Battery for portable fan

Chrissticks · Sep 3, 2017

Hi Guys,
I'm a total non-electrician looking for advice please.
I want to power a portable 12v 9w fan.
I'm looking at this battery to power it:
SW280 (12V 7Ah) Yuasa High Rate VRLA Battery
Capacity at 20-hour Rate (Ah): 7.6
Is this battery suitable and how long will it last before it needs charging please?

telectrix · Sep 3, 2017

1. needs to have a fuse in the battery lead. 2A should be about right.
2. @ 9watts that's 0.75A. so your battery will last 9 hours , but should be recharged before going totally flat. 5 - 6 hours is practical.

Chrissticks · Sep 4, 2017

Thanks for that, that's what I'd worked it out, but not with any great confidence.
What I want the fan for is to circulate the air when I leave my dogs in the back of the van. I cant see that I would ever leave them fo 5/6 hours in one go but possibly might with a good walk in between.
Would it be ok to run it off my van battery rather than have a separate one?

telectrix · Sep 5, 2017

let's say to fan pulls 1A ( as a round figure ). an avearage car/small van battery is 65Ah, so to drain completely would take 65 hours. therefore a couple of hours won't hurt. problem with dogs is that they overheat very easily.your van is like a greenhouse in sunny hot weather, so you's still need to leave windows open.problem arises in vans with bulkheads and no rear windows, .my advice is avoid leaving dogs in wherever possible.

Chrissticks · Sep 5, 2017

telectrix said:
let's say to fan pulls 1A ( as a round figure ). an avearage car/small van battery is 65Ah, so to drain completely would take 65 hours. therefore a couple of hours won't hurt. problem with dogs is that they overheat very easily.your van is like a greenhouse in sunny hot weather, so you's still need to leave windows open.problem arises in vans with bulkheads and no rear windows, .my advice is avoid leaving dogs in wherever possible.

Thanks again for your reply. Yes, we've had dogs for 30 years so we know you have to be careful. We are about to head off for our second winter caravaning in Spain. We had it sussed with our previous van (Vauxhall Vivaro) as the back half of the load compartment was caged out for the purpose and we bought security bars to enable us to lock the side and rear doors slightly open (Cool Dog Car Ventilation Tailgate Lock at Doggie Solutions Online Pet Store - https://www.doggiesolutions.co.uk/cool-dog-car-ventilation-tailgate-lock-14773-0.html)
However we've just bought a Vito crew-van with back seats and and 2 sliding doors. The plan was that the 3 dogs would travel on the crew seats using a bridge over the gap and we assumed we would be able to lock the sliding doors ajar using the same bars. However we've found that isn't possible with this van because of the way the locking works, but we can lock one of the back doors to be slightly open. So the plan now is for them to travel on the crew seats and go in the back when we have to leave them, with the back door locked ajar and the fan mounted directly inside the top of the door to suck in and circulate air.
We always try to leave them in an underground or multi story car park or other shaded place - all the supermarkets and shopping centres and many other places have shaded parking spaces. If we can't get in the shade we also have a good quality, made to fit reflective cover which fits around the outside of the windscreen and front windows - but we would never leave them in full sun on a hot day anyway, even with that.
One final question. My plan is to buy an extension lead and take the lighter socket plug off the end and fix directly to the battery terminals, then just either switch off at the fan or unplug the fan lead from the extension lead when not needed - is there any reason why not?
The battery is 92AH and 850 amp.