Backup battery

As far as I know, Drobos have batteries installed so they can protect the data which happens to be written during the power failure by maitaining the interrupted transactions’ state in memory and then gracefully resuming them once the power backs up. Much like the hardware RAID controllers. From what I read/saw somewhere, these batteries are of the Li-Ion/Li-Po type. Besides many advantages of this battery chemistry, there is one quite serious drawback - pronounced aging. They are considerably deteriorating with time by just sitting there (whether used or not) and the effect is worsen by both elevated temperature and the state of full charge. As we know they’re not user replaceable so I wonder:
[]What is their life expectancy and if this was evaluated/tested by DRI
]What could be the consequences of the battery failure during power outage
[]What is (if any) the safety margin assumed by DRI which takes the battery aging into account
]For how long could new battery hold the data intact
[*]If there are any battery diagnostics performed by the firmware and if yes, how the malfunctions are handled.

question 4: for the drobopro’s its a minimum of 72 hours

the rest - i have no idea

fortunately if we have power cuts in England its usually quick powerfluctuations rather then full blown outages but yes, this will be handy info to obtain.
must be a way to replace them, unless they are superglued or something (assuming they can be purchased)

Oh, that seems like a lot of headroom. I was expecting some hour or two :)[hr]

I think I’d manage to replace it too - I was rather meaning “not typical end user replaceable” :wink: Regarding the availability - what really matters is a voltage (cell count) and capacity (needs to be only roughly the same, I guess). You can buy almost every size and capacity Li-Po cell you could imagine so this is not going to be a problem.

its a pretty hefty battery, and all its doing is keeping some ram alive, it doenst really draw a lot of power

bottom of this page:


7.5Ah = 7500mAH (obviously) which is about 50% bigger than my enormous laptop battery!

I think you might have overlooked the voltage aspect. The battery pack on this photo is rated at 3.7V and clearly consists of 3 cells so they are most probably 2500mAh cells wired in parallel. BTW, I was wrong with my Li-Po assumption - by the look of the pack you can tell that most probably they are “classic” industry-standard 18650-sized Li-Ion cells, very much like the ones found inside the most (conventional; Mac Airs, ultraslims and the likes aside) laptop batteries (and some electric cars!). This (7.5Ah@3.6V) yields some 27Wh. Laptops operate at much higher voltages usually so the capacity you mentioned (5Ah) most probably reflects to the battery pack consisting of several cells connected in series/parallel combo (misses the @xxV part), 3S2P being not uncommon example. This way (2 packs of (3 cells in series) connected in parallel), assuming 2Ah cells, you get: 210,8V2Ah =~43Ah. That’s why I personally think it’s always better to use watt-hours figures when talking about batteries. But that’s still some impressive backup battery in the Drobo, nonetheless.

BTW, thank you for that link - I think I’ve seen these photos before but forgot about them.

I’d recommend no relying on their batteries and keep your drobos, and every other piece of computer gear, plugged into UPSes. Clean constant power will save your electronics.

is a ups something i can buy in the uk, faily cheap, and which can be simply kept plugged in permanently to the mains supply, (eg a bit like those surge protector units)?

its a surge protector with a built in battery

One like this


is going to be fine for most home needs - it will power your pc (and drobo long enough for your pc to shutdown and then drobo will go into standby and all will be safe :)[hr]
this one is actually much nicer (but i HATE ebuyer)


incidentally that is also the exact UPS my NAS is plugged into.[hr]
oh and cheap is NOT good, stick to very large brand names

APC tend to be by far the best, belkin also make quite reasonable units.

@Paul: Yes. It’s an uninterruptible power supply. Fairly cheap is possible, but keep in mind the ultra-cheap ones are “disposable” purchases rather than something you buy, run, and maintain for a long time.

In the US at least they’re sold by APC, TrippLite and other vendors. For the sake of software compatibility and availability of replacement batteries, you probably want to stick with a name-brand.

Also, there are generally two types - the cheaper “simulated sine” which simulates a sine wave using stepped square wave, and the more-expensive “pure sine” which provides a pure sine wave to equipment (just like the mains).

Pure sine is generally used for servers and sensitive equipment. For the occasional outage, either is fine.

Wisdom I’ve gleaned so far:

  1. VA != watts. The UPS itself will have a maximum wattage, for example, my 1300 VA UPS is 780 watts max. You must avoid drawing more than the max - the UPS will alarm and shut itself down, cutting power to the attached equipment.

