I ran across these batteries several days ago. Even though they are not as compact as the cells, I thought that with them being around the same size as SLA batteries they might be viable for our uses. https://dakotalithium.com/product/dakota-lithium-12v-14ah-lifepo4-battery-twin-pack/?v=7516fd43adaa
I don't have any experience with the lithium batteries and don't know much about them in general. Just getting up to speed with lipo's now and am looking to future possibilities
That is not what the specs say. That is what they recommend for long life, but is rated for 20a max continuous, which is still low, approx 3c discharge rate. if you want lithium then a prismatic is the way to go depending on the size of the ship.
I like the LIfE chemistry as it is a lot more stable and forgiving in daily use. Lipos can burn quite spectacularly if over charged, shorted, ECT. I have seen firsthand the effect of flash burns from a guy plugging in the wrong bullets. Shorted a 12 cell pack direct to itself. The life chemistry batteries are not so prone to the fires. Are able to be stored indefinitely at full charge without damage. Lipos require a storage charge and periodically must be discharged and recharged back to the storage charge level or they go bad. If a lipo goes below it's minimum voltage it's done. Forever. Toss it. Life won't go below that voltage from sitting unless you let it sit for 10 yrs or more. I have one I have not charged since I was in Alabama. 5 yrs ago. It's still good. Can't do that with a lipo. However. Lipos have a higher discharge rate and energy density. So each have their place.
Not always true. I have bought a brand new lipo before that came to me below minimum voltage. Did the unsafe trick of charging on low amps in on NiMH, which got it above minimum voltage for my charger. Was then able to fully balance charge it and revived the battery. Still have it even. And I still did that after having experienced an overcharge lipo explode right in front of my face
Those batteries definitely have too low of a C rating C rating is how many amps the battery can safely discharge per amp hour of battery. So a 5000mah 25c battery would give you a safe discharge rate of 125 amps. (5000mah = 5ah, 5ah x 25c =125 amps) The more capacity the battery has the lower C rating you can get away with. I have 5.2ah 10c batteries for my ship. That gives me a 52amp safe draw. However I run 2 of those together. It gets a little messy with that, I've seen it explained a few different ways. The way I understand is I still can only pull 52 amps from the batteries, but at where they connect I have 104 amps available. And 10.4ah
It’s on the spec sheet, but their recommendation is the same with any chemistry which is constant high load discharge can reduce the life of the battery. It’s not a guarantee but I think that using lower current to increase longevity is universal advice. I always look at the max continuous when evaluating batteries. My previous set of 20ah prismatic cells was used with dual pumps using titan 12t and they were in great condition and are still in use in MI today after 10 years. I doubt they have even come close to 20% of their rated cycle lifespan even today.
To increase the C rating you need to put the cells in parallel, to increase voltage put them in series. when I first put in two pumps with only two 20ah life cells the voltage drop was very apparent, and you could hear the pump drop in rpm when I switched on the second. I then added two more cells, put two of them in parallel (3c x 2=6c x 20a=120a max) then put that pack in series with another for a 40ah 6C 6.6v pack and it worked perfectly. The Titan 12T has a specific pitch when operating at full rpm and that is what I worked for and never looked back. this is not theory, I ran this for several years with no battery related failures. Granted I made a huge solid #00 copper bus bar... the whole system must support the current you want to use. I switched to lighter zippy packs with a 20c rating and to save on hazmat shipping.
While I am aware of that and have done it myself. I don't ever even mention it to a person who is not well versed in batteries. As it can get you dead in a worst case.
All my experience has been with SLA, X-Cell/Cyclon, NiCad and NIHM's. I personally prefer SLA batteries due to their durability and ease of maintenance. But in using them I am limited to larger ship sizes and with a bad back, not smart hauling all that weight around let alone the container of batteries. NiCad batteries are illegal and my experience with NIMN's is that they are very fragile. I made the move to LIPO's this past year and like the weight savings and the power. What I don't like is dealing with an unforeseen issue with a cell then having a spectacular fire in my boat. Looks great on video but very expensive. I knew it would be temporary pending my experience with them, but still am very uneasy about them. What is the go-to Lithium battery people use?
as a general referce, these are the batteries most people talk about from what I have gathered. 20ah Prismatic Cells https://www.batteryspace.com/lifepo...h-10c-rate-64-wh-6-0---un38-3-passed-dgr.aspx 15ah Cylinders https://www.batteryspace.com/lifepo...h-with-6m-screw-terminal---un38-3-passed.aspx I can't speak for buying from that place as I never have bought from them, but they do have good descriptions and pictures of the batteries. I do see they don't have the high C rating 8ah cells though, I think i heard something somewhere about someone(s) going to them because of the higher discharge rate. but i haven't seen it for myself the 15ah cylinders are made into 2 cell packs with balance leads and charged as 2 cell LiFe packs of course; the 20ah are just ran individually with a series connector for voltage. Others probably also vary that up with parallel or series connectors for different voltages. With the cylinders you could make a 3 cell with 2 on the bottom and one sitting between them if you wanted to go that route with a 9.6v pack.
Question for you with the LiFe batteries. Do you need to have a voltage regulator\limiter in line so the batteries do not totally discharge or is that covered in the ESC circuit? Thanks for the list of vendors Weston. Told you I knew very little about these types of batteries..
Treat the low voltage cutoff basically the same as a lipo. The best part of the life Batts is the very flat discharge curve. They hold voltage till almost dead. No slowly slowing down. But you cannot use a volt meter or load meter to gauge discharge state.
one reason I chose Lipo over Life is that the ESC I have has built in Lipo cutoff. It does not have a Life cutoff, just Lipo which has the cell count auto detect and cutoff , and NiMH mode with no cutoff at all. When I ran it on 2 cell Life, it ran on the soft cutoff, so it was extremely underpowered, and eventually hit the hard cutoff which cut out the drive capabilities, and I had to be pushed ashore. I could just have set the ESC to NiMH mode and it would run, however there was no cutoff at that point. Pretty much it's best to go way over on capacity and not worry about having a cutoff. I have the entire bow of my Baden that will be empty, so I am thinking I will try and fit 2 more batteries up there if I can. Then I'd be at 11.1v with 20ah, which should be way more than plenty for a sortie. Just means I would need 16 batteries for 2 battles.
