Poor Man's Trimetric?
I want a cheap sort of 12v battery monitor that can measure at least 100a and keep track of AH. Need some advice here on whether these possibles are any good in the first place, and then about the ac...
Forum Discussion
Methinks el BFL is looking for hour storage function hasta 300 horas amperes
ANY AND ALL amp hour or kWh meters should be tested for accuracy using a simple 100 watt 12-volt bulb and timer. Start with 12.7 volts in the battery and you'll end up with around 12.3 after a four hour test.
Establish lamp ampacity with a known reliable ammeter independent of the DUT
Connect load through shunt to battery
Tick off 240 minutes reasonably close.
The ampere hour tally should be close enough to 32.5 amp hours to not raise the hair on the back of your neck.
Charge the battery at C10 exactly the number of amp hours extracted plus fifteen . Not time, not voltage, amp hours. Right to zero plus fifteen percent (115%) .
If you started with a rested utterly full battery, and look at the ammeter amperage at the end of the charging regimen and 15% extra, and more than 3% of amp hour capacity is amping its way back into the battery.
Either the battery is really old, bad, or the meter is a laugh-track. 115% is a reasonable CEF* correction for a 2.75% flooded antimony battery. It's a bit liberal in fact. A really good battery should be in the 112% range.
Testing with a kWh meter is a lot more revealing, but it opens up heavy caliber (calibre for BFL) math, which many forum members are not comfortable with.
*Charge Efficiency Factor
The above test is realistic and surprisingly easy to conduct. A light bulb, lamp socket base few feet of dual speaker wire (12 gauge) and two battery charger clips. This gizmo is invaluable when looking for phantom battery drain, so it's not a waste of money. make the leads long enough and you won't have to do repair work by the light of the silvery moon.
NAPA stores stock the 100 watt 12 volt bulb. They are sometimes available coated in nylon to resist breakage. Get it and the battery clips here. Wire too. The bulb base is available at Home Despot. Ceramic or plastic. pull chain or plain.
ANY AND ALL amp hour or kWh meters should be tested for accuracy using a simple 100 watt 12-volt bulb and timer. Start with 12.7 volts in the battery and you'll end up with around 12.3 after a four hour test.
Establish lamp ampacity with a known reliable ammeter independent of the DUT
Connect load through shunt to battery
Tick off 240 minutes reasonably close.
The ampere hour tally should be close enough to 32.5 amp hours to not raise the hair on the back of your neck.
Charge the battery at C10 exactly the number of amp hours extracted plus fifteen . Not time, not voltage, amp hours. Right to zero plus fifteen percent (115%) .
If you started with a rested utterly full battery, and look at the ammeter amperage at the end of the charging regimen and 15% extra, and more than 3% of amp hour capacity is amping its way back into the battery.
Either the battery is really old, bad, or the meter is a laugh-track. 115% is a reasonable CEF* correction for a 2.75% flooded antimony battery. It's a bit liberal in fact. A really good battery should be in the 112% range.
Testing with a kWh meter is a lot more revealing, but it opens up heavy caliber (calibre for BFL) math, which many forum members are not comfortable with.
*Charge Efficiency Factor
The above test is realistic and surprisingly easy to conduct. A light bulb, lamp socket base few feet of dual speaker wire (12 gauge) and two battery charger clips. This gizmo is invaluable when looking for phantom battery drain, so it's not a waste of money. make the leads long enough and you won't have to do repair work by the light of the silvery moon.
NAPA stores stock the 100 watt 12 volt bulb. They are sometimes available coated in nylon to resist breakage. Get it and the battery clips here. Wire too. The bulb base is available at Home Despot. Ceramic or plastic. pull chain or plain.
