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Old 09-08-2016, 09:06   #16
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Re: Measuring Amps and Watts

A $10 digital meter is all you need. They read up to 10 amps, 2-3x what a 50 watt panel puts out. Goes in series with panel, so connect red meter lead to positive terminal of panel the other lead from meter to your battery or controller, depending on which current you wish to read. Amps x volts = watts, like everyone else said.
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Old 09-08-2016, 11:31   #17
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Re: Measuring Amps and Watts

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Originally Posted by 44'cruisingcat View Post
True. The LiFEPO's are pretty much fully charged (say 95% +) when they hit 14 and a bit volts. And they'll accept just about whatever you can feed them up till then.

Lead acids need to absorb for a while, so current will be reduced, so time increased..
It is an easy target anyways.

Q: what about the remaining 5% - how fast can this be charged?

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Old 09-08-2016, 12:53   #18
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Re: Measuring Amps and Watts

I have a Fluke 365 which also measures DC to 200A and has a detachable head the reach difficult to access points. It also measures all my other electrical needs. A brilliant bit of kit and super quality.

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everybody treat themselves to one of those:
https://www.amazon.com/Best-Sellers-...ial/5011680011

8attention: not all measure A DC!)
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Old 09-08-2016, 13:13   #19
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Re: Measuring Amps and Watts

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Originally Posted by barnakiel View Post
It is an easy target anyways.

Q: what about the remaining 5% - how fast can this be charged?

THX
b.

Doesn't really matter, reason is they don't develop memory nor does it shorten life, in fact I think not fully charging them may in fact extend life. It's another reason why LifePO is so attractive
A Prius for example will not charge it's battery bank more than 85% of capacity nor discharge it less than 40%. That is for a 2010 model, new ones may differ as I think the battery is different now.


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Old 09-08-2016, 14:10   #20
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Re: Measuring Amps and Watts

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Doesn't really matter, reason is they don't develop memory nor does it shorten life, in fact I think not fully charging them may in fact extend life.

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This is my understanding too.
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Old 09-08-2016, 14:16   #21
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Re: Measuring Amps and Watts

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Originally Posted by barnakiel View Post
It is an easy target anyways.

Q: what about the remaining 5% - how fast can this be charged?

THX
b.
It may not be 5%. Just an estimate. But the batteries are just a little short of 100% charged. You could completely charge them pretty quickly by raising the voltage setpoint on the charge controller at which it goes into float mode.

But as stated above, being a little conservative on chasing full charge is said to increase the cycle life.
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Old 12-08-2016, 17:16   #22
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Re: Measuring Amps and Watts

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Shunt? Hall effect DC clamp meter?
So to dispute the claim that to measure current you need to /be/ the path, you brought up shunts as a counterexample? And how exactly do /you/ think a shunt works?



You're getting close to a counterexample with Hall Effect, but you surround the wire you are measuring, and become coupled to it. So its not a great counterexample.

The OP seemed to be expecting a multimeter to be 'internally designed' to be able to measure current despite being hooked in parallel to the circuit they care about. The point of my post was that wouldn't be possible unless it had psychic powers. To measure current in a particular circuit, you need to be being influenced by that particular circuit. Really its not even a question of electronics, its like information theory or something.
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