Big battery or small battery plus a spare?

Still haven't yet taken the plunge to go electric and one of the debates I'm having with myself is should I insist on a bigger battery (say 500+Wh) or would I be better with a smaller battery (say 250Wh) and take along a spare for longer trips? All my riding is for leisure only, often short (10-15 miles) excursions on forest trails, but sometimes longer road-trips when I would run out of juice with a smaller battery. Any views or experiences with the above?

I use small lighter battery for local riding and then take extra battery capacity for longer rides, when not on longer rides I alternate the smaller batteries so all get used.

After you convert to e-bike you will probably cycle more often and for longer distances. One decent battery should be enough.

Two batteries are good, you can alternate the charging use, and take both if you need longer rides.

 

Plus your not completly dependant on one battery which you could forget to charge or it might develop a problem.

So, does that mean a 2-gallon jerry-can goes further than 2x 1-gallon jerry-cans?

One big battery will always be better than two smaller batteries. A big battery passes less current through each cell, so you get less voltage sag, which means higher average voltage and the lower current means less stress on the cells, so the cells will last longer (life of cells).

 

Putting that in simple language, A bigger battery will give you more power during a ride and your battery will have a longer life.

I'm firmly in the multiple batteries camp. Two batteries means two chargers which means double the charge rate. Opens up possibilities for longer trips.

 

My Shimano collection of 5 are all 400 or 500 Wh. Except for specialist short trip/light load use, I wouldn't go below 400.

1 big battery, you'll spend more time riding around with more power. Less strain on the battery.

 

A half full 36v 600wh battery will have 20% more power than a 300wh at the end of it's range. (36v Vs 30v) Only a small minority of my trips I need more than 50% range

Obviously a smaller battery means the bike overall is less weight, and while that might be ideal for an eMTB where it needs lifted over gates or when putting it onto a roof rack, for general use, how often do you need to lift the bike up to shoulder height.

1 big (20 ah / 960 wh) battery for me, I usually charge between 30 - 80 % with a full cycle every 8 charges.

This means I only charge the battery every 3 days or so rather than every day.

There is no answer to this question. It depends on many ungiven factors. Like any design conflict, when you add something, you lose something else. Ultimately, you have to balance the characteristics to meet your needs of weight, convenience, life, power, range, aesthetics, ease of installation, reliability, etc.

Yup, depends entirely on what you want.

For myself I run two 14Ah batteries in parallel. Gives me less voltage sag around west Wales hills so extending battery life.

Obviously a smaller battery means the bike overall is less weight, and while that might be ideal for an eMTB where it needs lifted over gates or when putting it onto a roof rack

 

For sure you would want to remove battery before putting bike on roof rack.

For my local use as a few on here will already know, is a 6ah 2p 12s HG2 diy bottle battery.

With diy small builds, one can use what ever cell/s are on the market so generally will be something far better then available in ready made ones.