How do you monitor your battery state of charge?

[GoreD]

I am planning a build and can't decide if I should spring for a cycle analyst as the budget is a little tight.

I'm leaning towards a geared Mac motor 25a controller and 48v battery but can't decide if I really need the cycle analyst. It seems this is the only good way to monitor the level of your battery. I would hate to run out of battery because I decided to take the long way home.

I have not found any less expensive options. Did I miss something or is this the only decent way to monitor the life of your battery.

Or should I just live without it and charge to full whenever I can and hope I don't run out?

 

[DAND214]

You really don't want to run your battery till it quits, That causes misbalanced cells.

What type of battery are you useing?

The cycle Analist is the one thging you should have. tells you how far you have ridden and how many watt hrs used. This way you know if you are gonna make it home.

I won't ride without one.

You can use a watt meter from HKhttp://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=10080&Product_Name=Turnigy_Watt_Meter_and_power_Analyzer' tere not as nice as a CA but can help

Dan

 

[wesnewell]

There or lots of alternatives to a CA. Search ebay for watt meter. Some for under $15. Depending on battery type, you may just need a volt meter for a fuel gauge. I took my watt meter off the bike not long after buying it. just not needed. I use this.
http://www.ebay.com/itm/Waterproof-Digital-Voltmeter-15V-To-120V-Red-Led-Voltage-Digital-Panel-Meter-G9-/161078127200

 

[dogman dan]

I did ride almost two years, about 4000 miles before I got voltage monitoring. Boy was that dumb. At the time, I was thinking I was fine, with a good bms. Mostly, I knew that I had 20 miles of range with a full charge, and didn't worry about my 15 mile ride home.

But a few times, the charger at work didn't work right, and I learned the hard way that green light means charged, or it means a broken plug and you never charged much.

At the very least, get a three buck shipped, two wire voltage readout. Lots of them on ebay, but look for the one with just two wires, so you don't need a separate battery to run it. You need to at least know you have a full charge when you leave, without having to break out a DVM. A dvm on the bike might not last too long, due to the bumps.

Next best, a cheap wattmeter. Mine didn't last so long, but if you get a year for 16 bucks, its not too bad.

YOU WILL NEVER REGRET WHAT YOU SPENT ON A REAL CA. I have the stand alone kind, and have really come to love them. It's just a truly high quality item, and worth every penny. The money btw, goes to the really great guy who pays the bill for this forum to not have ads.

 

[GoreD]

Thanks for your input. I am leaning towards a cell man battery. Likely hard plastic case one wiirh Samsung cells. I was hoping to order soon as the dollar here is taking a nose dive. But its sounds like saving a few more dollars for a CA would be a good investment.

 

[dnmun]

http://www.ebay.com/itm/360695107856?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

or this one, can you tell which is cheaper?

http://www.ebay.com/itm/360695110123?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[drsolly]

Digital voltmeter. Easier to read than the cheap wattmeter. £1.83 on Ebay

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=261411957582

Or if you also want to know how much current you're pulling, splash out £3.59 and get a combined voltmeter/ammeter. It takes a bit more installing, though, because A) you need to power it and B) you need a shunt.

http://www.ebay.co.uk/itm/161224223929?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

 

[Punx0r]

Another option: The Batt-man:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=151218543805

It claims to be waterproof, too.

 

[999zip999]

I love a C.A. and it plugs into a em3ev controller. Plus a C.A. was invented by Justin a canadian @ ebikes.ca. good website and gave us E.S. so to speak.

 

[alsmith]

.... and Justin gives continued excellent support for the Cycle Analyst..........

 

[heavymetalthunder]

I have a Chinese conversion kit that has a set of blue lights which gave me about the approximate voltage. For about the first few weeks of riding, I used a watt meter along with the blue lights, after I learned how the lights displayed the power curve I took off the watt meter. I've put on over 3500 miles using just the blue light display and have had no problems. I use Lipos and I always check each cell voltage after I charge them, early on I once put in a battery that wasn't charged up and ran low on power. You will need to get a volt meter to display your battery voltage, also monitor how much your charger is putting into your packs when charging. I usually limit my draw down to about 60% capacity.

 

[Matt Gruber]

There or lots of alternatives to a CA. Search ebay for watt meter. Some for under $15. Depending on battery type, you may just need a volt meter for a fuel gauge. I took my watt meter off the bike not long after buying it. just not needed. I use this.
http://www.ebay.com/itm/Waterproof-Digital-Voltmeter-15V-To-120V-Red-Led-Voltage-Digital-Panel-Meter-G9-/161078127200

wes
thanks for that link! volt meter on order for my micro scooter, the one with the 23" wheelbase. it makes a u-turn on a walkway 2 feet wide. lots of FUN! fits in my car front seat. for car shows etc.
i don't want to be distracted with too much info, it could fall into a hole
volts is all i need to know.

 

[tmho]

Yes, I also want to monitor my battery state of charge. A CA will be too expensive and complicate for me. Now I am using just a digital voltmeter which is not too perfect. Recently, I found the below meter from taobao.com (a Chinese "ebay"). According to what it said, it can show the percentage of power left. Of course, initially, we need to input/set the Ah and the lvc of our battery. Then it can tell how much Ah is left. Also, it can based on the current that we are drawing to show how much time left we can continue to run at the same speed. This seems quite suitable for me because it is not as expensive as a CA but it can tell me how much longer I/my ebike can run. I have ordered one. If you are interested, I can post my test results after I have received it and test it out. But please note this may take 1 or 2 months at least.

