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Oset 48v with Boost Battery


Yjo
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**Update - Boost Bikes battery serviced the battery at a cost of £135, after one charge the battery was worse than ever and the owner has basically told me tough luck - for a £900 battery after 2 1/2 years is very poor considering the original battery is still perfroming well**

 

Howdy folks,

Recently got my Oset and it came with the Boost Battery and the original, but I am disappointed with the Boost Battery range. When fully charged it seems to get to around 56v but the bike cuts out after what I think isn't long enough given the reviews I've read online. I measured the voltage and it still at 51v? If I measure the actual OSET 48v battery, it was still preforming superbly at 48v.

My question, is there a problem with the Boost Battery? I've emailed them but have not had any response?

Is there anything else I should be measuring? The boost battery is 30ah so it should considerably out last the standard one.

 

Any thoughts would be appreciated.

Thanks

Kirk

Edited by Yjo
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How long do you get before the top LED starts blinking? My 24R is 3 years old and during the summer the ride time starting dropping so I replaced with the Boost Battery. When the top LED starts blinking under load the performance drops. I get about 7 miles before that happens. The past few weeks I did some fast trail riding and after 6-7 miles the thermal cutoff switch would trigger and cut power to 1/4. LEDs would show full power and after cooling down it would run fine. I never did trail riding on the stock battery so I don't know if the Boost battery is making it overheat. It never overheats when I am doing backyard trials riding. I was wondering if the stock 48 volt would be better for fast trail riding with all the dials turned to full or maybe I need to turn down the power level with the Boost.

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Strangely, using the boost battery, my top light never flashes but I can feel the power drop under load when the battery is tired. I've never had the bike cut the power in fairness (although this could be me thinking the battery is tired...)  I didn't think of the thermal cut off switch stopping the bike. I just thought it was a battery issue as both times it has run out it was reading 51 volts (which I thought should still be plenty). I read on some other forums that when using a boost battery, the leds don't function to give you the life of the battery, they certainly don't seem to on mine. I'm currently get around 6-7 on my bike but it is a mixture of fastish trail riding and some slow is downhill mountain bike sections. Next time I'm out (today hopefully) I'll just use the standard battery and see what my distance is and at least the LEDs will give me some idea of range. When I tested the standard battery and a reasonable amount of riding it was sitting at 48.8 volts and it was going well, so I am more curious about why the Boost is dying at 51, unless it as as you say the thermals...

I shall report back asap

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It sounds like you have a battery bms problem. out of interest what do your charger say is the output voltage is?,  as 56v is to high for a 13s battery and to low for a 14s battery, this can also be caused by the battery bms ( not fully charging the battery ) but it may be the wrong charger.

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Photos attached. I have contacted by Boost Bikes, and they mention IF it is an older version of the battery then it may be off balance...which could be the case....I think the battery is a 2018 so hopefully that is all it is and it will be sorted....I will let you know how it goes.

Thanks

IMG_20210102_115139.jpg

IMG_20210102_115125.jpg

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ok so if your battery is only getting to 56v then this is way to low, the only thing I can suggest is to leave the battery on charge for at least 24hours then measure the output to see if this increases the battery voltage... i advise charge in a fire safe area i.e outside some where, dont charge indoors for this long!!. final fully charged voltage should be 58.8v

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I bought my boost battery in 2020 and the charger is way bigger that the stock one. 9”x3”. It looks the same as yours but mine has a laser printed label with a different output spec of 8A. It also says “battery type suited: 14S Li-ion battery pack. Maybe I have an updated charger.

When riding, if the motor gets too hot to touch, the thermal switch is likely to cut power. I installed cooling fins and a meat thermometer and plan to get a bar mounted digital one. When the motor starts getting hot I’ll pour some water on it.

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yes a 8 amp charger will reduce the charge time.... I think you have a few cells with in the battery that have got very out  balance and thats why it is cutting out at 51 volts it should cut out at around 44v for a 14s and around 41v for a 13s. Worst case scenario is that there a few duff cells in the battery. this can be repaired, but you do need to check the voltage output of your charger it should be 58.8v if its lower then you battery will never charge to full capacity anyway.

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I just found out about this recommendation to cut the thermal switch wire. Mine is a mid 2017 model and goes into limp mode when riding fast. Does anyone know if they got rid of the thermal switch in the newer models? Mine has three wires coming out of the motor.

FDF86455-DD6A-48C3-84FC-4DCB70CF717E.jpeg

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The US Oset importer responded to my question and said the bulletin was intended for early lithium models to diagnose if they have a faulty thermal cutoff switch that cuts off too early. Otherwise, not advised to disconnect or risk burning up the motor. The sensor goes into limp mode at 194F and should turn the motor off at 212F.

Another tip he recommended is to turn the key switch off on long downhills to prevent heat buildup.

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  • 2 weeks later...

Just an update on the 48v Boost Battery. I sent the battery back to Boost Battery (who coincidently on lives an hour's drive from me). He tested it and as it was built in 2018 and he informed me that that models BMS didn't balance the battery so a few of the cells were well out of balance. He has put in a new BMS and replaced the dodgy cells so it should be back to nearly 100%. I will let you know how it performs once I get it back. It cost me £135, £80 for the new BMS, £35 or the parts and labour and £20 for delivery by DHL. Cheers

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So I got the Boost battery back and have tested. It now charges to 58.8v. feels very slightly quicker top end than the standard battery. I didnt get to see how long it lasted but I will be able to test sometime soon.

Many thanks to those who replied previously

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Finally got to test the bike and it lasted way longer than it had previously. My son and I spent 2-3hr riding trails rather than trials, some at full tilt and others more slowly, anyway, I quit before the battery did and it still was stilling at 51.9v.....great job...or so I thought....next time I went out the battery was worse than ever....contacted Boost bikes and they told me tough... Which is very disappointing...

Edited by Yjo
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