how to carry a spare battery?

[pagheca]

Hey guys,

I am planning to purchase a second battery for my Trek Powerfly 7 FS to extend the range of my trips. I could reach almost every corner of the island with it.

The battery is a Bosch PowerTube 625 (BBP291) Vertical, weighs about 4 kg and is 416 mm long, not including the case. Where would you carry it? The FS doesn't allow you to put it on the back, but it wouldn't be easy to put it on the top of the main tube either (not enough space - see picture). The alternative is to put it on the handlebars or under the saddle, but that would be quite high and would add to the instability of the bike, which is not the best IMHO...

Bear in mind that the trails here are really bad and steep, so the vibrations are pretty strong and I need a very stable mount. I recently bought a Thule Pack'n and Pedal on Amazon to bring my stuff with me, but it was never delivered (waiting for a full refund) because it got lost and/or customs is a real nightmare here. I was thinking of purchase something to mount UNDER the front tube, just past the front wheel. There would be just enough room even with the front suspension fully compressed, but not easy to find something workable.

Any suggestions or experience with this?

This is the bike:

 

[major masingil]

That's a tough one. There isn't a lot of extra room on the bike. Have you thought of carrying the spare battery in a backpack? Hopefully someone else on here has a better idea. Good luck

 

[Snoop]

My thought would be either finding a way to mount a rear rack on that bike (would probably require some work), or as stated, popping it in a backpack.

I wear a backpack every day on my commute, which is a nice quality leather (with some associated heft), and contains my laptop, and some papers/folders. All said, it probably weights at least 10-12 lbs, and I don’t even notice it.

Edit: Just noticed you’re wearing a backpack in your avatar picture.
Have you tried seeing if the battery fits in there?

 

[pagheca]

Have you thought of carrying the spare battery in a backpack?

Thanks for the suggestion, but I wouldn't like bringing something so heavy on a backpack as it would affect balance.

 

[pagheca]

My thought would be either finding a way to mount a rear rack on that bike (would probably require some work), or as stated, popping it in a backpack.

I wear a backpack every day on my commute, which is a nice quality leather (with some associated heft), and contains my laptop, and some papers/folders. All said, it probably weights at least 10-12 lbs, and I don’t even notice it.

If I used it for commuting (like I did for years in the past) it would be perfectly fine, but as I wrote, I would prefer not going off-road and for so long with a heavy backpack on my shoulders....

There is an old shoemaker nearby who also does good works on backpacks and travel bags. I was thinking of designing something tailored for this specific use to attach somewhere. He is incredibly cheap: time ago he asked me 5 (five!!) euros to change the zipper on the bag I carry under the diagonal tube, which had broken, and he made a perfect job... The problem would be eventually how and where to fix it so that it is safe and durable.

 

[DieselTech]

If I used it for commuting (like I did for years in the past) it would be perfectly fine, but as I wrote, I would prefer not going off-road and for so long with a heavy backpack on my shoulders....

There is an old shoemaker nearby who also does good works on backpacks and travel bags. I was thinking of designing something tailored for this specific use to attach somewhere. He is incredibly cheap: time ago he asked me 5 (five!!) euros to change the zipper on the bag I carry under the diagonal tube, which had broken, and he made a perfect job... The problem would be eventually how and where to fix it so that it is safe and durable.

Could you use a seat post rear rack to carry your battery. The also sell a padded ebike battery transport bag. With the rack, a padded transport bag & some tie downs you would be on your

way.

 

[HumanPerson]

With the added weight i'd add some support arms down onto the frame from the rear of the rack somewhere.

I'm saying this because i had one of those same rear racks and it broke by the seatpost at the weld, all i had on the rack was a box of cereal,
some lunch meats and a few canned goods..that little bit of weight was just to much...so be careful and add support arms

 

[DieselTech]

With the added weight i'd add some support arms down onto the frame from the rear of the rack somewhere.

I'm saying this because i had one of those same rear racks and it broke by the seatpost at the weld, all i had on the rack was a box of cereal,
some lunch meats and a few canned goods..that little bit of weight was just to much...so be careful and add support arms

Yeah I found a couple different models, & I should have mentioned that. A guy would have to be crafty to mount this style of rear rack on his style of rear suspension bike. But I think it could be done.

 

[pagheca]

Thanks folks for the suggestions!

The Bungee Bike looks like a smart solution, but as @HumanPerson I am concerned about its capability to support heavy shocks on a trail on the long run, and a tied down solution would be a bit difficult to design for the PowerFly FS, although I am thinking about that.

Regarding the other solution, @DieselTech, I do not think it is feasible for a full suspension: or it hangs on the seat post or on the suspension, but not both. That's why I was planning to purchase this Thule Pack'n Pedal:

Unfortunately I couldn't find a way to have it delivered here (custom issues). And, to be honest, I would have designed that in a quite different way.

Any other hint???

 

[Seaguy]

I have done a lot of research and the Thule P and P is the only rear rack I would use on a full suspension bike. I'm on my third gravel ebike conversion, and all of my batteries have been mounted on rear racks, but hard tail only.

I use both conventional and seat post racks but I wouldn't use a post rack on trails...not strong enough. You could also use a bosch power pack and mount it within the triangle on water bottle bosses, or use strap on bosses. Is the PP compatible with your drive system?

 

[pagheca]

Thanks for the advice, Tipomarino (Seaguy, in Italian... ). Actually, I came to the same conclusion, and ordered the P'nP again from another vendor. I should receive it by the end of this month.

