Recharging 12v devices from domestic bats

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neil1967

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I recently bought a rechargeable 'Hoover' which is advertised as 12v, and comes with a mains adaptor for charging. One of the attractions was that I would be able to recharge it direct from the domestic battery, with a suitable cable, which I could make up. Investigating further, it appears that the mains charger is about 15v, which I guess makes sense. Question is, if I connect the Hoover to the domestic battery, which will be at around 12.6v, will it ever charge the Hoover, or am I best using the mains adaptor through a low wattage inverter off the domestic battery?

Thanks

Neil
 
It won't charge off the boat battery. Why not dump the rechargable battery and power it directly from the boat battery through a long lead and cigar lighter plug?
 
neil1967 said:
I recently bought a rechargeable 'Hoover' which is advertised as 12v, and comes with a mains adaptor for charging. One of the attractions was that I would be able to recharge it direct from the domestic battery, with a suitable cable, which I could make up. Investigating further, it appears that the mains charger is about 15v, which I guess makes sense. Question is, if I connect the Hoover to the domestic battery, which will be at around 12.6v, will it ever charge the Hoover, or am I best using the mains adaptor through a low wattage inverter off the domestic battery?

Thanks

Neil
Click to expand...
Buy a Kensington DC/DC charger.
 
elton said:
It won't charge off the boat battery. Why not dump the rechargable battery and power it directly from the boat battery through a long lead and cigar lighter plug?
Click to expand...

If its anything like the 12 volt vacuum cleaner I have its not worth the bother .. chuck it away.
 
why not go corded?

Just a thought.

You could consider attaching a 12volt power cord and by-passing the battery in the Hoover. In most boats you are never very far from a 12 volt power outlet anyway.
I know this goes against the "cordless everything" philosophy, but consider:
The power lead will be lightweight and flexible.
No charger or battery to worry about.
reduced weight in the hoover when you remove the battery.
As long as your house batteries are charged (and i assume this is always) then you can always use the Hoover...

I have a battery-less battery drill on my boat to which i have fitted a cord.
Wouldn't swap this for the hassles of charger and batteries on the boat, though i also wouldn't be without my battery drill for home maintenance.

Drat- i started my reply before Elton but got distracted. Does this mean i have been lakesailored? or has Elton been lakesailored by me?
 
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Charging 12v batteries from the ships 12v supply

All of the above is correct. However to charge the batteries in the Hoover probably 10x NiMH rechargeable batteries you need around the 15 volts of DC. This higher voltage is needed to push the current into the batteries. As said you can get a converter that produces higher voltage from the ships battery for such purposes. A bit like a mini "Alternator to battery charger from Stirling" which has the same problems charging a domestic battery and solves the problems the same way.
For a crude charger you could put a couple of D cells in series with the ships supply. You could use rechargeable and recharge them when you are not charging the Hoover. Use an amp meter or Digital volt meter on amps to check actual charge current. If you know the amp Hour rating of the Hoover batteries you can determine charge time needed. You can't leave it on long term unless charge current is quite low.

Most people I think find it easier to use an inverter to mains mains charger. however be careful a cheap inverter with "modified sine wave" output may be very inefficient or even destroy the charger. So a pure sine wave would be safest. especially for other devices you might want to run. olewill
 
One of the chargers the RC people use sometimes called a hobby charger will charge it, and almost any other battery, directly and rapidly from 12v.
 
I have tried various 12v vacuum cleaners for on-board use, and they've all been next to useless. One, a black and grey 'wet and dry' device, had a motor that screamed unbearably loudly. Another, a blue Maplins special, disintegrated on first use, the suction fan blowing itself into pieces. Various 12v car vacuums and rechargables have also disappointed, generally because they have insufficient suction for serious cleaning.
However, as I fitted a 1000w inverter last year, which seems to run a microwave oven and large power tools quite effectively, I have just invested in one of these : http://www.dirtdevil.co.uk/our-products-1/1000w-mains-powered-handheld-with-motorised-brush.html - so far, I haven't tried it with the inverter but it looks as if the rating should be compatible - I'll report back!

** Update - I have now tried the 1000W mains Dirt Devil DHC003 with my on-board 1kW inverter, and it works really well, completely knocks the spots off any 12v vacuum that I've tried. Very versatile, with the option of using the rotating brush or the detachable extending hose with a round brush on the end. It's also quite light, though still solidly built. Best thing is that I got it from Tesco Direct, cashed in £15 of Reward vouchers and doubled their value with their latest 'Clubcard Exchange' promotion, so the vacuum actually cost me less than a fiver - bargain!!
I would be interested to know if anyone has tried the Draper 1000W vacuum with an inverter - afaik, all other mains-powered vacuums are too powerful for a 1kW inverter to handle. **
 
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Battery (12v) powered vacuum cleaners are generally useless because they lack power. However a few, the Dirt Devil included are quite powerful but will therefore run for only a very short time even on a full charge. If the internal battery is by-passed to run from the boat battery the current drawn will be very high (example a 600watt will draw 50amps from 12v) so connecting through a cigar lighter type connector is not practical. It would mean connecting directly to the batteries using croc clips.

You could use the boat batteries to recharge the vacuum cleaner internal 12v battery but as previously stated the boat battery voltage will have to be stepped up to 15v or the engine run continuously while charging which might take several hours - again not practical. The alternative would therefore be to use an inverter to create 230v and use the cleaner mains charging unit.

So cheap low power 12v cleaners are useless and powerful ones not practical

My conclusion is a dustpan and brush is far cheaper and much less hassle and will not drain the boat batteries.

Unless you have the luxury of a shore supply in a marina. In which case a mains cleaner could be the solution.
 
VicS said:
If its anything like the 12 volt vacuum cleaner I have its not worth the bother .. chuck it away.
Click to expand...

Meh - we've got a 12V mini-Dyson clone (from Black & Decker) - non-rechargeable - plugged into a 12v socket it draws ~5A and does a great job for cleaning up and sucking air out of vacuum bags for bedding, etc.

The similar (rechargeable) model we have at home is nowhere near as useful - I guess it's tiny internal battery is no match for our MightyHouseBank (recently re-calibrated down to 160AH on the NASA BM-1)
 
Greenalien,

A stiff brush will get rid of most surface dirt but how dirty does the upholstery get?

I have had my boat for over 7 years. Last winter I removed the fabric upholstery covers for the first time and washed them. The water in the washing machine was hardly discoloured and the covers looked almost the same as before. The most noticeable difference was that they smelt fresher.
 
neil1967 said:
Question is, if I connect the Hoover to the domestic battery, which will be at around 12.6v, will it ever charge the Hoover, or am I best using the mains adaptor through a low wattage inverter off the domestic battery?
Click to expand...

I have some gizmo's which charge fine from the battery, some which don't, and some which will charge but only if the engine is running.

Your best bet is to try it and see what happens.

Personally, I would stick to dust pan and brush but I'm sure you don't really want to have that discussion. :)
 
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