Matching Ohm's

[Martin J]

I'm looking to install guages in my fuel ands water tank etc 7 in total 5 fuel 1 holding and 1 water.

I've found the ones for a decent price etc but the ohms are slightly adrift.

What I have is "0-190" ohm senders working with a 10-180 ohm gauges.

2 questions
a) what will the effect be?
b) will it work?

The guages will be digital in % and I can calibrate the % to Galls by transfering fuel through a meter etc.

Hoping some electrical tfers out there can answer this.

 

[ranger58sb]

Are you saying you need to install new gauges? Or new senders in the tanks?

If you mean you already have 10-180 gauges... I think you can get 10-180 senders from various makers. Probably WEMA comes to mind, but maybe Stewart-Warner, Teleflex etc.

Or if you have senders and need new gauges, the CruzPro digital gauges might be set-able for 0-190.

-Chris

 

[Martin J]

There has never been guages or senders installed before, the boat was set up with a dipstick since it was built in 81. I have a source for 0-190 ohm senders at about 30% of the US cost and the Digital meters for 20% of the cost of Cruz pro. I had cruz pro on my last boat, but going that route would cost me closre to 3k as the route I am trying to do would be less than 1K.

Thats why I was hoping someone techy in the forum could explain what the consequnces of being a few ohms out at each end is.

 

[twistedtree]

Having never tried it, I can't say for certain.... but I think you would just lose the very bottom and very top of the measurement range. So any level reported by the sender between 0-10 ohms, and 180 to 190 ohms would display as full or empty. I'm not sure which end of the range is full and which is empty.


One option would be to buy one sender and one gauge and try it. At least that would minimize you exposure if it doesn't work.

 

[ranger58sb]

Ah.

Can't get 10-180 senders from the same source? Or some other inexpensive 10-180 senders?

If not, I'm guessing math could maybe pencil-whip it to a certain extent. 190 range (0-190) mapped to 170 range (10-180). In general, resistance within that kind of range is a straight-line function (as far as I know), and the only other possible glitch to that (that I know of) might be is if your tank is irregularly shaped.

Given tank dimensions, it's possible to roughly calculate volume (which can be converted to gallons) at various sender float levels... but that might get kinda complicated it the senders you're thinking of are articulated float-arm things -- i.e., unlike the straightline senders like WEMA sells. I don't quite know how to tell where the sender arm is at any given time (level) on those articulated guys...

-Chris

 

[kenk]

I got the Liquid Level Sensors - SSS/SSL and gages from WEMA. I found them to be very accurate and the price was not bad.

 

[Martin J]

One of the reasons I want the 0-100% digital guages is I carry 5x500gall tanks. Wema make the usual analog 1/4 , 1/2 full etc . I can profile my tanks to read within 1 % using digital. Thus much easier to rganise moving fuel down into my double bottom day tank. I used cruzpro, and a wema/Kus sender in my last boat. I profiled the double bottom fuel tank with a laser and excel, and got it within 1% of the stated capcity and consumption matched the floscans I had. Odd shaped tanks and dipsticks in inchs don't do it for me! Particularly on offshore passages on windy wet nights!

 

[Martin J]

Ah.

Can't get 10-180 senders from the same source? Or some other inexpensive 10-180 senders?

If not, I'm guessing math could maybe pencil-whip it to a certain extent. 190 range (0-190) mapped to 170 range (10-180). In general, resistance within that kind of range is a straight-line function (as far as I know), and the only other possible glitch to that (that I know of) might be is if your tank is irregularly shaped.

Given tank dimensions, it's possible to roughly calculate volume (which can be converted to gallons) at various sender float levels... but that might get kinda complicated it the senders you're thinking of are articulated float-arm things -- i.e., unlike the straightline senders like WEMA sells. I don't quite know how to tell where the sender arm is at any given time (level) on those articulated guys...

-Chris

Thanks for the comments Chris
One of the reasons for this is I can do all my 7 tanks for less than 1k including digital guages. Or go wema ($150-$190)and Cruzpro ($235 Each) for over 3K. I can easily build a chart in excel % in tanks to galls. This is all part of fetching my boat into this decade with a full pumping to any tank and polishing any tank. My engine room saddle tanks are around 55" deep (and 500galls) each and two further 48" dep x 500Galls under the aft cockpit floor. If you think I would lose some sensitivity/accuracy when full and empty I don't think that would be a problem. Just trying to install a reasonable priced system.