bvz

Sorry if this has been asked before, but a quick search for "timer" just comes up with "first timer" and "old timer" posts

I just purchased my first e-bike. A cheap REI Gen 1.1 - but I am pretty happy with it so far.

I don't want to over-charge the battery. So I thought maybe a timer between the charger and the wall would be a good idea. Depending on how depleted the battery is, I could set it for anywhere from 1-6 hours after which it would auto-shut off. That way even if I forget to manually shut it off (something I am VERY likely to forget) then I know it will stop charging after a given time.

Does this make sense? Has anyone else here done anything like that? Any recommendations if so?

Thanks.

Doc_Wui

It's a good idea just in case both the battery and charger fail at the same time, which is unlikely, but sure seems to be common in New York City.

I try to never leave my batteries charge overnight, and have gotten put of bed a few times to go unplug them.

bvz

I actually found this. I am going to do the same thing myself.

[Edit: I am not allowed to post url's yet - which I get. Makes sense for new users.]

What I had found was a blog post by a guy who made his own timer (sort of - he repurposed a higher quality wall timer, the kind you find in a bathroom to control a bathroom fan for example). His blog is titled "Tales on Two Wheels" and the blog post is titled "Ebike Battery Charge Safety: Heavy Duty Cutoff Timer". It is not that hard (I have rewired my house so I am comfortable with basic electrical work like this) and it feels like a very solid solution that should add safety and life to my battery.

He also has another post where he figures out exactly how long to set his timer for based on how many volts are reading from his battery. I am going to have to read that one a few times because the first time through it went over my head. But it seems like a useful skill to have.

2old

The other aspect that will increase the life of your battery is to charge it to 80% (90% is OK, but not as good) unless you are going to use it (there are chargers that can be set to 80%, 90% and 100%, as well as even more sophisticated ones).

Lambkin55

I have been using this timer the last few months...

https://stanleyacpower.com/products/timermax-countdown

IT works fine. (I wish it had a 5 hour setting though.)
I got mine at the local Ace Hardware store for $9.00.

Polaris OBark

I use a WeMo plug that gives me a continuous power consumption read-out (so I can follow the charging process) as well as allowing me to program it as a timer.

tds101 

I use one from Amazon. It works well for my ebike charging needs (also escooters, but I currently don't own one):
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

bvz

Thanks all for the replies!

It seems like I really should use a timer then. I am going to build one like I referenced in that post. I was considering a WeMo (I had one a while back) but I really like the idea of a mechanical timer which won't suddenly behave differently if somehow the settings get changed (power surge, outage, or software update). That said, if I could get it it react to the amount of power draw, that might change the equation a bit. The amazon link (and stanley) timers also look interesting... I might try one of those instead.

Thanks again!

Smaug1

I use one from Amazon too; this one:
https://www.amazon.com/dp/B00MVDTEXS...t_details&th=1

It's similar to the one tds101 has, except that the timer is mechanical instead of electronic and it has more settings.

I don't use it for safety as much, as I trust the BMS (battery management systems) and Listing on the chargers. What I use it for is to try to limit the charge under most circumstances to 80% of battery capacity to extend the life of the battery packs.

For example if I run the battery down to 25% on the battery gauge on my display and I have a 20 Ah battery pack, 25% = 5 Ah left. I want to charge to around 80% (let's call it 75% to make the math easy) to get it up to 15 Ah. So I need to put 10 Ah back into the pack. My charger supplies 2 A charge rate, so setting the timer for 5 hours will put back approx. 10 Ah. (2 A x 5 hrs = 10 Ah)

It's all just approximate, but it's better than fully charging the battery and then maybe not riding for a week due to weather. The Li-Ion packs don't like sitting at a fully charged or fully discharged state, as it cuts their lifespan. (same for being fully discharged)

Update April 3, 2024: I don't recommend the aforementioned timer due to poor quality. I set it for 2 hours and came out the other day 5+ hours later to find it stuck on 1 hour. I will be throwing this one away and replacing it with a digital timer from another brand.

polyrhythmia

One time I had to wait 10 days with a full charge because I was unable to ride. There should be a USB port so battery can be discharged when riding is not possible. I was nervous as heck about that.

2old

Fully charged and idle isn't nearly as bad as the reverse. My Haibike had a switch malfunction when it was fully charged and I was about to embark on a long ride. It took about a week to fix, but the battery doesn't seem to be affected.

soyabean

The Grin Satiator stops charging according to its program and profile choice.

It's a BIG timesaver.

I don't worry about these kind of things anymore so I can just enjoy cycling.

Smaug1

With the proliferation of eMopeds, it's about time they made one with double outputs.

speedy25

Its hilarious that so many of you recommend a timer from Amazon which electrically is probably more likely to start a fire than your battery.
Buy something thats better quality and make sure the timer is rated for double the amps of your charger.
I dont use one, and have never felt the need to. Having over 150 batteries in my shop I could worry but I'm not . I only have quality brands.

-SP

Smaug1

How do you figure? They’re safety certified just like anything else that plugs into the wall.

