Daly common port BMS questions for 12v trolling motor

[petee_c]

I'm building a trolling motor battery for my father. He wants to use a small 30lb thrust 12v trolling motor on a paddleboat to put around his cottage.

It will be a 4s2p battery made up of 8 Navitas 25Ah LiFePO4 batteries. Max amperage it should draw is 30amps

I will need a basic BMS to make this a plug and play battery for him. Some reading suggests I should get a BMS that handles around twice the amperage to avoid problems so I am looking at 50 or 60amp BMS's.

I see these on Aliexpress. I think they should work for my application. He has a 12v battery charger for the trolling motor battery on his big boat, but it only has a lead acid profile. I am thinking about advising him to get one of these: https://www.amazon.ca/Automatic-Mai...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

The battery will likely go in a custom plywood enclosure if I can't find a suitable sized dry box. The output will be to an xt60 connector. I will put a mating connector on his trolling motor and on the charger.

I do not believe he will ever be charging the battery when it's below 5C , but I put a label on the battery not to charge it when cold. He will likely charge it in the cottage which will be fine temperature wise.

Is there a Canadian/US supplier of a Daly BMS like above? or is there one that you would recommend for this application?

 

[sshibly]

Go for it, I got a LI-ION bms for my LIFEPO4 cells (same cells) for their lower cut off voltage. The LIFEPO4 ones have a VERY low cut off voltage.
Make sure you set your CHARGER max volts to 14v or lower. I charge with 13.9v max.
you will be fine with 30A and the system amps is more like 10A

 

[petee_c]

thx for the reply.....

Researching further, looks like this bms is not ideal for longevity of the cells. I should be looking for one with a upper cutoff of around 3.56V per cell and a lower cutoff above 2.5V/cell....

Will keep looking

 

[Positronium]

You may need a Smart BMS like this 4s 60A LiFePO4 UART on Aliexpress where you can set the parameters you need.

49.21US $ 5% OFF|4s Or 3s Li Ion Battery Smart Bms Or 4s Lifepo4 Bms With 60a To 120a Constant Current And Uart Or Rs485 Communication - Integrated Circuits - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

Are you certain the trolling motor start-up is 60A or less? I would go for at least the 80A version to ensure BMS can handle the inrush during start-up.

 

[petee_c]

Dad is looking for a 30 lb thrust motor for his pedal boat... They generally draw about 1amp /lb of thrust.

I may set him up similar to how I am planning mine... Just get him a balance charger like they use in hobby rc and get him a lipo alarm and set the low voltage alarm to 2.7v which appears to be as low as they go....

I'll discuss it with him

 

[Bob B]

Did you mean 2P4S? A 4S2P would be 2 independent batteries and would require 2 BMS.

If he has a smart phone do him a favor and go with the Overkill Solar JBD BMS that he will be able to actually monitor for SOC and cell health.

 

[petee_c]

yeah 2p4s

 

[petee_c]

Working on my dad's trolling motor battery this week after making the prototype for my fishing kayak.... I did not top balance the cells in parallel and seem to recall they were all reading right around 3.29V before I put them together....

I decided to balance charge them with my knock off Imax b6 charger at 1.4amps (highest it will charge 4s)....been taking a while, but they are almost there....



Still waiting on the Daly bms from aliexpress, but will likely send the battery off to him with just xt60 terminals on the end and add the male xt60 connector to his trolling motor.

 

[Just John]

10 amp power supply set to 13.6v works well. Around $55 on Amazon.