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 hi everyone jeff cote here with  boatingtechtalk.com uh we've got   a question from a fellow voter uh gregory asked  jeff i've got a perkins a 50 horsepower diesel   with a victron orion tr a tango romeo smart 12  to 12 meaning starting voltage is 12 volt output   voltages 12 volt 18 amps isolated dc to dc charger  work well with a ball mark 100 amp alternator   to charge a 400 amp hour dakota lithium  battery bank okay lots of jargon in here   uh let's sort of demystify the darken right for  all of us because once we demystify the jargon   then questions make more sense so for context uh  gregory's telling us that he's got a diesel engine   and he's got a 100 amp alternator onboard  a bulmar 100m um and his challenge is how   does he get his 100 amp alternator to recharge his  lithium battery bank so what gregory doesn't tell   us in the question but we can safely assume and  we've got to put some parameters here right uh the   parameters are that most likely his alternator is  directly connected to his engine battery and what   gregory's trying to do is he's trying to share  the charging voltage from that bulbar 100 app   alternators running off his perkins 50 horsepower  engine he's trying to share that charging voltage   with his house battery bank which is made of  a 400 amp hour dakota lithium battery bank   all right so that's why gregory's choosing  a 12 to 12 dc to dc charging converter right   smart he's going with an isolated model again  i we most most of the times we choose isolated   now the rate limiting factor here is 18 amps you  know i'd have to say gregory an 18 amp charger   you know if your alternator is opening  100 amps and you've got an engine battery   most of that capacity is not going to be needed  with your engine battery so your lithium is   only going to draw about 18 amps out of that  available 100 whenever there's a charging voltage   so it will work but it's going to take you a long  time it'd be like filling out an olympic pool with   a tiny garden hose right 18 amps is not a lot of  power that's why you have 100 alternator imagine   having an 18 amp alternator not a lot to brag  about right there's no set i mean generators maybe   have a 10 15 20 amp 30 amp alternator it's tiny  so it will work but it's going to take a really   really long time and it would be aggravating  to run that alternator which is decent size to   only get 18n so i would suggest to consider a  30 amp alternator a 30 amp a dc to dc converter   and some folks would actually install two of them  in parallel so that you can get a net 60 amps of   charging because remember your 100 amp  alternator is never going to output 100 amps   not when it's hot that's a cold rated output  so you're generally going to see about and   again assuming that you have a smart external  regulator which you should uh but if you don't   you know you're looking at you might get about  80 85 ounce tops out of that alternator once the   alternator is hot and less if it's internal  regulated because it's just overly cautious   so i would say you know if you've got a smart  external regulator on that ball mar then i would   suggest to consider the 30 amp model and you know  on some boats we actually installed two of them in   parallel i've done three in parallel so there you  go good question gregory um good on you to think   about that uh because we can't and this is very  important for all of us because otherwise we're   gonna learn the hard way it's much easier to learn  from others than ourselves right making our own   expensive uh sort of discoveries or mistakes um is  that when you have an alternator an alternator is   set to only one charge profile right so it  can charge agm it can maybe whatever it is   but if you've got mix and match battery types  one battery type agm or lead ass flooded lead   acid for your starter and then a lithium for your  house many of us are going to basically share   that alternator via dc to dc smart charging  converters just think about the size um because   otherwise it's just going to take forever for that  engine or that alternator to recharge the house   battery bank via a dc to dc charging converter  so great question gregory thanks for asking   all of you out there that have solved this  problem share please you know what i mean   that's the whole point of doing this i learn as  much from you as you do for me by the way um it's   amazing i read every single comment that gets  posted the good and the bad and you know what   it's it's worth it because uh i learned something  every time i go on that site and i see what you   share so thanks everyone for doing that all right  and keep watching if you're curious we've written   whole articles about this go on our website  search it out and we've got a lot of other   tech talks about this very topic if you haven't  subscribed to this channel please do it actually   it really does make a difference it encourages to  keep posting so if you're watching this video and   haven't had a chance to subscribe we really do  care because the more of you that are watching   the more of us over here are willing to spend  more time in creating content so thanks again    Tools  Tools