I think it’s hilarious that you assume timers are inherently more dangerous, considering that they such a mature technology and are so much less complex.

[…]

-SP[/QUOTE]

speedy25

I dont assume that timers in general are dangerous, but you should be wary of ANYTHING from Amazon! Its full of cheap goods, and goods that are NOT certified, and even any appearance of being certified can be faked.
Many electrical goods are UL certified, but many more these days are not.

-SP

Smaug1

Good point, they DO sell a lot of junk.
The mechanical timer I showed is ETL certified, which is not as good as UL, but (a lot) better than nothing.

Leisesturm

Two things: 1. Amazon is just a retailer. Nothing more, nothing less. They don't sell more junk than anyone else. Or less. If you can buy something at Ace or Home Depot or Lowes, by all means do. But chances are GOOD that anything you can buy at those box stores is the exact same stuff you are getting on Amazon. Last SEVERAL trips to Mall 205 to buy stuff I came home empty handed because everything I wanted was online. Why does that matter? Because if you are doing it right, a trip to the mall cost you something in time and energy, because you didn't just jump in the car to get there! Buying online from retailer sites like Target, H-D, etc. takes days to two weeks for delivery and delivery charges that are up to 50% the price of what you ordered. Amazon rarely charges delivery fees and Prime delivery is never more than 48 hours, and in many cases 24. They are getting it down to 8 in many cities. I'm practical about things like this. Life is too short to spend it tilting at windmills.

2. You don't put a timer on your battery because an overcharged battery will explode and kill everyone in your house. It is a good idea to have an idea when your battery is fully charged because even the smartest chargers do not completely stop charging a topped up battery, they just continue charging at a much lower rate. The last charger I bought was pretty expensive and had all kinds of fancy features and may, for all I know, stop charging a fully topped up battery, but MOST do not. If your charger cost less than ~$100 it is safe to assume that your battery will continue to charge until you take it off the charger. Why is that important? Because overcharging shortens a battery's life. Once won't kill it, nor even twice, or even ten times but if you are overcharging your battery by four hours every day, you WILL see 30% or more reduction in battery capacity by the end of the first year. It will be worthless in two years. For my small battery packs I use my cell phone timer to alert me when the battery should be fully charged.

Smaug1

False. They sell a LOT more junk than most other retailers:

a) because they sell a lot more quantity than other retailers, and

b) because they don’t filter what they sell by applying any sort of standard. Whoever pays can sell there.




Also false. You’re assuming lithium chargers =power supplies. Or you’re thinking of old nickel or lead battery chargers.

They charge at a constant current until the pack voltage reaches it’s maximum allowed level, then they switch to constant voltage and current decreases. Once current gets to a certain very low level (typically around 100 mA) The output switches off and the indicator LED changes state to show the user the pack is full.

Leisesturm

True. But not everything Amazon sells is junk, and not everything Home Depot sells is above reproach. It isn't up to Amazon to protect you from shoddy merchandise. You have to do your research and vet your purchases same as anywhere else.




I am not assuming anything. Are you saying that Consumer Reports and other sources that advise removing battery packs from chargers when done are all wrong? I don't think so. I think there has been enough empirical evidence to show that battery pack life is increased when taken off the charger when the green light comes on. You are assuming that all lithium pack chargers are 'smart', and that simply is not true. Most are not. The Grin Satiator is not most chargers.

2old

I've never used a timer. The batteries are maintained at 20% - 80% for longevity, then charged to 100% just before use, sometimes a lower SOC (state of charge) if I'm going on a short ride. When they're charged to 100% they can remain on the charger for hours after reaching full charge because the BMS (battery management system) protects the cells.

bvz

I wound up buying a wall timer from Lutron, installing it in an electrical box and connected to a heavy duty extension cord. So far it has worked wonders. It is UL listed and hooking it up to an extension cord is pretty trivial if you have any DIY skills whatsoever.

I am on a budget, and while I would love a Grin Satiator, but that is just not within the cards for me this year. The timer is a decent alternative.

I am not concerned that this timer will start a fire. I am more concerned that the battery might do so - even though it is a UL listed battery itself. But mostly, I just don't want to over-charge my battery. This way I can set it to charge (more or less) however long I want it to and not have to worry about forgetting to unplug it. Simple solution to accidentally over-charging my battery and reducing its life. Nice safety bonus on top of that.

That said, I would very much suggest that people purchase a quality timer and check its rating (like you suggest). I am not sure that everything sold online is trustworthy. I would pick a known brand and buy one of those. An in-wall timer (like what I purchased) seems to probably be made to a higher standard as well - though that is just a guess.

tesla_exp

It's good to have a timer, but I don't think it is necessary. you definitely do not want to charge your battery at night while you are sleeping.

Dudelsack 

Geez, usual suspects…

Like several others here, I use the timer to undercharge the battery. I put 2 hours on it, come back and see how many lights come on when I push the battery button.

BTW, my batteries reportedly “sleep” when they’ve not been used for 48 hours. What exactly is a sleepy battery, and what happens when I wake it up?

tds101