Below is the link for that meter. But sorry it is in Chinese only. May be later it will be up on ebay. Also, one weak point of this meter is that it is quite small. The display size is only 28 x 21 mm. Hope they will have a larger one later.


http://item.taobao.com/item.htm?_u=41nfs4845dff&id=17349165707

 

[friendly1uk]

I have a Chinese conversion kit that has a set of blue lights which gave me about the approximate voltage. For about the first few weeks of riding, I used a watt meter along with the blue lights, after I learned how the lights displayed the power curve I took off the watt meter. I've put on over 3500 miles using just the blue light display and have had no problems. I use Lipos and I always check each cell voltage after I charge them, early on I once put in a battery that wasn't charged up and ran low on power. You will need to get a volt meter to display your battery voltage, also monitor how much your charger is putting into your packs when charging. I usually limit my draw down to about 60% capacity.

Everyone seems to tell me the lights don't work. I'm with you though, of course they do, they are a voltmeter. The range is a little limited being just a few lights, but once learned it should do me nicely too. Until then, it's the cheap blue watt-meter for me. It counts actual Ah which is what my batteries are rated in, so makes real sense to me. I have little interest in refining that further. I want less.... I want the leds to work. Mine don't giving a 36v controller 44v, but I have a 48v controller sat here with 6 or 7 bars of display. It's close... but I might move to a 48v battery to get it right.

With many chemistry's a typical voltmeter is adequate, and very cheap and simple. I would still need an Ah meter to learn what it was telling me though.

 

[granolaboy]

meh

http://www.ebay.ca/sch/i.html?_trks...battery+capacity+indicator&_sacat=0&_from=R40

 

[Matt Gruber]

There or lots of alternatives to a CA. Search ebay for watt meter. Some for under $15. Depending on battery type, you may just need a volt meter for a fuel gauge. I took my watt meter off the bike not long after buying it. just not needed. I use this.
http://www.ebay.com/itm/Waterproof-Digital-Voltmeter-15V-To-120V-Red-Led-Voltage-Digital-Panel-Meter-G9-/161078127200

wes
thanks for that link! volt meter on order for my micro scooter, the one with the 23" wheelbase. it makes a u-turn on a walkway 2 feet wide. lots of FUN! fits in my car front seat. for car shows etc.
i don't want to be distracted with too much info, it could fall into a hole
volts is all i need to know.

.
got it! very nice! i just made 2 flat mounts out of wood to fit the round handlebar on 2 scooters. used a header as a plug out of an old vcr, and 5 "jack" cables. will put velcro on meter and swap it onto anything i want to measure, chargers too. polarized so no way it can go backwards.
it only uses 15ma!
UPDATE- sunny day, it completely washes out! Works in the shade.

 

[Hasaf]

I have given a lot of though to the CycleAnalysist; but, I read the CA thread. Here it is, I am only an electronic technician, not an engineer (reading the degree on my wall).

Having read the headaches, and reverse engineering, people have gone through to get the CA to work I am not willing to try it. Clearly it does not work out of box and there seems to be no good set of directions. Each application seems to be an individual design exercise.

I think they are really limiting their market until they release a product that people can buy and expect to be able to make it work. I suspect that if I buy one I will be left with an expensive widget sitting at the bottom of a box.

I really would like to like the CA; but, I just don't think it would work for me (or the vast majority of people who want a CA-like device). The issue of the CA came up on Bike Forums, my advise to the person was to read the CA thread here and make an informed decision. Anyone reading that thread is going to stay a long way away from the CA.

 

[motomech]

I love my C.A., but, depending on your needs, there is a way to ride without any monitoring.
I wanted to keep my daily driver as simple as possible and it consists of only the batt. pack, the controller, the throttle and the motor.
Most of my rides are less than 10 miles, so the batt. pack is only two bricks making 11S of Lipo. If I think I may go further, I carry another pack of 11S 5000mA in the rack bag. If I hit the controller's LVC(low Voltage cutoff), I change out the packs(30 sec. max.)and turn around for home.
The KEY is having the LVC set correctly, so it shuts off before the cells over-discharge.

 

[alsmith]

I take you are talking about v3, have you looked at v2? Its straightforward, I just plugged it in, set wheel size, and that's it. It's far simpler and has the essential figures and records needed.

 

[Hasaf]

I take you are talking about v3, have you looked at v2? Its straightforward, I just plugged it in, set wheel size, and that's it. It's far simpler and has the essential figures and records needed.

I may look at the V2. You are right, I have been reading the thread here, which is about the v3. I am hesitant to purchase the v2 because I do not want to pay full price for an end-of-life product. But I will give it another look.

 

[Samd]

https://www.hobbyking.com/hobbyking/store/__18588__Hobbyking_2_8S_Cell_Checker_with_Low_Voltage_Alarm.html

 

[alsmith]

I take you are talking about v3, have you looked at v2? Its straightforward, I just plugged it in, set wheel size, and that's it. It's far simpler and has the essential figures and records needed.

I may look at the V2. You are right, I have been reading the thread here, which is about the v3. I am hesitant to purchase the v2 because I do not want to pay full price for an end-of-life product. But I will give it another look.

I don't think that the v2 is end of life, more 'mature'- there's a software upgrade to come which means continued support is happening (but Justin is busy with lots of things, on the V3 thread you'll have seen a lot of the support work is being done by teklektik and others).
It's just that the v3 is newer, has more interfaces (complication) and more memory for the extra features so it's still getting improved.

I recently (as in the last few months) had some problems with my early large screen V2 (so it has to be 2010/2011) and Justin answered my questions quickly, helped identify the problem (a corrupt eprom) and even volunteered a free repair. That may not always be the case but support could not be faulted in any way. The guy not only runs the company, he designs stuff for us and gives personal support quickly- I think there's not much chance of being left with an old unsupported product, but if it concerns you why not email and ask about continued support for the v2?