Emax Sport too difficult to keep up

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e-commuter
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Re: Keeping Emax for another couple years

Chas, thanks that's helpful. If I'm only going to run on four batteries, I would have plenty of space to mount four chargers in the empty battery bays. However, that is probably a much more confined space and I presume Vector chargers aren't sealed like your waterproof ones and need good ventilation (maybe someone can challenge this presumption). I could get ones like yours, but if I'm going to be charging at work I would probably need a faster charge than they can deliver. For a minute there I thought I was onto a nice solution for carrying bank chargers on the bike all the time.

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Re: Keeping Emax for another couple years

PJD,

I agree with what you are saying, using some form of balancing is a must IMO and PowerCheq or other similar devices do a very good job of this. I just think bank charging is far better in the long run.

BTW, have you received any of the kits I haven't. The last thing Gary told me was they would have some ready this coming Monday, they had a last minute circuit change.

Grandpa Chas S.

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Re: Keeping Emax for another couple years

e-commuter,

You said you only travel 2.5 miles I would estimate your power consumption to be about 3 to 4 amp hours. If it is 4 amp hours these charges could replenish the batteries in 5 hours. If you are at work all day they will be fully charged for the return trip home. If you go home for lunch then in 4 hours the chargers will put back 3.2 Amp Hours which would be almost a full charge. I don't see a problem here unless I am missing something.

Grandpa Chas S.

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Re: Keeping Emax for another couple years

That's how we will be charging our 16-cell LiFePO4 packs (with the help of a BMS for balancing)

I agree. However, if you're going to use the Gary'n'Bob kit then that's a fundamentally different approach to balancing during charging than a Powercheq or BattEQ. The PowerCheq's balance batteries - the Gary'n'Bob kit manages the charging process (they also refer to it as a CMS (charge management system). Their's is also multifunction and provides LVC which PowerCheq's don't.

Really what's been discussed so far is PowerCheqs/BattEQs vs. Bank Charging. I don't think anyone has done a comparison of CMS vs. Bank Charging. I expect they never will (now that our CAPS loving friend has departed) ;-) I also think that the CMS is a fine and elegant solution. I really take my hat off to those guys for engineering a solution that is robust, can be scaled to fit pretty much any solution, is cheap and can use any power supply (with enough volts of course). Amazing.

When I save up my pennies for TS LFP's then I'm getting a couple for sure!

John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.

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Re: Keeping Emax for another couple years

The testing between the CMS and bank charging has been done on endless. If you look at the charging A123 post I think it is in there. Maybe I just thought I saw that but they did do a lot of testing the bank charging of the A123 batteries. I was going to use that method until I saw the CMS.

Grandpa Chas S.

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Re: Emax Sport too difficult to keep up

Thanks Chas.

Can anybody point me to information, maybe another post on the forum, that will help me understand the life of batteries with regard to how many times they are charged? I hear people talking about the number of times you can recharge a battery being one of the main limitations in the EV world, but I also hear that recharging whenever possible is wise to maintain battery health. So, if I charge while I am at work AND overnight, will my battery life expectancy be half as long as it would be if I only charged at night? (imagining for a moment that there was no benefit in battery maintenance attained by charging immediately after riding.)

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Re: Emax Sport too difficult to keep up

"So, if I charge while I am at work AND overnight, will my battery life expectancy be half as long as it would be if I only charged at night?"

If you go the EB20-12 data sheet here:

http://www.bb-battery.com/productpages/EB/EB20-12.pdf

You will see that cycle life becomes much greater at shallower depth of cycles. At 100% depth of discharge the the usable cycles is 300 at 50% it is 800 or 2.67 times more, so even discounting the effect of leaving the batteries at a partial state of discharge, you are still well ahead doing more shallow charges than fewer deep ones.

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Re: Emax Sport too difficult to keep up

Chas,

I haven't ordered any kits yet, I'm waiting for an announcement that they are available, then I waiting on your report on their "user-friendliness". I've soldered some repairing some stuff, but I'm not a skilled or knowledgeable electronics tech by any means.

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Re: Emax Sport too difficult to keep up

e-commuter

PJD is right on the money about charge cycles of the batteries. The deeper you discharge the batteries the fewer charge cycles they can withstand. The only thing he did not say that is important as you alluded to it is the fact you should not leave lead acid batteries in a partial charge state. They do not like this and that is why everyone says to charge at every opportunity. There are many here that will disagree with what I am about to say - I leave my lead acid batteries on the charges anytime the bike is not in use, 27/7.

