I found this yesterday in an RV store.

[caguy]

It plugs into a cigarette lighter and gives you the voltage of your battery. Best part about it besides the simplicity is the cost, $15.

 

[cbsailor]

Question the reliability and accuracy?

I purchased a similar item from Wally World a couple of years ago. I compared its voltage readings against measurements taken on the 12V bus at my breaker panel. Although my Fluke digital meter hadn't been calibrated recently, the disparity between the voltage readings was significant. Just moving the tester around in the cigarette lighter socket could get readings 1+VDC different from the Fluke.

Battery condition (voltage) and current draw are critical to cruisers with lots of money invested in large house banks. IMHO these low cost voltage testers are no substitute for battery or bus direct connected quality volt and amp meters.

 

[biggio]

It plugs into a cigarette lighter and gives you the voltage of your battery. Best part about it besides the simplicity is the cost, $15.

Could you give a link or brand name to the tester? I think it would be a quick and easy way to aid in troubleshooting.

 

[kenn]

I purchased a similar item from Wally World a couple of years ago. I compared its voltage readings against measurements taken on the 12V bus at my breaker panel. Although my Fluke digital meter hadn't been calibrated recently, the disparity between the voltage readings was significant. Just moving the tester around in the cigarette lighter socket could get readings 1+VDC different from the Fluke.

Agreed. Myself, I would crack open the cheapie to get rid of the cig lighter plug, and solder on some leads so that it could be connected directly to the boat's DC panel, and I'd tweak any calibration to make the cheapie agree with a known good meter.

Battery condition (voltage) and current draw are critical to cruisers with lots of money invested in large house banks. IMHO these low cost voltage testers are no substitute for battery or bus direct connected quality volt and amp meters.

Well, sure, but on a 25 ft boat with just one or two batteries, I'd give one of those cheapies a try, after doing the above mods. A better idea would be to buy a halfway decent digital multimeter (DMM) on sale, and provide test points on your panel so that you could easily monitor the batteries with the DMM.

 

[Benny]

They sell a similar unit at Harbor Freight Tools for $9.99.

 

[Ron20324]

Sears auto stores used to have them last time I was there.

 

[Scott]

I agree with Kenn. A decent multimeter is "must have" on my boat. It's saved me alot of time and trouble over the decades.

 

[caguy]

I had planned on wiring it directly to the main switch. I need a cigarette lighter plug to charge my cell phone on long weekend trips. I'll compare to my voltmeter after setting it up and let you know. The meter only measures to one decimal place so I don't expect an accurate reading. It will serve as an indicator whether my alternator is charging or not. Plugging it into the dash on my truck showed a jump from 12.4 to 13.4 volts when the motor is running.