HP RAID battery mod

I have a bunch of older Gen 6 and Gen 7 HP servers that all use the battery-backed RAID cache. The RAID cache makes a big difference with disk read and write performance. When the battery won't charge anymore then the RAID controller won't use the cache and disk performance suffers.

Aftermarket mod to the rescue!

Yes, it is possible to force the controller to use the cache even without the battery, but write cache without the battery is a really bad idea - if the server loses power then any data not yet written to disk is lost.

Used battery pack, via eBay, that came with a broken clip

New battery modules are $100 if you can find them, and I didn't put much effort into getting them at that price. It's not that the electronics in the battery module go bad, but the obscure NiMH batteries do. It's possible to buy those near-proprietary (non-standard) NiMH batteries, but they're expensive

There's a pretty good used market from computer recycling companies for these battery modules, directly or via eBay, but used five-year-old rechargeable batteries are a crapshoot. Maybe they'll be good when you get them and last a week, or maybe they'll last a year. I needed a better solution.

I found a blog post that not only showed what's possible with consumer rechargeable batteries but most importantly how to get it to fit some of the 1u HP DL360 G5 servers that I have. The blog is in Russian, but Google Translate (via Chrome) made quick work of translating the blog.

For some of the bigger servers I used a 4-AAA battery holder that stacked two over two. That fit better in those servers and held in place with Velcro.

I chose Amazon's AmazonBasics AAA batteries, mostly based on price, but also Prime shipping. In the past, I've had great luck with Panasonic Eneloop batteries, but they're a bit more expensive.

For the 1u servers, I used a flat 4-AAA battery holder, soldered it all together, and then melted the plastic of the battery holder to the plastic tray to make it all fit together. After making a bunch of these modules I powered down the servers, plugged them in, and powered each server back on. Between the regular and pre-charged AmazonBasics batteries, I didn't find any difference - they both needed to charge in the servers before the cache was automatically reenabled.