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Old 06-21-2016, 07:38 AM
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Aaron Aaron is offline
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Join Date: Feb 2007
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3 battery splitting the positive basic

Quote:
Originally Posted by BroMikey View Post
Battery voltage must reach 12.6v in the 3 battery series line up with each of the three batteries needing to top out at 4.2v.
BroMikey,

You're doing some great work here and I hope you keep posting your results.

What was the highest voltage batt 3 (single reversed batt) went to when it didn't climb any higher?

Lithium lifepo4 and lithium ions (usually cobalt based) are constant voltage batteries and not constant current batteries (like lead acids) so although they can show a higher voltage for longer, it can be deceiving to see a voltage last so long.

However, with that said, you are right about joules vs joules so whether it is a constant voltage or constant current battery, work is work from a certain voltage down to a certain voltage and that is what you want.

The Peukert Effect doesn't apply that much to lithium batteries like they do with lead acids. A lead acid 20 hour discharge will give you a certain amps discharge for 20 hours. At a 10 hour discharge, it will be 90% of that and at a 5 hour discharge, which is the most any lead acid deep cycle should be discharged at will be about 80% of the 20 hour discharge. So with lithium batts, this effect is supposed to be non existent so whether you discharge a lithium at a 20 hour rate or 5 hour rate, you should still have the full capacity.

If this is the case, then a 1 or 2 hour discharge rate should be an honest test with your little lithiums and won't take too long before you have to rotate them.

With your conventional discharge chart - 6000ma you're showing 300ma for 20 hours. If there is no Peukert effect, you should be able to hammer them with a 1 or 2 hour discharge rate and get the full real capacity.

6000ma for 2 hours is 3 amps * 3.x volts = about 10 watts. It would be a good test with all 3 batts charged and discharged at a 1 or 2 hour rate to see if you get the same as the 20 hour rate. If so, you validate the claim that lithiums have no Peukert effect and therefore, you can accelerate all your tests with multiple rotations in one day.

Do you have a factory charger for the batts that charges them up and a green light comes on when they're done? If so, what voltage are they at when they're supposed to get done?

Also, if you charge it conventionally and then discharge it at x hour rating, what voltage does the battery drop to when you get 100% of the rated amp hour capacity? If you know that number, then charge all 3 batts with a conventional charger until they're full. Then discharge one battery until you get 100% of the ah rating and it is considered dead. Put that battery in position #3 and have 1 & 2 in series and run the 3 battery test to calculate how many joules you windup getting until they're all dead. Starting with 2 full charged batts and one fully discharged, you should not be able to get more than 4ah's of capacity at the 3.x volt range until all 3 are dead.

This is the old original concept and has nothing to do with pulsing, recovery, anything other than just the simple basic 3 battery schematic John had posted for ages.

I may have missed something here, but just wanted to get a few clarifications.
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Sincerely,
Aaron Murakami

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