Let's dump BMS !!

Let's dump BMS !!

Since we need a way to balance our ebike's battery pack somehow.

+ Cheap BMS cannot be trusted. They are too quiet and never say much. So, we don't trust them. :?
+ Smart BMS with Bluetooth to monitor virtually of everything via phone is complicated - some even can't get it to work - tons of headache. Even if it works, still, add more things to worry about i.e. : voltage of each cells group, communication error, Android version compatibility, accuracy, reliability, etc. See how complicated it is :

Re: bluetooth BMS?
https://endless-sphere.com/forums/viewtopic.php?f=14&t=88676&p=1412233&hilit=bluetooth+bms#p1412233

30-page of complications until now. LOL. Why don't we just leave all these hassles behind and go for balance charging to simplify life and enjoy riding more ? This is nothing new for the experienced users, but for newbies - it is quite an interesting approach.

I spot this :

ISDT T8 BattGo 1000W 30A Smart Battery Balance Charger For 1-8S Lipo Battery
Price: US $99.99 / piece free shipping

Pic1 : ISDT T8 BattGo




It brags tons of advance feature of modern charger but whether it will really be beneficial to the charging of our ebike packs. I currently use 14S7P and more of the 14S packs to come. So I think I might be dumping BMS and use some of the balance charger, doesn't have to be the one mentioned above but anything that have higher charging amp. Plus this ISDT T8 has balancing current of 2.2A/cell (per specsheet) ..waaaayyy higher and much more practical in real life usage than most of the 50-100mA BMS balancing rate (might take weeks or months to balance big pack LOL).

Still, I might install a basic BMS simply to watch for those over/under voltage/shorting incidents for peace of mind. While balancing functions (or balance charging) will be for the balance charger's duty. My 14S pack might need to be electrically splitted in half 7S+7S and parallel balance charged ? Physically they can be in the same pack.

Regarding the 80-90% charging to full capacity to extend pack's life, this ISDT T8 BattGo might have this pre-set function built-in ? Any comment ?

OR .... I think of connecting one or two germanium diodes (0.3V drop each) to the return wire (negative lead) going back to the charger instead of connecting 7 diodes to 7 wires on positive leads ?

I don't know the pros/cons associated with this type of charger. A better charger / more appropriate than the said ISDT T8 BattGo ? Still more to research.

Any real benefits to still use BMS noob like me don't know of ?

Any comment to the benefit of the community will be greatly appreciated.

Thank you.

This comes up a lot and if you search you can find several topics about it.

The charger you show is similar to the iCharger, which many people use.
https://www.progressiverc.com/icharger-1010b.html

The iCharger in the link above can handle 10s packs. These chargers tend to do a great job of handling the charge and balancing the cells.

The downside is the 10s limitation. If you want to charge a pack with more than 10s you need two completely isolated setups or you take turns with sections of the pack. You also have to connect a ton of wires from the pack to the charger and those wires are prone to getting damaged or misconnected.

These also do nothing to protect the cells during discharge. With a perfectly matched, balanced pack, the LVC in the controller can be used to prevent over discharge, but you won't be able to detect if a cell group goes bad or deteriorates and goes low before the others.

ichiban said:

Let's dump BMS !!
. . .Why don't we just leave all these hassles behind and go for balance charging to simplify life and enjoy riding more ?

Click to expand...

A balance charger is a fancy BMS with charging included. And you still need overdischarge and overcurrent protection on the battery anyway, so you can't get rid of a BMS on either end. (Well, I guess you could if you can afford new batteries regularly . . .)

I'm not sure if this is relevant, but that photo looks a LOT like a not particularly good 3D rendering. So is this even a real product?

I moved the other way, from fiddling with those small hateful jst-xt connectors (which unless you have fingers of a guitar player, they will hurt you when disconnecting..) and breaking up packs all the time to a smart bms. RC lipos with smart bms, cheap, simple, safe and powerful. Balancing at 200mah, but they can start balancing far earlier, like at 3.9v. If you have a pack that needs long exhaustive balancing every charge, that is IMHO an error to fix, not something to work around with faster balancing.

Just being able to charge easily is great. Being able to monitor all cells & temps at the same time with a phone, anywhere in the house, is another. Watching over cells as they discharge, so they don't fall off the cliff unexpectedly one day. Being able to check up on the pack health on the trail by just picking up the phone is pretty good too. I push this pack pretty hard, so I need to keep an eye on it.