kat Posted March 17, 2018 Report Share Posted March 17, 2018 Is the voltage a good indicator of battery life? I tested one fully charged 3Ah battery and it showed 19.5V. Another fully charged 5Ah battery showed 19.9V. I don't have a new one to test but I think the "normal" voltage should stay at 4.2 * 5 = 21V. Right? Quote Link to comment Share on other sites More sharing options...
HiltiWpg Posted March 17, 2018 Report Share Posted March 17, 2018 Is the voltage a good indicator of battery life? I tested one fully charged 3Ah battery and it showed 19.5V. Another fully charged 5Ah battery showed 19.9V. I don't have a new one to test but I think the "normal" voltage should stay at 4.2 * 5 = 21V. Right? The voltage rating of individual cells is 3.6v.(5*3.6=18)The standing voltage will be slightly higher. In order to test a battery to determine whether it is good or not, you have to test it under load. If the battery significantly falls below its rating under load, then it is no good. Sent from my ONEPLUS A5010 using Tapatalk Quote Link to comment Share on other sites More sharing options...
kat Posted March 17, 2018 Author Report Share Posted March 17, 2018 But how can I test it under load if there's nowhere I can put the multimeter leads when battery is connected to a tool? Quote Link to comment Share on other sites More sharing options...
HiltiWpg Posted March 17, 2018 Report Share Posted March 17, 2018 You can provide a resistive load between your meter and the battery. You may want to google it if you are unsure how to do it.Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
HiltiWpg Posted March 17, 2018 Report Share Posted March 17, 2018 You can also min/max with your multimeter and use extensions from the battery terminals while connected to the tool, but be very careful!Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
kornomaniac Posted March 18, 2018 Report Share Posted March 18, 2018 Are we sure that maximum voltage after charging is an indicator for how much life the cells have left ? Quote Link to comment Share on other sites More sharing options...
m.k Posted March 18, 2018 Report Share Posted March 18, 2018 In this special case it could kinda be an indicator Normally, it really isn't - even a worn pack will show similar voltage directly after charging, because normally a Li-Ion battery is charged with a CC-CV charging characteristic. So first the current is limited and when the voltage comes up, as the battery fills the voltage is held constant, to slowly fill up the last few %. Makita doesn't do that, they skip the CV phase. I don't really know why exactly maybe the self balancing effekt (which they used at their early LiMn2O4 batterys, the non star ones) works best that way, or they said "we at the site ain't have time for topping the battery up". Yes that looses some capacity, on the other hand it is good for lifetime. If you take that into account with your old/new battery therory - the charger always cuts off at 4,1V per cell in CC mode. A worn battery will have higher internal resistance and therefore more voltage drop when charging - and will have a lower "idle voltage" when finished. But there are a lot of factors to take in account when doing this, mostly battery chemistry and temperature. A worn 5Ah will have a lower voltage after charging than a new 5Ah (if they have the same cells). But to compare a 3Ah and a 5Ah can be misleading, the 3Ah will probably have worse internal resistance right out of the box so... Quote Link to comment Share on other sites More sharing options...
Kato Posted March 18, 2018 Report Share Posted March 18, 2018 You can't tell battery life by voltage, you have to read amperage under load. As HiltiWpg said, you have to test under load...which is easy to do if you know how to do it. It's a pain in the neck, but easy to do. Connect a wire to one leg of the circuit, say connect positive to positive with a wire. Then, connect negative to negative with the test leads of your meter. Connect one test lead to the negative on the battery and the other test lead to the negative on the tool. Set your meter to DC amps, and there you go. Pull the trigger on the tool and watch the amperage levels. If the amperage drops a lot...the battery is close to failure or has failed already. It helps to know normal amp draw but it's not necessary, any significant drop will tell you if the battery is good or not. I test batteries all the time, at least once a week, and the best thing to use is a dedicated load tester. However, reading amps under load will give you basically the same results. Quote Link to comment Share on other sites More sharing options...
kat Posted March 18, 2018 Author Report Share Posted March 18, 2018 By drop, you mean a drop from the initial amp draw value that is displayed on the multimeter? Like after a few seconds? So basically if the amp draw is constant the battery is ok? Quote Link to comment Share on other sites More sharing options...
Kato Posted March 18, 2018 Report Share Posted March 18, 2018 I'd have to test a battery to see what kind of amperage numbers are actually present, but as an example: Let's say the tool uses 5 amps while running. When you have a good battery and live in a perfect world, the reading should be around 5 amps. If the battery is bad your amperage level is going to drop pretty quickly to a much lower amp reading. This tells you that the tool is pulling way too many amps from the battery, indicating that the battery can't keep up with the amp draw required by the tool. If the amperage goes from 5 down to 1 at a quick rate, the battery is most likely going bad. So, you hook up your meter to a battery and tool, then pull the trigger. The meter reads 5 amps and stays fairly constant, your good to go. Your meter starts out at 5 amps and then drops to 4, 3, 2, etc., then your battery is probably bad. Of course this is a perfect world and your battery is fully charged. Quote Link to comment Share on other sites More sharing options...
m.k Posted March 18, 2018 Report Share Posted March 18, 2018 Eh, you should be aware that tools and batteries are capable of a lot more than the 10A current range of your Multimeter. You could damage it. I used a clamp meter when measuring battery current. If you want to know if your battery is still good, just try out the tool. If you can screw in a screw with your known good pack, the other one should be able as well. Quote Link to comment Share on other sites More sharing options...
