Need advice on changing battery

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cleanair
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Need advice on changing battery

Hi all, I recently bought a used 2003 EVT 4000e knowing that the original lead acid batteries were almost dead...

Now every time I squeeze the throttle hard the energy gauge turns yellow or red with a beep -even in E mode. Then as I reduce speed, it goes back to green and no beeps...

So I think it's time to change the batteries...

I have a 48V 20ah LiFePO4 battery (Ping) from a previous ebike that I'd like to use for the EVT4000e. That Ping used to feed a thirsty Crystalyte 5303. On my daily ebike commutes, I used to draw +/-1670W constant @ about 49V -per Cycle Analyst reading- for about an hour without tripping it!!! My understanding is that the EVT's got a 1500W motor, so if in E mode and not hard on the throttle -to stay away from peak discharges, I should be OK with the Ping... And with the Ping, I'll save 110 lb!!!

Here are the relevant specs of my battery:

Voltage: 48 Volts
Capacity: 20 Amp Hours
Charging Voltage: 60-61 Volts
Charging Current: <5 Amps
Rated Discharging Amperage: 20 Amps
Max Continuous Discharging Amperage: 40 Amps
Maximum Discharging Current: 60 Amps
Discharging Cut-off Protection: 50 Amps

My questions:

1- Would the Ping work on the EVT without tripping?

2- Will the LiFePO4 chemistry work with the stock controller/motor without mods?

3- Any special wiring for connecting a LiFePO4, or just hook the two battery wires to the main Anderson connector.

4- Will the stock energy gauge still work with the LiFeP04?

Your comments much appreciated.

reikiman
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Re: Need advice on changing battery

I have an 2002 (maybe 2003) EVT 4000e ...

My batteries are old as well, and they go to yellow on full throttle from a dead stop as well. Sounds like yours are worse off. The "go to yellow" or "go to red" behavior is based on its conceptualization of state of charge, the discharge rate you're putting on it at a given moment, and it's an estimate of remaining range based on those two factors. It's an educated guess hardwired into the circuit. The educated guess is based on lead acid battery discharge curves.

This is likely to fool the dashboard on a lithium pack because lithium has a different flatter discharge curve. The dashboard lights will be less accurate than they already are, but you're obviously familiar with the cycle analyst so I'd just suggest installing one of them in the bike rather than trust the dashboard lights.

The nominal voltage of a 48v lithium pack is different than the nominal voltage of a 48v lead acid pack. It's not enough to screw up the controller and the motor is known to handle up to 72 volts (at the risk of burning up the brushes faster). The higher nominal voltage on the 48v lithium will make the dashboard lights even less accurate than they already are.. so definitely go with the cycle analyst.

That answers question 2 and 4 (yes and get cycle analyst)

Question 1: I doubt the Ping will work w/o tripping. But for that matter 1500w / 48v = 31A and that's within the rated capacity of the Ping pack so maybe it'll be okay. 20A is less useful capacity than the 50A lead acid that's stock. I'd suggest going with an even larger lithium pack. Maybe 40A thundersky?

Question 3: nothing special on the connector. There's nothing different between lithium electrons and lead acid electrons, right? ;-)

- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
- Electrified Electra To

cleanair
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Re: Need advice on changing battery

Thanks for your fast and detailed reply, reikiman!

I think I'll still try my 20ah LifePO4 and see what happens. I prefer to avoid buying a new pack...

My major concern isn't the battery itself, mainly due to its cutoff protection. But I definitely don't want to fry the stock motor controller. You're right, when hot from the charger, my LifePO4 could give up to 54V, which is 6V more than the stock controller's nominal voltage rating.

I think the stock controller's rated 48V 120 amps, but usually controllers could take a little bit of extra voltage. Do you know max voltage you could run through this controller?

antiscab
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Re: Need advice on changing battery

I think I'll still try my 20ah LifePO4 and see what happens. I prefer to avoid buying a new pack...

My major concern isn't the battery itself, mainly due to its cutoff protection. But I definitely don't want to fry the stock motor controller. You're right, when hot from the charger, my LifePO4 could give up to 54V, which is 6V more than the stock controller's nominal voltage rating.

I think the stock controller's rated 48V 120 amps, but usually controllers could take a little bit of extra voltage. Do you know max voltage you could run through this controller?

I recommend installing the Cycle analyst before changing the batteries, so you can see how many amps are drawn in original condition.

The fully charged voltage for a 48v lead acid battery and a 16 cell LiFePO4 battery are both 57.6v (they are the same).

