inverter and inflator

I have a magic air inflator
the big orange one
can inflate a 3 man tube in no time

in the old boat, I plugged it in to a fairly small inverter and the thing worked like a charm

in the new boat, I have a Cobra cpi 1550...a 1500 watt inverter
it is wired to a distribution block which in turn is routed to a stringer fuse holder, then to the battery.. uses a 5AG60A fuse

the first trip out, it blew the 40 amp on a portable inverter....we found a marina with electrical outlets and the inflator worked fine

tonight I plugged it in to the 1500 watt inverter and it ran for 5 seconds and then blew the 60 amp fuse

when we got home, I plugged it into my work bench...it dimmed the lights bigtime....then ran well

not sure where to go from here

Cobra recommends a 200-250 amp fuse
but the inflator does seem to start hard

how can you tell if there is a problem with the inflator? ..... if it runs..after the hard start?
I would take it apart, but not sure what I am looking for

the inverter runs other...smaller...gear just fine

my simmer pumps for the ballast system are connected to the same distribution block....they ran fine

what do yall think?

anybody know anything about these small vacuum motors?
thanks

The Magic Air comes in at least two 110v versions: DIDA2 and DIDA4

The DIDA4 takes 11.25 amps at 110 volts to operate. Thats ~1200 watts. 1200 Watts at 12 volts is 100 amps. The DIDA2 takes takes 7.5 amps at 110, or 825 watts, which requires 68.75 amps.

If your inverter only has a 40 amp fuse then the most that it could sustain is 40 x 12 = 480 watts, which would only provide 4.3 amps at 110 volts. The situation gets worse if the wiring to the inverter is a little under sized and there is a voltage drop. If the voltage drops to 11 volts then the maximum power you can sustain on a 40 amp fuse is only 440 watts. To further confound things, the inverter is probably only about 80% efficient, so to get 800 watts to the inflator would require drawing 1000 watts from the battery, which at 11 volts would require 90 amps.

If you want that inverter to operate reliably then you need to supply it with a much larger current capacity. I would follow the manufacturers recommendation and use a 200 amp fuse with wires that will handle that load (like, #2 awg) and keep the wires as short as possible to the battery.

Rod is right, and I wouldn’t be surprised if the amp rating on the pump for constant draw, electric motors always have a higher draw initially due to over coming the internal friction and inertia of the motor.

If stinger doesnt make a fuse big enough check out Blue Sea Systems for REAL marine electrical hardware and Ancor for tined copper thin strand wire http://bluesea.com/category/5/22/productline/overview/134

http://www.ancorproducts.com/Products/Wire_Cable/pdf/wire_cable_pag19.pdf



I would suggest a gas powered leaf blower I heard they'll blow a tube up really fast.

Trash the tube and get a wakeboard...problem solved.

Rod/Walove thanks for the response

Mikeski, have many wakeboards. the problem is that my 9 year old is only interested in 1 run on hers
....so to keep her interested in boating and to insure her fun, we have a tube

mine is the DIDA 4
the thing is awesome when it works

my Cobra CPI1550 is rated at 1500w continuous and 3000w surge for .1 sec

I did just notice that the manual says the inverter will start a motor with single phase induction and one-half horsepower or less

mine is a 4 horsepower motor

I am thinking about wiring it through a breaker and doing away with the fuse altogether

do yall think that that will work?

also
when I tried to use it last, the boat engine was not running
does that matter?
....the unit started but only ran for a few seconds
thanks again

Running the engine matters a lot. A healthy battery sits at 12.7v When your motor is running depending on your alternater and RPMs you electrical system is somewhere from 13.5 - 14.4 v. Since Watts/volts=amps the more volts in the system the less amps needed to run the same componet.

As for the breaker, it should work fine. Most large fuse's are what they call slow blow, which means that they require a small amount of time to pass with the system to be overloaded before they blow. Make sure the breaker is rated the same as the sugested fuse. The inverter being under rated for the hp of the pump, concerns me. Most likly it will work fine for the time being, but might burn out faster then you expected. You could buy an inverter with a larger capacity but they are expencive. Or you could look for a pump that has a litle less draw. If you go to a good (not west marine) marine hardware store they'll probaly have a experianced employee to help you out with your system. RV's use simalar units so if an RV store is close you could always check that out.

thanks WAlove
I will do some more research
perhaps just using the breaker will get me through the week of the 4th

then I can upgrade the inverter later

Cliff,

sorry for the previous post, too many tubers the on the water the night before.

The higher quality inverters may produce a cleaner sine wave, the old one might have been more crude squarish wave but capable of handling more power. Using an inverter on higher power loads is always difficult. It would probably be best to go with a 12v DC blower and wire it direct.