I thought I would save a few dollars on getting a 5kWh LifePo4 shower for my wife’s off grid home. Little did I know that this visualization would forfeit me over a hundred hours of my time and take scrutinizingly a year to get working properly. This vendible is a tale of my woes that stretched over the largest part of a year and how I finally got the shower to work properly without replacing the BMS and one of the damaged cells. This story is not for the meek of heart so here we go.

It all started with Aliexpress

Aliexpress is owned by the same folks as Alibaba with the one big difference is that it looks a lot increasingly like ebay and it is designed for people who just want to buy a couple of a particular thing instead of a couple of thousand of a particular thing. I got online and started shopping, I didn’t want the cheapest battery, but I moreover didn’t want the most expensive. I settled on a 24v 5kWh LifePO4 shower with a personal charge/discharge rate of 250 amps. I have unbearable wits with chinese companies to know that a personal charge/discharge rate of 250 amps really ways a charge/discharge rate of 100 amps, but all I needed for our solar system was 80 so that was fine. The shower was well-nigh $1400 shipped so I paid the money with paypal and then the shower shipped. Considering I bought this at the time of the shipping slipperiness it took well over 6 months to get here. I notified the sellers and they would send me a shipping manifest in chinese which I fed into google translate so I could follow my shower wideness the sea.

The shower arrives, but is smashed from shipping

I got the shower which showed 22v of voltage but would not tuition or discharge. There was small plastic pieces in the box, there was no thunderstroke showing what side was supposed to be up on the outside of the box and the 80lb shower had unmistakably been shipped upside down. They told me to take the shower untied to trammels the inside, but the top was glued on. There were handles on the top so I hung the shower from the handles and then heated up the glue virtually the rim of the box and used a screwdriver to unshut up the steel shower box and wearing my finger pretty immensely in the process. Once the box was untied I could see what had happened. The shower was shipped upside lanugo and one of the spot welded aluminum pieces on the first lamina had wrenched off. That is why it was showing voltage (it was touching the battery) but why I could not tuition or venting considering the connection was not good unbearable to pass any real amperage through.

There was a worthier problem with this shower construction. The positive shower terminal was installed well-to-do versus the metal specimen top. There was supposed to be a plastic wadding to alimony the lug from touching the specimen but there was none. I looked in the box thinking maybe it had broken, but no it just was not installed. Then I saw that the plastic piece had been installed on the other side of the lug leaving the powered lug up versus the metal of the case. It had shorted out a tuft of times while stuff shipped (there was a lot of soot from the arcing) and I’m sure the BMS just kept wearing out preventing a fire from starting. When I looked at the construction it seems like they installed that lug higher considering it didn’t well-spoken the aluminum welded busbars (they were up too high). Is it any wonder why planes delivering lithium batteries from China splash into flames on a pretty regular basis?

Retapping the damaged cell

I did some research on tapping the LifePo4 lamina to reattach the aluminum bus bar. it seemed like the trick was to not indulge the drill to go too deep. I bought some Metric taps online and then set well-nigh to do the deed. It was relatively easy and I managed to get the busbar that had wrenched off reconnected properly. The key is to not over-tighten the vendibles that holds the busbar lanugo otherwise you end up stripping out your tap. The next problem I had was the lamina that had the wrenched busbar did not want to tuition at the same rate as the others. I thought maybe if I bought a lab charger and just charged that lamina individually I could get them all to be well-nigh the same level. Unfortudently, it never worked out that way, the lamina was slightly dented and it just couldn’t alimony up with the other cells on the battery. This could have been due to a damaged BMS but was increasingly likely to just be a damaged cell. I decided to replace both the lamina and the BMS just to be safe.

I bought a LifePO4 BMS from overkill solar which claims 100Amps continuous charge/discharge for about $130. My take on this BMS is that it seems to unquestionably be worldly-wise to do what it says (in the BMS settings it unquestionably says it can do 120 Amps). It comes with a Bluetooth module that allows you to monitor the shower in realtime. This BMS was the weightier investment I have overly made and if you have Lithium batteries that you use with a solar system that are stored inside you should not skimp on the BMS. Replacing the BMS was relatively straightforward, and programming it with bluetooth was a snap.

The next issue was getting a replacement LifePO4 cell. I had to measure the existing lamina dimensions and get a matching lamina online. I opted to get a lamina with a welded studs on it considering I trust that increasingly than the crappy aluminum tapping I had washed-up on the other battery. Without looking for a long time I managed to get one that looked decent from Aliexpress for well-nigh $140. I ordered it and it came in well-nigh a month later. I installed the new lamina without too many issues other than the stud on the top widow a couple of mm to the height so I had to thoughtfully wrench the aluminum busbar then drill it out so the stud could fit through it. Once it was together and the shower was duct taped together I put it on a test tuition cycle. It seemed to do really well, I wasn’t interested in waiting for the lamina balancing to bring the cells to the same voltage so I used the variable voltage lab power supply to get the voltages of all the cells with .02 volts of each other. Without well-nigh 100 hours of labor and a lot of thoroughbred sweat and tears I finally had a shower that worked.

Moral of the story?

Don’t buy lithium batteries from China. Even if this shower had not been damaged in shipping, considering the positive terminal was touching the metal case, this shower was literally a death trap and fire hazard. It is well-spoken to me that whoever assembled this shower knew veritably nothing well-nigh electricity or they never would have made such an obvious mistake. If I had to buy a LifePO4battery today, I would just get an EG4 server rack battery from Signature solar. The price is well-nigh the same and the quality is probably 1000 times better. Lesson learned.

Ride On.