Anyone convert a Mako to LiFe

[logandzwon]

Hey everyone,
Has anyone replaced the batteries in. Mako with a LiFe pack? I don’t mind assembling my own battery pack; I’ve built them for other things in my R/C days. I have two big questions.
(1) I’d certainly like advice on which cells are best for this.
(2) My biggest concert is that I think the weight difference would make the DPV very positively buoyant. (I know I could just add weight, but my biggest goal is reduce dry weight of the DPV.)

 

[tbone1004]

1-Powerizer LiFePO4 Battery: 24V 10Ah (240Wh, 40A rate) --- Replace SLA 24V 10Ah with 4 times cycle life, lighter weight -- UN 38.3 Passed (DGR)
Battery space has confirmed that this can be run in parallel. You will likely have issues with the higher voltage though and may have brushboard problems. If you're doing that, I would highly recommend upgrading to the newer brushboard from Silent Submersion because the extra heat and power will cook the stock ones. That said, it may be less effort and not much more cost to just replace the motor which will get you some extra speed since the brushboard is almost $300

2- buoyancy doesn't work like that. The scooter displaces some volume of water and to keep it neutral, it has to weigh the same as the water it displaces. Surprisingly something as little as 1lb is VERY annoying underwater whether it is positive or negative so you really need to keep it the same weight.

 

[logandzwon]

Thank you tbone! That is great info, but I have a couple follow-up questions.

(1) I was under the understanding LiFe put out similar voltage to SLA, and that was only a thing with LiPo. Am I mistaken?

(2) I get it needs to stay the same buoyancy. Whats what I asking is if anyone has a suggestion to make the dry weight lighers while maintaining neutral or slightly negative buoyancy. Like, is there some sort of lightweight material I can fill some of the body cavity with to displace air?

 

[tbone1004]

@logandzwon
1- the voltage drop under load is where the motor will spin at a slightly higher RPM. Not a huge change, but it is there. It may not be an issue, but it will eventually cook the brush board.

2-replacing air with something else is just adding ballast, the only way to reduce dry weight is to reduce the non-compressible volume, only way to do that is to make the body physically smaller to displace less water. Filling what is inside of the non-compressible volume with something other than air is just replacing air with ballast and won't reduce how much it floats.