June 14, 20241 yr My wife has piddly Swytch battery packs whilst I have plenty of capacity in my Yose pack. I’m thinking of making up a jump lead that goes from the power output socket of my battery, and connects to her charge port on the Swytch battery - for when we are out and about. All I need to add is a current limiter so that I don’t exceed 2A. Ebay has various circuit boards that’ll do the trick so I’m now seeing which current limiter is the smallest/cheapest. Any thoughts?
June 14, 20241 yr ..... Any thoughts? Yes ---- EEK! Do a google search on Constant Current/Constant Voltage (aka CC/CV) which is how lithium batteries are charged.
June 14, 20241 yr My wife has piddly Swytch battery packs whilst I have plenty of capacity in my Yose pack. I’m thinking of making up a jump lead that goes from the power output socket of my battery, and connects to her charge port on the Swytch battery - for when we are out and about. All I need to add is a current limiter so that I don’t exceed 2A. Ebay has various circuit boards that’ll do the trick so I’m now seeing which current limiter is the smallest/cheapest. Any thoughts? All you need is an adjustable charge controller. There are many similar ones to this. https://www.ebay.co.uk/itm/395406170799?itmmeta=01J0BWVTNH4TAQFJCNWYA212GJ&hash=item5c100b5aaf:g:kiYAAOSwfxdmRJAC&itmprp=enc%3AAQAJAAAA0Mrkjyu8E%2FioT2hyD3B%2F9czRNeFp20dCglN0an0JWWq%2FxFdc%2Br6Ku7kXNFsodi89azDkurRReZuhMsheqcjwyatId0iVOlpskQNKPJ5S8iSxbNordvN9UeePsG60sN5H9a19FlUlZiw47ceW%2BD%2FiYHiqrzAjmPFFql4JqvYDSeGiRUQjZYYpJ8gd%2FrQ3mcs0s%2FXpDPJdN%2FUk%2FGiDGGwWRvrL2ZmBvzN2oeFeC%2Fnd%2BYb25SI9YlWy5wkmKcWHsKC1b72wFzjonH%2Bc8j8NoG0qu24%3D%7Ctkp%3ABk9SR_Cq7_yCZA It's still going to take a couple of hours to get any meaningful charge into her battery.
June 14, 20241 yr My wife has piddly Swytch battery packs whilst I have plenty of capacity in my Yose pack. I’m thinking of making up a jump lead that goes from the power output socket of my battery, and connects to her charge port on the Swytch battery - for when we are out and about. All I need to add is a current limiter so that I don’t exceed 2A. Ebay has various circuit boards that’ll do the trick so I’m now seeing which current limiter is the smallest/cheapest. Any thoughts? Chargers for 36V lithium ion batteries output 42V, so the BMS may just say no. If the BMS effectively allows a direct connection, then the current flowing will depend on the state of charge of the two batteries. Could be rather high, might just blow fuses if present, or might destroy things. Short answer: don't do it!
June 14, 20241 yr Author So the concensus is - bad/poor idea! Fair enough. I spend my life thinking up solutions for problems that don’t sometimes exist.
June 14, 20241 yr So the concensus is - bad/poor idea! Fair enough. I spend my life thinking up solutions for problems that don’t sometimes exist. It's dead easy to fit another battery to that bike - just two wires. You can fit any battery you want wherever you want to get whatever range you want.
June 14, 20241 yr Author Yes, my bike has a Yose down-tube pack, a Swytch handlebar battery holder for a Swytch gen 3 pack, and a connector on the rear pannier to take some swytch gen 2 packs that I got off my brother! I can use all three simultaneously if I wish, to get me unheard of distances! It’s just my wife won’t let me modify her bike, and in her words, over-complicate it - as if I would…
June 14, 20241 yr It’s just my wife won’t let me modify her bike, and in her words, over-complicate it - as if I would… https://www.halfords.com/motoring/trailers-towing/towing-accessories/aa-2-tonne-tow-rope-181911.html
June 15, 20241 yr ...... I can use all three simultaneously if I wish, to get me unheard of distances! … Out of interest when you say 'simulataneously' do you mean running the batteries together in parallel, or just using them sequentially as in when one is discharged you disconnect and plug the other one in? If running in parallel, do you 'join' them together with some clever 'box of tricks' or just after careful voltage measurement?
June 15, 20241 yr Author Out of interest when you say 'simulataneously' do you mean running the batteries together in parallel, or just using them sequentially as in when one is discharged you disconnect and plug the other one in? If running in parallel, do you 'join' them together with some clever 'box of tricks' or just after careful voltage measurement? In parallel. I isolate each pack with part of a MR30 shottky diode. Very little voltage drop (around a quarter of a volt). I can slap on a quick and easy swytch gen 3 pack for going down the shops, or add other packs to go further. The beauty of multiple packs is that I don’t get significant voltage slump when going up hills as the draw on each pack is reduced. Obviously the pack with the most charge will predominate until the voltages are level.
