So It's looking like later in the month I will have the money to buy batteries. And when the wife says yes, I must, otherwise who knows when the opportunity will come again. There has been a lot of debating on what to run, not just on my part, but what is needed per sortie or per battle. I have made a spreadsheet and have priced everything out, with shipping, and broke down the costs per back. some you can tell are per sortie, others may be per battle, but what really matters is what how much of what I'm buying. I do want to plan ahead some, being that my 4th built ship I want to have a 6+ unit ship, but at the same time I need to keep the cost down. If there isn't anything that makes sense on the spreadsheet, I probably have an explanation, at least for a little while until I forget why I put it on there, lol Anyways, I'm looking over that sheet, and I think my best option is to go with 4s Lipos. I can get 8 of hardcase 4s 5ah lipo for $262.48 with free shipping from hobbyking. I could run 2 together in the Australia for a total of 10ah or 148 watt hours. I would also have enough to swap between each sortie, and go for 4 sorties without having to start charging them. Everything currently in my boat should be able to handle the higher voltage of a 4s pack. But I do have other options I've looked into, and everyone has an opinion. I just need to decide what would be the best option, and would like to hear those opinions, whether they are a thought of option or not. One thing I would like to note though is that my current motor in my bilge pump didn't run fast enough on the 2 cell 20ah prismatic. I'm looking at higher voltages which seems to have solved the problem. I tested it in my sink with a 6 cell NiMH and it worked fine, I will be testing tomorrow fully installed in the boat outside and slowly pouring water into the hull and see how it does. I can always switch pump motors, but if I do that, all 3 motors in my boat would not be the same.
4s LiPO is going to be 14.8v, pretty high for any brushed boat and on the upward end of what some of us run in our brushless ones. Even 3s lipo some say is too much for your average brushed motor boat, resulting in motors being burned out much earlier than normal usage. I run Zippy brand 11.1v 3s 8000mah packs in everything I own. I made the choice to standardize my boats on that pack. 1 pack in a cruiser, 2 packs in a smaller battleship/battlecruiser, 4 packs in a large battleship like my Jean Bart. They are very energy dense and I was able to pick up a bunch of them on sale for like $26 a pack. If you are thinking of standardizing on 5AH packs, which is a good idea, the best deal on Hobbyking right now would have to be these guys: (USA warehouse) https://hobbyking.com/en_us/turnigy-battery-5000mah-3s-25c-lipo-pack-xt-90.html or these guys if you dont mind shipping from CHYNA: (https://hobbyking.com/en_us/turnigy-5000mah-3s-20c-lipo-pack-xt-90.html) 8 of those would be cheaper than the option you have picked and be a more reasonable voltage. Hard case, in my opinion, is not necessary. If you are worried about the soft side packs being damaged in battle, most members have started building small wood boxes in their boats to keep the batteries shielded. This also has the side effect of making sure the batteries don't move around. I double up the internal armor around the battery spaces and make sure the armor rolls under the batteries at the bottom and over the batteries at the top to create a good shield. Hard case batteries also don't warn you when they are starting to go bad...you won't notice the "puffyness" of the battery at all until the battery, now trying to force its way out of the hard case, finally decides to let go.
LiPo batteries can be violent when breached and don't react well to water. LiFe are generally less reactive. I use LiFe , and keep the camera ready to record LiPo ships when they go POOF.
The motors I bought are 24v motors, so my bilge pump doesn't work like it should. I looked at 4 cell lipos to fix that, as it worked fine on 7.2, so i figured the closer to 24v I can get, the better for the motors I currently have installed. IIRC, the hard case 4s packs were only a few cents more than the soft ones, but that is non-issue for me, any pack is getting extra protection. Same with Capacity standards. Right now I am looking for batteries to power my Australia, I do have my Posen and Duca, but my main concern right now is getting my own set of batteries so I can quit borrowing them. I didn't have much time to work on this sheet, I got home from work at 7:15 ish and after talking to the wife for a bit, was told to start looking at batteries, made the list and had posted this topic (8:38 btw). I figured I would start with a general list of what cells GLAS uses, and went from there. not much time was spent looking at hobbyking or other places. LiFe is still an option on the table. I need to check sizes, but if I can, I can standardize with the GLAS group and I'd run 2 packs of the 2 cell 15ah LiFe cells. Other than the size though, I think the only problem, which can easily be solved by just installing a part, is not having a voltage cutoff. I do have a voltage telemetry module, I just need to waterproof it and wire it in once I figure it out. the 3 cell 10ah batteries on my list also look like a good cost to battery ratio, 96 watt hours, so 1 sortie, 4 total packs for 4 sorties, all for $236.82 shipped. Though for only a few dollars more, I can make some 8 cell NiMH packs for the same watt hours, same 4 packs for 4 sorties as well. And yes, LiPos can go poof, I know that, I had flames nipping at my eyebrows back in the racing days cramming 5 guys and one of their kids in a tiny pit room. The kid forgot to plug the balance lead in and the charger switched over to NiMH. When it went off I was so close that I lost all thought on what to do and was dazed by the pretty dancing flame, lol. My current LiPo's get stored in a surplus ammo can. I would need something bigger for the Life Cells though.
