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      hi everyone we've got a question from a       fellow boarder named matt       matt asks jeff i have three battery       banks on my boat a lead acid starter a       lead acid thruster and an agm       bat house battery but eventually i'd       like to upgrade to lithium i'm looking       at buying a balmar          uh     amp with an external regulator       m        mc             what would be the best setup for       charging from the alternator happy to       install an additional kit       i also have solar installed       i have an ac charger that will also be       upgraded in the future to an inverter       charger       well matt asks it's a pretty open       question right because currently the       setup is lead acid on two batteries agm       on one thinking of going lithium later       on doing     amp alternator external       regulator existing battery charger being       changed to an inverter charger       there's a lot of meat here i'm not sure       i'm going to be able to cover it all       within one tech talk       so if you've got a single engine and       you're looking at recharging let's say       three battery banks       one way of doing that would be a battery       isolator a one to three but the       limitation with that is that       the battery isolator does not modify the       alternator voltage so whatever the       alternator voltage is coming from the       alternator       uh that is for one battery type only so       if you have lead acid lead acid and agm       you're going to have to pick       you're going to have to decide which one       of the batteries that is connected to       that battery isolator is the most       important to you       and can the other batteries tolerate       either being undercharged or overcharged       because most likely the charge profile       for different battery chemistries is not       going to be the same battery voltage       so the first step is generally to have       all batteries be the same chemistry       especially if you're going to use a       battery isolator       alternatively you could look at what are       called dc to dc charging voltages and       that might be a good way for instance in       this setup is to have your house battery       bank recharged from the alternator and       that could be a lithium battery bank and       then having the lithium battery bank       share its charging voltage via dc to dc       charging converters and we have those uh       on our website with lots of talks about       those as well       and then has basically lithium charged       the lead acid house and have the lithium       charge the lead acid thruster and to do       that by       each one of those battery banks the       thruster and the engine battery having       dc to dc charging converters connected       to them       now the good news with that is that you       can actually rate you can actually       configure what charge profile you want       so even though you're coming from       lithium you can modify the charge       voltage so that it actually gives your       lead acid starter or lead acid thruster       battery the right voltages that it wants       so that's definitely one setup       now again same problem with a battery       charger having a three bank output       battery charger in this instance i would       keep it and have it recharge my thruster       and engine battery and then i would       install an inverter charger       and that inverter charger would be meant       to recharge either my current agm house       battery bank or your future lithium       house battery bank and that's how i       would do that as well your external       regulator that is connected to your ball       bar alternator should be configured with       a lithium charge profile       and it should be directly connected to       your house battery now that being said       if ever your bms on when your lithium       battery disconnects your battery because       of overcharging or whatever the       condition is       and you only have       one connection from your alternator to       your lithium and suddenly your lithium       battery disappears because your bms       decided to protect the battery and       disconnect the charging bus       or the battery itself       then you're going to lose your       alternator and so that is one of the       issues with having a high output       alternator connected to a lithium       battery bank without having more       another battery bank connected in       parallel the reality is all of us when       we bring lithium on our boat aboard our       boats are making compromises       on how we're going to go about       charging our battery banks       and many of us are making decisions that       have pros and cons there's no perfect       solution it's really about minimizing       the risks that we all individually       perceive on our boats       and so with the setup that i gave you       there       you're pretty much       protected for having different charge       voltages to different battery banks       having all the alternator power that is       required on your lithium but if ever       your lithium battery bms decides to go       say enough       you might lose your alternator in the       process so that is one of the downsides       and if you're curious about more lithium       setups google on our website or search       on our website we've got lots of setups       and lots of videos talking just about       lithium so great question matt and       thanks for asking