# Electric aficionados, question.... (1 Viewer)

#### Just smiffy

Ok you leccy guys... I have a voltage meter wired direct to my leisure batteries... I have solar going in so my monitor would for example say 14.5v as it is now.... if I plug my iPad on charge in said monitor to the 5v 2amp socket it could go down to 12.9v...

Now,
If I turn my waeco MSP1512 inverter on and plug into the iPad charger output 5.2v and 2.4amps on the mains my battery monitor will say 13.8v ...

So, in conclusion it appears having a big inverter on rather then plugging straight to the batteries uses less power...?

Plus the iPad charges quicker on the mains... I’m puzzled.... which isn’t hard...

I want to learn something today

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#### Lenny HB

LIFE MEMBER
See what results you get using an old fashioned analogue meter if you want an accurate answer.

#### hilldweller

LIFE MEMBER
Ok you leccy guys... I have a voltage meter wired direct to my leisure batteries... I have solar going in so my monitor would for example say 14.5v as it is now.... if I plug my iPad on charge in said monitor to the 5v 2amp socket it could go down to 12.9v...

Now,
If I turn my waeco MSP1512 inverter on and plug into the iPad charger output 5.2v and 2.4amps on the mains my battery monitor will say 13.8v ...

If the voltmeter is the one in the picture the answer is voltage drop. Wiring to the voltmeter/charger is so poor you are losing volts due to cable resistance. It probably won't cause you any bother though.

#### pappajohn

LIFE MEMBER
I have solar going in so my monitor would for example say 14.5v as it is now.... if I plug my iPad on charge in said monitor to the 5v 2amp socket it could go down to 12.9v...
Something makes no sense there.
Plugging in your 5v 2a ipad charger should make no practical difference to the displayed voltage.
To reduce the battery voltage that much would need a current draw of maybe 100amps or more.

Sorry, just seen the picture... See Hilldwellers post above

#### andy63

##### Free Member
So, in conclusion it appears having a big inverter on rather then plugging straight to the batteries uses less power...?

Plus the iPad charges quicker on the mains... I’m puzzled....

the power to charge your I pad will not change regardless of the source you use..
what might make it faster is the ability of one charging source to supply more power ini a shorter time ..ie supply a higher current..
your first socket pictured is rated at 2amps... your inverter socket rated at 2.4 amps... so it will have the ability to charge your I pad in a shorter time... but the total power consumed to do the charging will be the same to fully charge the device..
using your inverter may in fact use more power in total as your inverter will have losses and running a light load on a large inverter is inefficient in terms of percentage losses
Andy

#### autorouter

If the voltmeter is the one in the picture the answer is voltage drop. Wiring to the voltmeter/charger is so poor you are losing volts due to cable resistance.
This voltmeter is measuring the voltage at the meter end of the wire connecting it to the battery. If you use a multimeter direct to the battery terminals, the chances are it will be 13.8 volts for both charging methods.

I'd check your connections, sounds like there's a bit of resistance somewhere in the voltmeter supply circuit.

#### two

You're right to be puzzled.
I'm with Brian here (post #3).
Have you tried using a different USB port?
The price of that voltmeter gizmo may provide an answer.

OP
OP

#### Just smiffy

If the voltmeter is the one in the picture the answer is voltage drop. Wiring to the voltmeter/charger is so poor you are losing volts due to cable resistance. It probably won't cause you any bother though.

The wire I used Brian is domestic 240v 13 amp cable if you know what I mean... think it came of an old hoover.... connections are good...

OP
OP

#### Just smiffy

You're right to be puzzled.
I'm with Brian here (post #3).
Have you tried using a different USB port?
The price of that voltmeter gizmo may provide an answer.

Ok,.... I have another similar one connected to the engine battery and plugged it in that and it only dropped .1 v so looks like a naff socket...

#### Lenny HB

LIFE MEMBER
The wire I used Brian is domestic 240v 13 amp cable if you know what I mean... think it came of an old hoover.... connections are good...
Won't make any odds what you wired the meter with it is only measuring voltage and will only draw a few milliamps to power it.

OP
OP

#### Just smiffy

Some things in life can be simple.... a bit like me sometimes

#### Guigsy

Only when that USB/voltmeter is pulling current will you see the voltage drop along its wires. When there's nothing plugged into the USB ports (so no current) the voltage drop will be minimal. As @hilldweller suggested, it's probably got skinny wires feeding it so just ~1 amp is quite a bit. If you ran the inverter as an extended spur from the terminals on the back of the voltmeter (which would be a bad idea as it's rated at 1.5kW!) you'd see the same drop on your USB port's display (if not slightly more... unless the wires burnt up from the initial power spike).

#### hilldweller

LIFE MEMBER
Won't make any odds what you wired the meter with it is only measuring voltage and will only draw a few milliamps to power it.

But it's not a meter it's a meter/charger.

#### hilldweller

LIFE MEMBER
The wire I used Brian is domestic 240v 13 amp cable if you know what I mean... think it came of an old hoover.... connections are good...

Should be good enough. But hoover cables are notorious for failing due to constant flexing.

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