The voltage under load will differ, but that doesn't matter.

If the BMS cuts out due to too high a discharge rate, you can just bypass the BMS on discharge.

Even better, you can use the BMS to power the controller logic section, with the power section wired directly to the battery.
That way the biek still shuts down when a cell voltage goes too low, but there will be no current limiting by the BMS

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

ChrisB
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Re: Need advice on changing battery

Question 1: I doubt the Ping will work w/o tripping. But for that matter 1500w / 48v = 31A and that's within the rated capacity of the Ping pack so maybe it'll be okay. 20A is less useful capacity than the 50A lead acid that's stock. I'd suggest going with an even larger lithium pack. Maybe 40A thundersky?

I've got the similar idea of using a Ping pack but sadly I think its a non starter after carrying out a few current readings came to the conclusion it was'nt going to work.
The EVT from stationary to full speed using full throttle can pull a peak of around 115amps !!! it drops pretty quick to around 80amps but its not until the last few mph to its top speed does it drop back to around 30amps and thats on the flat with no head wind, a bit of a hill or head wind soon gets the amps up again and very quickly you see 40-45amps, with a cut off on the ping pack at 75amps I think even driving carefully it would be hard to keep it within this.

So with that I'd say the Pings a non starter unless we could get him to custom build a BMS with a better cut off .....as long as it doesnt upset the batteries ???

ChrisB

cleanair
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Re: Need advice on changing battery

Thanks, ChrisB!

Last week, I tried the 48V 20ah Ping and experienced that in order to avoid the cutoff I had to accelerate (from stationary) ridiculously slow.

Once got the scoot going, I reached a 48kph speed in E mode.

In conclusion, I totally agree with you: Pings aren't a practical solution for the EVT. Even if top speed is not that bad, the lack of acceleration is unsafe under real world traffic conditions -not to mention if the battery shuts down completely.

For the last few days, I've officially been on the hunt of a lithium pack capable of delivering at least 120a continuously (40ah 3C).

I think I'm going for the GBS 48V 40ah pack.

I've been sending emails to several stores in the US and Canada (including Elite Power Solutions) and no answer. Nobody wants to sell me a pack!?!?!?!?!?!

I tried Headway Headquarters, and same bad luck...

I thought about the Thundersky's. But I'm not skilful enough to build my own pack (i.e. assembling cells, BMS, etc.) So not an option.

Can anybody provide me with info about a responsive North American supplier of high discharge lithium packs?

Thanks

gmogmo
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Re: Need advice on changing battery

cleanair,

I'm currently evaluating two 48 V 20 Ah ping batteries (parallel connected) on my EVT4000e .
Acceleration works fine with my 2 kW engine (one battery does not). I have so far only done a test run of 5 km (3 miles), as I need better cooling of the diodes...

By connecting batteries in parallel you get the max current possible to withdraw from the combined pack as the sum of the max current from the individual batteries in the pack. This means that if you use your current battery toghether with another battery, you don't have to buy such an expensive pack as you otherwise would need to.

Cheers!

antiscab
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Re: Need advice on changing battery

Thanks, ChrisB!

Last week, I tried the 48V 20ah Ping and experienced that in order to avoid the cutoff I had to accelerate (from stationary) ridiculously slow.

If you Bypass the BMS on the main powerside (so heavy cables go directly to the battery, the light cables still go to the BMS) the max discharge rate limitation of the BMS is bypassed, but the low voltage limit is not.

If your discharge rate really is only 30A continuous, that will work fine

The charger does of course still need to be wired to the BMS as normal

The problem here is the BMS, you will have the same issue with any Lithium pack.

Its was my understanding that GBS doesn't package cells, they merely provide them compressed together.
Same as Thundersky, CALB, etc

Headway can do a complete pack:
http://stores.headway-headquarters.com/-strse-42/48v10a-Headway-LiFePO4-battery/Detail.bok?category=BATTERY+PACKS

But I would rather get a PING of twice the size.......

An EVT isn't a powerful enough scooter to require high power cells to work

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

Electric tony
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Re: Need advice on changing battery

Hi everyone! I'm a total noob to the V NETWORK(so be kind please ;) . I have recently bought a used 2006 evt 168 and I'm really excited. If anyone can give some tips and tricks to look for and apply to the bike I would really appreciate it. I have question on batteries.... The batteries that came with the bike are close to dead and will be upgraded to lithium soon. However for the time being would it be possible to put in 5 6dzm 20's as a power pack aand if so..... What should I look out for? Thanks in advance for the help.

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