24v 280ah build, need help

[John Frum]

page 30 in this manual https://www.samlexamerica.com/documents/manuals/11025-EVO-2212-3012-2224-4024-0320_Lrez.pdf
Item 15 from the legend.
"+12V Input Terminals for “Remote On Off” (9 to 15V, 3mA) - Screw M 2.5; AWG #30 to #12"
Its says its 12 volt but I suspect it will be 18-30 for the 24 volt samlex evo.
That needs to be verified but If memory serves you are using a buck converter and we can just work from there if we have to.
No battery protect required.

I have confirmation that the remote off expects +12 volts even on the 24 volt units.

 

[floridianman27]

Minnkota ultrex trolling motor 112 lbs thrust is a 36 volt trolling motor. It requires three 12 volt batteries. But if I can build my own lithium battery I can get enough cells to make a 36 volt. But if it’s going vern36 volts it will damage the motor. I think I would need a voltage regulator to bring the voltage down

 

[John Frum]

Minnkota ultrex trolling motor 112 lbs thrust is a 36 volt trolling motor. It requires three 12 volt batteries. But if I can build my own lithium battery I can get enough cells to make a 36 volt. But if it’s going vern36 volts it will damage the motor. I think I would need a voltage regulator to bring the voltage down

a 36 volt lead acid battery is going to have a substantially higher voltage than 36 volts when fully charged.
For instance typical alternator voltage for a 12 volt system is >13.5 volts.
Best to check the load's requirements.

 

[Bob B]

Minnkota ultrex trolling motor 112 lbs thrust is a 36 volt trolling motor. It requires three 12 volt batteries. But if I can build my own lithium battery I can get enough cells to make a 36 volt. But if it’s going vern36 volts it will damage the motor. I think I would need a voltage regulator to bring the voltage down

There are a lot of people doing it with lithium .... pretty much all the pro's except they aren't building their own.

I think MinnKota does recommend not running on the highest speed for long periods of time if using lithium.

 

[Jusbechillin]

My Samlex showed up today. I can’t believe how much more stout this is than the prior unit I was going to use. This is a beast!
Thanks for the recommendation.

 

[John Frum]

You now have a teir 1 inverter.
You have ~the best their is.

 

[Gazoo]

My Samlex showed up today. I can’t believe how much more stout this is than the prior unit I was going to use. This is a beast!
Thanks for the recommendation.

I'm envious...lol. I have looked at those and read the manuals. Of course the problem for me is the cost. I can afford the 1200 watt model but the 2200 would be tough. Glad you received it ok....it does look very nice and I have no doubt it will it will "play" nice as well.

 

[floridianman27]

a 36 volt lead acid battery is going to have a substantially higher voltage than 36 volts when fully charged.
For instance typical alternator voltage for a 12 volt system is >13.5 volts.
Best to check the load's requirements.

I assume it would be alright. Just don’t want to overload a $2400.00 piece of equipment

 

[doppler]

100 amps * .66 = 66 amps.
You should design to not put more than 66 amps through the fets on the bms.

that's not what overkill solar says

 

[John Frum]

that's not what overkill solar says

I'm aware.
I've heard that he has tested the BMSs to >100% rating.
Which I don't doubt.
The question is, how long was the test?
Field effect transistors like most electronics are subject to heat stress.
BTW I de-rate Daly's by .5
May have to revisit that as the new one's look beefier and are more expensive.
Just for perspective, the dedicated circuits in my kitchen are fused at 15 amps.
15 amps * 120 volts = 1800 watts.
My tea kettle draws 1500 watts for ~5 minutes.
My space heater draws 1440 watts and is designed to run continuously.
Its not coincidence the 1800 * .8 is 1440 watts.

I call it like I see it, best I can with imperfect information.
Overkill is likely going to be my next BMS.

 

[John Frum]

Some FET related reading https://electronics.stackexchange.com/questions/27124/do-mosfets-usually-burn-open-or-closed

 

[doppler]

I'm aware.
I've heard that he has tested the BMSs to >100% rating.
Which I don't doubt.
The question is, how long was the test?
Field effect transistors like most electronics are subject to heat stress.
BTW I de-rate Daly's by .5
May have to revisit that as the new one's look beefier and are more expensive.
Just for perspective, the dedicated circuits in my kitchen are fused at 15 amps.
15 amps * 120 volts = 1800 watts.
My tea kettle draws 1500 watts for ~5 minutes.
My space heater draws 1440 watts and is designed to run continuously.
Its not coincidence the 1800 * .8 is 1440 watts.

I call it like I see it, best I can with imperfect information.
Overkill is likely going to be my next BMS.

I do agree not approaching 1200 watts on a single 12 volt 100 amp BMS is a good idea and if that was my plan at least I would be secure in the fact the man says he has tested and therefor I would be guiltless in asking for refund in event of failure. Oh yea I also would not power my pacemaker ( that's a joke)

 

[Factory400]

No idea what this means. Is this English you speak? ?‍

derating means running the system at something LESS THAN the advertised rating. On the low-cost stuff, the ratings are typically rather dubious. Most people run them at a lower current to avoid a flameout.

Personally, on the cheap Chinese products - I consider running them at 50% to be the limit. Others may be more brave than me.

I am a power electronics engineer and do enjoy examining the smokey failures though.

 

[Jusbechillin]

I started my build thread. Thanks for all of the input!

600w solar, DIY 280ah 24v LIFEPO4 build thread for travel trailer.

Here we go! Today I’m going start mounting the panels. The battery cells are still in transit from China (via alibaba). This weekend we’ll see how far I get with the rest of the project. here’s the list of equipment: 8 3.2v 280ah prismatic cells from Shenzhen Luyuan Technology Co.)...

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