Electric pump advice

Riverman

Active Member
#16
It takes less than two minutes to inflate my 12' Maxxon tubes with an LVM pump, and the pump only gets barely warm. I don't run the truck engine when inflating the tubes either, the extra alternator voltage can warm a delicate pump up quickly. That short period won't run your car battery down either, unless maybe you have a bad battery anyway.
 

PT

Physhicist
#17
My lvm is going on many years of use. Sometimes it gets warm but that's it. I use it with the valves in the closed position and have had no problems. It's a nice piece of equipment. That and a small K pump make a good combination. I've never run my battery down either.
 
#19
I use a cheap air mattress pump that cost me $30, and has lasted 2+ years. (I always pump with the valve open) I think it has over 150 days of use in that time and hasn't failed yet. I top it off with a K-Pump 100. (pump with this with the valve closed)
 

Stewart

Skunk Happens
#22
http://www.nextag.com/O'Brien--2701001/inflator-pump/brand-html

I've had this brand for about 10 years. I bought it to inflate the tube I pull behind my boat. It has inflated air mattresses and the tube a zillion times, inflates my pontoon tubes really fast. I have had to repair the wire connections on the battery clips and the cigarette lighter thing, but for the price you can't beat it.


Edit: The tubes and airmattresses I top off with lung power. My pontoons get topped off with a double-action pump. The electric pump is a low pressure item and won't inflate against any significant resistance.
 

Kent Lufkin

Remember when you could remember everything?
#23
rule 12 volt inflator/deflator. 1/2 the cost of an LVM if you search the web...I bought mine a few years ago for $62. Looks exactly like the LVM, but the impellar is a silimeter smaller.http://www.boatersland.com/rulid20.html
+1 for the Rule inflator. It's a virtual clone of the LVM for less than half the price. I hadn't seen them offered lately, leading me to think they'd been sued for infringement so I was glad to see the link. Anyone on the fence about buying a LVM but hesitating because of the cost should definitely consider the Rule as an alternative.

K
 

Tim Cottage

Formerly tbc1415
#24
Thanks for the specifics shawn k!

I think we can take some preventative measures to mitigate over-heating. I usually inflate my WaterMaster using the procedure Bruce Baker posted above. Perhaps I will 100% of the time now! Just in case the manufacturer has not made appropriate design changes.

shawn k... How large is your raft? How long was the pump run continuously when it failed? Valves in open or closed position, if applicable?

Anyone else experience this issue on a more recently manufactured LVM pump (say, in the last 5 years)?
I was told the same thing (not to have the vehicle running) by Whitewater sports were I bought my pump. The explanation was that when you start your vehicle it changes the voltage going to the pump. I can neither confirm or refute that information but I definitely trust the source.

TC
 

Preston

Active Member
#25
My experience with the LVM has been almost entirely positive. I did have the leaf switch crack and sent it to NRS for repair; the shipping cost more than the repair. I've used the same pump for nearly twenty years to inflate a 12 1/2 foot raft (an NRS Sprite and now, an Achilles). Inflation of all three chambers takes less than ten minutes and the drain on the car's battery is negligible.
 
#26
You guys got my curiosity up. I went out to the shop and did some live testing on my LVM that's about 15 years old. Here's what I found:

Start current (initial surge) is too fast for my digital meter but it quickly drops to the running current with no air load which was 21.15A. When I put my hand over the air outlet and try to stop the flow completely the current drops down to 17.51A. I thought it would go up. I think there must be a relief valve for the air in the pump to prevent overheating when the air flow is obstructed (or the tubes are full). I can hear the pump speed increase when I do this which is what I'd expect a relief valve would do.

The voltage at the battery at the end of the original 10 ft power cable for these 3 situations was: 12.5 for motor off (no electrical load) - 11.6 running without an air load - and 11.6 when I try to stop the air flow with my hand. i.e. no change. I was using 2, fully charged 12 V deep cycles in parallel.

If it takes 10 minutes (I'll use 15 minutes worse case) to fill both of my 14 ft by 25 inch diameter tubes then I will have used up 4.375 ampere-hours of my battery capacity (17.51A times .25 hrs). I'd say most car batteries are at least 75 ampere hours capacity. Probably more like 200. So, if your battery is fully charged - as it probably is after driving to the river - then filling even 2 or 3 rafts should not really affect your ability to start your car at the end of the day. This agrees with Preston's conclusion above.

Heat generated by the motor is I (17.51A) times the voltage drop (11.6V) = 203.1 watts. That seems enough to heat that small motor up but it's designed with vents so air flows around the motor internally when its running. Also, at 17 to 20 amps the switch is possibly more likely to fail at higher operating temperatures. Running it in the shade on a hot day is probably a good idea. And if it gets noticeably hot (not just warm) to the touch, although mine never really has, I'd shut it off and let it cool down a while. It also confirms the advice to not run the vehicle engine while using the pump. The higher voltage (maybe 14 VDC) would add a lot to the amount of heat generated by the pump motor (now 245 watts). If it gets warm at 11.6 V I'm pretty sure that would overheat it under most conditions.

The curious thing is that if these measurements are correct the pump generates less heat (uses less current) when it's pumping air into the tubes than it does running with no resistance against the pump. I think they designed it that way with the relief valve spilling more air around the motor windings as the airflow into the raft decreases but maybe someone with more knowledge about DC motor air pumps can educate us on what's going on there.
 

Gregg Lundgren

Now fishing on weekdays too!
#27
Thanks for your testing Ray. Based on your last paragraph, I don't think I will bother to start inflating a chamber with an open valve. Generates less heat with some air resistance anyway.

My takeaways...

1) Don't use the LVM pump when the vehicle's motor is running (lots of warning documentation regarding this)
2) If the LVM pump does get hot, shut it down to cool.
3) Shite can happen sometimes anyway.
 

Stewart

Skunk Happens
#29
You guys got my curiosity up. I went out to the shop and did some live testing on my LVM that's about 15 years old.

...

Here's what I found:maybe someone with more knowledge about DC motor air pumps can educate us on what's going on there.
Nice post. Wish I understood it better, but I like deduced and quantified. :ray1:
 

Ed Call

Well-Known Member
#30
Nice post. Wish I understood it better, but I like deduced and quantified. :ray1:
I agree with Stewart. Great post. I don't understand it at all, but I'm totally conviced because it was so well presented. I have a hurricane that will fill a watermaster to about 1.75 psi about 5-6 times from a small UB 1280 battery. If that little battery can do all that there is no way I'm worried that my fully charged truck battery is at any risk of dying.