Kato Posted March 18, 2018 Report Share Posted March 18, 2018 23 minutes ago, m.k said: Eh, you should be aware that tools and batteries are capable of a lot more than the 10A current range of your Multimeter. You could damage it. Of course I mistakenly assume that people know stuff like this. I use a clamp meter capable of reading DC amps through the clamp, and it's capable of reading up to 600 amp. The stuff I said previously hinges on the person doing it...their ability and type of equipment used. Quote Link to comment Share on other sites More sharing options...
kat Posted March 18, 2018 Author Report Share Posted March 18, 2018 I tried connecting the battery to a drill with some copper plates and alligator clips and put the clamp meter in between, but the drill doesn't work correctly. The light turns on, the motor starts to spin for like 1 seconds and then it stops. I guess I need to use wires and find bigger clips Quote Link to comment Share on other sites More sharing options...
m.k Posted March 18, 2018 Report Share Posted March 18, 2018 May i ask what this test is all about? You test if the battery can supply the current of a tool idling? What does that tell you? Only thing you do is risking shorting your battery out and bricking it with what? copper plates? I mean, you can test the battery against the cell manufacturers datasheet - capacity and high current runs with a electronic load. Or you can measure internal resistance with an impedance meter. Even then - what are you going to do, you have data. But what counts is if the battery works for what you do WITH the particular tool under LOAD. You have probably discarded batteries with 85% State of Health in your life before, and still use some with 60%. The current under idle test is superfluous, you can pull the trigger and hear if the motor slows down. If it doesn't your battery current is constant. Have fun.. Quote Link to comment Share on other sites More sharing options...
kat Posted March 18, 2018 Author Report Share Posted March 18, 2018 I guess you are right. I just wanted to know what's the current state of my batteries... Quote Link to comment Share on other sites More sharing options...
XTsallaD Posted March 19, 2018 Report Share Posted March 19, 2018 I’ve had really good luck with my makita batteries. I use them professionally and some are a decade old. The really old ones don’t hold a charge as long as the new ones but I give them away when I don’t think they hold a charge long enough. If you aren’t always buying new tools and you want new batteries, eBay has some good prices for makita batteries. Quote Link to comment Share on other sites More sharing options...
0delusion Posted November 12, 2018 Report Share Posted November 12, 2018 The correct answer to this question is.... Use the Makita MAKSTAR ADP03 Automatic Refreshing Adapter. AFAIK it's the only makita product that refers to "remaining capacity" of a batt pack in this manner. It will give your Makita lithium or NiMh battery packs a "refreshing" charge/discharge cycle that may take between 4 and 9 hours. After the cycle it will report how worn out your pack is, reporting remaining pack capacity percentages of... less than 40 40 to 60 60 to 80 80 to 100 IT WILL NOT REVIVE battery packs reported as dead by standard chargers. Neither will the full battery checker system. If it did, we'd have reports of people going into service centers with dead packs and returning with revived packs. IT WILL RESTORE some "useful service lifetime" to old packs. It is not a charger by itself, it must be used in conjunction with a standard charger which you almost certainly already have. To use with NiMH packs you'll need an additional adapter. It has been available to Makita service centers since around early 2010, as a part of the larger "MAKSTAR Battery Checker System", which includes another adapter and computer software. I have uncovered evidence the ADP03 started to become available as a separate item in 2014. You will find It's quite expensive, but if you use a service that watches prices and reports when they reach your price point, you'll be able to get one much cheaper. I saw one that sold for $41 but paid $91.71 for mine. It's up to you if you have enough batteries that need conditioning to justify the expense. Quote Link to comment Share on other sites More sharing options...
kornomaniac Posted November 13, 2018 Report Share Posted November 13, 2018 @kat Reviving old thread but I believe a fully charged Makita pack gives 20.2 volt. I have the new model battery tester at work. I'll check tomorrow Quote Link to comment Share on other sites More sharing options...
SchenzhenSpecial Posted November 13, 2018 Report Share Posted November 13, 2018 On 3/18/2018 at 11:22 PM, kat said: I guess you are right. I just wanted to know what's the current state of my batteries... Working, I'd guess. Quote Link to comment Share on other sites More sharing options...
Mycrossover Posted December 18, 2018 Report Share Posted December 18, 2018 Is the voltage a good indicator of battery life? I tested one fully charged 3Ah battery and it showed 19.5V. Another fully charged 5Ah battery showed 19.9V. I don't have a new one to test but I think the "normal" voltage should stay at 4.2 * 5 = 21V. Right? More like 3.6 x 5. Virtually all rechargable batteries read higher than their nominal voltage, fresh off the charger. A fully charged car battery reads 13.8. They all rapidly drop to their nominal voltage with least bit of use. The lithium cells in power tools are 18650's. Look on ebay, Amazon, Battery Junction or almost anywhere and you will see the cells for sale and advertised as 3.6 volts. This is where we get DeWalt, using 4.2 and Milwaukee using 3.6 coming up with 20 and 18 volts. Back to your question. Lithiums have what is known as a flat discharge curve .It starts at 4.2 and almost immediately drops to a little over 3.6 and very gradually drops a little lower over the whole discharge cycle until it is amost fully discharged and then the voltage drops like a stone. The decrease in voltage is so slight over most of the discharge cycle, that unless you are way over or under at the start or the end it is very difficult to tell what percentage is left, over most of the discharge cycle. Temperature also alters the voltage.Sent from my SM-G900V using Tapatalk Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.