Battery Life

[qdos]

Qdos should be along any minute now to illuminate us further on the MEV trike, I hope!

I'd be interested to hear how it's going, too, especially as there's now a motorcycle sized >10kW continuous hub motor becoming available that would seem to suit it rather well.

Jeremy

The bodywork I've been working on to fit the MEV etrike has taken a lot longer than I wanted but it is getting very close to being finished. It's turned out quite well though not exactly how we were aiming for but as we've got a customer wanting to have the first one we've continued with the style as they like it. Fraid I'm not going to post anything up in the shape of pictres yet until we've actually got it all done.

I'd be interested to know more about the hub motors Jeremy if you can enlighten us anymore............

[Greenbeast]

qdos, i used that email address you gave me, did you get my email?
looking for a little more info on the trike

sorry to use this thread

[qdos]

Yes greenbeast, I believe I have it, been busy with some shows this weekend

[Jeremy]

The 10kW+ hub motor details are in this thread on the ES forum: http://endless-sphere.com/forums/viewtopic.php?f=10&t=7718 although this is a bit of a monster thread, with well over 300 posts. The latest on the test program with production standard motors is towards the end.

Mark (the chap who's been developing this with the Chinese manufacturer) is pretty close to having production units for sale, from his website: http://www.doingitall.net/EnerTrac/product.php. The units are essentially beefed up Crystalyte "5000" series hub motors, produced with a double width stator/rotor to make them more suited to a light motorcycle.

They seem to run well using the rather expensive Kelly brushless controllers, although I think it would be quite possible to run one from a heavily beefed up 18 FET Infineon controller, like the cheap ones I'm experimenting with.

I think something like this would be ideal for your trike, as it frees up space for batteries and greatly simplifies the drive train. The hub even has provision for a disc brake, that just needs a simple caliper mount on the swing arm.

The only downside is the cost, $1295 for the wheel with hub, so more expensive than something like a Mars motor, but comparable with the cost of an Agni or LMC brush motor.

To save people digging around in that long thread, here is a direct link to Mark's latest pdf newsletter, with order details and other useful info: http://endless-sphere.com/forums/download/file.php?id=23338

Jeremy

[duxuk]

Greenbeast,
my battery pack of choice is 6 Elecsol 110Ah carbon fibre lead acid batteries. They weigh 25.2kg each and are suprisingly compact. I have heard reports of poor life expectancy but here is my recipe which I hope will sort this. I will not charge to >14.4V (per battery) as Elecsol say you must not! I will never mix them with any other brand since other lead acids will usually need charging to 14.8V, and this will kill the Elecsols quickly. I will check that the batteries are perfoming equally by measuring the voltage in a charged and discharged state and, if needs be, charge each battery seperately to try to equalise them. If this does not give me good battery life I will curse the company and all who work for them! So watch this space. "E-Day", when I get it all running should be sometime around September. Wish me luck.

Duxuk.

[Greenbeast]

cool, good luck

[evisfuture]

battery life is basiclly depended on if you have a good BMS sytem, I think

[Jeremy]

battery life is basiclly depended on if you have a good BMS sytem, I think

I'm not at all sure that this is wholly true. Not having a BMS at all will certainly drastically shorten the life of any lithium chemistry battery, but will also make it too dangerous to use, so it's a bit of a moot point.

Whether having a very accurate BMS over just a moderately accurate one increases cycle life appreciably is very debatable, given the inherent variability between individual cells. I'm pretty sure that any BMS that keeps individual cell voltage within the minimum/maximum limits specified by the manufacturer will be OK - if it doesn't do that basic job, then it's not really a BMS.

There are far greater influencing factors on cycle life than the quality of the BMS, depth of charge/discharge being far and away the most significant one. The next most important factor is manufacturing quality control, something that seems pretty poor from a great many far-Eastern manufacturers.

Jeremy

[ChrisB]

Greenbeast,
my battery pack of choice is 6 Elecsol 110Ah carbon fibre lead acid batteries. They weigh 25.2kg each and are suprisingly compact. I have heard reports of poor life expectancy but here is my recipe which I hope will sort this. I will not charge to >14.4V (per battery) as Elecsol say you must not! I will never mix them with any other brand since other lead acids will usually need charging to 14.8V, and this will kill the Elecsols quickly. I will check that the batteries are perfoming equally by measuring the voltage in a charged and discharged state and, if needs be, charge each battery seperately to try to equalise them. If this does not give me good battery life I will curse the company and all who work for them! So watch this space. "E-Day", when I get it all running should be sometime around September. Wish me luck.

Duxuk.

Theres not a lot wrong with Elecsols, I had a set in my Fiesta and they seemed pretty good, although I've heard that the QC on the batteries can be flakey and sometimes you get a good set and sometimes you can get dodgey ones ??

In my view their nothing that special, reasonabley priced multi purpose marine type units, treat them well and they should do you a good turn. As with all these types dont give them a hard life, re-charge ASAP after use, although due to the fact Elecsols run (or always did run) with a reduced acid concentration they arnt as prone to sulphation as others. Dont run them flat, once the perfomance drops off thats the time to re-charge ASAP but its better to do it before that point. My 110ah units where able to almost deliver 50ah C1 which wasnt bad TBH but I'm not sure I'd like to run them at that figure all the time.
The fiesta would pull about 35A-40A from memory @ 30mph so was fairly well in, although @ 75mph it was 200A which while they would deliver I dont think they took too kindly to it ??

From personal experience now, if I was to return to Lead Acids I'd pay extra and opt for some Trojans but now I'm a Nicad boy I just love those.

Good luck and keep us up to speed with the project

ChrisB

[Peter Eggleston]

I can't stand by and let you waste your money on Elecsol batteries. For ev use they are complete junk. I bought a set of 10 Elecsol 220 batteries for my truck and although they seemed good at first, performance dropped off very quickly and they were useless after 6 months. Compare this to my present batteries which are ex British Telecom lead gel back up batteries which have so far lasted me 6 years and are still going strong and at a fraction of the cost.
Peter