HeyTexasmark1

guido

Well-known Member
Hello,

Did not want to keep stealing Geo's thread. So here is my question:
You got my curiosity up. You said one of your Ryobi packs is 18.5 volts, and charges to 19 volts?
Can you explain battery cell type and configuration? Never ran across anything like that.

Guido.
 
No I can't unless I ask Ryobi (fat chance) or tear one apart. I figured 18.5 from multiplying 3.7 per cell voltage till I got close to 18. Having not dwelt into the chemistry of LIs, just the info published with a purchase and some online safety/usage postings concerning RC flying, I just swagged the 18. I did however check one after the recommended Ryobi charger green light went solid and it was around 19.5 which puts it way lower (in proportion) than the recommended 4.2 max on a 3.7 single cell.

Considering how the single cell lead-acid cell is found in umteen gillion uses and variants, figured LI might be too. Butttt that still leaves the problem of individual cells potentially being overcharged (with no discrete cell monitoring on 2 terminal devices) when the total is within range due to some cells being weak....whatever that means. I did notice in the Ryobi instructions that they do caution about letting the battery cool before charging, keeping it out of the sun, and protecting it from impact and using the prescribed charger.
 
Hello Texasmark1,

Even though the cells are rated @ 3.7V what your have is then 18V pack. That makes sense now. But they should charge to 21V not 19. Check the other packs, that voltage does not sound right. It means that you are charging the cells up to 3.8V only.The pack should charge to 21V. That would bring the cells to 4.2V, then after a few minutes resting though, they usually measure 4.1V each or 20.5V for the pack. The 3.7 volts rating is the midpoint between the max recommended charging voltage of 4.2, and the recommended discharge voltage of 3.0 V,

Guido.
 
I'll run a test and pay more attention to details. I got the 19.5 number after a test and was just curious. Now that you mention it, I pulled the battery as soon as the green light went from blinking to solid, indicating that the battery was ready for service. With the discussion here, the Ryobi charger may be doing one of two things:

1. Not fully charging in an attempt to not over charge any single cell in the battery which makes a lot of sense since there is no separate cell monitor.

2. Do as the smaller mahr battery chargers do and that is to fast charge to the 3.8-9v range and then if you don't take them off the charger slow charges on up to 4.2. The other thing this process does is by slowly charging on up to the max value it reduces the internal dissipation and thus the overall battery temp reducing the potential for a heat induced fire. Make sense?
 
Hello Texasmark1,


Smart-auto chargers do not fast charge then slow charge. Charge rate is tapered as battery potential rises. Fast charging achieves maybe 70% of battery capacity. A totally saturated battery-100% charged
is achived with a charge of 1/2 battery rated capacity, this is not set in stone either, many variables determine the rate at which a battery can be charged to 100% capacity without rasing its temperature to an ansafe level. A reason for this is battery resistance. the battery gets warm-hot depending on the rate of charge. The warmer it gets, the quicker will stop charging. A single cell, usually a low capacity one, will spike up the voltage of the pack, againg making the smart charger stop the charging process. Many variables in battery charging of any type.........

Guido.
 
I am talking about the Ryobi 18v LI battery charger recommended for my LI batteries. Has nothing to do with auto battery charging.
 
Hello Texasmark1,
I meant
auto as in automatic , smart charger. Punctuation on my kindle, only happens when I don't need it!

Guido.
 
Gotcha. What I said about the LI mahr chargers came from the charger manual. It also described how each cell was either increased in charging rate or bled off to keep them all charging at equal voltage. Utterly amazing what microchips are doing these days, just absolutely mind boggling, having come from the vacuum tube, old school. Reiterating what I have iterated and originally said numerous times, the younger generation has absolutely NO idea as to what's in their hand and what it took to get it there.
 
(quoted from post at 09:53:52 09/20/16) Gotcha. What I said about the LI mahr chargers came from the charger manual. It also described how each cell was either increased in charging rate or bled off to keep them all charging at equal voltage. Utterly amazing what microchips are doing these days, just absolutely mind boggling, having come from the vacuum tube, old school. Reiterating what I have iterated and originally said numerous times, the younger generation has absolutely NO idea as to what's in their hand and what it took to get it there.
lot more in hand than I can deal with!

 
Hello Texasmark1,

I wish I had a penny each time I get a period when I hit the space bar!!!!You can tell the new generation that you walked 5 miles to school each way barefoot in the snow up hill both ways. You would get zero sympathy.
By the way I got a pretty good memory, watch your dots and crosses! He!HE!



Guido.
 
Hello Texasmark1,


I meant to say, dot your I's and cross your T's. I will closly scrutinize you grammar, and your punctuation from now on!....HE!HE!


Guido.
 
Looks like they are serious about being safe. What absolutely blows my mind is the marvel of volume and mass production. That whole circuit
board probably cost a nickel to make. You and I couldn't buy one chip resistor for that.
 

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