Inverter charger

Stretch40

Active member
Jun 26, 2019
326
133
Durham
Hi all I'm buying an inverter to run my charger for our up coming Wales trip from my sums my giant 6amp charger draws 4amp input x 230v is 920w biggest inverter I can find is 6000w peak which sounds great but it's continuous output is 1000w rated at 2000w do we think that will power my charger to charge battery ?
 

nosenada

Member
Nov 26, 2019
50
29
California
If you have not done so already I would buy a cheap watt meter to see the actual draw of your charger. It may not be 920w. I would be surprised if it was that high.

My Shimano 4 amp charger (e6000) only draws around 180w max when measured.

Other recommendation is to spend the extra for a nice pure sine wave inverter. While your charger may work with a cheap modified sine wave inverter it may run hotter (shortening its lifespan) and could be damaged if the cheap inverter dies suddenly.

I use a 600w pure sign wave inverter (800w peak) to run 3 Shimano 4 amp chargers chargers. It was only $116 US.

The peak wattage rating does not really matter for a charger load. The peak wattage rating is more important when you are running a motor from the inverter such as a fan or refrigerator compressor motor where the start up load spikes.
 
Last edited:

Stretch40

Active member
Jun 26, 2019
326
133
Durham
Tbh I thought it was high I've never had a wattage meter and I've been a service eng for 20yrs lol I use multimeter insulation tested and oscilloscope occasionally but never wattage meter ? I just did the calculation and came up with 920w I'm off googling now thanks
 

stiv674

E*POWAH Elite
Mar 4, 2019
777
600
Wiltshire
The 4 amps on the charger refers to the output current not input, as mentioned above my Focus charger draws just under 180 Watts, 4 amps at 42 volts plus losses for electronic stuff inside equals the 180 Watts.
 

stiv674

E*POWAH Elite
Mar 4, 2019
777
600
Wiltshire
It's not my charger is 6amp smart charger the input is 4amps 100-240v I'm Gona measure it ?

Oops, my mistake, I didn't read your first post properly... just read the 4 amp charger bit :rolleyes: Mine says 2 amps max input current, only ever seen 180 Watts max though so hopefully yours won't be much more than 300 Watts... ?
 

thebarber

E*POWAH Elite
May 28, 2018
986
598
Norfeast
I use a 12/1200 victron pure sine inverter and it's overkill but keeps my 240v freezer (converted to fridge) rocking full beer 24/7
A 600w would probably have done the job.
 

speshhead

New Member
Mar 4, 2021
7
0
South
Hi All ,
Please forgive my intelligence. I seem to be having problems with working out if i have the right inverter its pure sine wave 1000w
my specialized charger specs are input 100-240v 2.5a with output 42.0v 4.0A

do i x 42v 4.0 which gives me 168 w
My lead acid leisure battery is 110ah

how many chargers to my 700wh battery can i expect

any help would be well appreciated.thanks
 

Stretch40

Active member
Jun 26, 2019
326
133
Durham
Hi no it's the input u work out but if it helps my giant charger is a 6amp charger I've bought a watt meter plugged it in and while charging the mist it drew was 180w so if your inverter is 1000w continuous you are well in ? I'm buying a 900w continuous inverter to charge two batteries but it says it's 2000w rated 4000 peak ?I think you will be fine ?
 

speshhead

New Member
Mar 4, 2021
7
0
South
Great cheers my inverter has a display on it that went to 179w whilst charging . can it be worked out how many charges i would get ?
 

jimbob

Active member
Aug 3, 2020
520
432
East UK
Hi All ,
Please forgive my intelligence. I seem to be having problems with working out if i have the right inverter its pure sine wave 1000w
my specialized charger specs are input 100-240v 2.5a with output 42.0v 4.0A

do i x 42v 4.0 which gives me 168 w
My lead acid leisure battery is 110ah

how many chargers to my 700wh battery can i expect

any help would be well appreciated.thanks

What is the capacity of your bike battery? You shouldn't really discharge lead acid below 50% (but every now and again is ok). Your 110ah battery has about (110 x 12) / 2 = 660wh available. If you know the capacity of your bike battery you can then work out how many charges you can get.

(Yes, I know this is very simplified, but good enough!)
 

Nickolp1974

Active member
Jul 30, 2019
236
174
Louth lincs
Hi All ,
Please forgive my intelligence. I seem to be having problems with working out if i have the right inverter its pure sine wave 1000w
my specialized charger specs are input 100-240v 2.5a with output 42.0v 4.0A

do i x 42v 4.0 which gives me 168 w
My lead acid leisure battery is 110ah

how many chargers to my 700wh battery can i expect

any help would be well appreciated.thanks

i get approx 3 chargers on 504wh shimano batteries out of 160ah. i have 2 x 180ah in my camper, so really i only have 180ah useable due to depth of discharge(50%). if you only have 1x 110ah, you really only have 55ah and wit that im not so sure it will even charge a 700wh battery even once fully.
 

Nickolp1974

Active member
Jul 30, 2019
236
174
Louth lincs
What is the capacity of your bike battery? You shouldn't really discharge lead acid below 50% (but every now and again is ok). Your 110ah battery has about (110 x 12) / 2 = 660wh available. If you know the capacity of your bike battery you can then work out how many charges you can get.

(Yes, I know this is very simplified, but good enough!)

dont forget inverters are only about 85% efficient! so only 561wh
 

jimbob

Active member
Aug 3, 2020
520
432
East UK
dont forget inverters are only about 85% efficient! so only 561wh
Very true, but I was just doing ballpark numbers! By the time you add in the lead acid will start at 13.8V which will give more power, the fact the battery being charged is unlikely to be completely empty etc it ends up being there or there abouts!

Back of the envelope maths...
 

speshhead

New Member
Mar 4, 2021
7
0
South
cheers lads thanks for the input ?? would i be right in thinking that a 12v specialized charger (42v @ 2A ) rated. that drew 69ah total over 10hrs running of the 110ah battery would be more effeciant say than inverter and standard specialized charger ?

thanks again ??
 

Nickolp1974

Active member
Jul 30, 2019
236
174
Louth lincs
cheers lads thanks for the input ?? would i be right in thinking that a 12v specialized charger (42v @ 2A ) rated. that drew 69ah total over 10hrs running of the 110ah battery would be more effeciant say than inverter and standard specialized charger ?

thanks again ??

Not sure, i used the 2 different shimano chargers on my testing but didn't go in depth at all. Didnt want to keep using the Van batteries when the van's not actually being used!! not long now hopefully. In my thread on my van it gives a little info, post #9 Transit Custom EMTB Camper van conversion - EMTB Forums
 

jimbob

Active member
Aug 3, 2020
520
432
East UK
cheers lads thanks for the input ?? would i be right in thinking that a 12v specialized charger (42v @ 2A ) rated. that drew 69ah total over 10hrs running of the 110ah battery would be more effeciant say than inverter and standard specialized charger ?

thanks again ??
It should be more efficient, but difficult to say by how much as its very dependent on hardware. I'd guess between 5% and 20% better than an inverter.
 

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