Now I will explain why most here do not do this. The charges I am using are designed to be battery tenders that is to say they monitor the battery and keep it at full charge. Most everyone else uses charges that are designed to charge the battery quickly then be removed. If they are not removed you can cook the batteries. I know because I have cooked a set myself in the past, that is when I changed to the "Battery Tender" charges. I discovered these charges many years ago when I used them on my boat to keep the starter and trolling motor batteries ready so I did not have to charge the batteries every time I wanted to go fishing. I have used them on my boat for over 10 years and have only replaced the batteries once in all that time. I do go fishing at least every other weekend so the boat and batteries get used often.

PJD,

Depending on how hard the kits are to construct I might be persuaded to put together a few extras.

Grandpa Chas S.

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Re: Emax Sport too difficult to keep up

PJD and Chas, I consider myself evangelized in the virtues of more shallow charges. Thanks. I'll plan to charge while I'm at work.

Should Greensaver batteries be treated in the same way as lead-acid batteries? How do I know if a charger is likely to cook a set of batteries? Are we saying that with most chargers, the batteries should not be plugged in overnight? I'm wondering if the 2 amp Vector chargers are among those that could overcharge. I really want to make sure that I get the most out of the new batteries I purchase.

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Re: Emax Sport too difficult to keep up

Chas, one more thing. Could you point me to a picture on the internet of the type of 120V AC relay that you use to combine your chargers. If I'm going to bank charge, I'll need to do that to accommodate the one plug outlet where I park my bike. That, or I go simple and use a multi-plug strip, but I'm curious about the relay.

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Re: Emax Sport too difficult to keep up

e-commuter,

I just cut the plugs off the chargers and wire all the 120 VAC wires together in parallel. Now you need to connect the 120 VAC relay coil in parallel with these connections, I use some of the wire which I cut off of the charges, just cut off the plug strip the wires back on both ends and reuse the wire. Then finally I connect one of the plug wires, which I cut off of one of the other charges, and make a parallel connection with all the other parallel connections so I can plug it in the wall socket. When power is applied the relay energizes and the charges are connected to their respective batteries. At the same time power is connected to the chargers so they can do their job. Here is a picture which may help.

Grandpa Chas S.

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Re: Emax Sport too difficult to keep up

Here is a link for a relay with 5 amp contacts. Since the charges only put out .8 amps this is overkill but I like overkill, it save trouble down the road. At $4.oo each they are a bargain. You must have a set of contacts for each charger. This relay can switch 3 chargers at a time.

Grandpa Chas S.

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Re: Emax Sport too difficult to keep up

Depending on how hard the kits are to construct I might be persuaded to put together a few extras.

Grandpa Chas S.

As a temporary measure I will probably just match up the LiFePO4 cells into groups of four with similar charging characteristics (voltages stay nearly the same through the charge cycle), then use powercheqs to provide charging balance and prevent undervoltage in the groups of four.

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Re: Emax Sport too difficult to keep up

PJD - sorry if this is a dumb question - but how can you use PC's for undervoltage protection?

John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.

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Re: Emax Sport too difficult to keep up

John,

The power check balances both while charging and discharging. And the e-max controller already has a built-in low pack-voltage cutoff. If the cells in each grouping of four are behaving reasonably similar, and the groupings are being balanced by the powercheqs, we can assume all the cells in the pack will stay close to the same state of charge and voltage, so the controller's low voltage cutoff will be adequate to protect against over-discharge of any one cell - at least as a short-term measure.

I've never ridden the scooter with a voltmeter yet to determine the value of the cutoff. But, considering that it was designed for a 48 volt lead acid pack** it's probably at least 34 volts, or 2.2 volts per cell for the new pack, so I'm ok.

Of course, I'll be riding with a voltmeter over the testing period to be sure.

**My 60 volt mod is set up so the controller's control systems still run on 48 volts, when switched to 60 volts only the power circuit sees 60 volts.

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Re: Emax Sport too difficult to keep up

Chas, just wanted to say thanks for the diagram you posted and the picture. I think I'm going to get the basics together first, and then give this a try as phase 2 or 3. Again, thanks.

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Re: Emax Sport too difficult to keep up

e-commuter,

I am on about phase 5 and I can see to about phase 8. So I am going to build a phase 6 bike next to be sure every one of my ideas work and I have a phase 7 idea I will maybe build into my EZ-3 before I build my phase 8 bike... LOL

I am a step by step kind of guy, I have found if you try thing one at a time if something goes wrong you don't have far to look to fix it.

Good Luck,
Grandpa Chas S.

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Re: Emax Sport too difficult to keep up

Here's a discussion I had with e-commuter:

Andrew:

Thanks for the advice you have given in response to the many questions I have posted on the forum about my attempts to get my E-Max back up and running on four batteries.

