LiPo batteries for Bravo pump

[Jerry]

Lead acid 12V/20Ah battery that I was using for my Bravo pump has died (lost pretty much all capacity, would go down to 9V half-way through inflating my Aerotec). I had a choice of either ordering something similar or something more modern.

I've decided to order two 3S 5Ah LiPo batteries, assuming these should work just fine with Bravo pump. This was a very good decision, it takes 2.5Ah to fully inflate my Aerotec, which leaves another 50% of battery capacity for eventual topups on the water (in reality a bit less because you never want to fully discharge a LiPo battery). Both batteries fit nicely into Bravo's bag, are light and small, charge in an hour with a LiPo charger. The only modification needed was to add a yellow 90A connector to the wires of Bravo pump (batteries come with this connector pre-soldered), which I added to the part of the wire just after the big automotive connector. I also added corresponding yellow plug to the remaining wires, so I can still use croc-clips to connect to a car battery.

Total cost of this operation was £40, so similar price to a new lead-acid battery.

These batteries will also be used to power Garmin Echomap 45 - I will need to think of a neat storage bag for the GPS+battery combo.

[Fenlander]

Jerry that's interesting. Was it dad's old scooter battery that died... because the one of the pair I kept was great last year but now exactly as yours drops voltage so much it won't finish the HP floor. So I'm looking at what to replace it with. I'm not familiar with the Li-po battery type though.

[Jerry]

Originally Posted by Fenlander

Jerry that's interesting. Was it dad's old scooter battery that died... because the one of the pair I kept was great last year but now exactly as yours drops voltage so much it won't finish the HP floor. So I'm looking at what to replace it with. I'm not familiar with the Li-po battery type though.

It was the old scooter battery, worked perfect last year! I think it's 7 years old (production date is stamped on them), so that's the time when lead acid batteries die anyway.

I got myself two of these: https://hobbyking.com/en_us/turnigy-...ack-xt-90.html. It's good enough for a full single inflation with enough charge left for eventual topups. If you're using 12V battery as a power source for anything else (a GPS?) then it's worth thinking about both Bravo and GPS in one go - consider batteries capacity, max discharge current, ways to charge them, how many batteries, etc.

You'll also need a charger. I have this one: https://www.amazon.co.uk/Elysium-LX6.../dp/B002TLR6N2 but any charger than can do at least 3S batteries and has a balancer connector will do. Mine is quite old, now there are double chargers, I just need my current one to give up a ghost and get something like this: https://hobbyking.com/en_us/turnigy-...c-uk-plug.html

I still have a few spare yellow connectors left, you're more than welcome to pop over here and I can solder this in 5 minutes. Just make sure that the battery has XT-90 yellow connector and not another one (there's a few standards for power connectors).

There is one thing you can't do with a LiPo - it's not allowed to fully discharge them. It's not a problem in a pump because single inflation uses only half of the battery, but you'd have to setup a low voltage alarm in a GPS to 9.9V. On the plus side it's easy enough to measure current draw by GPS to have a pretty good idea of how long a single battery will last.

PS: In LiPo world, "3S" means three lithium cells connected in series. Fully charged cell is 4.2V, discharged is 3V but I wouldn't go below 3.2V. This means that a "3S" battery has 12.6V when fully charged and 9.6V when discharged - so that's a really good match for lead acid voltages.