Will my RC battery charger work for top balance?

[Bazzar]

I did, I used stainless nuts, washers and 25mm long set screws although 20mm or 16mm would have probably been better.

https://www.amazon.com/gp/product/B07957B3X4/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&th=1

 

[Mike Jordan]

Well its working so far. Time counter only goes to 999 and then resets it and the mah reading but other then that its all good. I have the parts for a better balance cable on the way also.

Hobby chargers have factory default cut off settings, because most hobby batts are in the mAH range, not 100s of AH range. Many hobby chargers will let you reset all of the timers, mAH limits, etc to get the big batts charged. I don't own that one, but you can probably find a manual online. I was able to turn all of that off on my hobby charger

 

[petee_c]

I have a 50w all in one hobby charger, as well as a 300w capable one...

I am researching building a 12v 4s2p 50Ah LiFePO4 battery to use with a small 20lb thrust trolling motor. Max amp draw should be 15-20 amps, but I will be running it through a PWM so draw will usually be lower.. This is for a kayak build.

The BMS's on Amazon don't get very good reviews, and I am not sure about shipping delays for the Daly ones from aliexpress.

My idea would be to top balance the cells in parallel if the V is close; then build the pack. If I don't have a BMS by the time it's warm enough to go on the water, I would use the RC balance charger, add a JST 4S lead and a low-voltage lipo alarm to manually monitor the cells.

After a day on the water, plan is to:

Set the RC Charger to 4s LiFe at 15amps, set it on balance charge profile, and bring the charge back up on the battery with the balance leads connected to the charger.
Max voltage on the LiFe profile is 3.6V; nominal voltage is 3.3V - I don't think I can adjust these numbers further; but they should be right. I can take off the Timer and the max capacity so it won't stop until the battery is full.

The balance discharge on my 300w charger is 200mA/cell

I thinking this is a safe way that I can operate the Battery until I get a BMS? The balance charger should protect the battery while charging, the LiPo alarm would alert me if a cell goes too low. I can set it in 10th of a volt. I am thinking of setting it to 3.1(?)V

Build is contingent on finding LiFePO4's for a good price. If not, I will run some 4S Lipos as a stopgap....

 

[Mike Jordan]

I have a 50w all in one hobby charger, as well as a 300w capable one...

I am researching building a 12v 4s2p 50Ah LiFePO4 battery to use with a small 20lb thrust trolling motor. Max amp draw should be 15-20 amps, but I will be running it through a PWM so draw will usually be lower.. This is for a kayak build.

The BMS's on Amazon don't get very good reviews, and I am not sure about shipping delays for the Daly ones from aliexpress.

My idea would be to top balance the cells in parallel if the V is close; then build the pack. If I don't have a BMS by the time it's warm enough to go on the water, I would use the RC balance charger, add a JST 4S lead and a low-voltage lipo alarm to manually monitor the cells.

After a day on the water, plan is to:

Set the RC Charger to 4s LiFe at 15amps, set it on balance charge profile, and bring the charge back up on the battery with the balance leads connected to the charger.
Max voltage on the LiFe profile is 3.6V; nominal voltage is 3.3V - I don't think I can adjust these numbers further; but they should be right. I can take off the Timer and the max capacity so it won't stop until the battery is full.

The balance discharge on my 300w charger is 200mA/cell

I thinking this is a safe way that I can operate the Battery until I get a BMS? The balance charger should protect the battery while charging, the LiPo alarm would alert me if a cell goes too low. I can set it in 10th of a volt. I am thinking of setting it to 3.1(?)V

Build is contingent on finding LiFePO4's for a good price. If not, I will run some 4S Lipos as a stopgap....

I do not run a BMS on my kayak batteries at all. I balance charge, just like RC guys have done for decades before the invention of the BMS, and still do after the invention of the BMS

For a battery that has completely separate charge and discharge cycles like when used on a kayak, there is not as much of a reason for a BMS. Discharge safety is the only argument you could make to use a BMS. So for on the water discharge safety, I have a volt/amp/watt meter to monitor the overall draw, and battery condition. I also plug a cell alarm into the balance leads to warn me if or when I have an individual cell issue. But I have not had one

Besides... I can see what is happening in the balance process with my charger. For the vast majority of BMSes you get no feedback. The only feedback that you can get is with one of the BT enabled BMSes. But why expose all of those electronics to possible water damage, when you can perform those functions at a dry place at home?

 

[bagmanmike]

Something to note - my B6 was way out of calibration but can be adjusted: IMAX B6 Calibration
I do not know if other brands have this feature or would be required.

 

[petee_c]

Thanks for the replies fellas.

My wife is getting me a Haswing w20 motor for my bday and I am modifying it to fit in the pedal drive spot of my Pelican Catch 130HD. Videos on Youtube show it drawing 16 amp on high, 7.8A on low at 13v. I will probably be running 5-10amp through it for trolling speeds of 1-2km/h

I have a B6 clone and a Turnigy Mega 400w x2 charger and a modified ATX PSU to run it from. I can't remember, but I think the PSU puts out 350-400w on the 12v rail. So plenty of power for a 50Ah LiFePO4...