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Old 06-12-08, 01:31 PM   #1
mshope
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Use a 12V 2Ah battery with 3 12V 12Ah batteries in series?

I just ordered a BL-36 kit. The kit comes with three 12V 12Ah sealed lead acid batteries connected in series. I'm not 100% sure if the controller can handle 48V. However, assuming it does, does anyone have any information on whether you could use a 4th 12V SLA battery in series with these batteries. The catch is the 4th SLA battery will be a 2Ah smaller SLA battery than the other three. The intention is that I would be able to have a little extra juice, given for a short time. So my question is whether anyone knows if this setup could potentially cause a problem given the different Ah rating of the 4th battery? Thanks for any input. By the way this will be my first ebike setup, and I am intending on putting this setup on a cheap 26" Huffy 18 speed bike from Walmart.
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Old 06-12-08, 05:35 PM   #2
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if its sla no problems i did it with the izip
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Old 06-12-08, 06:51 PM   #3
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1. To avoid ruining the 10Ah battery, you will have to limit yourself to using less than 99% of its capacity. SLA batteries are not know for lasting very long, actually, unless you use them to 50-60% of their capacity or less.
2. You won't be easily able to tell when the battery is running out of juice by feeling the system get slower, nor will a low voltage cutoff circuit designed for a 48V pack do a good job of protecting your battery.
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Old 06-12-08, 06:57 PM   #4
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You'll need to make sure you don't discharge beyond the capacity of the lowest capacity cell. Otherwise, the other cells start reverse charging that one and it'll kill it.
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Old 06-13-08, 08:36 AM   #5
mshope
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Yeah, I was wondering about the other batteries reverse charging the smaller battery. I will probably scrap this idea and just get a 12V 12Ah SLA battery to go in series with the other 3 if I find that I need the extra juice. My main reason for thinking I may need this jump in power is that I live in a somewhat mountainous area in western North Carolina. But most of my commuting will be done on relatively flat land so I may not need the juice and don't want to risk damage to the rest of the system for a short boost of power. I'm getting anxious for my kit to arrive so I can get to work, thanks for the input!
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Old 06-13-08, 11:03 AM   #6
ken cummings
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It would not be the battery I'd worry about so much as the BL-36 controller. if I ran 48 volts through a 36 volt light it would not last too long. Like 10 hours instead of 1000 hours. Probably would void your warranty. Have you called tech support for the machine to ask about it?

edit; I went to the site for the kit and asked for you. Will post any answer.

Last edited by ken cummings; 06-13-08 at 11:12 AM.
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Old 06-13-08, 12:13 PM   #7
mshope
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Cool man, I appreciate the help and you asking the company about the controller. I know there are other threads some of which have people who have pushed the controller on 48V but hopefully Wilderness Energy will get back to you.
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Old 06-13-08, 12:15 PM   #8
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I know this is completely off subject of the thread topic. But does anybody have any experience installing a SRAM MRX grip shift on a bike. I ordered one for the bike I am going to convert, because my old front grip shifter broke the other day when I was performing some maintenance. If anybody has any advice on this I would appreciate it.
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