Is a B&D Simple Start safe to use?

[HarryM1BYT]

Originally Posted by VMax1000

In all the discussions we have assumed that the Black & Decker unit supplies 12 Volts. Well, it doesn't.

According to the spec it has 3 x 6 Volts batteries = 18 Volts
http://www.blackanddecker.co.uk/auto.../catno/BDV040/

I cannot see the mention of 3x 6v batteries, but it does say 6aH which might be enough to start a small moped.

[VMax1000]

Originally Posted by HarryM1BYT

I cannot see the mention of 3x 6v batteries, but it does say 6aH which might be enough to start a small moped.

Here you go

6v.JPG

[SD1too]

Originally Posted by HarryM1BYT

I cannot see the mention of 3x 6v batteries...

Click on the Specifications tab Harry.

Simon

[HarryM1BYT]

Originally Posted by SD1too

Click on the Specifications tab Harry.

Simon

Found it, thanks. 18v will certainly shift the current in, but 6aH???

It also says it recharges the battery in 20 minutes - does it mean its battery or the car battery?

[VMax1000]

Originally Posted by HarryM1BYT

Found it, thanks. !8v will certainly shift the current in, but 6aH???

6Ah = 12A per 30 mins = 360 A per minute.

Might be just enough


Where did you get your degree again ????

[SD1too]

Originally Posted by VMax1000

6Ah = 12A per 30 mins = 360 A per minute.
Might be just enough
Where did you get your degree again ????

Herman,

I have a document which says that the relationship between current delivery and time is not linear, so I am afraid that your calculation of 360 amps per minute is unrealistic.

The rating of 6Ah is true for a discharge current of 0.6 amps (the standard C divided by 10). At 20 times this current (your example of 12 amps drawn) the battery's life may be as short as 3 minutes. The exact figure will depend upon manufacturer's data which is not given, perhaps not surprisingly.

Put in a simpler form, as the current drawn increases linearly, the percentage capacity decreases almost exponentially. So a 6 Ah battery is woefully inadequate, as might be expected when the current requirements of a starter motor are known.

Simon

[SD1too]

Originally Posted by HarryM1BYT

It also says it recharges the battery in 20 minutes - does it mean its battery or the car battery?

It means its internal batteries. Note also the meaningless statistic: "constant power 8 amps".

Simon

[VMax1000]

Originally Posted by SD1too

Herman,

I have a document which says that the relationship between current delivery and time is not linear, so I am afraid that your calculation of 360 amps per minute is unrealistic.
The rating of 6Ah is true for a discharge current of 0.6 amps (the standard C divided by 10). At 20 times this current (your example of 12 amps drawn) the battery's life may be as short as 3 minutes. The exact figure will depend upon manufacturer's data which is not given, perhaps not surprisingly.

Put in a simpler form, as the current drawn increases linearly, the percentage capacity decreases almost exponentially. So a 6 Ah battery is woefully inadequate, as might be expected when the current requirements of a starter motor are known.

Simon

Please post the document as normal logic dictates that 6Ah = 12A per 30 mins = 360 A per minute.

Just a matter of dividing hours to mins to secs

If 6Ah doesn't equate to 360Amin you have to let me know where you picked that one up

Because as far as I know there are 60 minutes in an hour so 6 Amps in an hour = 6 x 60 Amps in a minute = 360

[persuer]

well guys you lost me after the word battery.

[SD1too]

Originally Posted by VMax1000

Please post the document ..

It appears to be a study by a group involved in staging Robot Wars. It's just called 'Batteries' and it is dated July 2004. I'm really sorry but I don't have the web address, but I will scan the page from which I obtained the information I posted.

... normal logic dictates that 6Ah = 12A per 30 mins = 360 A per minute.

Arithmetic yes, but logic? Consider a KV6 starter motor rated at 1.8 kW (MG Rover data). This draws 150 amps, approximately. So when connected to a 70Ah battery, fully charged, are you saying that the battery would turn the starter continuously for over half an hour? We both know that this is not the case. You'd be lucky to get 5 minutes.

Simon