Not as I understand it. It is NOT a constant reduced charge as you imply but a 'topping up' charge to compensate for natural drain. The 'equipment' to check is simple and cheap. Just plug it into a current meter. No current = no charge. I can assure you my charger, in common with most modern chargers DOES not continue charging on reduced current. It does however 'top up' as do my smart chargers for my AAA, AA etc batteries. There is a caveat to this though. If you aren't riding regularly it is best NOT to leave the battery on charge, not because it will overcharge, as it won't, but it does put the cells under more pressure. Is that what you are thinking of? I ride almost every day and have absolutely zero worries about leaving my battery on the charger but if I were to 'mothball' my bike for the winter it would be best to leave it at no more than two thirds charge and only recharge when it gets down to one fifth or 20% charge and charge back up to about 60%. If you have an older charger then just buy a current meter and plug the charger mains plug into that. It will then record what current it has used over a set period of time so you can act accordingly. Bosch guarantee my battery for two years and state a minimum of 500 FULL charges (a partial charge is exactly that, partial and the battery actually records all the partial charges and calculates just how many full charges that equates to). However Bosch state that the battery used correctly should be good for 1000 full charges or eight to nine years of use. I threw out ALL my older chargers (over two years old) a while ago and invested in modern smart chargers. I just don't have battery problems at all but nor do I buy cheap Chinese chargers (smart or not) off eBay. I buy once and ensure I have the right charger for the job. Do not buy cheap chargers or for that matter cheap batteries. As for an already facing battery it is far cheaper to re-cell your own battery. That way you can ensure cell quality as well as cell capacity. It isn't a particularly difficult job but you do have to have some electrical circuit nowse and have or make (reasonably simple) a spot welder. The BMS can be utilised from the old battery making it a viably economic proposition. Re-celling yourself can save you over 75% on a new battery or 40/50% if you have it done professionally. I certainly wouldn't buy a new one 'off the shelf ' at current prices.
You are seriously misunderstanding the problems with most chargers.....and I personally have never "seen" a perfect charger, though I have only seen about 10 in total.
Remember that a battery has a fixed number of recharges in it, that depends upon many things, manufacturer, quality, usage and the charger.
If we take as a middle value say 2000 charges.
These do not need to be full charges, they can be partial charges, that is why running a battery to the correct level of "empty" gives the best overall distance per charge. Then charging full and removing the charger when the LED goes green!
That can be helped with having two batteries, so that at the correct point, the battery can be changed while out riding.
As you say, a charger switches itself on and off, even when the battery is probably well over 95% charged.
This Hysteresis is designed into the charger.
I find it to be really bad.
You call it topping up!
Each time the charger turns on, that is part of a charge cycle of the battery "used up!", exactly how much is difficult to quantify as I will not risk my own batteries !
The longer the charger is connected after the full charge is achieved, the more charge cycles are lost!
Also, leaving a charger switched on does not in any way help the charge leveling as many erroneously believe, as this charge leveling is internal to the battery as charged cells are equalised.
There is apparently no need for the charger to be connected that I can find detailed anywhere.....
High quality cells, and I believe Panasonic are one of the best manufacturers myself, definitely do last longer and can be charged more times than badly made ones. There is also less risk with fire and explosions..
They build batteries with tested cells of the same characteristics, after testing each cell individually. This "reduces" the work needed to be done by the charge leveling. Especially when the battery is fairly new......
As they get older, and differences are "noticed" by the electronics, then capacity is gradually lost! As all cells are apparently brought to be the same as the lowest capacity cell.
The greater the capacity differences are between cells, the lower the capacity of the whole battery. The shorter the distance that it can cover.
I really don't know whether you can understand these (I feel) simple principles, and I don't really care either way!
But I find it mildly interesting in just how people who with little or no technical knowledge or training, "know so much, but always believe wrong information!"
Fascinating!!
The information I have posted here on this forum is as correct as possible.
But its a free choice, who you want to believe!!!
Andy