onboard lipo charger?

[DeathBlade]

I'm thinking of a new lipo setup for my GM motor I'm guessing a total 12s2p(or4P) from two 6s packs(still deciding on which are the best/cheapest on hobbyking). Now I've got some 0.083" aluminum diamond plate I'm going to make my battery box out of for my diamondback response and the way I'm designing the box it will be a pain to open it up every day or so. So I'm thinking an onboard charger.

Just how? I know I could get a set of chargers and put them in with the lipo but then most chargers aren't meant to go on the RC let along a ebike.
So after some googling I saw this http://www.experiencerc.com/store/product_info.php?products_id=8969
and this http://www.robotmarketplace.com/products/0-UB26.html

The first has a nice screen and the second just seems rugged from a KISS stand point. So I'm thinking I could use two of them and parallel the packs and throw in a interrupter switch between them to take them from 12s to 6s. Now for a charger I've got some inverter power supplies (sure one is inverter arc welder but a power supply is a power supply :lol: ) that do 48volts or 40 open circuit in the case of the welder. I'm thinking a relay to disconnect the power supply after it reaches a full charge I can probably set up some type of charger this for this I think onsemi or national have some decent programmable charger ic's that are simple enough I know I have some in 12volt I just need to remember were I got them.

The only problem is how do I get it all together. Anybody done this on their builds? I really want this to be KISS high speed charging fast charging is not needed If I'm anywhere I can charge I'm staying there a while ie: work, home, hackpittsburgh, etc. I'm going to feel really stupid if there is a premade onboard charger our there.

Any thoughts?

 

[Ykick]

You don't have to balance RC Lipo every charge but if you do, you need some different bricks. That 1st link is also known as BM6 (battery medic)

When I need to charge 12S on the road I bring a current limited 48V Meanwell in my backpack. I believe very few chargers or power supplies will survive mounted to a bike. They're simply not designed for shocks/vibrations that will be encountered while riding.

 

[wesnewell]

Check the battery section for lipo bms board. There is one or more. However, bulk charging using preset charger works too and you've found you can balance them while charging using various gadgets.

 

[dogman dan]

Be aware that niether chargers nor power supplies are really built to be moving. So you may need to beef up some stuff inside the boxes, so nothing bends over and shorts. Carrying chargers is best in a pack or messenger bag on your body, unless you have good suspension to smooth out the ride.

Pop open any charger, and any controller, and you will see what I mean. The controller is built knowing it will be shaken.

 

[kevo]

The Battery Medic in the first link takes forever to balance or discharge and loads the first cell for its juice. They work great, they just have some tradeoffs.

 

[ddk]

proper packaging
A typical mid-powered R/C charger of a few hundred watts weights almost nothing in comparison to the bike with all its components. Therefore that type of charger only requires a suspension system that also weighs almost nothing to protect it from shocks.
Heat transfer is a concern
Many ways to approach this; I mount such devices surrounded with air gaps supported between multiple layers of foam and/or bubble wrap (different densities of foam chosen by guesswork lol) further suspension-mounting that structure in another box... which has proven adequate for my use on bikes and trailers i.e no failures associated with shock... (its a lot simpler than it reads.:lol: )
IMO having a battery correctly packaged with its BMS would be a better choice, as my Panasonic battery is packaged. The external charger for the Panasonic battery is nothing more than a simple switching power supply mounted in a plastic case that weighs a few grams -so I just place that in the basket
I suppose if one rides technical trails additional thought should be given
...the only technical riding I do involves negotiating speed bumps

 

[dogman dan]

Speed bumps killed two of my chargers, till I got suspension on the bike.

 

[DeathBlade]

Did some searching I think I like this.... http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=30021

edit: never mind, read the through the thread to the end and the sale thread

 

[DeathBlade]

Now I see BMSbattery has a 'smart BMS' for $19 anybody have any experiance with that one? I see it only charges at 5a so whats that 1-2c? And it needs a $199 programmer (anybody have the programmer?)
http://www.bmsbattery.com/smart/330-lifepo4lithium-ion-smart-bms-for-513-cells-in-series.html

And a higher power version for LiFeP04 cells I wonder if I could convince them to do a lipo version?
http://www.bmsbattery.com/bmspcm/322-17s26s-24a-max-discharge-current-bms.html

But I dont need any type of speed if I'm riding my ebike anywhere I'm staying for a few hours, Now to see about ruggedizing a powersupply.

 

[dogman dan]

If you are just doing a paritial charge, like half hour here, half hour there, you can use anything. Cheap sla charger close to your voltage,cheap bms battery charger, whatever. If you don't fill the cells, you can't hurt them with 5 amps.

Just don't let it finish, and carry it in pack or suspended pannier. So handlebar bag if you just have front shocks.

 

[DeathBlade]

Found another BMS anybody use this supplier or this BMS?
It said its good for 10-16S and 40amp discharge/charge

http://www.ebike-bmsbattery.com/dispro.php?id=157

So it should be good for my proposed 12s3P 15ah turnigy lipo pack.

http://www.ebike-bmsbattery.com/dispro.php?id=157

Now I've got my GM yescomusa 1000w 48v rear hub(coming tomorrow) and its cheapo 48v SLA charger.
I'm just wondering if this bms will cut it. It seems like it will.