CA or watt meter

[chisixer6]

I know the cycle anaylst is the best thing to hit e-bike, I will get one, on my 3rd e-bike. But for now, can I get by with a watt meter? I now mainly want one for a gas gauge function. My controllers on my 1st 2 e-bikes don't have an interface for a CA. I really don't want to go the stand alone route, unless you guys say it is a must, so I will spend the extra $30. But for now I am hoping for $30 watt meter to suffice. thanks in advance.......Jerry

 

[Drunkskunk]

it really depends on what you need it for.

Basicly, you can get by with a watt meter just fine. it will tell you your voltage, amps, and watts.

Though, once you have used a CA, you'll hit your self for not getting one sooner.

 

[ohzee]

Agreed i used a watt meter for a few months and at lower volts it made a good fuel gauge.
Just upgrade when you can.

 

[chisixer6]

okay...thanks... I will get an CA when I get the 40A controller for the 3rd e-bike.

 

[amberwolf]

As long as you are under 60V fully charged on your pack, the watts up, turnigy watt meter, etc., all work fine for a fuel gauge. If you are over that voltage, you risk damage to those meters, but the CA operates up to 100V (more for some models).

 

[Samd]

I've stopped using my 30 dollar turnigy wattmeter in conjunction with my 4 dollar bike speedometer.
I now just use one of these voltmeters with the speedo, works fine at 33.6 volts:
http://www.ebay.com.au/itm/Digital-Voltmeter-Panel-Meter-DC-Voltmeter-4-5V-30V-Panel-Meter-LED-Red-/280777788171?pt=LH_DefaultDomain_0&hash=item415fa90b0b


There are a stack of types, all for about 5 bucks. Some read amps too, some don;t need external power. Search ebay-> voltmeter and sort by price.

 

[amberwolf]

Problem is, you can't judge some chemistries' SOC by voltage very well, especially LiFePO4.

If you don't have a reliable cell-level-monitoring BMS or at least cell-level-LVC on a LiPo or LiFePO4 pack, then it's safer to use something to count Ah charged up and then Ah discharged. Just going by pack level voltage could lead to cells discharged below safe levels, if they become unbalanced or one cell (or group) is having a problem for whatever reason.


The same is true of any chemistry, but it's often more critical with Li.

 

[MadRhino]

You can get away with using nothing, if you always ride the same usual course and have more battery capacity than needed.

I have a CA for each of my bikes, but took it off my daily mountain ride, now that I know for sure its max power draw on one lap of any of my racing trails. When I change something in my setup, I use the CA and temp monitor for a week or so, until I can safely go without. I keep this bike as lean as can be, optimizing performance and minimizing crash damage.

 

[chisixer6]

thanks for the replies, amberwolf....I am using around 40v on one bike and will be using 50v on the 2nd still be completed e-bike. so getting something that reads AH charged and discharged is better, will look around for that. Madrhino.. you're right, I been ridinge-bikes since August, I usually ride the almost same course, I have an idea of how much I have left over. Samd... I look at other items he has, and he has a digital meter that reads 0-99v, for only a few bucks...thanks everyone.........Jerry

 

[d8veh]

I use both. The cheap wattmeters do the job and give you everything you need, but you need to modify them by removing the shunts and mount them at the battery otherwise you have to have very thick wires running all over your bike if you want to be able to see the wattmeter while you're riding. Also, most of the cheap wattmeters aren't waterproof. The CA is simple: Just add your own connectors and fix it in place. It also has speedometer functions that are useful. I delayed buying one because of the cost, but now that I've got one, I'm kicking myself for not getting one sooner.

Ther'e a new wattmeter just come on the scene. I don't know much about it, but it looks like a good candidate for removing the display, or even doubling up the display so that you can have a display on the handlebars. Might be a bit easier than doing the remote shunt mod. For the price, it could be worth a punt.
http://www.ebay.co.uk/itm/Multi-function-Wattmeter-FD-WM-/160642323746?pt=Radio_Control_Parts_Accessories&hash=item2567075522

 

[ebent]

just call it your dues. It is nice to simply do business with Justin. We owe it to him. Not at our expense, but his stuff is my first consideration. The Ca is a no brainer as best in class by far. You will get one sooner or later so save cash by not buying it twice. Support Justin...support yourself!

 

[chisixer6]

d8veh & ebent.....ok, I'll do it correct way, I will hold off buy any meter till after the holidays, then I spend $150 to get a standalone CA, something I was going to do anyway, but was suppose to be later, but what the hey, a post Christmas present for me this time, I was meterless all this time, what's another month, besides, I doudt there will be any riding for the next few months here. thanks....Jerry

 

[Samd]

Agree that Li chemistry is sensitive, but I only balance my turnigy LiPos once per 6 weeks and have never found any single cell more than 0.01 volts different to the others. I still think a 5 dollar voltmeter and a 5 buck speedo is a useful combo to keep your volts above 3.7v per cell at all times. In doing so, you ensure that the cells don;t become unbalanced in the first place...

 

[ebent]

Jerry,

My motto is , it doesn't cost any more to go first class, you just can't stay as long......... Nothing now. In a few weeks the right choice. No wasted cash on a temperary fix. Been that way for a while, soon to be perfect. I like it! Good luck.

Harvey

 

[chisixer6]

Nice motto.............

I wish Spring was here already....