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DIY LifePo4 Battery Build

otrfun
Explorer II
Explorer II
Was right on the edge of purchasing a pair of 100ah BB or LifeBlue LifePo4 batteries ($1600-$2100) for our truck camper. They were going to replace two GC2's. About 2 weeks ago decided to get adventurous and build our own LifePo4 200ah battery pack instead. Didn't want to wait 4-8 weeks ordering from China, so we purchased the cells and BMS from US distributors (~$750; probably could have saved $150-$200 ordering it from China; however, nearly zero recourse if you have any problems). Received everything about a week ago. It was a bit of a learning curve understanding and adjusting all the BMS presets, but managed to get everything working smoothly . Top balanced the cells before doing a whole slew of discharge/charge/temp tests to verify all the various cut-offs worked properly on the BMS. All seems well.

Have no idea how this battery pack is going to work out for the long haul, but for now it massively outperforms our two GC2's. I might add the GC2's we replaced were only 2 years old, well maintained, probably cycled less than 30 times, and performed like new batteries. These LFP's easily supply more than double the usable ah, especially when under very high loads (>100a). I can power a ceramic space heater (110a load) on high for at least 90-95 minutes (down to 15-20% SOC). The two GC2's could barely muster 35-40 min. at 110a before activating the low voltage cut-off on our inverter (50% SOC). No such issue with the LFP's--even down to 10% SOC. Did I mention weight?! This LFP battery pack and BMS only weigh 40 lbs. The two GC2's combined weigh almost 130 lbs! A 90 lb. weight savings---a very big deal when you're trying to trim weight off the rear-end of a heavy truck camper. Bluetooth and low/high temp cut-off is icing on the cake. Lastly, these LFP cells and BMS easily fit inside a small, group 24 battery box.

This battery pack offers more than double the ah performance, 1/3 the weight and 1/2 the size vs. two GC2's! Doubt we'll ever totally cycle this battery more than 30 times a year. With a projected 2000-3000 cycle lifespan, odds are this battery will outlive us---lol!

23 REPLIES 23

otrfun
Explorer II
Explorer II
FWC wrote:
Nice work. I am coming up on year 5 of my 160 Ah DIY pack and it is just humming along.

Which BMS are you using?
Thank you! Hope we get the same, reliable service from our pack.

We're using the Daly 4S Smart 200a BMS. Purchased it solely for its 200a rating. For various reasons I didn't want to build two 100ah battery packs with two 100-120a Overkill BMS'S.

The Daly Smart BMS's have a well-earned, checkered reputation. There's very little technical support available. To my knowledge, there's not even a manual of any kind available. Even the apps and software to support it are 3rd party. The presets on it from the factory are crazy off. If you use it as-is, you'll surely destroy your batteries. If you're willing to take the time to learn how to preset everything in the BMS (using Sinowealth), IMO it's a decent BMS. As for its ability to support it's claimed current rating, I can't say for sure. FWIW, Will Prowse was able to push 290a through a Daly 4S Smart 250a (with fan) with no issues.

I've forced our Daly into a number low/high voltage/current/temp scenarios during testing. In every situation the mosfets shutdown quickly and reliably. So far, so good.

time2roll
Nomad
Nomad
otrfun wrote:
IMO this standard converter is a better match for our battery pack than the single-stage Progressive Dynamic dedicated Lithium 45a converter which produces a constant 14.6v. As per BattleBorn Batteries, if a 14.6v single stage converter is inadvertently left connected to fully-charged LifePo4 batteries for weeks, months at a time it can overcharge the batteries. No such concern with our converter.
I am still concerned about the daily 15 minutes at 14.4 while in storage along with 13.6 continuous seems a bit high from what I read.

otrfun
Explorer II
Explorer II
Darryl&Rita wrote:
Source?
Ordered the batteries from Ninthcit on Amazon. I believe they're a Chinese company that distributes out of CA. I received the batteries 8 days after I ordered them. The cells were well packed, brand new, exactly as pictured on Amazon, with zero sign of use---even had the protective factory coating on the terminals still intact. They were well-balanced (.009 delta as received) and came with intact, legible QR codes.

As for the BMS, I ordered it from Dexter at currentconnected.com. A new, start-up company with outstanding customer service and technical support. I had a few technical and shipping issues, which were totally out of his control. He was able to help me promptly resolve everything with zero drama. Highly recommend!

As for the battery box, bought that at Walmart--lol!

2oldman
Explorer II
Explorer II
otrfun wrote:
This pack will charge up to 1C (100a).
Yeah, the charge rates are pretty amazing. Just have to make sure your charge cable is big enough! I'm sure you'll be happy with this setup for many years.. may even want more!
"If I'm wearing long pants, I'm too far north" - 2oldman

otrfun
Explorer II
Explorer II
2oldman wrote:
Excellent! What are you charging with?
Thanks!

We use the standard 3-stage, Progressive Dynamic 45a converter in our truck camper. Use a Charge Wizard to lock it into bulk 14.4v mode for a fast bulk charge, then manually drop it to 13.6v when charging is complete. It charges this pack to 100% SOC with zero issues. It produces a full 45a of charge current for nearly 90-95% of the charge cycle. Fast and efficient.

IMO this standard converter is a better match for our battery pack than the single-stage Progressive Dynamic dedicated Lithium 45a converter which produces a constant 14.6v. As per BattleBorn Batteries, if a 14.6v single stage converter is inadvertently left connected to fully-charged LifePo4 batteries for weeks, months at a time it can overcharge the batteries. No such concern with our converter.

FWIW, we were able to get almost 85-90a of charge current by charging with both the PD 45a converter and our Renogy 40a dc to dc charger at the same time. This pack will charge up to .5C (100a).

Corrected charge rate from 1C to .5C.

FWC
Explorer
Explorer
Nice work. I am coming up on year 5 of my 160 Ah DIY pack and it is just humming along.

Which BMS are you using?

Darryl_Rita
Explorer
Explorer
Source?
***UPDATE 2006 3500 SRW MegaCab pulling a 2007 fleetwood 5'er

Lwiddis
Explorer II
Explorer II
I look forward to a long term report.
Winnebago 2101DS TT & 2022 Chevy Silverado 1500 LTZ Z71, WindyNation 300 watt solar-Lossigy 200 AH Lithium battery. Prefer boondocking, USFS, COE, BLM, NPS, TVA, state camps. Bicyclist. 14 yr. Army -11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad

2oldman
Explorer II
Explorer II
Excellent! What are you charging with?
"If I'm wearing long pants, I'm too far north" - 2oldman