Multiple Subpack Balancer

[Hybrid-Battery-Repair]

Originally Posted by boelle

i have only pictured it in my head, the way i first thought of it was:

one plate in wood that is fixed to a plate that the pack is placed on.. another end plate in wood that are either fixed or slideable

then for each stick a combo of nuts and a bolts plus springs... then either slide one endplate or pull the nut/bolt combo enough to slide out the pack

the bolthead will thouch the end of the stick... then a spring to press it against the stick... a noylon washer to isolate.. then the wood endplate... another washer... a noylon bushing and then 2 nuts with a a ring terminal between....

those are just loose thoughts, but should be enough to get the picture of whats inside my head, springs are choosen so that they press the bolthead hard enough against the end of the stick... on one side you could add a second but much thinner endplate between the 2 nuts and put a piece of wood in triangle shape in between the to endplates to pull back all the bolt/nut combos at the same time

I tried making a plate from plexiglass with 20 holes drilled. The plate was larger than the end of the battery and would replace all 20 bolts from the junction board end. Screwing in the bolts would apply pressure against the lip of the battery casing, so there would be a good contact for the ring terminals under the bolt heads. The wires from the ring terminals went to a block of PowerPole connectors. The wires were stapled in place (into the plexiglass) so that it didn't matter if the bolts fell out while assembling.

The problem that I discovered was that it deflected too much and as I tightened bolts, others loosened up. Nylon (or whatever) spacers would be great, but I was not able to find any. I thought about using PVC pipe, but I couldn't find anything small enough.

Now I just use big alligator clips in pairs with a powerpole on the end. I then plug the chargers into them.

[boelle]

have been fooling arround with designs and prices... sadly the price for a homebuilt charger is so close to the price of a superbrain that it is a bad deal even before the solder iron gets hot

and the homebuilt does not even come close to what the superbrain has to offer, ie no discharge and only 5amp charge on the homebuilt

what i'm now thinkering about is to take 2 22 mm MDF plates (glued or screwed together) and drill a series of holes and put a combo of bolt/nut/spring's in each hole... on one side that plate is just fixed to a single 22 mm plate that the pack is resting on... on the other side the same setup but with an 10 mm MDF plate that can be used to pull back all bolts at the same time.

but if the bolt head touching the end of the stick is enough i dont know... i guess it's a matter that the spring is pushing hard enough against the stick.

one of these setups for the first gen packs and another similar to the second gen packs...

the wires from the setup to the superbrain could be connected via a dsub40 connector so that the switch is easy and fast... i assume that the superbrain can at least hold 2 profiles so that you dont have to waste to much time telling what type of battery you are going to charge

to make the whole setup faster to start/stop each button on each superbrain could have a small relay attached and then run wires to a set of 5 buttons.. in that way all the brains are doing the same job at the same time

well better stop before someone thinks that i'm insane....

//bo

[Hybrid-Battery-Repair]

Originally Posted by boelle

i assume that the superbrain can at least hold 2 profiles so that you dont have to waste to much time telling what type of battery you are going to charge

It actually has 35 user-settable profiles (0-9 and a-y). It however is a pain in the posterior to swap back and forth. Okay, one Superbrain isn't that bad, but I have to swap up to 20 chargers at once.

[retepsnikrep]

I'm revisiting this project and redesigning it cope with a full twenty subpacks as I need to do something to speed up and automate my pack refurbishing for UK owners. Ron has a good setup running in the US but I need to try and help more over here as the cost of shipping packs and import duty etc is just horrendous.

As most IMA batteries I have worked on have required subpacks changing, then you may as well remove them all from the case first. This gives a number of advantages IMO which i'll elaborate on.

1) When cycling the packs will now be fully exposed and can be cooled more effciently.

2) Physical problems can be detected like a blown/leaky cell etc.

3) It is a lot safer as no high voltage pack to deal with.

4) It allows my new design to be utilised.

The new design will use a large wooden board as a building block. On it will be fixed a length of 90degree angled copper or aluminium drilled at intervals for 20 subpack bolts. This negative end of each subpack will be bolted to this - BUS. The postive end of each subpack will be bolted to small seperate sections of individual angled brackets. These will then attach to one side of an individual 70A 12v high power relay. The other side of all the 20 relays will again be attached to a common + BUS

A PWM controlled 0-50A load and charging source will be attached to the BUSES.

Each subpack can be selected at will via the relays.

The current flowing and voltage of the BUS will be measured. All the ptc strips will be connected in series using some simple crocodile clips on short lengths of wire to duplicate the OEM connections. The whole board will be covered with a clear plastic cover/enclosure with a fan to allow forced cooling air to be drawn over the subpacks. An enclosure temp sensor will also be fitted.

The 20 relays will be driven via the main board and controlled via a Picaxe chip driving a MAX6956 I2C I/O expander and ULN2003A driver IC's

The board will have a mini LCD display some simple buttons and will send data via USB to an attached netbook PC running excel, which will basically gather all the data the subpack cycler spits out.

It's early days again and I do have a few other things to sort out, but I have seen a bargain set of 25 x 12v 70A relays on e-bay in the UK which look ideal for this project.