Elect. Guru help

[jruiz]

I did this test on my Rule 24(360GPH) at 6V and it drew less than half the current as compared with running it at 12V. So about 2.3A at 12V and <1A at 6V, so the relationship is not linear. Li-ion batteries go up in increments of 3.7V running voltage so you're probably going to dealing with 7.4V which would bump up the current draw a little bit.

20Ah would be nice for islander trips where you either have no access to power or just don't want to hassle with charging.

PM me whatever questions you have or you can put them right on this thread. I design/manufacture lithium batteries and am an EE.

[RedSledTeam]

Originally Posted by jruiz

...PM me whatever questions you have or you can put them right on this thread. I design/manufacture lithium batteries and am an EE.

HOW do you keep them from randomly catching fire?

[jruiz]

Don't charge them above the rated charge current and buy from a reputable manufacture.

Most companies nowadays incorporate safety features like shutdown separators, PTCs, and vents to minimize these occurrences. There are also safety standards they must meet before they can be shipped by air or ground. I personally wouldn't buy a large format lithium ion battery unless it has a UL, IEC, or ANSI marking on it.

[danjor]

LifePo4 battery's are not the same as LiPo which are what most people think of when they say battery's catching fire or exploding. LifePo4 batteries are very safe and if they are sealed in a plastic waterproof housing there as safe as sealed lead acid batteries. They are more expensive than lead but the big difference is out of a 10ah lead battery you get roughly 4-5ah of use able power before the voltage drops too low but with a LifePo4 10ah battery you get roughly 8ah of use without voltage drop! So you get almost double the use able life and depending on the battery you can jump start your car with it. I have a 100ah LifePo4 that I plan on using on a trolling motor setup whenever I get around to setting it up.

[GregAndrew]

Depending on the size required, the larger capacity batteries would be for travel use. Mothership and trips to Mexico for me in particular. Thanks for all the timely info guys.

[PescadorPete]

Greg,
I measured the Hobie bank tank pump (Tsuanmi 500) with no load (no water in the tank).

12V --> 0.32 amps 3.84 watts
6V --> 0.23 amps 1.38 watts

so roughly 40% of the power @6V vs. 12V.

I can measure it with a full tank of water this weekend if it helps, let me know.

BTW, Ohms law is not the way to look at this, its an inductive motor load, not a resistor.

Pete

[GregAndrew]

Hey Pete, how did you measure it, and did you happen to measure it with water? Looks like the batteries are going to be very affordable for LifePo4.

Originally Posted by PescadorPete

Greg,
I measured the Hobie bank tank pump (Tsuanmi 500) with no load (no water in the tank).

12V --> 0.32 amps 3.84 watts
6V --> 0.23 amps 1.38 watts

so roughly 40% of the power @6V vs. 12V.

I can measure it with a full tank of water this weekend if it helps, let me know.

BTW, Ohms law is not the way to look at this, its an inductive motor load, not a resistor.

Pete

[momo fish]

interesting... Where is best place to buy batteries? Looking to get 2.. Are you all saying a 6 can last as long as a 12? Sorry not an ee so keep it simple for us non-mcgiver types

Originally Posted by danjor

LifePo4 battery's are not the same as LiPo which are what most people think of when they say battery's catching fire or exploding. LifePo4 batteries are very safe and if they are sealed in a plastic waterproof housing there as safe as sealed lead acid batteries. They are more expensive than lead but the big difference is out of a 10ah lead battery you get roughly 4-5ah of use able power before the voltage drops too low but with a LifePo4 10ah battery you get roughly 8ah of use without voltage drop! So you get almost double the use able life and depending on the battery you can jump start your car with it. I have a 100ah LifePo4 that I plan on using on a trolling motor setup whenever I get around to setting it up.