Build Thread - 120Ah LifePo4 - 40 mile range for less than $1200?

[eprovenzano]

Thanks for posting... I'm looking at building something similar. 16s system, using 3.2v batteries. I'm just starting to research exactly what I want. For my use, I feel a 100 ah battery will more than fit my needs

[AussieInSeattle]

Originally Posted by eprovenzano

Thanks for posting... I'm looking at building something similar. 16s system, using 3.2v batteries. I'm just starting to research exactly what I want. For my use, I feel a 100 ah battery will more than fit my needs

If you don't need a lot of range, then you just need to find an Ah capacity that has the continuous and peak discharge rates that you need. I wish I'd stuck a cheap $20 amazon amp meter on my cart or used the AllTrax logger to determine what my continuous amp needs were for my setup while driving my normal routes/course.

If I do this again I'd seriously look at LTO cells - due to voltage difference I think you'd need a 24s setup but due to their high discharge rates you could get away with 40Ah cells ($1200ish from china I think) and they last an insane number of cycles. From what I understand they are a newer tech so hopefully they come down in price too.

[eprovenzano]

I'm still using 6 8 volt batteries, fully charged and settled the voltage is just over 50 volts. As I stated we only use it at out campground. An average day I see us going about 5 - 8 miles. Knowing the batteries are getting old, we've become accustomed to backing into the cart's parking spot, and connecting the charger. Yes I know we're killing the batteries, but this is the only way to ensure we'd have enough juice to make the next trip.

[reiter284]

Awesome build. Thanks for the detail.

I ordered 16 Lifepo4 100ah 3C from alibaba for $605 shipped and a Daly BMS for $115 with LCD screen, bluetooth, etc... I am going to build something very similar. I have a few months to get all the other parts waiting on shipping. If it all works out I may be right around $900 with charger and misc.

A couple questions.

Do you have a link to the charger you bought?

Also, Do you hook up the charger to the pack, read the voltage, disconnect, adjust, hook it back up, read the voltage, disconnect, adjust. Or do you just hook it up and adjust?

And what final voltage did you decide on?

[mattkovo]

What kind of LCD screen are you getting? I have a Daly BMS but no LCD screen.

[reiter284]

I ordered the Daly Touch Control Screen. It's an optional accessory

https://www.aliexpress.com/item/4001...94dc4c4det3I9F

I ordered all the accessories just because it was relatively cheap and I'm not sure how I'm going to set it up as far as putting it to sleep/waking it up and how I'm going to manage a low voltage shutdown.

That's another question I had. Are you guys just having the bms shut down the cart at 20% reserve so you can lower the threshold, get back home and charge it back up? OR do you wire in a relay override or a separate low voltage alarm?

[Mike from Texas]

Originally Posted by reiter284

Awesome build. Thanks for the detail.



I ordered 16 Lifepo4 100ah 3C from alibaba for $605 shipped and a Daly BMS for $115 with LCD screen, bluetooth, etc... I am going to build something very similar. I have a few months to get all the other parts waiting on shipping. If it all works out I may be right around $900 with charger and misc.



A couple questions.



Do you have a link to the charger you bought?



Also, Do you hook up the charger to the pack, read the voltage, disconnect, adjust, hook it back up, read the voltage, disconnect, adjust. Or do you just hook it up and adjust?



And what final voltage did you decide on?

Would you mind sharing the links for the batteries you purchased?

How long did it take you to get them? Is the 3C rating continuous or peak?


Sent from my iPhone using Tapatalk Pro

[reiter284]

Originally Posted by Mike from Texas

Would you mind sharing the links for the batteries you purchased?

How long did it take you to get them? Is the 3C rating continuous or peak?

https://www.alibaba.com/product-deta...7acf2fc21LBwpQ

https://www.aliexpress.com/item/1005...7ea42162Y8pqZm

They are Liitokala on alibaba/aliexpress. If you contact them through alibaba they lower the price to $605. $30/each plus shipping.

Continuous 1C peak 3C.

Some other sellers gave better detail like 3C for 10 seconds, 2C for 60 seconds or whatever. But at some point I don't trust any of it. You really don't know what you are buying at this price range. So I said screw it. I was tempted to go with the 200ah batteries for a little more $$$ to overcome this but I'm just going to limit with the navitas and be conservative and adjust up until I'm happy with the performance. I need to read up on lifepo4 and understand the risks, etc... with a high amp draw.

