On Thursday 19 April 2007 05:08, PaddleWise wrote: > Based on the photo of your battery pack, it looks like you are running a > 12 volt pump with a less than eight volt power pack. That will greatly > reduce the pump capacity. The pump will probably take normal 12 volt > lead acid battery voltage of 14.4 volts without burnout problems. > Increasing your power supply voltage will have more effect on the pump > flow rate than marginal increases in flow due to changes in flow > resistance in the hose and outlet fittings. But beware that as the voltage go up, the amps skyrocket, not necessarily improving the pump volume per battery set, but sure improving pump capacity per minute! I have spent lots of $$$ and time on playing around with electric power and propellers, as I was quite early in that part of airplane modelling - nowadays its the norm! So I know my rechargable batteries! SLAs and othe lead acid batteries are great on amps, with fairly constant efficiency over time, while NiCDs and NiMHs are easy to overheat, unless you keep the amps down, or cool them well! Heat-losses are an effect of amps, squared, so you'd want low amps and high voltage! For bilge pumps I think Li-ion batteries would be ideal, as they don't discharge over time nearly as fast as other types, including lead-acids. Our first try was with one of those textile hoses that flatten itself when not in use - like those used by firemen - and that resulted in that the pump didn't get enough water to start sucking (in essence it just tried to compress air, very inefficiently). Using a full size rigid hose, would have taken much space, and created transport problems as we're using Kleppers, thus have to demount the installation each time, so next best proved to be inserting a thin rigid hose inside the textile hose! Looks weird works well, as then the air always can be pushed away from the pump house, and when that happens it goes into top gear! The flowrate is almost up to par with a rigid hose, and easier to handle! Tord *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Tord Eriksson wrote: > SLAs and othe lead acid batteries are great on amps, with fairly > constant efficiency over time, while NiCDs and NiMHs are easy to > overheat, unless you keep the amps down, or cool them well! > Heat-losses are an effect of amps, squared, so you'd want low > amps and high voltage! Always put a fuse on the pump. My pump, rated at 1A has a 2A fuse inside the battery case. This is one reason I recommend the Attwood 625 - other brands need much higher currents - 3.5A are not uncommon! > For bilge pumps I think Li-ion batteries > would be ideal, as they don't discharge over time nearly as fast > as other types, including lead-acids. True, but I find that the high-capacity NiMH that are available now are fine in most kayaking uses. I've left my batteries in the kayak for over a month with no noticable decrease in pumping power. Li-Ion, OTOH, are quite a bit more expensive and the combination of a good, general-purpose Li-Ion with a good charger is hard to find. Given that NiMH AAs are common and good, fast chargers are readily available, I'd only recommend Li-Ion for specific purposes, notably extended cold weather paddling. If you're rich and like to reserve bragging rights, go for Li-Ion :-) Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Thursday 19 April 2007 05:08, Philip wrote: > As I mentioned in response to Dana's comment, I'm going to try fully > charging the batteries (I'd used them fresh out of the pack as they're > supposed to be "ready for use"). We'll see if that makes a difference. If your AAs are 2.5 Ah (some are, most much less) and your pump consumes 25 Amps, they'll last just a few minutes! Tord *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:44 PDT