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Post by Deleted on Jan 9, 2019 7:24:59 GMT
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Post by quaysider on Jan 9, 2019 7:43:16 GMT
 i bought one o of the smaller ones..... thus far I've only used to to Jump start a neighbour but it worked fine and still showed 98% soc - wasn't dear either at 51 quid. |
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Post by Jim on Jan 9, 2019 9:47:50 GMT
How many ah? I bought a set of batteries this summer, 440ah £380. But thinking about it having read stuff here 200 of those ah never get used, so what's the cost per usable ah of lithiums? All the ah is usable. Looking at the ebay ad it's 150Wh, my brain hurts, where's Telemachus when you need him? If they really mean ah then that's good value. |
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Post by ianali on Jan 9, 2019 10:10:34 GMT
i bought one o of the smaller ones..... thus far I've only used to to Jump start a neighbour but it worked fine and still showed 98% soc - wasn't dear either at 51 quid. Your neighbour wasn’t a patient of Dr Frankenstein I suppose? |
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Post by quaysider on Jan 9, 2019 15:23:45 GMT
How many ah? I bought a set of batteries this summer, 440ah £380. But thinking about it having read stuff here 200 of those ah never get used, so what's the cost per usable ah of lithiums? All the ah is usable. Looking at the ebay ad it's 150Wh, my brain hurts, where's Telemachus when you need him? If they really mean ah then that's good value. it's CCA rather than ahs ... it did say somewhere what the ah are - but I can't remember.... point its, it's easy than faffing with long jump leads and /or a spare battery which I did have before - for rescuing other people when you can't just jump start of their leisure cause they're flat too. |
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Post by JohnV on Jan 9, 2019 15:33:41 GMT
How many ah? I bought a set of batteries this summer, 440ah £380. But thinking about it having read stuff here 200 of those ah never get used, so what's the cost per usable ah of lithiums? All the ah is usable. Looking at the ebay ad it's 150Wh, my brain hurts, where's Telemachus when you need him? If they really mean ah then that's good value. I am not going to bother doing the maths but I think you will find it works out as about 12.something Ah |
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Post by Telemachus on Jan 9, 2019 15:45:29 GMT
How many ah? I bought a set of batteries this summer, 440ah £380. But thinking about it having read stuff here 200 of those ah never get used, so what's the cost per usable ah of lithiums? All the ah is usable. Looking at the ebay ad it's 150Wh, my brain hurts, where's Telemachus when you need him? If they really mean ah then that's good value. To get to AH from WH you divide by the voltage. So about 12 AH. Whilst all the AH in Lithiums is usable, for best life you should use them between 80% and 20% SoC. Which gives a usable capacity of 60%. However if you occasionally go (carefully) up to 100% or down to zero, it isn’t going to have a dramatic effect on cycle life. So I would calculate the capacity needed based on using 60% routinely, but occasionally up to 80 or 100%. But if you are going to 100% or 0% you have to be very careful not to go beyond that. |
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Post by Jim on Jan 9, 2019 17:26:38 GMT
Thanks, so no better value per ah by a long way than lead acid. I now have a proper setup, solar is keeping it at 13.2 resting, on our normal trips out we now never get anywhere near 12.2v, I bought a battery top up bottle with valve so I keep them topped up easily. They should last me a few years.
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Post by Deleted on Jan 9, 2019 20:40:56 GMT
I think the pack will have a Low Voltage Cutout to protect the cells. It would be the obvious thing to do and protect the manufacturers from masses of returns by people who ran them too low. I've got a Suaoki jump start pack I have run it "flat" from the USB port but it charged OK afterwards. I believe they are cheap as chips LiPo batteries in there like the ones used in remote control models. They don't handle being discharged too far as it causes some sort of chemistry thing and I'm no good at chemistry. I've also made a diy jump start pack with a 5000mah LiPo 4s (16.8v fully charged) cell from Hobbyking connected to proper croc clips. The advantage of the high voltage of 4s is it should give a decent kick to a low lead acid battery. The battery is rated to 30C which means it is capable of discharging 150a through the leads. Yet to try that one out  I just thought the made up packs were quite tidy. Could diy it but it would always be a bodge. |
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