Lithium Battery charging.

[PCeBiker]

As far as I figure it, if my charger remains ON because of a timer failure, all I end up with is a fully charged .

Not the worst possible outcome if you can trust your battery's BMS to not overcharge your battery and start a .

I can be awake during all charging cycles, so I'm not too worried.

 

[PCeBiker]

I decided to plug my bulb into my battery to see what happens.
It's kinda cool ,..

The bulb still gets pretty damn hot .
Lol

My cat don't like it at all.
I think she burnt her nose sniffing the bulb.
I burnt my fingers. Lol

 

[m@Robertson]

Amazon tells me I have purchased 5 of those BN-Link countdown timers over the years. Not 5 because I have had any failures. 5 because I use them in so many different places. One at home. One at work. Another one at my work residence. A 4th goes with me on the new bike that has a built-in charger, in case I have occasion to need it (its in the back of the bag where I pull out the charger AC cord).

I just found the 5th in a box unused. Saving it as a backup I guess.

As to all the concern about charger failures: Focus on that as your next place to improve safety. I don't use chargers that are cheap, so I'm nowhere near as concerned about charger failure affecting the timer as everyone else probably should be. Been there and done that and found the fix for it. Never a single failure in many years, and I have had 3 Chinesium chargers fail in much less time than that. Charging twice daily, I put on a pretty heavy duty cycle that reveals flaws a lot faster than a weekend rider.

An Ultra Reliable Ebike Battery Charger…

How about a charger – quickly adjustable for voltage and current – that is rated for hundreds of thousands of hours of use before it typically fails?

talesontwowheels.com

These things are potted, rated for use in damp areas and essentially bulletproof. CC+CV mode so it behaves like the common understanding of what a 'smart charger' is. The 185w version that I have built into the bike above is good for 3a and its MTBF is 192,200 hours. Thats not a misprint. These things are meant for commercial and municipal outdoor street lighting and they are made to last through literally decades of use.

 

[m@Robertson]

I decided on using an Intermatic commercial-grade timer for my load resistor. I want something by a name brand that is built to take a hard life. Saw alternatives from Tork, No-name and even BN-Link. Since the pack's survival is at stake I want to go top end... and that still is only about $30. I'm getting a 60-minute timer. a 12-hour timer is pointless on a 7-amp draw as thats plenty to drain the pack down to nothing and kill it.

https://amzn.to/3OJRBka

 

[6zfshdb]

I have 3 of the BN-LINK timers which I use for various tasks. I ordered two more a couple of weeks ago for another project. One of them failed over the weekend and my charger stayed powered up overnight. It's a very reliable Grin Satiator though so there was no real danger. The incident has me rethinking the timer strategy. I'm now looking at the Intermatic FF412H with DPST contacts. It's twice the price but the 2 pole switch contacts are less likely to fail. The chances of both welding closed at the same time are negligible.

https://www.intermatic.com/Catalog/us/Products/In-Wall-Controls/Spring-Wound-Countdown-Timers/FF412H

 

[m@Robertson]

I ordered a 60-minute Intermatic for my load resistor. Also a powder-coated box; will get the fittings locally at the big orange store.

BTW they are rated for 875w and at most my resistor on a 52v battery is going to pump thru 412, so a reasonably good match.

 

[PCeBiker]

If you really want to go overkill, you can get a contactor.

I use it to turn my two 500 Watt power supplies on and off.
They would spark like crazy when I would plug them in, and I didn't want all that going through my timer, so now my timer turns the contactor on and off.


The thing turns on and off with a HUGE crack when it slams on and off.
It startles me every time it goes off if I'm anywhere near it.

The thing is a beast.
I could turn my entire neighborhood on an off with that switch.

It's designed to turn commercial AC units on and off.

 

[circuitsmith]

I use these timers and unplug the charger manually:

https://www.amazon.com/gp/product/B07FRTKBMK/

I've figured out how long to charge my bike, laptop, or smart phone to 80%.
I never charge batteries overnight or unattended.

 

[PedalUma]

Who's been drinking my beer? Turn off the fridge at the circuit breaker. Swap the bulb with the DC one. Turn on fridge again.

 

[PedalUma]

 

[m@Robertson]

Well this worked out nicely. Thanks to the participants here for getting me off my duff to do this. Its always been an unnecessary risk to rely on a timer in the kitchen to remind me to go out and turn off the thing draining the life out of the battery.

I use a credit card tied to my bank account to make all my purchases - and it gets paid every month. The point of that is I earn rewards which I use to buy Home Depot gift cards, and that paid for all the parts here. So free stuff. Sort of.

$28 Intermatic timer
3/4" 3-hole weatherproof box
two 3/4" cord strain relief box fittings

I already had the 12 ga XT60 male and Anderson pigtails for each side, and a marine heat shrink butt end connector for the pass-thru connection on the neutral wire. And I have been sitting on the meter for years as its not accurate (off by 0.65a) and this non-critical device finally gives it a job.

Set it for 10 minutes and it pulled 0.8v out of a 30ah pack, then shut right down. I did another gift card and have another order being put together at HD today. I actually have two of these things. I got a Y adapter from Grin Tech meant to let you run two of these together. In practice, a sustained 14a draw - while not unusual riding the bike with a BBSHD - is not necessary. I'll use one to cover me at home and the other for my work residence.

 

[Aushiker]

Bump: I have been reading the Tales on Two Wheels blog post on eBike safety charging and would like to set up a timer, for particularly when I am touring. but at home as well. Playing with the maths/electrical currents is not my forte, so I was hoping someone might know what the volts added per hour are for a Bosch 2 AMP and 4 AMP charger charging a Bosch PowerTube 625 (2) batteries or will I need to get out the multimeter and do it that way? I am sure Google will help

The information I have found online includes:

2 AMP Charger takes 9.3 hours to charge the PowerTube 625.
4 AMP Charger takes 5.4 hours to charge the PowerTube 625.

Bosch PowerTube 625 - 16.7 Ah 36V

 

[GizmoEV]

Bump: I have been reading the Tales on Two Wheels blog post on eBike safety charging and would like to set up a timer, for particularly when I am touring. but at home as well. Playing with the maths/electrical currents is not my forte, so I was hoping someone might know what the volts added per hour are for a Bosch 2 AMP and 4 AMP charger charging a Bosch PowerTube 625 (2) batteries or will I need to get out the multimeter and do it that way? I am sure Google will help

The information I have found online includes:

2 AMP Charger takes 9.3 hours to charge the PowerTube 625.
4 AMP Charger takes 5.4 hours to charge the PowerTube 625.

Bosch PowerTube 625 - 16.7 Ah 36V

The voltage isn't really added, it is that the voltage goes up as charge is added. Further more, the voltage change isn't linear. For all practical purposes, when a battery is below the upper states of charge (SOC), the 2A charger will add 2 Amp-hours of charge for every hour of charging and similarly the 4A charger will add 4 Ah of charge for every hour of charge. Near the end of charge the current will decrease to not go over the maximum charge voltage.