at one point when on that output curve you're actually seeing a charging voltage now the other issue is that battery isolator might cause a 0.7 voltage drop so depending on what the output of the battery of the alternator is you might be getting less of a charging voltage on your lithium so the battery isolator might not be the right choice it gets our another little subtle question in there how do I know that my setup is safe and that my alternators are not going to blow up there's really the battery isolator is going to allow for sure and that's a good news that the alternator is always going to see two batteries it's going to see a lithium battery in any GM battery so if the lithium says I'm too full and the BMS says enough I can't charge anymore you've been running that engine for too long my battery's topped off I I don't need more power if it ever disconnects itself the good news is in your setup you have a battery isolator in between the alternator and the house and so if the house takes some itself out of the circuit at least the engine battery is still going to be there and your alternator won't suddenly die because it got instantly disconnected from the battery it was charging in this case you've got two battery Banks so that's a win the flip side is a battery isolator is not a device that modifies the charging voltage so whatever your alternator outputs minus the cost for efficiency so there's going to be a voltage drop in that is pretty much what both the engine and house battery are going to see so you're basically going to be charging your battery bank for a standard lead asset profile and the lithium is just going to get it and so the question is well how is that lithium battery going to react to being charged on a lead acid charge profile all the time so that would be something to consider in atom setup and with lithium you know what it's it's a little scary but it's not I think the what Adam is doing is good is being curious and wondering about the implications of our choices and in the right direction and that's why we have this channel is just to start sharing those right I mean it's everything's pros and cons and you got to weigh those pros and cons the good and the bad to make sure that you create a system or solution for your boat that is going to mitigate the cons and promote the pros so that you can have something that's you know reliable and safe overtime so great question from Adam and uh for all of you watching thanks for joining me and be safe out there 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  Co