FAQ
TL;DR: Typical LPG solenoid coils draw ≈1 A (≈12–15 W) and will feel hot; "These coils don't have + and -." To diagnose, power each coil separately and listen for a click. [Elektroda, psooya, post #17303704]
Why it matters: For DIY LPG car owners adding a second cylinder, this FAQ shows how to fix hot coils and non‑opening valves safely and fast.
Quick Facts
- LPG tank solenoid coils are non‑polarized DC loads; connect either way (+/− doesn’t matter). [Elektroda, psooya, post #17303704]
- Typical coil draw: Approx. 1 A at 12 V; power dissipation about 10–15 W. [Elektroda, psooya, post #17299879]
- No gas flow = less cooling; flowing LPG cools the valve body and coil. [Elektroda, przemek25l, post #17304039]
- Common culprit: a not‑fully‑open manual shut‑off on the new cylinder. [Elektroda, poStaremu, post #17313387]
- Quick check: Listen for a sharp plunger “click” and verify supply at the coil. [Elektroda, Strumien swiadomosci swia, #17303650]
Why is my LPG solenoid coil burning hot?
Heat is normal. A coil dumping about 10–15 W will get hot, similar to a 15 W bulb. Heating alone doesn’t prove a fault. “15W must heat up.” Ensure it opens and flows gas; temperature will drop with flow. [Elektroda, psooya, post #17303363]
Does coil polarity matter on LPG tank valves?
No. These DC coils are non‑polarized and work regardless of lead orientation. “These coils don’t have + and −.” Reverse wiring will not fix heating. Focus on power, mechanical movement, and the manual shut‑off instead. [Elektroda, psooya, post #17303704]
My coil heats but the valve doesn’t open—what should I check first?
Open the manual shut‑off on the new cylinder fully. A partially closed hand valve blocks flow even if the solenoid energizes, so the car switches to petrol when the first tank empties. This exact issue resolved the thread. [Elektroda, poStaremu, post #17313387]
How do I test my LPG solenoid valve in 3 quick steps?
- Power each coil separately from 12 V to isolate it.
- Listen for a clear plunger click on energizing.
- Confirm about 1 A current draw per coil during hold.
“Provide each separate power supply and listen to the valve.” [Elektroda, psooya, post #17303704]
Why did replacing the coil not solve my issue?
Because the fault was elsewhere. In the thread, a new coil still ran hot and the valve stayed closed until the manual shut‑off was opened fully. Replace parts only after basic mechanical checks. [Elektroda, poStaremu, post #17313387]
What current and power should I see on an LPG solenoid coil?
Approx. 1 A at 12 V, which is around 10–15 W. Use a multimeter or clamp meter to confirm draw. Oversized wiring isn’t required, but connectors must handle continuous 1 A per coil without voltage drop. [Elektroda, psooya, post #17299879]
Should I measure voltage or current when two coils are wired in parallel?
Measure current on each branch. With parallel coils, voltage will read the same on both, so it won’t reveal imbalance. Comparing currents quickly flags a weak or open coil. Use a clamp meter or in‑line meter. [Elektroda, Anonymous, post #17303687]
Does the magnetic core affect DC coil current or heating?
No. On DC, coil current depends on applied voltage and the coil’s resistance, not the core position. “The DC coil current is not influenced by the magnetic core.” Differences in coil design explain temperature variations. [Elektroda, Strumien swiadomosci swia, #17303540]
I don’t hear a click—what should I do next?
Check for power at the coil and compare both valves side‑by‑side. A missing click suggests no supply or a mechanical jam. Measure voltage to both coils at the same time and inspect connectors. “Do you hear the plunger ticking?” [Elektroda, Strumien swiadomosci swia, #17303650]
Is it safe to unscrew the valve while the cylinder is full?
Do not. Unscrewing valve parts on a pressurized LPG cylinder will release the gas and dump your tank’s contents. Plan service only when safely depressurized and by qualified personnel. “All the gas from the cylinder will escape.” [Elektroda, poStaremu, post #17303564]
How can I confirm the valve actually opens under power?
With the engine running on LPG, briefly lift and reseat the energized coil; the valve should reopen audibly. The thread shows 12.8 V at the working coil during this test, confirming supply and operation. Use caution around moving parts. [Elektroda, poStaremu, post #17303697]
What’s the best way to power two tank coils to reduce heat?
Use a simple switch to energize only the active tank’s coil. Continuous hold without flow runs hotter; switching tanks cools the energized valve via gas flow and reduces unnecessary heating on the idle tank. [Elektroda, przemek25l, post #17304039]
can you read 10 to 15 watts? Take a 15W bulb and what? Will it be cold?
