DIY Battery build

[Davids29]

So being who I am, I couldn't stand to buy a prebuilt battery when I knew I could build it myself for 1/2 the price.

I didn't want to trust a Chinese seller off Alibaba or aliexpress, so I found some cells that were already stateside. I got my cells for $60 each on a black friday sale from a stateside supplier. $960 total. I also got the Daly 250 amp BMS from them to for $140 and a battery display board. Total $1110 plus shipping, total $1192.84 for the cells and the BMS. I spent about $100 at my local electronics store for the 4 gage wire, crimps, and other things I needed for the build. I also ordered a Renogy 500 amp battery monitor from Amazon for $75 and a charger from Amazon for $135. Puts my all in cost at about $1500.

I had been traveling quite a bit, so it took me a little time to get it put together. I took it for a prove out run before I left for new years. This past weekend, I finished the build. I installed it into the cart and it works like a champ. 5 miles depleted about 10% of the pack, so I'd say I can go reliably 40 miles or so on one charge. I use my cart at the beach, so that should be plenty of range for us.

The pack is:
16 105AH EVE LiFePo4 cells (18650batterystore.com)
1 Daly 250 AMP continuous, 375 amp surge BMS (18650batterystore.com)
1 Renogy Smart Meter (amazon)
1 HTRC Smart charger (amazon)
1 12V Regulator (amazon)

I'll get some pics of it installed next weekend when were down at the beach house.

[hojolabo]

Looking forward to seeing the final install pics. Thanks for sharing

Sent from my SM-T387V using Tapatalk

[augiedoggy]

Very cool, I'm still waiting on my 90ah cells which honestly have to arrive in the next 5 days or they will be late. You got a hell of a deal on those cells from the 18650 battery store. I almost bought mine at docan in houston since I used them in the past but I decided to risk it on aliexpress this time around.

It looks like you have a 5a active balancer there too though I dont see it mentioned? I bought the same one and intend to add a switch to the enclosure to only turn on if needed to top balance if the cells wander and the passive balancer on my jbd bms isnt enough. This is how most people use them. From your last pic it looks like you changed your mind and removed it.
I see you decided against compressing the cells. I bought a steel hoffman enclosure which should hopefully be just right to fit the eve cells I bought and I intend on compressing them slightly.

From what ive read so far though, those bussbars are meant for low current solar applications and are going to heat up pretty bad and cause a lot of current loss. I would keep an eye on them. I went with a piece of 1/4" thick copper im going to cut and make my bus bars out of. a member here Sergio made a pack a while back and reported his results on this.

[Pat911]

Originally Posted by augiedoggy

It looks like you have a 5a active balancer there too though I dont see it mentioned? I bought the same one and intend to add a switch to the enclosure to only turn on if needed to top balance if the cells wander and the passive balancer on my jbd bms isnt enough. This is how most people use them. From your last pic it looks like you changed your mind and removed it.

That is the correct way to use an active balancer, only turn it in once the first cell goes above about 3.45v. Leaving it in continuously will cause more problems than it fixes as it will put your pack out of balance at lower SOC’s

Very low balance current has been Daly’s Achilles Heal but they now have an external active balancer that can be turned on by the BMS once certain conditions are met. I don’t believe the older BMS’s have this function.

Cheers
Pat.

[Volt_Ampere]

Very nice!!! This is the way I will go next time I need a battery. Where did you get the huge size heat shrink? Let us know how the rest of the install goes! That is a decent price for good cells and I'm with you trying to avoid ordering them from China.

[augiedoggy]

Originally Posted by Volt_Ampere

Very nice!!! This is the way I will go next time I need a battery. Where did you get the huge size heat shrink? Let us know how the rest of the install goes! That is a decent price for good cells and I'm with you trying to avoid ordering them from China.

You might find this chart useful for you next build, Especially if you have a higher current controller.
https://copper.org/applications/elec...bus_table3.php

[Davids29]

I swear I've replied to this thread twice already!

The buss bars have the same cross section of a 4-6 ga wire.

I got the shrink wrap on Amazon.

I was going to include an active balancer with a switch to top balance it. I have the space in the box for it, and I will add it back later if I need to. As of now I plan on charging the battery every so often with my power supply at 1.1 amps if the batteries go out of balance. I only use the cart on the weekends so I have the time to let it charge over a few days if I need to.

The cells have a little bit of compression with the shrink wrap, but driving the cart around, It really never pulls more than 1C at WOT. I just have a stock cart for now and the most current pull I see is about 100 amps.

Also not included in my build cost was a tool that I bought, but its not exclusive to the build, but it is awesome. I got the hydraulic crimper from Harbor Freight. Its bad *** at crimping the large terminals and even down to 14 gage terminals.

[kgsc]

Looking at the last picture it appears that you ran the main pack positive and negatives from the far end of the pack. Any reason?

[jasonojordan]

Curious on final weight of this build including the wood enclosure.

[augiedoggy]

Originally Posted by Davids29

I swear I've replied to this thread twice already!

The buss bars have the same cross section of a 4-6 ga wire.

I got the shrink wrap on Amazon.

I was going to include an active balancer with a switch to top balance it. I have the space in the box for it, and I will add it back later if I need to. As of now I plan on charging the battery every so often with my power supply at 1.1 amps if the batteries go out of balance. I only use the cart on the weekends so I have the time to let it charge over a few days if I need to.

The cells have a little bit of compression with the shrink wrap, but driving the cart around, It really never pulls more than 1C at WOT. I just have a stock cart for now and the most current pull I see is about 100 amps.

Also not included in my build cost was a tool that I bought, but its not exclusive to the build, but it is awesome. I got the hydraulic crimper from Harbor Freight. Its bad *** at crimping the large terminals and even down to 14 gage terminals.

Heres the diy tip thread I was referring too. I have those same bus bars. They came with some larger 230a eve cells I bought. Theres some youtub video were people show whats going on with a thermal camera under higher amp current conditions. If they are working for you without too much heat, great.

I only mention it because it can get dangerous fast if someone where to try to use them to climb a steep grade in a loaded down cart with an aftermarket controller.

https://buggiesgonewild.com/showthread.php?t=185959