Battery booster pack?

[Bobsiii]

On the "Best E-Bikes USA" fB page there was a post (Aug 25th) about booster batteries. Wondering if anyone here has done it, and results?
Would it require changing controllers? I have a Magnum Metro w/48v 13ah batt fitted into frame.

Here's some of the post explaining the idea :

"We can add a voltage booster pack like Rolf Steinkamp 7.2v 20.3ah booster. This will add another 2s7p to a 14s7p to make a 16s7p or 60v 20.3ah. A 1s pack would make a 48v a 52v or a 52v a 56v."

"Yes, they must be exactly the same cells in the booster as the main pack. Other wise you have situation where the booster pack or the main pack runs out of energy first. This will drive the weak battery voltage too low and cause damage. Each pack has 7p of Panasonic PF

"The booster pack in the picture does not have a bms. Rolf Steinkamp charges the battery using a LiPo balance charger.

"I dont like to run 2 bms in series unless they are designed for it. The problem is if one of the bms cutsoff you have full pack voltage across a fet that might not be rated for the higher voltage and it will blow up."

No idea if non-mbrs of fB page can access this pic of booster.

(Link Removed - No Longer Exists)

 

[harryS]

Being a tinkerer, I've done it, but only to run a 36V bike on 48V. I took apart a 10S-2P pack to make a pair of 3S-3p packs with BMS. In additional, my 36V bikes have dual voltage 36/48V controllers, so there was little risk.

I was aware that putting two packs in series risks blowing out the BMS in number two if number one fails, but that's a remote possibility. I also didn't worry about different capacities packs, because I didn't plan to run the batteries down past half way. WIth these additional risks, I really saw no point in going on after I did a few speed runs.

No, I never considered trying out 60V or 72V on my ebikes which I could do by stacking enough packs in series. . 52V (and I have 52V packs) is is high as I want to run my ebikes.

 

[AHicks]

Unless you already have some experience messing with LiPo batteries, I think messing with something like this is playing with fire. Literally.....

 

[harryS]

Bobsii, I'm pretty certain the capacitors in your Magnum controller are rated for 63 volts, That means the life is shortened if run higher. Run significantly higher, they will vent and pop. Other components. like DC-DC converter modules will also fail if subjected to volatages far beyond their capabilities. Your bike is probably good for a 52V pack (58.6V at full charge),

Also safety issues. Some old ebikers scoff at the notion that 100V DC is dangerous and brag about how they can grab it with their hands. Bet they would say different if they were riding in the rain and a battery wire came off. As a kid, we had portable tube radio kits that used 90V batteries, and yes, the shock hurt if some joker were to press the terminals against you.