BlackTip Batteries

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Don't worry! It fits to Blacktip! The 20Ah battery dimensions as shown above, FYI! Travel is not my first concern, but the run time is more important to me. It is negative buoyant, and make a longer tube for compensation.
 
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Got my Blacktip from Backscatter two days ago, and have done my very first two DPV dives.

I built my own battery packs using Samsung E50 lithium-ion 21700 cells which are 5Ah and rated for 9.8A max discharge. Cost was 95 euros for 20 batteries, 28 euros for 2 housings and 1 euro for the nickel strips.
View attachment 631369 View attachment 631370
These cells are in a 5S2P configuration, allowing 19.6A maximum discharge, which means using the 8th gear is a no-go. I might create another set with 5S3P, allowing 29.6A max discharge with a total capacity of 15Ah, but that might be overkill outside of caves.

Battery pack 1 weighs 898 grams, pack 2 weighs 902 grams. Tried these yesterday without weight adjustments, but the DPV kept me dragging towards the surface.
I added extra weight to the nose with lead pellets and two extra lead blocks on the inside, total nose weight is now 2759 grams, resulting in a nose down, slightly negative buoyant DPV (in fresh water).

I ran it for 20 minutes in gears 3 till 6, voltage changed from 20.05V before the dive down to 19.48V and 19.30V after the dive. Both packs are still displaying 3 lights.


I'd love to hear what weight changes have been made to get the Travel neutrally buoyant and horizontally trimmed, for the specific battery packs you use.
 
Dumb question about the Blacktip... There's two PTB batteries, are these wired in Series or Parallel?

If in Series, then it should be possible to take only one battery out to disconnect the circuit?
 
Dumb question about the Blacktip... There's two PTB batteries, are these wired in Series or Parallel?

If in Series, then it should be possible to take only one battery out to disconnect the circuit?
In series. The blue wire is connected between the packs and measures the voltage in between. That might drain the lower pack.....
 
OK, more questions from a Blacktip newbie...

How long to drain batteries installed into a Blacktip? One would assume that it's OK to install the batteries in the car park and then carry the scooter to the boat; couple or three hours to steam out to the site; then dive, then leave the batteries in for the journey back to port and to the car? (say 8 hours)

Has anyone actually measured the quiescent current drain?


(BTW have had a couple of dives thus far and it's utterly brilliant! Wondered about training then thought sod it and jumped in for a couple of 30m/100' dives. Being neutral in the water it's not at all an embuggerance like a stage cylinder and nicely clips off on one's chest D-ring. Need to finesse things, but am going to have so much fun with it!)
 
OK, more questions from a Blacktip newbie...

How long to drain batteries installed into a Blacktip? One would assume that it's OK to install the batteries in the car park and then carry the scooter to the boat; couple or three hours to steam out to the site; then dive, then leave the batteries in for the journey back to port and to the car? (say 8 hours)

Has anyone actually measured the quiescent current drain?


(BTW have had a couple of dives thus far and it's utterly brilliant! Wondered about training then thought sod it and jumped in for a couple of 30m/100' dives. Being neutral in the water it's not at all an embuggerance like a stage cylinder and nicely clips off on one's chest D-ring. Need to finesse things, but am going to have so much fun with it!)

It is definitely no problem to put them in first thing in the morning and leave them in all day.

My guess is that you wouldn't lose THAT much in putting them in the night before. To ME, the biggest issue with putting them in the night before is my own fallibility. If I put them in the night before, I feel like I'm a lot more likely to forget they're in there and then leave them, in the case where the next day is canceled for some reason.
 
It is definitely no problem to put them in first thing in the morning and leave them in all day.

My guess is that you wouldn't lose THAT much in putting them in the night before. To ME, the biggest issue with putting them in the night before is my own fallibility. If I put them in the night before, I feel like I'm a lot more likely to forget they're in there and then leave them, in the case where the next day is canceled for some reason.

Someone else on another forum measured the stand-by current draw of the Blacktip with a mulitmeter and measured it at about 200mA standby current. Assuming that's at 40V it's 8 Watts. I wouldn't put the batteries in until you're 3-6 hours from the dive unless you're willing to lose 5-10% from a 12AH battery from installing them overnight. Personally, I installed them at the dive site or before I get on the boat since its so easy compared to other scooters where you have to open up the whole body first.
 
in New Zealand we can only carry 100wh without written approval even with the 12 ah 18v battery and splitter im still 108 wh - so what do others do for travel restricions
 
Ananoverthing...

For the couple of times I've used the Blacktip, ended up with a small amount of water in the tube.

Is this simply because I opened it vertically? Am assuming that the drips came in from the 'cap', opening the cap when horizontal won't drip?
 
https://www.shearwater.com/products/perdix-ai/

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