Boston Power Swing Cells

Benjahmin

Esteemed Pedelecer
Nov 10, 2014
2,669
1,783
70
West Wales
Just over a year ago I had Jimmy make me a battery from these cells. He rated it at 15Ah. It hasn't been used as much as originally envisaged and I've recorded only 21 charges in that time - all partials.
The battery gets used either on a Panda eco conversion or my Ezee conversion. Both bikes have 5 led battery indicators.
All along the battery dropped one indicator led very quickly but then seems to hold this for quite a while. It seems to suffer from hill climbing sag quite a lot dropping two leds during a stiff climb. This would be true on both bikes.
I got out for a ride yesterday, first time in weeks due to work and weather. I decided to take both batteries, on the Ezee, and use the partially discharged bga battery first, thinking I'd not get far on it. Within 4 miles from home it had dropped to the last red light. Local town obligatory tea and cake stop (one has to support the local economy:rolleyes:) was 5 miles from home. Battery recovered one led during the stop. I took a stiff 2 mile climb out of town and didn't expect the battery to get to the top. One red led all the way up. However it not only made it to the top but went on to cover a total of 17 miles on this ride before the lvc cut in. Bearing in mind that this was a cold and windy day and that the battery was approx half depleted at the start.
I am suprised and bemused at the response curve of this battery. I've always used the rule of thumb of having approx. 5 miles left when the last led comes on. This battery has confounded that theory. It seems to drop some voltage quickly but then plateau and operate at this for ages.
So no problem with the battery, just thought I,d let everyone know my experience with these cells.
 
D

Deleted member 4366

Guest
You can't go by LEDs. Different batteries have different discharge curves. You need either a battery discharge tester and/or a wattmeter to find out how your own battery behaves.

The main advantage of the Boston cells is their life. It'll be interesting to see how that pans out, but by the time we get the answer, there'll probably be much better cells to choose.
 

Steve UKLSRA

Esteemed Pedelecer
Oct 29, 2015
318
293
Porthmadog
www.ukbusas.org
I've got Boston Power cells in two of my batteries, both two years/2k+ miles old and not showing any signs of age yet. They suffered from new with voltage sag on long climbs but recover quickly once the stress is off them...not the best for drawing prolonged high power, but seem to be lasting well otherwise.
 
D

Deleted member 4366

Guest
I built a 20Ah battery from re-cycled LiFePO4 cells about two years ago. I use it for all my testing. I've never attached a charger except the first time I balanced it 2 years ago. I checked it yesterday when I got it out for the latest test and it showed 39.5v.

A local lad has a Kudos Safari with a LiFePO4 battery (exactly the same cells). He bought it as a rather well-used second hand bike and uses it every working day as his only way to get to work. When he got it, the forks were seized and it had two broken spokes. It must have been at least 3 years old then. Over the last year I had to repair some corroded connectors for him and replace his LED panel. I put the battery on my battery tester and it gave the full 10Ah.

LiFePO4 is heavy, but has no problem with life.

BTW, I made quite a few batteries out of the scrap cells and sold them to various forum members for next to nothing.
 

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