Meter to test charge left in battery

[partymarty]

Is there a meter that can tell me how much charge is left in my sla pack? It is a BL36 but the throttle lights are fried (my bad). I will be investing in a Cycle Analyst but not yet. Thx.

 

[Zoot Katz]

The Cycle Analyst or any of the popular meters don't tell you how many Ampre hours you've left in your battery. They can only tell you what you've used.
You can check the voltage with a cheap volt/ohm meter.

 

[partymarty]

How does my electric razor and laptop figure it out then?

 

[Anonymous]

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[dak664]

Very roughly, for a 12 volt SLA battery the resting voltage drops 0.1 volt for each 10% of discharge. Something like 11.7-12.7 volts for 0-100% charge.

 

[partymarty]

Thanks everyone. I found this at Canadian Tire for $13: http://www.canadiantire.ca/AST/browse/5/SportsRec/Marine/MarineBatteries/PRD~0790319P/Battery%2BMeter.jsp

 

[torker]

That meter if it is really sensitive may be able to sense to a tenth of a volt and give you a ballpark of the state of charge but it won't tell you much. If you know how many amps your charger puts out then with that and the time it takes to recharge you can figure out how many ah you used. I would do the math but I would probably screw it up. :?

 

[Anonymous]

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[partymarty]

nutsandvolts: can you recommend a meter please?

 

[Zoot Katz]

I bought the CT 30 dollar model when it was on sale for $20. (Equus 4320a)
A friend compared it to his calibrated Fluke 115 meter and it's within 0.2% on the 20 and 200 Volt scales.

 

[dak664]

The Harbor Freight meters can be (in my experience usually are) a few tenths of a volt off, but stay reasonably accurate after adjusting the internal pot. I measure the output of an LM7805 and adjust to 5.00 volts.