2a. Not all “battery backup” units have user-replaceable batteries. The really cheap office store special types are designed to go for the lifetime of the battery, then you’re done.

2b. Batteries have a fixed lifespan. Your typical lead-acid UPS battery will have a 3-5 year lifetime. If the environment is warm or you have heavy load, expect lifespan on the shorter side. The newer more-efficient UPS models tend to have longer-lasting batteries, but they will eventually die and replacements are not necessarily cheap (especially when it’s a “pack” like the newer APC ones, rather than more-standard terminaled batteries like the older APCs and others.

  1. Avoid the temptation to “ride through the outage” by getting a unit with huge wattage. The goal is to provide enough battery-backed time for your attached equipment to complete whatever task it’s doing and safely shut down. That’s it. You don’t need to have uninterrupted power to everything, just to the stuff that’s actively manipulating data. This means Drobo and the computer connected to it, and maybe the monitor if you need to manually shut down.

  2. Larger is better than more. It’s more efficient to have a larger-capacity UPS rather than lots of smaller-capacity ones.
    If you have a house, you may want to consider a whole-house UPS or line-conditioner, keeping in mind previous point.
    I once had 13 UPSes (almost every outlet was a UPS, because almost every outlet had equipment - see previous point again) and my power bill was insanely high. I’m down to 5, I’ve downsized significantly equipment-wise, and my power bill is way lower.

  3. Omnipotence gets expensive, but is available. If you’re crazy like me and want to remotely-manage the UPS (reboot it, check power condition, etc) there are options to do this (I have an APC Smart-UPS 750 with a network management card attached on my server), but you do get into the more expensive zone - pure sine, larger capacity, etc - to have that option.

and to bridge back on to the original topic…
My concern with Drobo’s battery is not so much its runtime, since I have my Drobos on a UPS, but rather the fact that hopefully my Drobo will be operational for a number of years from now. The battery, however, may not be. I read an article (forgot where, sorry) recently about old, otherwise-good equipment often being ruined by leaking or exploding batteries. That’s where my concern about Drobo’s battery comes in.
I might still have DroboCare on the chassis, but if the battery dies and physically damages more the hard drives… :frowning:

wow bhiga - and you didnt mention line-interactive versus standby ones?!?! shame on you!


thanks for the links docchris, and for info bighugga (just kidding) :smiley:

thats interesting - if the drobo hardware outlasts 1 component, its like the weakest thing in the chain bringing everything down to that level (if it even is that weak). i always thought that batteries like the heat though?

eg if you dont start a car in winter, the cold drains it quick, but if you warm it up a bit, it starts

batteries are like people - they like moderate to cool temperatures… long term storage (i.e. not decreasing their life) probably around 15C

ouch,that rules things out for australians :slight_smile: just kidding guys)

@Docchris - Yeah, I didn’t want to get tooo technical. :wink:

@Paul - LOL! As for temperatures, too cold actually impedes the chemical reactions and prevents the battery from providing juice, though too hot will also do bad things too. So Docchris hit it on the head - people-friendly temperatures. If you battery needs a winter jacket or starts to sweat (leak) - it’s not a good thing.

It’s a good idea to record the date of manufacture and date you put it in service. Most of the ones that communicate with a computer can store this info (though sometimes it’s stored just in the software and not the UPS itself), but it’s good to record it anyway. Also, for ones with user-replaceable batteries, it’s a good idea to visually check the battery state every now and again - make sure there’s no bulging or warping caused by sulfation, as excessive warping can cause the battery to become stuck in the UPS. I’ve had that happen a few times in the past.

Don’t forget that various battery chemistries can differ from each other in just about every aspect. Li-Ions / Li-Pos for example, like to be stored in a cool place (fridge) about half-charged when not used, while the Lead-acid ones (car, UPS…) should be topped all the time and, like you said, stored in human-friendly temperatures. Also, I wouldn’t worry about exploding Li-Ion (Drobo backup) battery that much unless seriously abused (extreme temperatures, shorting-out, severely exceeded charging current). They just tend to lose their charge acceptance and increase internal resistance over time.

Here’s a great read on various battery types: http://www.batteryuniversity.com

Good point on the Li-Ion.

I have “bulged” Li-Poly (APC Universal Notebook battery - maybe that’s why they don’t make them anymore), but I haven’t seen what happens with Li-Ion yet.

+1 on BatteryUniversity. I keep thinking I should buy his book, but keep putting it off… maybe if it’s available as an eBook. I’m only an off-and-on book reader.