diy solar

diy solar

My five BigBattery OWL MAX batteries arrived!

mikemccand

New Member
Joined
Dec 5, 2020
Messages
26
I finally received my five OWL MAX batteries!

They were back-ordered for ~1.5 months and finally shipped, arriving this past Friday (day before yesterday), ~two weeks earlier than BigBattery had estimated, yay! I failed to apply the @Will Prowse referral discount code at first, and BigBattery was great: I emailed them shortly after placing my order and they quickly, retroactively applied the discount.

TL/DR: I unpacked them, unscrewed their covers, and they look great, but I did discover a few quality issues:

They were packed well, arrived via FedEx in good shape, each battery in their own box:
IMG_8574.jpeg

with large custom-shaped internal foam to hold them securely:

IMG_8605.jpeg

And a small red/white "this side up" sticker on the outside of the box that I doubt FedEx noticed/respected.

Each battery comes with a sticker attached with QR code identifying when/where this one battery was assembled, and three spare QR code stickers each, I guess in case you want to stick them somewhere more visible in your final installation. Mine were all manufactured April 15 2021, indeed very fresh.

I removed the batteries from their shipping boxes, and placed them cells-down (to reduce vertical stacked weight on the cells and hopefully reduce chance of leaking, thank you @Will Prowse!), volt-meter facing up, and then took the front and top covers off (total nine screws). No cells seem to be leaking so far, so that is a good start.

But one quality issue immediately surfaced, and was a problem, to differing degrees, in all five of my batteries:

IMG_8771.jpeg

Notice how the green/yellow insulation on one of the red wires going into the BMS has a cracked fragment that falls off and slides down the red wire, dangerously exposing the underlying metal contact. I am not sure which wire this is, but it is alarming ... what if that exposed contact touches ground, e.g. the case of the BMS, or the outer case of the battery? I pushed that green/yellow fragment back up over the metal contact and then wrapped this in electrical tape, for all five of my batteries, looking like this once I "fixed" it:

IMG_8746.jpeg

to be continued ...
 
Last edited:
...continued (split apart because of 10K character limit):

I suspect this green insulator material is a bit brittle, and during the manufacturing process, it gets bent in order to be zip tied, and that results in cracking it curiously always at nearly that same spot, and then sliding down the wire.

That was the first problem.

The second problem is the screws used to hold the case together! They are tiny screws, and they use two different (tiny) lengths!

IMG_8741.jpeg

At first I did not notice that the nine screws holding top and side panels were not identical, and took all screws off the first battery and only noticed the difference as I was reassembling. So then I paid more careful attention as I unscrewed the second battery and discovered that the short screw is supposed to be used on the hole just covering the gray SB175 connector, because the long screw would pierce / put pressure on the connector:

IMG_8765.jpeg

So I carefully (using shorter screw above the SB175 connector) re-assembled my first battery.

But then I noticed some of my batteries used the wrong screws in the wrong places! Short screws on a hole that had plenty of space, and a long screw above the SB175 connector digging into it with too much pressure and gauging it a bit:

IMG_8751.jpeg

I also noticed a few of the screw heads were already stripped, making it hard to unscrew/rescrew them. I'll try to figure out which type of screw this is and get some replacements.

Anyway, using a too-long screw for the hole above the SB175 connector isn't such a big deal: the SB175 connector is really tough and I don't think any real/permanent damage was done by those incorrect long screws, except gouging/scratching the surface a bit. I re-assembled, being sure to use short screws above the connector. I would suggest BigBattery updates the OWL MAX design so that the same screws are used for all screws in the case.

Besides these two small issues, I am impressed with these batteries. 300A fuse physically isolated from the BMS with internal metal walls. White fiberglass sheath to protect the low-AWG wires beyond their own insulation. The fire-supressor device. Even the choice of SB175 instead of exposed lugs, greatly reduces the risk of accidentally shorting the battery.

Besides these quality issues, the batteries look great ... next up I will do a capacity test of each, and then attach them in serial connection to make 48V battery bank.
 
