• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

Fogstar DIY 4s case

asderferjerkel

New Member
Joined
Dec 6, 2022
Messages
5
Long-time lurker, first-time poster. Surprised not to have seen this discussed yet but I guess there's less of us off-grid in the UK and this is only really good for small van/boat setups.

Fogstar DIY 12v kit with Envision Grade B 315Ah - £350

Here's a good unboxing/assembly video (but I'd only torque to 4Nm!):


Frankly this looks like a steal at £350 delivered (8.7p per Wh), call it £50 per cell plus £150 for a solid-looking metal case with compression and BMS. Fogstar confirmed that it comes with the JK B2A8S20P (with CAN/RS485) and the output terminals are M8. Preordered mine to replace 300Ah of tired AGMs in my boat, gonna drill an extra hole in the case to run the UART out from the GPS port to talk to my Victron gear. Not sure if the BMS has the optional heat interface but not bothering with a heat pad as in any case it never gets below 0 in my engine bay, and running the engine to charge in winter will warm them up anyway. Absolute max temp they'd see in the height of summer is maybe 40C.

Got a couple of adjustments to make to my current setup, swapping the ArgoFET for an Orion XS for alternator charging, and moving the SmartShunt from covering everything to just the DC loads so they're compensated for in the charge/discharge current limits. Easy peasy!
 
Looks like 1/2” a Luyuan 8s case.

I wonder who else sells these, seems like a nice option for the 12v world.
 
@740GLE looks decent eh? I had a quick look around but couldn't find anything similar with the terminals recessed like that. Maybe it's a custom build from one of the usual manufacturers, the PCB for the balance leads looks very familiar.
 
Yeah for the package deal it’s a nicer option than the nylon cases I’ve seen.

I only say it looks like the Luyuan case cause of its screwed together with a compression plate and mounting location of the BMS behind the front plate.

The terminal location is very smart and easier for this to move the battery around without fear of damage to the terminals.
 
Those do look good, I couldn’t find any for 12 volt 4s so I had a dual 12 volt box made. These will be 608ah @ 12 volt. I have four of these mobile boxes depending on how much capacity I need with me.

5F723D91-8B23-44E1-B1BC-0162A80549A9.jpeg82EB99ED-3A65-492F-942E-83AC0F7AB1B2.jpeg
 
Finally picked up the box of cells today - lack of postal address is a bit inconvenient! Fogstar said to allow a few days for the courier to do a risk assessment but it turned up next day anyway.

Not that I have anything to compare it to but cells look perfect, no discernible swelling and each measures dead on 3.295v. Sticker on the side dates them October 2024.

Box is very solid and well built, no burrs or anything and all edges rounded. Comes with flexible busbars (cells also came with flat ones), plastic and foam sheets and a 400A mega fuse. From a quick look it did seem a little light on bolts - missing 4 M8 12mm bolts (plus flat + spring washers) to connect everything up, including for the external terminals, so ordered some elsewhere for speed. Very happy so far though. Assembly this weekend!
 
Quick update after a week of use - more than happy with everything. Haven't had the chance to take them quite empty yet but pulled 315Ah from full to 3.1V so looks like they're a little over nameplate capacity at least. Stayed very well in balance with max delta of 10mV before the balancing kicked in. Here's an assembly pic and a comparison to the 3x 100Ah AGMs they replaced:

IMG_20250123_154910.jpg

IMG_20250125_150423.jpg

As far as quality of life goes it's night and day - from maybe a day and a half of autonomy in the winter with the lead acids, to a full 4 days now. Woo!
 

diy solar

diy solar
Back
Top