Current best way to monitor battery time left?

[shambolic]

Hi, I have just bought an Iped lite electric Moped/bike and my one big issue is the lack of straightforward battery monitoring. There is a readout of current voltage but I am never really sure what it is telling me as regards time left on the battery. It is crucial to me to know this as this bike is an alternative to a mobility scooter. I have limited mobility and to end up somewhere with a flat battery would be very difficult. Insurances like Cycleplan or ETA will cover breakdowns or punctures with a recovery service but I doubt a flat battery would count.
At the moment I spend a lot of time out on the bike worrying whether I can get back home and it is impacting my enjoyment. Something like this would be ideal:

but seems they no longer do the version required

For peace of mind I would even stretch to a Cycle analyst V3 if it gave me a clear indication of battery state: http://www.wimbikes.co.uk/cycle-analyst.html

Or should I just go with straightforward ammeter types as already recommended.
http://www.ebay.co.uk/itm/DC-0-200V-0-150A-Programmable-Meter-Controller-Volt-Amp-Power-Ah-Auto-Shut-Down-/171330857434?pt=LH_DefaultDomain_0&hash=item27e41d69da

I need to clearly be able to see when the battery is above half capacity so that I know to head back home.
Also I wouldn't be able to fit this myself. Is it the kind of thing a motor bike shop could do?

Anyone with limited mobility looking at mobility scooters who can balance on a bike should really go for this kind of thing because it is a quarter the price, twice the speed and generally a better build.

 

[shambolic]

How about one of these:

http://www.ebay.co.uk/itm/New-48V-Battery-indicator-meter-gauge-tri-colors-for-Car-Truck-Golf-Cart-/281330029676?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item418093946c

Looks like the kind of simple read out I need as long as it will do the job?

 

[Deleted member 4366]

That above one is only a voltmeter like he already has.

Look on Ebay for the GT Power wattmeter.

 

[eHomer]

That above one is only a voltmeter like he already has.

Look on Ebay for the GT Power wattmeter.

Yes, excellent little gadgets at a very low price.

I fitted one permanently in my pannier bag with the battery and controller, and the composite photo shows a graph of one of my trips with the readings on the BMS lcd controller panel, and the ah used on the GT power meter.

Dave published a diagram and clever instructions on how to modify the GT meter to work remotely at the handlebars, but the straightforward connection between the battery and controller meets my needs so far, being able to stop and look in the bag to check exact current usage. (maybe I'll get braver and do Dave's mode later though !).

 

[shambolic]

Wish my bike had the BMS panel yours has, that's all I need is a clear battery readout. Nothing else, simpler the better.

 

[pdarnett]

The little ammeter you link to on ebay is very good. had one on my bike for a while, good thing is the current measurement is quite accurate and so the Ah (i.e. how much you've got left) is pretty good too. Quite bulky though!

 

[Deleted member 4366]

All the wattmeters work. The GT Power one is the easiest to make waterproof and modify to mount remotely. It also has a back-light and most important of all, it's only £11. If anybody can find a better one for that price, please let us know.

http://www.ebay.co.uk/itm/201048320816?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

If you can't afford £11, you can get this one for about £8. It doesn't have a back-light and is not easy to waterproof:

http://www.ebay.co.uk/itm/Hot-Digital-60V-100A-Battery-Balance-LCD-Voltage-Power-Analyzer-Watt-Meter-New-/360935110278?pt=UK_ToysGames_RadioControlled_JN&hash=item540968b686

The Speedict Mars for £70 is the cheapest remote one. It sends it's results for display on an android phone.

 

[shemozzle999]

New versions are coming out all the time shambolic.Today's favorite will be condemned to the scrap box when superseded.

http://www.ebay.co.uk/itm/8-36V-Precise-Capacity-Tester-Coulometer-for-LiFePO4-Lithium-LiPo-LiIon-Battery-/231180039604?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item35d36775b4

New IC's are coming online:

http://amigobulls.com/news/multi-cell-battery-monitors-increase-safety-protection-for-12-v-to-48-v-industrial-li-ion-batteries

 

[Deleted member 4366]

I told you before: That wattmeter isn't suitable for an ebike as it stands. Look at the size of the pins on the connector and the tracks on the PCB. You'd need an external shunt of some sort, which they call "external sampling unit".

 

[shambolic]

shame, that's the sort of clear display I need. Guess it wouldn't work any way because my battery is 48V. Reckon I might go with the Speedict. It looks fairly simple to setup?

 

[shemozzle999]

I told you before: That wattmeter isn't suitable for an ebike as it stands. Look at the size of the pins on the connector and the tracks on the PCB. You'd need an external shunt of some sort, which they call "external sampling unit".

Exactly, that is why they show the circuit diagrams in the listing

 

[Deleted member 4366]

It's not just that. You'll have a job waterproofing it. By the time you've found an enclosure, shunt and everything else, the price goes up. Then you're not far off the cost of a Speedict or one of these:

http://batt-man.com/batt-man-DashBoard

 

[shambolic]

.....Ahh now that one looks really straightforward

 

[shemozzle999]

As I said, new ones hitting the market all the time

 

[drsolly]

I have a wattmeter at the back with the batteries, that tells me how many AH. And I have a digital voltmeter on the handlebars. After I used both for a while, I think I have a good feel for knowing how many AH are left, by glancing at the voltage.

 

[shemozzle999]

If I remember correctly you also carry a spare battery - the best way to know you can get home safely - when the first one expires you are exactly at the halfway point.

I expect we can't be far off having these fancy monitors built into the battery as standard and I assume they will appear in the high end priced ebikes quite soon.

 

[shambolic]

well the spare battery for my bike would be over £400? (48v 16aH Lipo) and I am not quite sure where I would put it on the bike.

 

[shemozzle999]

On a more serious note I have just looked at your scooter - are you sure it is classified as an ebike as the pedals don't seem to be able to propel the bike unassisted - a previous court case deemed this type of bike a motor vehicle and the owner was found guilty. I would double check with the shop where you bought it.

 

[shambolic]

Yes I am out on it now. You're certainly not going to break any speed records but it pedals. Not so easy for me though.

 

[drsolly]

If I remember correctly you also carry a spare battery - the best way to know you can get home safely - when the first one expires you are exactly at the halfway point.

I expect we can't be far off having these fancy monitors built into the battery as standard and I assume they will appear in the high end priced ebikes quite soon.

It isn't so much a spare battery. I use 8s, 5AH. I take 2, 3 or 4 of them with me, depending on how far I'm expecting to go. I might have a go with 10s; I tried it out and there's definitely more pep.

I doubt if they'll appear on batteries as standard; most people wouldn't know what the display means. More likely is a blobmeter, showing 1, 2 or 3 LEDs according to what the voltage is.