I think most of the other under drop-ins all have a problem with the BMS, not the cells discharge capacity.

I just ordered them last week. They said 35-45 days. I wasn't in a hurry, as I still have to do some engineering and buy all the other stuff.

[AussieInSeattle]

Originally Posted by reiter284

https://www.alibaba.com/product-deta...7acf2fc21LBwpQ

https://www.aliexpress.com/item/1005...7ea42162Y8pqZm

They are Liitokala on alibaba/aliexpress. If you contact them through alibaba they lower the price to $605. $30/each plus shipping.

Continuous 1C peak 3C.

Some other sellers gave better detail like 3C for 10 seconds, 2C for 60 seconds or whatever. But at some point I don't trust any of it. You really don't know what you are buying at this price range. So I said screw it. I was tempted to go with the 200ah batteries for a little more $$$ to overcome this but I'm just going to limit with the navitas and be conservative and adjust up until I'm happy with the performance. I need to read up on lifepo4 and understand the risks, etc... with a high amp draw.

I think most of the other under drop-ins all have a problem with the BMS, not the cells discharge capacity.

I just ordered them last week. They said 35-45 days. I wasn't in a hurry, as I still have to do some engineering and buy all the other stuff.

That price seems about right for 100Ah. Appears that you have aftermarket (high amp draw) components, so will be interesting to see how your cells go at max continuous of 100A. I drive the same "path" all the time and wish I'd logged my amp draw on that path via AllTrax or an external meter prior to the project - if you're starting out that approach is a great way to work out how much continuous draw you need. My understanding of LifePo4 is that at the higher amp draws, your batteries will heat up so you need to ensure your BMS has temperature sensors (multiple) to ensure you can monitor as you turn up your Navitas.

Here's the charger I got from amazon - it is the UY600 model - there are a lot on amazon that all look the same so I believe they are a generic charger that resellers rebrand:
https://amzn.to/3cwxV0g

If I was to do this again, I'd go with the EVE 105Ah cells (I got a quote for $900 shipped last week) as they are a lot easier to fit into "one side" of a cart. My setup is a really tight fit that required cutting of my battery tub. We know that the RoyPow packs use those exact cells so you can think of them as being "pre-tested" for the amp needs of a golf cart.

While you're waiting for your cells do a lot of reading and youtube watching of building out packs - Will Prowse YouTube channel is pretty good - mostly his older videos.

I'll post an update to my build soon, but my main piece of advice is read a lot, watch a lot and be very careful with these cells and always use insulated tools - I had a brain fart during installation that ruined one cell in my pack but could have been far worse safety-wise.

[AussieInSeattle]

Originally Posted by reiter284

Awesome build. Thanks for the detail.

I ordered 16 Lifepo4 100ah 3C from alibaba for $605 shipped and a Daly BMS for $115 with LCD screen, bluetooth, etc... I am going to build something very similar. I have a few months to get all the other parts waiting on shipping. If it all works out I may be right around $900 with charger and misc.

A couple questions.

Do you have a link to the charger you bought?

Also, Do you hook up the charger to the pack, read the voltage, disconnect, adjust, hook it back up, read the voltage, disconnect, adjust. Or do you just hook it up and adjust?

And what final voltage did you decide on?

Those BMS's look pretty sweet - what Amp version did you go for?

Charger I purchased linked above.

For adjusting the charger voltage you use a meter with it disconnected, not connected to the pack - this is mentioned 3 or 4 times in Sergio's thread - while you're waiting for your cells to arrive read all 40+ pages of it - lots of good info in there even though it gets off track a little in a couple of places.

I'd also sign up for the diysolarforum mentioned earlier and read the DIY LifePo4 section and the pinned thread on top balancing.

I went with 54.8V in the end and pushed 48Ah into my pack (measured via a shunt). I stopped the charger at 48Ah pushed into the pack - the BMS was showing that it was still pushing 6A into the pack from the 10A charger at that time. Given that they usually ship the cells at around 40-50% capacity I was happy with that number - I am not looking to get maximum range out of my pack. I dont need 120Ah of capacity and the plan was to run the pack in the 20% SOC - 90% SOC range for longer life. My cells were within 6mV after settling and the above charge so I decided not to top balance.