The original battery is too long for the triangle, but the Bosch Power Pack would not guarantee me enough energy, I am afraid. As I wrote, an alternative could be to hang a battery to the main front tube but in a very exposed position.

Yesterday, I did another "range test", this time driving for three quarters in Eco mode, but then I was exhausted and had to switch to Tour. Until that, I was exactly at 50% (see vertical line in the profile plot below), and there were no other very hanging portions to cover, so I was sure to reach home:

The tour was really e x h i l a r a t i n g, in a number of different scenarios: dense pine forests, astonishing view of the Ocean, crossing of recent desertic lava flows, direct sunlight but also heavy fog and big temperature excursions. However, doing it in ECO was pretty tough for my limited resources: more than 5 hrs pedalling, sometime walking because the dust and the ash from a recent (2021!) volcano eruption nearby was so thick tires sank!

In a nutshell, 58 Km, 1400 m uphill with up to 13% slope. I got home with my legs (aka my internal battery) exhausted, but also with a staggering 26% "Bosch" battery left that makes me think I could safely extend the range by another 20 km and more - with a similar ascent - IF I could get trained enough to ride in ECO ALL time. I am more than three times in my twenties but that apparently doesn't give me three times my past strenght!

However, with two 625 Wh batteries I could really circumnavigate the island, get to the highest peak (2400 m), reach the coast on the other side, and still go back home with no major range anxiety...

 

[sandman]

You might want to try different places before you do something permanent. The reason I say that is adding a little extra weight can in certain places can make a bike unstable. In my case I first tried putting my extra battery on a rear rack. That caused my front wheel to go into a dangerous shimmy (wobble) when I would make quick movements at higher speeds. Moving the battery to a front carrier was a lot better but not perfect. Adjusting my seat as far as it would go forward also helped. In my case weight distribution, even a small amount, is important. I suspect hanging my battery below the front frame and just behind the front tire might be best but would need to build something. That would keep the extra weight low. I have a Radpower step-thru.

 

[Seaguy]

Sounds like you want more power than bosch batteries can provide. Will the drive system allow the use of generic third party batteries? I use new 21700 cells on my latest build and they are an improvement over the earlier 18650 cells.

 

[Battery Powered]

Following, we carry extra batteries for our longer rides. I
have a kids trailer that we used for the dogs before the ebikes. I put the batteries in a 3" foam holder we made.
The cart being old and inexpensive has failed so I'm also looking for a way to mount the extra battery on the bike.
I might get a another trailer, better of course. Lol

 

[pagheca]

Will the drive system allow the use of generic third party batteries? I use new 21700 cells on my latest build and they are an improvement over the earlier 18650 cells.

to be honest, I do not know. I am trying to understand better how the Bosch Performance system works and eventually do something similar if possible. I understand the communication is through a CAN bus but I do not know if the motor query the battery to understand if there is a "fake" battery pack installed. I should try.

Alternatively, I could connect the battery pack directly to the charging cables, maybe with a DC-DC, but I should account for losses, and stop to recharge as it doesn't permit to recharge while riding...

 

[pagheca]

You might want to try different places before you do something permanent. The reason I say that is adding a little extra weight can in certain places can make a bike unstable.

yes, stability is an issue, actually. If I was an ebike manufacturer, I would design some contraption to easily mount a second and even a third battery if required...

An additional issue I haven't mentioned is that here all items imported with a value more than 150 euros get stuck at the custom and pay a heavy import tax (plus custom agent fee). And buying it somewhere else (I travel quite often) and bringing it here as personal luggage is not possible because only practical way to come here is by flying...

 

[pagheca]

hard to believe, but also the second attempt to buy the Thule Pack'n pedal is going poorly. This time I tried Deporvillage rather than Amazon, and frankly very bad experience so far: ordered on Sept. 7. Yesterday, 11 days later, I got a message saying it maybe arriving Oct. 4 instead of Sept. 27 as promised.

Plus they promised a 15 euro coupon when ordering, which turned out to be a scam: it was only valid if I subscribed to a service costing ... 15 euros. A month! I had to send an angry email to get an immediate cancellation of the automatic subscription that had taken place. No, that's not how it's done, we're not all morons ...

 

[munirider]

I don't know if the Thule rack would be any stronger than a seat post rack. I was curious and had a quick look on amazon and in the reviews there are several pictures of them mounted on full suspension bikes and full suspension e-bike including a Trek similar to yours. Pictures with heavy loads and also this review in the picture below.

The lightweight aluminum tubing and a lot of bouncing up and down, it doesn't look like a very strong design to me.

Here's the link to it on Amazon USA, https://www.amazon.com/Thule-Pack-P...&hvlocphy=&hvtargid=pla-4584413749724393&th=1

 

[pagheca]

Thanks for the info, but I think that along with Antarctica and some remote villages in the Amazon [sic] Basin, the Canary Islands are among the few places where Amazon does not deliver most items.

Anyway, good news! I found out that the local shop where I bought my ebike can actually have it... and at a much lower cost than other online shops: 99 € including the two frames!

Ordering was not that easy, but in the end it worked. I should receive it in the local shop in a few days. I will let you know my impression with it, as I am also doubtful about the reliability of the item. My plan is to eventually improve the design with something I made.

 

[pagheca]

... except a minute ago they called me the item is not available and they will refund the money