I'm thinking of 2 300 AH LITHIUM batteries with a200 Ah BMS. The question is all the lithium battery folks say not to use them for starting, as the load is to great. With that said, we all know know that there are times that the boost sw is necessary to
Make good things happen. Has anyone had any issues doing that? Just asking questions before dumping a bunch of $$&, and the having oh by the way problems. Thanks
Not with the 3 200 ah ones I have.
Just trying to cover all my bases, don't need any O S$&@T moments.
Look at the max current limits of the batteries you are looking at. I had considered lithium's when I did my house battery replacement a few months ago, but stuck with AGM's. The Battle Born 8D lithium's are rated for 300A continuous, 500A for 30 sec and 500A+ for 1/2 second. With two, that would give you an additional 1000A for cranking when needed.
270Ah 12V LiFePO4 Deep Cycle 8D Battery | Battle Born Batteries (http://battlebornbatteries.com/product/battleborn-270ah-12v-lihtium-deep-cycle-8d-battery/)
I have not timed how long my starter turns before engine starts, but I would think it would be more than 1/2 second
My understanding from the manufacturer I went with is that they should not be used for starting. I went ahead with the installation and took a three month trip across the country. Thank goodness I never needed the boost. I will use it in an emergency.
I just put the start batteries on a trickle charger when we parked for over a week at any one spot.
When I bought my coach, they were using the boost (Gel Batteries) to start. I just cleaned and tightened connections to the battery and starter until it started more easily.
I am apprehensive of using the boost with my set-up. I have not needed to as of yet.
-FT
Been using boost to start the ISM almost exclusively for 4 years with my 6 100 ah Battle Born house cells.
Electricity takes the path of least resistance so with the start batteries right next to the starter, and the house batteries 30' away, the lithiums are the path of most resistance and the start batteries pull most of the current. i.e. in boost mode, the BB's are giving a voltage boost to the start batteries more than a current boost. Prove me wrong.
500A for 30 seconds. 2 batteries = 1000A for 30 seconds...plus your chassis batteries. Still not enough?
I'm running 4s 6p 3.1v 120 ah lifepo4 for a total of 720 ah. That is 24 cells in the bank. I can put 2 more banks in the space. Also I use a 200amp bms. I use the boost switch on the first start of the day. After that the red tops work fine. No problem with the lifepo4 so far. As stated it is about the surge 14.6 v . My ISM turns real fast with the boost. Probably going to change the starter to a gear reduction in the future.
I'm curious why you think your healthy chassis batteries need help from the house bank. Most class 8 tractors with engines bigger than yours only have chassis batteries.
Gel cells have a lot of internal resistance compared to flooded or lithium cells. If you haven't spun an ISM with stock starter, boosted by the house bank, particularly 13.5V lithium house bank, you don't know what you're missing.
With 720 ah of lithium there's no spinning ( if boosted ) I can barely let go of the key fast enough. But then I do have over 2400 cold crank amps for starting.
Rarely need to boost....