Dewalt A123 BMS battery interface solution

[csm]

The interace boards have a protection diode so you can easily parallel packs, even if they have different voltages.

What happens when one of the batteries is low. Do you just have less capacity. Or do you notice by how the bike performs?

Seems like the 36v lithium packs are being phased out by most cordless power tool companies. I have notiec that 18-20 volt lithium packs are becoming a standard in cordless tools. Costco sells a cordless craftsman drill that comes with 2 20volt lithium batteries, for about $129 on sale right now (normally $199 for the kit http://www.costco.com/Browse/Product.as ... d=11682299 ). I don't know how many amp hours or watt hours are in each pack or what chemistry the packs are using. They seem to have 4 screws with a star type hex pattern on thier heads. Seems like it would take a long neck, thin, tool to get the screws unscrewed, and remove the cover and see what is inside. I am guess there are probably 6 - 3.2v cells?? (amp hours??). I suppose they have a BMS in them and probably could string 2 together in series for 40 volts and then string another 2 in parallell for more capacity? I can not see these packs being sold at Sears.. not sure if these packs will continue to be made. They are square in shape, similar to the 36v DeWalt battery packs. I am gessing, by weight, they may be 4 amp hour cells??

[kfong]

You just get less capacity, the discharge curve is very flat. You will only notice it if only 2 or less packs are doing the bulk of the work or are drawing more current than the 20-25amp limit of each pack.

Unfortunately, A123 is having financial problems and I suspect these batteries will be hard to find soon. Already reports of Dewalt substituting other cell chemistry in its place that are not as good.

The interace boards have a protection diode so you can easily parallel packs, even if they have different voltages.

What happens when one of the batteries is low. Do you just have less capacity. Or do you notice by how the bike performs?

Seems like the 36v lithium packs are being phased out by most cordless power tool companies. I have notiec that 18-20 volt lithium packs are becoming a standard in cordless tools. Costco sells a cordless craftsman drill that comes with 2 20volt lithium batteries, for about $129 on sale right now (normally $199 for the kit http://www.costco.com/Browse/Product.as ... d=11682299 ). I don't know how many amp hours or watt hours are in each pack or what chemistry the packs are using. They seem to have 4 screws with a star type hex pattern on thier heads. Seems like it would take a long neck, thin, tool to get the screws unscrewed, and remove the cover and see what is inside. I am guess there are probably 6 - 3.2v cells?? (amp hours??). I suppose they have a BMS in them and probably could string 2 together in series for 40 volts and then string another 2 in parallell for more capacity? I can not see these packs being sold at Sears.. not sure if these packs will continue to be made. They are square in shape, similar to the 36v DeWalt battery packs. I am gessing, by weight, they may be 4 amp hour cells??