72v battery ?

[crimsonsnake0]

hi all i would like to upgrade my ebike in the new year and was hoping someone could give me some help please ? . at the moment i have a 72v 1500 watt controller with 15ah sla batterys. the extra torgue over my original 48v controller is great and would like to keep this great pulling power. my question is where can i get 72v lipo or lifepo4 etc of the shelf complete with charger? ebay only goes up to 48v.also the 15ah sla batterys are okay for my distance to work so what would be similar for lifepo4 etc ? any ideas or links to good shops please regards .

 

[michaelplogue]

These are a bit pricy - but they are 'off-the-shelf..'

http://www.batteryspace.com/ev-rand-d-lifepo4-battery-packs.aspx

.

 

[DAND214]

All you need to do is get 2 - 36v packs and series them. Gives you 72v and what ever ah you chose.
Dan

 

[BMI]

I recently supplied a 72V 15Ah XPS LiFeTech LiFePO4 battery to a guy for his custom e-bike conversion. He sent me a couple of pics of his e-bike "creation" using the standard factory LiFeTech pack. He tells me the top speed of his bike is around 100kph (60mph). You wouldn't get me on that bike at that speed.

 

[stocked-up]

I have two of these sets, but i chose to use them in separate 36v bikes. They come with individual battery monitors, but have fewer features than real bms (these have no balancing I believe)
http://elitepowersolutions.com/products/product_info.php?cPath=27_36&products_id=123

I haven't ordered these yet, but will next week. These 10ah lithiums probably have at least as much usable energy as your
14ah sla's.
http://www.manzanitamicro.com/index.php?option=com_virtuemart&page=shop.browse&category_id=29&Itemid=64

These both seem to be the cheapest sources for each kind.

For BMS system, you can probably get one at batteryspace - the "spaghetti" kind. I have their 48V / 40amp spaghetti bms on my 40ah thundersky's -seems to work okay but I took it off after I found out which cell was weakest - now I just monitor it with a cheap voltmeter wired in place.
http://www.allelectronics.com/make-a-store/item/DVM-810/ECONOMY-DIGITAL-MULTIMETER//1.html

 

[Samba]

I have two of these sets, but i chose to use them in separate 36v bikes. They come with individual battery monitors, but have fewer features than real bms (these have no balancing I believe)
http://elitepowersolutions.com/products/product_info.php?cPath=27_36&products_id=123

Those have balancers, but not the LVC or HVC features of a BMS. If the balancers work right, then pack-level LVC and HVC - in your controller and charger - should work fine. But those balancers work better if charged as 2 seperate 12cell 36vstrings than as one 24cell 72v string.

They sell 72v systems with a very fancy full-featured BMS, but only 40AH and up.

You can get their 12.8v X 20AH (4s)batteries - with or without their balancers, and a 72V charger to make your own system from their off-the-shelf parts but would be better off getting 2 of their 36v packages - they do free shipping on 'packages'.

 

[BLUESTREAK]

I have a 72volt 20ah. set up with balancers and I charge them in 36volt setup and it works great. Thay are from (ELITEPOWERSOLUTIONS.COM)

 

[stocked-up]

Thanks Samba - good to know about charging the 36's separately - and setting me straight on the balancing. It makes sense the more I think about it and what I've noticed now in the past week or so after charging it the second time.

The charger comes with a poor manual (complete with comically bad English translation). I had to open one of the 36V chargers to figure out which wire was dc positive (the blue one). As is often the case, I got nowhere trying to use a voltmeter to test the charger (chargers tend to sense the lack of voltage and respond with no voltage also, which makes sense given the basic features of a charger). Also, the charger comes with an 3-prong, AC-type male/female plug set - the kind that plugs into the back of my computer
http://www.google.com/products/catalog?q=computer+power+cord&oe=utf-8&rls=org.mozilla:en-USfficial&client=firefox-a&um=1&ie=UTF-8&cid=15861800569984012286&ei=RrYJTazPC4bQsAPiw_mpCg&sa=X&oi=product_catalog_result&ct=image&resnum=5&ved=0CE8Q8gIwBA#

Guess it was rated for the current and voltage and was cheap - and most people probably put on their own preferred plug anyway.

I haven't run my packs at 72V yet - just a few times at 36v. So far, with my 20ah/36v lifepo4s, I can commute approx 24 miles between charges, with moderate hills being 50% of the trip (flat the other 50%), but some peddling, Seattle, 55psi, mtn bike, WE brushed motor, 20A controller. The pack replaced a 12ah lead acid pack, which got me about one third that distance, under same circumstances, with the SLA pack estimated at about half it's useful age. Given that the lifepo4's are pretty light compared to me (220 lbs), a 72V pack should provide about double or 48 miles of hilly use for someone my weight.