First battery build - Where do I start?

[DamoNZ]

Hi All,

I just came across this forum and I hoped I could find some answers. Recently I had the ide of buiding a battery for a motorised kayak. Now my friends are also keen to do the same. Until now we have basically been using car batteries and they are ridiculously heavy and cannot be stowed in the kayaks hull. I would very much like to build packs I can store in the hull out of the way. Our motors draw 45 amps at full speed. Recently a friend used a 25AH golf cart battery and found it gave him good life. I'd like to build 2x 30AH pack from Headway cells, at least that seemed a good solution. I know my friends here are also keen to have similar packs.

What I cannot understand though is how to make sure I have enough grunt for the 45 amp draw, and how I can fin a battery management cirucuit suitable. I have contacted a few battery sellers and really had no decent answers. Canb anyone please suggest any helpful guides, wiring diagrams or info for a complete newbie ?

Any help much appreciated!

Regards,
Damien.

 

[rojitor]

http://endless-sphere.com/forums/viewtopic.php?f=14&t=26383

 

[dogman dan]

In general, headways can handle 40 amps if you have a 10 ah pack. So a 30 ah headway pack will easily handle 45 amps.

Go for it, Headways fairly easy to assemble into a larger pack. Use a voltmeter to be sure to stop discharge in time, if you don't use a bms.

 

[DamoNZ]

Hi,

Thanks for your replies. I will use a BMS. Whilst I find it easy to get most info on things online, Battery making seems a little harder. I will go through the links in the post above and see what I can learn. I like the idea of the headway cells as I wouldn't need many cells per pack so the build would be easier. If I built 4s2p packs with 15ah Headway cells I'd get 12.8 volts and 30ah if my calculations are correct? and there'd only be 5 balance leads to conenct up n each pack so the build would be easy.

I do have a question though about the BMS circuits, can they handle being fitted into the pack, wrapped up (waterproof) and not have issues with heat?

Cheers,
Damien.

 

[Nobuo]

I've never seen a BMS heating problem inside shrink insulator, just face the aluminium heat sink to the outside, closest to an air flow area. If the BMS has not heat sink, face the Fets side to the outside. Then wrap all in shrink, don't worry about heat. Standard BMS's don't really heat just more than slightly

 

[markz]

2x 30AH pack from Headway cells

You must have cash burning a hole in your pocket. Headways, are pricey! Im guessing, $2.5K.
Dont touch RC Lipo even with a 10 foot pole. Unless you know what your doing of course. :wink: :wink: :wink: :wink: :wink:

 

[DamoNZ]

2x 30AH pack from Headway cells

You must have cash burning a hole in your pocket. Headways, are pricey! Im guessing, $2.5K.
Dont touch RC Lipo even with a 10 foot pole. Unless you know what your doing of course. :wink: :wink: :wink: :wink: :wink:

If we are talking about the same thing, I see prices around the 20USD region online per cell. That's fpr 15AH cells which I guess I'd need 8 of the make a 12volt 30ah pack.

Cheers,
Damien.