Charging none removable SLA batteries on ebike

[Footie]

I am in the process of building an ebike with a front hub.
Unfortunately, I can’t justify the expense of another LiFePo4 battery so I have had to go with SLA. I am building panniers to hold the three 17amp SLA batteries. The plan is to put two batteries one side and the third and the controller the other. This should even the load and keep it as low as possible. However, this will make it impossible to remove the batteries for charging, so I will have to charge the batteries on the bike.
I have a 36v 2amp SLA battery charger from when I bought my Cougar but I dumped the 8amp batteries when they died at 8 months old. Hopefully these 17amp will last a bit longer.
My question to those with the knowledge is; should I have a means to isolate the controller when charging?
(Like an off switch to kill all power to the controller?)
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[Fecn]

Controller should be fine with charger voltages. The charger should top-out at about 42-44V (around 14.1-14.5V per battery) - Personally I wouldn't worry about disconnecting it myself, as it will have been designed to cope with the voltages from a freshly charged pack anyway. Only if you have some fancy pulse charger would I worry about disconnecting.

I would worry about the amount of unsprung weight in the panniers though. You'll need some very tough bags to hold all those heavy batteries without the corners poking their way through the fabric.

 

[Sir_Bob]

What is SLA battieries? If youre battery died at 8 months why did you throw it away? i would have sent it under warranty.

 

[Footie]

I’ve been working on the build all afternoon .... Batteries are finally in and wired up - putting out 39.7 volts. During the building I've realised the controller can be after the on-off switch anyway. So if I "T" in the charging wires between the fuse and switch (have the switch off when charging) the controller will be outside the charging loop anyway, so ok
SLA is an abbreviation for "Sealed Lead Acid". My Cougar’s small 8amp SLA batteries died very early (Cornish hills killed them). The bike was warranted for 12 months. Unfortunately, the batteries were only guaranteed for six months so were not covered

Update: If anyone's interested, I have had to bin the plan to house the batteries in panniers (for now anyway), they are too heavy to go in bags on a normal bike frame without a seriously heavy duty rack of some kind (would have to be home made).
Looking at putting them in the trailer for now.

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Cougar Mountain Electric Bike 36v 200w Hub motor (Jul07)
fitted with 10 Ah LiFePo4 battery (Apr08)
Maximum range (road/hills - Cornwall) 18 miles
Maximum range (on flat) 25 miles
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