Last edited:
...continued (split apart because of 10K character limit):

I suspect this green insulator material is a bit brittle, and during the manufacturing process, it gets bent in order to be zip tied, and that results in cracking it curiously always at nearly that same spot, and then sliding down the wire.

That was the first problem.

The second problem is the screws used to hold the case together! They are tiny screws, and they use two different (tiny) lengths!

View attachment 46698

At first I did not notice that the nine screws holding top and side panels were not identical, and took all screws off the first battery and only noticed the difference as I was reassembling. So then I paid more careful attention as I unscrewed the second battery and discovered that the short screw is supposed to be used on the hole just covering the gray SB175 connector, because the long screw would pierce / put pressure on the connector:

View attachment 46699

So I carefully (using shorter screw above the SB175 connector) re-assembled my first battery.

But then I noticed some of my batteries used the wrong screws in the wrong places! Short screws on a hole that had plenty of space, and a long screw above the SB175 connector digging into it with too much pressure and gauging it a bit:

View attachment 46700

I also noticed a few of the screw heads were already stripped, making it hard to unscrew/rescrew them. I'll try to figure out which type of screw this is and get some replacements.

Anyway, using a too-long screw for the hole above the SB175 connector isn't such a big deal: the SB175 connector is really tough and I don't think any real/permanent damage was done by those incorrect long screws, except gouging/scratching the surface a bit. I re-assembled, being sure to use short screws above the connector. I would suggest BigBattery updates the OWL MAX design so that the same screws are used for all screws in the case.

Besides these two small issues, I am impressed with these batteries. 300A fuse physically isolated from the BMS with internal metal walls. White fiberglass sheath to protect the low-AWG wires beyond their own insulation. The fire-supressor device. Even the choice of SB175 instead of exposed lugs, greatly reduces the risk of accidentally shorting the battery.

Besides these quality issues, the batteries look great ... next up I will do a capacity test of each, and then attach them in serial connection to make 48V battery bank.
Curious if you can give an update seeing as it’s been a few months and time to assess early satisfaction level?
 
Curious if you can give an update seeing as it’s been a few months and time to assess early satisfaction level?
Hi Mia,

The batteries have been great so far! I wired them up in series to a 48V inverter/charger from Renogy, to serve as a giant UPS for some of my more demanding home computers, and stress tested them (drawing down to ~10% capacity successfully). I also attached a Kilovault battery balancer to shuffle electrons between the four in-series units to try to keep their voltages the same (seems to be working), and a Renogy battery capacity meter with shunt to measure the current, and a red kill switch. I did not install a series fuse (I have for past installations) because each battery seems to have its own fuse, which I am trusting.

This is the installation:

IMG_9742.jpeg

I like the LED voltmeter (even though it consumes a wee bit of power) in each battery. I validated them against a high quality (Fluke) voltmeter and they were accurate enough. Be sure you get the right Anderson connectors, crimping tools, wires, etc., if you will install/build your own bank.

Since then I left them fully charged at 100%, and we've had a few sudden power outages and the batteries + inverter did a great job keeping the computers up, not noticing the AC power outage.

And no leaking of the battery blood (I just double checked).
 
  • Like
Reactions: Mia
Do you have a pic of how you connected the batteries in series parallel to the inverter? Did you use the BigBattery series cables going into a parallel cable?
 
Do you have a pic of how you connected the batteries in series parallel to the inverter? Did you use the BigBattery series cables going into a parallel cable?
Hmm this is not a series/parallel connection, just series. Four 12V nominal batteries in series = 48 V.

I crimped my own AWG 4 welding cables into the Anderson Power SB175 connectors (I bought these from Powerwerx), put heatsink over the ends. I considered getting the cables from Big Battery but the cables were crazy longer than I needed if I remember right.

Series cables are quite simple, just sort of daisy chained together in the length that you need:

IMG_9749.jpeg

Though, the colors are a bit confusing, since positive (red) from one battery plugs into negative of the next and vice/versa.
 
  • Like
Reactions: Mia
OK. I can see what you did. I thought the OWL's were 24v, that's why I thought they were connected in series parallel. Nice set-up your have there.
 
Back
Top