Any idea how much power your boats consume in a sortie and what is the max current draw is? (excluding short circuits and stalled motors, etc) More battery isn't always better, even more true when it comes to battery prices.
I don't have an exact number, or a way to tell currently. I do know I ran Craig's 20ah Prismatic LiPO4 cells, 2 of them in series. I was able to go 2 sorties with them. I do need to think about motor swapping for the bilge pump, or higher voltages for the currently installed motor, it being a 24v motor, it is rated for 19,300rpm at 18v. I've been told several different things about what capacities and watt hours I should get, and the conflicting info made me put planning for batteries on a back burner until I had a fully working ship with most of the kinks worked out.
I suppose a motor swap could also be of value to buying batteries. My current motors do run on 6v, and work fine for drive motors, however, they are operational on 6-24 volts, with 12-24 volts optimal with peak efficiency being at 18 volts. It's listed with 85 amp stall, 70% efficiency, no load RPM of 20,000 with RPM Peak efficiency of 17,000.
You are asking the correct questions. look at true voltage needs first. while motor RPM and efficiency are rated best at certain voltages, the fact that yours run well in drive with 6V and for pump on 7.6-8 tells the story. 6 cell NiMH is similar to 2S LiPO but 2S Life ie, prismatic is more like 5-6 volts. sounds like your present needs run to 2-3S LiPo or 3S LifePO. In fact, 2S Lipo is the voltage equivalent of what you say would be fine with your pump. That higher voltage on drive with the same motors can work well you just need to adjust throttle endpoints. 3S would give a nice extra kick to the pump but might get harder to handle for drive without a motor change. or you could use 2 S for drive and 3S for pump. all legit options. 2S is fairly cheap and might be your best option. the prismatic are large , expensive, and lower current handling for their capacity. For capacity, Snipe is right. check your current usage and recharge numbers. That said, after 20 years in the hobby, I have found that ships under 15 pounds do well on 12v 5 Ah or 6V 8-10 Ah batteries Hard case Lipos are nice and I have used them for prob 6 years in various ships. that said, most of us build robust battery boxes - mine are epoxy impregnated 1/8 inch masonite - and with this extra, hardcase protection may not be necessary. I will prob go to Will's suggestion of non-hard case in the near future. I am seeing significantly cheaper prices and larger selection on the non hardcase types during my research over the last 2 weeks. I saw a 3S 5000 mAh Lipo for $18 - ie, $144 for your 8 batteries. might be easier on the budget. Most frequent failure mode of all of these is not a horrible fire but a puffy pack. I have seen as many with LiFePos as Lipos. just my experience. Good Luck.
At 12V expect to consume 1 - 2 Ah for drive and 1 - 2 Ah for pump per sortie (less if you keep the Prius pump). 3S LiPos are probably best choice, can always get one battle's worth and recharge between sorties / battles via car battery with DC charger or standard AC charger if power is available
so the 10ah life cells will be fine if I ran 3 or 4 cells. Standardization with GLAS and planning ahead, If I get better motors, I could go with the 15ah cells as a 2s and be fine for a battle then.
Everyone here is saying pretty much the same thing, 3s 11.1v LiPO 5000mah packs. 2s LIFE is going to be 6.4v when the hobby as a majority is moving away from 6v boats. The LiFE bricks are hard to fit in smaller boats at the voltages you want to run (11.1+) and don't have very great discharge characteristics vs the much smaller, cheaper, easier to get LiPO packs or even Zippy LiFE packs. You will be hard pressed to fit 4 of those LiFE bricks in an I-boat.
If I go LIFE, I'd get the cylinder cells like the Glas guys use, not the square ones, but 2 of those do fit perfectly in the Australia. But I think I might go for the 4s. it's pretty much the same price as 3s, and I don't have to swap anything. However, with that, I may settle for 2s packs and can run those in parallel or series, and decide on that later, or whatever pump motor I decide to run. I only want to plan for my current ship, the Australia, and bigger ships. I do have the Posen to contend with, but I would guess that I could fit the same as the Australia. I have a plan for smaller ships (Duca) that should be quite cheap, and is farther on down the line anyways.
What! Do I have to build a steel box for my little cruiser batteries when I drive halfway around the planet for nats?. R
my local harbor freight has them for sale for like $2.99 most every time they have a sale. they work great. I think I'm going to get a few more and modify them to have some kind of fireproof grommet to feed charge and balance wires through.
What would be the ideal watt hours per sortie to aim for? I ask, because here is a $10 4s pack https://hobbyking.com/en_us/multistar-high-capacity-4s-6600mah-multi-rotor-lipo-pack-1.html only a 10c rating, so 60 amps, but sounds like a boat should not pull over 50 amps, as from what I've gathered, amp draw on these boats are tested with a 50 amp meter
It looks like an older style Multistar. The newer ones have different outside wrappings. 10c "should" be enough if you have drive and pump running off same battery. Definitely should be enough with pump and drive seperated. I like my 240a discharge rate for ultimate fire-starting potential.
