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Hmmm. I watched this video: https://www.pedelecs.co.uk/forum/threads/high-current-charging-protection-without-fuses.34602/ which explains that a crowbar circuit is used to protect a voltage/power-sensitive circuit form over-driving, but it does it by short-circuiting the power supply...

Thanks Andy, I'll research the crowbar.

Thanks for the advice vfr.

Hi Daniel, a couple of reasons. Firstly charger working on this principle are very slow becuase the MOSFETs which do the bleeding are whimpy and you can't charge the pack any faster than the highest cell bank can bleed or it would "overtake". Secondly, it wears out batteries, since the charge...

Hi, I am building a LiPo 7S bike battery charger. Rather than taking the conventional approach of charging the bank from its two ends and bleeding individual cell banks if they rise above the average, I want to charge all cell banks individually with a TP4056 or similar charge controller. I am...

Danidl, You didn't mention your long career in electronics, but then I didn't mention mine either. I learned a lot about aircraft control systems but bugger all about EBikes. Perhaps you specialised in them? If you had presented yourself as an expert, then I might have seen your advice as more...

I understand that people are just giving advice in an effort to be helpful, and I've made sure I said that I appreciate that. When people tell me emphatically not to do something or that the consequences are dire, then I've explored their thinking to see if there is something I need to learn or...

d8veh, yes I see what you mean, but there is no contradiction. I've been responding to contributors' comments. This thread was originally about how I should build my new battery. Specifically how to organise cells with different characteristics. I didn't get much help on that, but I got lot...

My balance charger is an iMax B6 mini. It is a balance charger. It is not a BMS. It works as all balance chargers do, which is to say that it monitors the voltages of cells within a battery during charging via a balancing lead, so that it can ensure that each cell is charged to the same level...

The BMS balances during charging only. Almost always, it does so by draining current from full cells/banks during charging. Most BMSs are made down to a price, and so they can only drain current slowly, maybe 100mA, and so the whole battery charge rate has to be dropped to the drain rate so that...

Danidl, OK - I see; thanks for your patience. But the danger you describe arises on charging, but I'm balance charging off the bike, so the danger you mention won't arise. It's not the £12 which prevents me adding the BMS, it's its unreliability as revealed by my testing of it. It doesn't...

Wheeliepete, thanks for your data point. It does help. Danidl, I have a BMS - one of those cheap Chinese things, but testing showed problems with it, and putting a cheap Chinese brain in charge and in permanent connection to all that power seems more dangerous rather than less. My bike has an...

Danidl - thanks for your interesting insights. Spanos - the benefit of experience - thanks. Kiwi, neath - more opinion points - thanks. The battery I have is a dog's dinner soldered brutally together by a gorilla with a blow torch, from a patchwork of different cells. It has no BMS. The person...

Hmmm. With a nominal 100 milli Ohms IR, the 10-ish amps needed to drive my 25V system at its rated 250 watts. Across 0.1 Ohm, 10 amps drops 1V and dissipated 10 watts. That's 70 Watts total in the 7P pack. The bike woks fine at 23V That's where my theoretical analysis runs out of steam. I was...

Thanks again guys.

Thanks for all your time and effort Danidl. Very helpful, and the biggest thing I didn't know was the rate of degradation rate of SLAs. So I guess I'll press on with the build. Thanks again.

So I've salvaged a number of 18650s from unused laptop batteries. Their capacities range from 1,800 - 2,500 mAh. Their internal resistance varies from 50 - 150 mOhms. I want a 10AH 7S (nominal 24 - max 29.2V) battery. My question is how best to organise those cells. I've read that you can place...

Thanks for the that.

Hi, I've been running a second-hand E-bike for 7 months. The battery had no BMS and was charged (not balance charged) using a power brick. It's a 24V system, the battery was homemade and is 7S5P. I've just stripped it down and can report that, when charged, the cell banks show 4, 3.9, 4, 4...

I googled the part, I saw the image, it looks like mine, and I sent you the picture. As you say, it is the wrong controller. But I tell you what, d8 - don't trouble yourself - the love is just too overwhelming. Have a nice evening.