Waterproof boxes for dry cell batteries? Need 9V - Page 1
Forum section: electronics / beginners

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 27, 2015, 10:38:37 am
content: Has anyone come across a commercial source for waterproof plastic or whatever boxes for PP9's or say an equivalent of six D cells? Thanks!Why do I want them? Small outside PIR radio alarms with internal PP3's that don't last very long. Tried the 9.6V re-chargeables from China, they are of very variable life and quality. Thinking of a separate battery box underneath the alarm boxes, with D cells or a PP( in it, externally wired to the PIR radio boxes, as there's no room inside for a bigger battery. Thanks.

author: orbiter
author_rank: Frequent Contributor
timestamp: August 27, 2015, 11:09:57 am
content: How about this..http://uk.farnell.com/hammond/rs5105s/enclosure-watertight/dp/1877262

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 28, 2015, 11:36:34 am
content: That's just the type of thing, unfortunately the internal depth isn't quite deep enough, a PP9 is 81 x 66 x 52 mmThat is only 48.2mm deep, sadly. Price was good, too. many thanks, at least I am on the right track now, cheers.

author: orbiter
author_rank: Frequent Contributor
timestamp: August 30, 2015, 03:28:28 am
content: How about this one...http://www.amazon.co.uk/Weatherproof-External-Junction-Complete-Connector/dp/B00DHHMJOISent from my Nexus 7 using Tapatalk

author: Gyro
author_rank: Super Contributor
timestamp: August 30, 2015, 08:57:57 am
content: I'd go for a smaller box and put in a battery holder for 6x AA cells. The last PP9 I bought for my Marconi TF2700 bridge was so dried out that it didn't last at all - it's an old, virtually obsolete (and so, expensive) zinc carbon battery design from the early transistor radio era. I replaced mine with a holder with 6 AA cells and am getting trouble free life.A PP3 battery really has a very small capacity (it's the smallest capacity vs price that you can buy), it also has the highest internal resistance so its voltage will drop more in cold weather. I think you'll find a decent set of 6 AA alkaline cells in a holder with a smaller waterproof box will be more than enough. You could go up to C or even D cells if you really want, but you get to the point where shelf life overtakes discharge life (if the sensor consumes low enough current for them to fit a PP3 as standard) as the end point.Dab a bit of Vaseline on the ends of the batteries as you put them into the holder for corrosion protection, even in a sealed box.Give the PP9 a wide berth though.Edit: Just for comparison purposed, a typical PP3 has around 600mAh at low load, an AA battery is 2500mAh at the same discharge current.

author: SeanB
author_rank: Super Contributor
timestamp: August 30, 2015, 09:08:28 am
content: Funny, I buy Duracell ones made within the last 6 months, and while they are expensive they do last well. Around double the price of the cheap one but will last a lot more than twice as long.

author: Gyro
author_rank: Super Contributor
timestamp: August 30, 2015, 09:11:26 am
content: @SeanB Was that PP9 or PP3?

author: SeanB
author_rank: Super Contributor
timestamp: August 30, 2015, 09:27:18 am
content: PP3, but the PP9 and PM9 are very common, though only in a zinc carbon stacked plate type, mostly Everready. Bloody expensive now though, they are around $5 each.

author: Gyro
author_rank: Super Contributor
timestamp: August 30, 2015, 09:45:55 am
content: QuoteAh, ok. I did look to see if anyone made an Alkaline PP9 but didn't find one. As you say, bloody expensive (even the cheapo ones). Although their spec capacity is pretty high, low demand means that a lot of them are quite old by the time you buy them and being zinc carbon, they would sag quite badly if used outside in UK winter temperatures.

author: SeanB
author_rank: Super Contributor
timestamp: August 30, 2015, 10:16:54 am
content: When I was young ( back when Noah was waiting for the trees to grow) they were both common and cheap, soi they were, along with the telephone 3V cells and 4V5 lamp and 6V lamp batteries, the battery of choice, as you could get a lot of run time out of them. Alkaline cells were not even sold then other than as a very expensive alternative , and rechargeable was limited to a lead acid or a C or D NiCd cell.

author: Chris Wilson
author_rank: Super Contributor
timestamp: August 30, 2015, 11:31:52 am
content: Very good point, I assumed the bigger 9V batteries were still commonplace, cheap, and available in other than zinc carbon. A multiple battery array is certainly better now I have done my homework, thanks for the warning. Age made me think they are still in every transistor radio....

author: Gyro
author_rank: Super Contributor
timestamp: August 30, 2015, 12:25:33 pm
content: QuoteHaha, I remember those days tooThe days of the 4 1/2V ones with the brass strips (just the right spacing to put across your tongue) , the bigger ones with the terminals were better, no need for paperclips. The best ones i got were from my Dad, replaced flag cells from the alarm system at workhttp://www.radiomuseum.org/r/ever_flag_battery_6.htmlThey would come home in a partitioned cardboard box and I used to have great fun connecting up the wire links to put them in series stacks (they were actually good for about 8A on a reasonably fresh set). it was easy to cut away the pitch at the top and extract the carbon rods complete with terminals. With a couple of those you could make a brief, and very smelly arc lamp

author: Gyro
author_rank: Super Contributor
timestamp: August 30, 2015, 12:43:12 pm
content: QuoteThe youngsters must be thinking we're a real trio of old crocks now!