burakol 462 Posted March 24, 2021 Just wondering what do you guys consider an acceptable lipo internal resistance value? I've been trying to watch and read about it and consensus is the lower the value, the better... also, they are saying the the value is really dependent of the quality of the pack and each baseline resistance will be different from one another... Well, I bought a 5in1 cell meter and it measures the internal resistance of up to 6s lipo battery... the lowest resistance i measured on one pack was about 5mOhm and the highest is 21mOhm... Share this post Link to post Share on other sites
Jonathon Gillham 4606 Posted March 24, 2021 1 hour ago, burakol said: Just wondering what do you guys consider an acceptable lipo internal resistance value? I've been trying to watch and read about it and consensus is the lower the value, the better... also, they are saying the the value is really dependent of the quality of the pack and each baseline resistance will be different from one another... Well, I bought a 5in1 cell meter and it measures the internal resistance of up to 6s lipo battery... the lowest resistance i measured on one pack was about 5mOhm and the highest is 21mOhm... Is that of the whole pack or per cell? My charger measures internal resistance and new packs tend to be around 2ohms per cell. I've heard people say they retire packs once they get to around 8ohms per cell, or the difference between the resistance of cells gets too high. I run mine until they either lose performance (NiMH just not holding charge) or they puff (I've got some shorty lipos which have puffed and split the case, or just don't fit as well even though looking at them they look ok). Usually 2 - 3 years of use. Share this post Link to post Share on other sites
burakol 462 Posted March 24, 2021 Thats per cell... im not sure if this thing is accurate since I measured a bnew, unused 2s lipo that i recently got and the measurement im getting is 18 and 10 respectively. unfortunately my charger does not have the capability of measuring the internal resistance so I opted in getting this 5in1 cell meter... maybe I should have just upgraded my charger... i was hoping for 15bux, it will give me some accurate readings given that it had decent reviews. Share this post Link to post Share on other sites
Jonathon Gillham 4606 Posted March 24, 2021 1 hour ago, burakol said: Thats per cell... im not sure if this thing is accurate since I measured a bnew, unused 2s lipo that i recently got and the measurement im getting is 18 and 10 respectively. unfortunately my charger does not have the capability of measuring the internal resistance so I opted in getting this 5in1 cell meter... maybe I should have just upgraded my charger... i was hoping for 15bux, it will give me some accurate readings given that it had decent reviews. It could be accurate. My lipos are all expensive for racing. I can't get them from overseas so have to buy local and the ones that would be cheap if I could get them from Banggood end up not much cheaper than the best once they are sold by a local retailer. Share this post Link to post Share on other sites
burakol 462 Posted March 24, 2021 16 minutes ago, Jonathon Gillham said: It could be accurate. My lipos are all expensive for racing. I can't get them from overseas so have to buy local and the ones that would be cheap if I could get them from Banggood end up not much cheaper than the best once they are sold by a local retailer. Should i be wary then? I mean ive been properly storing them. No puff or visible/physical damage to the packs and all lipos I have are relatively new... less than a year old... but yes, these are all sourced abroad but it serves my purpose though.. Share this post Link to post Share on other sites
Jonathon Gillham 4606 Posted March 25, 2021 1 hour ago, burakol said: Should i be wary then? I mean ive been properly storing them. No puff or visible/physical damage to the packs and all lipos I have are relatively new... less than a year old... but yes, these are all sourced abroad but it serves my purpose though.. I wouldn't worry, most people wouldn't know the IR value and if they are performing as you expect and have no visible puffing or damage then they should be fine. It sounds like you're doing everything right. I found that even with proper storage charging (and not charging the night before a race meet etc) that mine were find for 18months - 2years before any sign of puffing, and it took probably 3 years for them to be noticably bad. They still perform well, I just chose to retire them being cautious Share this post Link to post Share on other sites
Fabia130vRS 2098 Posted March 25, 2021 9 hours ago, Jonathon Gillham said: Is that of the whole pack or per cell? My charger measures internal resistance and new packs tend to be around 2ohms per cell. I've heard people say they retire packs once they get to around 8ohms per cell, or the difference between the resistance of cells gets too high. I run mine until they either lose performance (NiMH just not holding charge) or they puff (I've got some shorty lipos which have puffed and split the case, or just don't fit as well even though looking at them they look ok). Usually 2 - 3 years of use. Be sure to throw away the puffed hardcases. Has a situation where we tried to open the hardcase all the way up to use the case for something and that **** thing exploded in a second. Share this post Link to post Share on other sites
sosidge 624 Posted March 25, 2021 IR is useful for monitoring the degradation of your packs over time (but only if you knew what the IR was in the first place). There are so many factors that affect IR that it is impossible to generalise what a "good" value is (big cells have lower resistance, and paralleled cells have lower resistance too). Having very different values between cells in a pack is a warning sign so I would be slightly concerned that your new pack has such a big gap (assuming the meter is reliable and the contacts are good). I have an older pack that I still use which has "bad" IR (c. 20 mohms per side) - but I know it is old and weak just from using it. The IR reading just helps me understand why it feels soft. It still works fine and isn't puffed. I have another smaller pack that has a big difference between the cells IR. Again, it isn't puffed and works fine, but it has a history of being a bit temperamental under charge and needs a lot of balancing. If the packs are puffed - time to get rid. Share this post Link to post Share on other sites
burakol 462 Posted March 25, 2021 2 hours ago, sosidge said: IR is useful for monitoring the degradation of your packs over time (but only if you knew what the IR was in the first place). There are so many factors that affect IR that it is impossible to generalise what a "good" value is (big cells have lower resistance, and paralleled cells have lower resistance too). Having very different values between cells in a pack is a warning sign so I would be slightly concerned that your new pack has such a big gap (assuming the meter is reliable and the contacts are good). I have an older pack that I still use which has "bad" IR (c. 20 mohms per side) - but I know it is old and weak just from using it. The IR reading just helps me understand why it feels soft. It still works fine and isn't puffed. I have another smaller pack that has a big difference between the cells IR. Again, it isn't puffed and works fine, but it has a history of being a bit temperamental under charge and needs a lot of balancing. If the packs are puffed - time to get rid. Thanks for the insight. So a good rule of thumbs is... once the pack if puffed, chuck it? But for my casual running, IR shouldn't be too much of a concern for me so long as: a) it is properly balance charged b) properly stored when not in use c) not being overcharged/over drained 1 Share this post Link to post Share on other sites
sosidge 624 Posted March 25, 2021 1 hour ago, burakol said: Thanks for the insight. So a good rule of thumbs is... once the pack if puffed, chuck it? But for my casual running, IR shouldn't be too much of a concern for me so long as: a) it is properly balance charged b) properly stored when not in use c) not being overcharged/over drained Sounds like a great battery regime to me Share this post Link to post Share on other sites
ewant81 33 Posted April 15, 2021 I recently got some used packs and the IR values at storage charge looked bad in terms of balance (they were 2S packs). However, I thought I would try charge them *carefully* to see how well they worked. THe IR inbalance was vastly reduced when the packs were fully charged with a good charger. I'm really new to the Lipo stuff, but it has already made me slightly wary of using IR values as a determination of a battery quality. Unless you had monitored the values on the pack from brand new, and had a reliable IR measurement. Share this post Link to post Share on other sites