In the morning, I am planning to call zbattery.com and order four EB20-12 batteries with the bolt connectors setup. You may recall that PJD had suggested I consider an HR22-12 because I am hoping to ride relatively short distances on 4 batteries. The fact that B&B doesn't list EV's among the applications for the HR series made me a bit skeptical and you wrote in suggesting the EB series (which I was planning on getting). Did you understand that I am planning on running on four batteries? Would you still recommend the EB 20-12?

Yea, I heard you were planning to just use 4. I think PJD might be right. The HR series can be used for EVs in my opinion. Actually, they already have in the Electric GPR: http://www.electricmotorsport.com I think they chose the HR series because of the higher capacity and lower resistance.

FYI, I'm using one of the HR22-12s on my BMW gas motorcycle for starting. It works really well to start the bike, and performs comparable to the stock battery which was a larger and heavier flooded battery. Though, this doesn't support it's use in a deep-cycle application (repeated deep discharges).

I'd contact B&B on the phone. Don't bother sending an email as they probably won't get back to you.
http://www.bb-battery.com/contactus.asp

Ask specifically to speak to a tech. Ask them how many 100% DOD cycles it will survive. This will give you a good comparison to the EB series which appears to be about 300.

It's mostly an issue of battery life. The HR will offer more capacity (better range) and perform slightly better but not last as long as an EB battery which is designed for deep-cycle use. Here's a comparison from the power time-tables from the spec sheets:

EB20-12: Watts for 15 mins to 10.2v: 470.6
HR22-12: 507.1
EVP20-12: 498

EB20-12 internal resistance(fully charged: <11 mohms
HR22-12: <9 mohms

I'd personally go with the EB, or EVP series. The EVP is kind of between the two, offering a lower cycle life (at least at lower DODs) than the EB series, but more than the HR. I'm using these on my bike.

Anyway, do you mind if I post this to the forum?

Regards,
Andrew

Andrew:

sure, you can post the information to the list. I'll also post after I speak to the folks at B&B. So, in the final analysis, were you saying that personally you'd go for an EVP as a compromise between the EB and HR?

I understand what you're saying about there probably being a trade-off in terms of range vs. cycle life. If 8 times out of 10 I'm only traveling 2.5 miles before charging, I wonder if I could go with the EVP 20-12 or EB 20-12 and not be discharging the batteries so much that I couldn't still get a pretty satisfactory cycle life out of those batteries.

Yes, you can go with the EVP20-12, or the EB20-12. If your controller has a low-voltage cut out, than you should be safe from discharging your battieres into the "kill-them-quick" zone. The HR22-12 have only slightly more capacity. I calculate it to roughly be about a half mile extra range in your application. This doesn't really equate to getting any significant advantage from discharging to a lower DOD in terms of life.

Here's how I'd run the calculations: Rough e-max power consumption: about 60 whrs/mile (just a guess, but it calculates to about 10 miles range which is what I think you got on previous pack)
Your ride length may be somewhere around 30 minutes (though probably less, but this can provide a direct comparison):
EB20-12 watts for 1/2 hr: 291 * 4 = 1164 * 1/2 hour = 582 whrs/60 whrs/mile = 9.7 miles

HR22-12: 308 * 4 = 1232 * 1/2 hour = 616/60 = 10.26 miles

This is a longer ride length than you may ride. You can do the comparison for the 15 minute rate from the power timetables if you want, both spec sheets have it.

Anyway, I'd go with the EBs hands down, unless you really need the extra 1/2 mile. I've read of some EVT168 users using the EB series 12v 50 ah batteries with good experience.

BTW, can zbattery get the EBs?

E-commuter:

I realized in my last comparison of the EB, and HR batteries that I did the comparison down to 10.2v. Here's the comparison down to 9v. I don't know what the controller voltage cutout is.

HR22-12 [I'll spare you the math]: 10.4 miles
EB20-12: 10.04 miles

Hope that helps, sorry for my endless rambling,
Andrew

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e-commuter
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Re: Emax Sport too difficult to keep up

Well, zbattery tells me they can sell me EB 20-12 batteries. I've spoken with two sales reps and they both said the same thing.

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Re: Emax Sport too difficult to keep up

Andrew, just wanted to let you know that I did contact B&B tech support and while the guy did not specifically give me the number of 100% DOD cycles for the HR 22-12, he recommended the EB 20-12 saying that while the HR 22-12 would give me a little longer run time, that I would probably find that the performance would decline over 3-6 months.

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Re: Emax Sport too difficult to keep up

e-commuter,

What price did zbattery quote for the EB20-12?

With lead prices still high, most places are wanting $75-$80 each.

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Re: Emax Sport too difficult to keep up

PJD,

4 EB 20-12 batteries were $64.26 each + shipping ($22.29)

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