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hello hello everyone uh welcome to boatingtechtalk.com i'm jeff cote and we've got a question from a fellow voter from idaho so toby asks jeff i've got a house battery bank of four group 31 firefly batteries they're about four years old and i love them hey congrats however in the four years that i've been living with this size battery bank i've learned that my capacity is adequate but not optimal okay i think my life would be enhanced by adding more capacity to my battery bank yes bigger battery bank will enhance our lives well said um now is this possible practical at this point um or am i pretty much locked into my existing or current configuration great question toby batteries are a little bit like car tires or vehicle tires um you can't really change one tire when you have a set of tires that have aged right so it's gonna cause uneven wear so what that means is that generally if you have a battery bank that's you know like in this case four years old and it's not time that makes things worse it cycles right so the number of cycles we use that's the true aging of a battery bank assuming it's been well kept and always on a charger of course but really that the question here is how many cycles right now the advantage of fireflies they say a lot of cycles are available right that's one of the advantages of battery is that you know you can get a lot of cycles from them but that being said i've never mixed and matched a battery bank or enhanced a battery bank um after four years now if the batteries have been on board for four years never used probably yeah you could you know it's not ideal um but probably but with four years of use and if you use the batteries you know and they've cycled you know maybe 50 100 times a year um then that's going to be too much and certainly if your batteries are a light acid even agn it would be a definite note it's one season and that's it so here's the explanation or like the reasons of why we're seeing this as a problem is the moment you put a brand new battery with old batteries the brand new battery is the moment the charger is removed the resting voltage of the new battery is higher than the resting voltage of the old batteries and so what happens is you end up actually having the new battery try to support rise up the older batteries and it can't so basically a new battery just gets discharged to meet um the lower voltage of the other batteries and so in the end you end up wasting you know it causes your new battery bank to really age prematurely be one way of describing it um so good question toby but i would be on the fence and you know only if you've used the batteries very very lightly like 10 times 10 cycles a year then maybe you can get away with it maybe but the manufacturer would say otherwise and the textbook would say no so you're really on the fence on that one great question and thanks for asking anybody of you have tried mix and matching battery banks share your story has it worked out did you get as long a battery life as you expected or did it completely go sideways let us know we're all here to learn thank you 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