Elect. Guru help

[GregAndrew]

I am talking with a company that assembles Lifepo4 batteries about making some 6v batteries for bait tanks. They need to know what continuous current will be required for the batteries. I have looked at the 5 or 6 pumps that I have and see 1.8 - 2.5a at 12v on them. I believe they will draw the same amps when stepped down to 6v, but wanted to double check. Anyone running a 500gph pump that draws more than 2.5a?
I am checking into both 12a and 20a versions with and without the sealed ABS housings depending on size.

[Nicko]

Power = volts x amps = 24watts= 12v x 2amps
if you use 6v on the same device, the current (amps) will need to double to do the same work!

[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.

[Iceman]

Personal experience has led me to believe that the draw is 1/2 of what you see on the 12 volt pumps running 12 because the same Ah battery 6 volt seems to run twice as long. My 6 volt 12ah will easily run twice what my 12 v 10.5 will.

[Lipripper92592]

Don't worry about the C rating for your pump. The rating becomes critical when you are pulling high amps, such as electric RC brushless motors. I have some 400 sized brushless motors that can pull up to 40 amps with the right speedcontroller. The packs I've run for the FF and bilge were 20 C 11.4volt packs, I can't remember the Mili amp hours, but somewhere in the 4000 range. Expensive batteries. If I remember correctly, the C rating is applicable to the charge rate as well, so depending on how fast you want to charge the pack, get the proper C rating for a fast charge.

[RedSledTeam]

...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?:eek:

[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

[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:rolleyes:


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.

[jorluivil]

Whatever it is you can add me to the list of potential buyers. So far I'm loving my Bioenno battery(thanks for recommendation Greg). Yes, it wasn't cheap but not having to worry about it going dead in 8hrs is worth every penny to me.

[momo fish]

where did you get it from?

Whatever it is you can add me to the list of potential buyers. So far I'm loving my Bioenno battery(thanks for recommendation Greg). Yes, it wasn't cheap but not having to worry about it going dead in 8hrs is worth every penny to me.

[danjor]

I used batteryspace for my battery they sell everything you need to make your own pack or buy a premade one. Honestly you could make a pack perfect for kayaking for around $100
I would use 2 or 4 of the 3.2v 16ah LifePo4 cells $39 each, pick up a pcm to monitor voltage and a charger. Assemble it in a pelican box and your good to go. Extremely small lightweight battery setup that's going to last a long time. For 12v they do have some nice premade setups like a 12v 20ah with led balancing for $179
Just my $0.02

[GregAndrew]

Am I wrong, or is there something more to these cells than just placing the right combination of them in series and parallel in order to get your required voltage and Ahs? All the cells seem to have a different discharge rate. At our usage, does that even matter?

[danjor]

Am I wrong, or is there something more to these cells than just placing the right combination of them in series and parallel in order to get your required voltage and Ahs? All the cells seem to have a different discharge rate. At our usage, does that even matter?

For the most part setting up these battery's are simple. Pretty much you use whatever combination you need to get the required volts and ah and what little power our fish finders and bait tanks use isn't enough to really matter since it really isn't much power.
From what I see others have posted a bait tank uses 0.25ah at 6v but if you use 2 cells like this http://www.batteryspace.com/LiFePO4-40160S-Cell-3.2V-16-Ah-160A-Surge-Rate-51.2Wh-with-M3.4-screw.aspx
These are capable of 160ah discharge continuously so that bait tank pump pulling 0.25ah is nothing compared to what it can supply. Most high end brand LiFePo4 battery's are around 10C rating so they will supply more than enough current to run out stuff. And that is why my 100ah LifePo4 battery is so use full, I have used it to jump start cars twice since it has 1000ah discharge rate, I just need to make a waterproof case so when I finally put it on the yak I don't risk shocking myself with all that current...

[bus kid]

I dont know if hes still around but I met a guy a long time ago when I worked in a hobby shop. He was building a full electric car before it was cool,and had a battery powered skateboard that did a easy 30 mph and knew all about batteries (lipos) before anyone was talking about them.

http://www.electriclouie.com/.

[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.

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

[bubblehide]

Am I wrong, or is there something more to these cells than just placing the right combination of them in series and parallel in order to get your required voltage and Ahs? All the cells seem to have a different discharge rate. At our usage, does that even matter?


Greg, your right. LION batteries produce heat as they discharge. The faster the discharge rate, the greater the heat produced (enough to melt right through a plastic kayak (recall the airline issues not that long ago). However, for the most part, placing small batteries in series/parallel hasn't up-ed the discharge rate to a point that would create a problem.

[jruiz]

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.


Here are the specs on the same pump under load for 12V and 13.6V. 1.4A current draw at 12V. So it should be less than that for 6V

http://imageshack.us/a/img854/3778/sc20130510074134.png

[dra8642]

HI,
I use these for SLA replacements in UPS systems. The life is 5 times longer than the SLA and the temperature specs are very good for us that like to fish in the cold. They have build in protection circuitry and are meant to be charged by the same chargers that SLA's use. Just check the maximum discharge current if you want to use for starting an engine. Otherwise a deep discharge can over-discharge the battery and it won't recover. Almost all of the SLA replacements here have all of the over, under, excessive (late night, cold and stupid moves) specs taken care of. They are all half of the weight of the SLA's and are sealed. They are pricey, but over time it will be cheaper. Great for lighting, electronics and pumps.

http://www.batteryspace.com/Powerizer-LiFePO4-Battery-12V-15Ah-180Wh-30A-rate-with-PCB-and-LED.aspx

I popped this guy in a Pelican box and added a waterproof connector so I could hook up a solar panel to charge it up in the car or home to get it ready for next time.
http://www.batteryspace.com/lifepo4battery12v20ah240whwithcontrollerforsolarpo werstorage.aspx

Look around the website and you will probably find something that will work well.

Dave

[GregAndrew]

Greg, your right. LION batteries produce heat as they discharge. The faster the discharge rate, the greater the heat produced (enough to melt right through a plastic kayak (recall the airline issues not that long ago). However, for the most part, placing small batteries in series/parallel hasn't up-ed the discharge rate to a point that would create a problem.

Yeah, that is not where I was going with my question. Seems to me that any batteries that are charged or discharged too quickly beyond their ratings will have a tendency to generate heat. Although that is a risk that everyone should be aware of when making their wiring connections to avoid shorts.My concern was that some of the cells seem designed for rapid discharge and some for slower discharge. And I was wondering if that was going to effect performance (battery life or run time). Also, I am not looking at LION batteries, but Lithium Iron Phosphate batteries (LifePo).

[bus kid]

Greg, your right. LION batteries produce heat as they discharge. The faster the discharge rate, the greater the heat produced (enough to melt right through a plastic kayak (recall the airline issues not that long ago)

bad example, heat was not the issue for the airline, the issue was the gases emitted by the batteries not being able to be vented properly as the box containing them was too small. which caused a small less then 1 inch blue flame to be produced.

[GregAndrew]

The battery that you have linked, as well as probably all LifePo4 batteries, requires a special charger (scroll down to charger). That would be a good alternative to a 12v 12a LifePo4 battery because it only requires the same space. Although neither will fit into the WalMart type battery cases, and both would have to be regulated to use with our small bait tanks. I am using a 12v 12a LifePo4 battery from Bioenno Power (for my FF) that I got shipped with charger for $150. I added a Square Trade warranty for $20 for 3 years of protection. I have not really tested it yet, but have run one for at least 16 hours over a weekend without my HDS5 shutting off.

HI,
I use these for SLA replacements in UPS systems. The life is 5 times longer than the SLA and the temperature specs are very good for us that like to fish in the cold. They have build in protection circuitry and are meant to be charged by the same chargers that SLA's use. Just check the maximum discharge current if you want to use for starting an engine. Otherwise a deep discharge can over-discharge the battery and it won't recover. Almost all of the SLA replacements here have all of the over, under, excessive (late night, cold and stupid moves) specs taken care of. They are all half of the weight of the SLA's and are sealed. They are pricey, but over time it will be cheaper. Great for lighting, electronics and pumps.

http://www.batteryspace.com/Powerizer-LiFePO4-Battery-12V-15Ah-180Wh-30A-rate-with-PCB-and-LED.aspx

I popped this guy in a Pelican box and added a waterproof connector so I could hook up a solar panel to charge it up in the car or home to get it ready for next time.
http://www.batteryspace.com/lifepo4battery12v20ah240whwithcontrollerforsolarpo werstorage.aspx

Look around the website and you will probably find something that will work well.

Dave

[PescadorPete]

Greg, I didn't measure it with water but I will this weekend when I gear up for my weekend jaunt.

[jruiz]

Yeah, that is not where I was going with my question. Seems to me that any batteries that are charged or discharged too quickly beyond their ratings will have a tendency to generate heat. Although that is a risk that everyone should be aware of when making their wiring connections to avoid shorts.My concern was that some of the cells seem designed for rapid discharge and some for slower discharge. And I was wondering if that was going to effect performance (battery life or run time). Also, I am not looking at LION batteries, but Lithium Iron Phosphate batteries (LifePo).

Short answer to your question, no. Long answer is that cell designers adjust the rate capability of a component cell by varying the thickness of the electrodes which directly affect your effective current density. Thicker electrode cells have lower current capability but higher energy density and thinner electrode cells the opposite.

Pack designers on the other hand adjust the current capability by adjusting the number of cells in parallel. Energy density in this instance stays constant and capacity increases.

Heat, fast charge/discharge, and the state you leave your battery at have the most impact on cycle life and irreversible capacity loss. Most battery manufactures ship batteries between 25-50 percent state of charge to maximize battery life and safety.

[PescadorPete]

Here it is with a Hobie bait tank, full of water, pump under load:

12V --> 1.37A
11V --> 1.20A
10V --> 1.06A
9V --> 0.91A
8V --> 0.77A
7V --> 0.64A
6V --> 0.52A
5V --> 0.39A

Good thing I did this. When I had the tank full, I noticed the front seam is split and leaking :(. Not from abuse, maybe a manufacturing defect? Time to get out the 5200.