June 15, 20241 yr No Thanks for that [mention=40675]Cisco-man[/mention]. I had thought of doing something similar with shottky diodes and had also started to look at 'ideal diodes' too as their forward voltage drop is even smaller, but haven't really got around to giving it a go. Another winter project I suspect . Edited June 16, 20241 yr by Bikes4two
June 16, 20241 yr No thanks for that [mention=40675]Cisco-man[/mention]. I had thought of doing something similar with shottky diodes and had also started to look at 'ideal diodes' too as their forward voltage drop is even smaller, but haven't really got around to giving it a go. Another winter project I suspect . I use the same technique for my solar trailer. If you use simple and quick connectors both on the diode setup and bike wiring it is quite a small job, and the diodes can be added/removed 'in an instant'. Hint: run a three ended 'black' cable as well as the 'red' three legs of the diode, so every connection is simply a +/- pair.
June 16, 20241 yr ....... Hint: run a three ended 'black' cable as well as the 'red' three legs of the diode, so every connection is simply a +/- pair. Er, sorry for being thick, but I don't understand the above .
June 16, 20241 yr Er, sorry for being thick, but I don't understand the above . I'll post a picture tomorrow.
June 17, 20241 yr I'll post a picture tomorrow. Like this: Two, two way input connectors on the left, one, two way output connector on the right. I just unplug the battery cable, insert this, and good to go, solar or not. The bike wiring does not need any modification if a convenient connector already exists. The negative wiring does nothing except make the connection and switch from one to two batteries easy. Backing board and cable ties for mechanical support. Cooling not needed as I run very low in the diode's capabilities.
June 17, 20241 yr I have never done this, and hesitate to jump into a discussion with people who have, but I am a bit worried that someone with no knowledge might read this thread and unwittingly connect two battery outputs together in parallel without isolating them as regards one charging the other. My concern is that if those batteries are not at the same level of charge, say one is low and the other not, you would get a very large flow of current from one to the other. This is pretty dangerous if done like that. It is not only the well informed battery folk who could read this. The completely naive can find it too. I have heard of fires caused by paralleling batteries badly. I know no one has suggested that, but maybe a warning is needed not to just connect un-alike battery outputs together. Am I wrong? Maybe I am.
June 17, 20241 yr Like this: [ATTACH=full]58238[/ATTACH] Two, two way input connectors on the left, one, two way output connector on the right. I just unplug the battery cable, insert this, and good to go, solar or not. The bike wiring does not need any modification if a convenient connector already exists. The negative wiring does nothing except make the connection and switch from one to two batteries easy. Backing board and cable ties for mechanical support. Cooling not needed as I run very low in the diode's capabilities. Thanks for posting about this. Which diode do you use? You may have mentioned it before on one of your solar trailer adventure threads, but I can't recall. While you're here, how many solar panels would I need to power 100 of these to make an atmospheric water harvesting system for my off-grid garden? https://www.ebay.co.uk/itm/296091068132 https://www.youtube.com/watch?v=ACadXn5lwV0:333 Edited June 17, 20241 yr by guerney
June 17, 20241 yr Connecting battery at .............. - I have not tried or seen anyone doing it. Then maybe for safety's sake you should delete your post rather than even begin to make the suggestion? Just saying. Edited June 17, 20241 yr by Bikes4two
June 17, 20241 yr Then maybe for safety's sake you should delete your post rather than even begin to make the suggestion? Just saying. Okay, deleted
June 17, 20241 yr The general principle I use when paralleling my bike batteries is this (and I've been running my battery packs in this way for a year now): 1. The battery packs are of the same nominal voltage (in my case 36v packs) AND 2. Before connecting them together (without any diode isolating, current limiting or other electronic means) ensure they are at the same charge state and this is determined by accurately measuring the off load 'at rest' battery voltage. If the battery voltages are within 0.1v (100mV) of each other then I am happy to connect them in parallel. Now that's the way I do it for the relatively low AmpHour capacity batteries I use. There are other methods but I don't use them and have no experience of them so I will not speculate as to their relative merits.
June 17, 20241 yr Thanks for posting about this. Which diode do you use? You may have mentioned it before on one of your solar trailer adventure threads, but I can't recall. While you're here, how many solar panels would I need to power 100 of these to make an atmospheric water harvesting system for my off-grid garden? https://www.ebay.co.uk/itm/296091068132 https://www.youtube.com/watch?v=ACadXn5lwV0:333 (1) Mine is an MBR6045WT, chosen because I read about someone else using it, and it was easily available. Not as a result of deep research! (2) Many! They seem to want (QM) 28W each, so 2.8kW for 100 of them. My three Sunpower lightweight panels are 110W peak output each, i.e. full sun and pointing at the sun, so you would need about 30 for instantaneous midday sunny day success. But energy questions are more nuanced than this. E.g. how long do they need to run for, per day? And so on, will allow energy per day to be calculated, and then a plan made for how to supply it: how many panels, how much battery etc.. Cheapest panels are the conventional heavy domestic glass surfaced, and often bargains available from solar farm upgrades. Try Bimble Solar.
June 17, 20241 yr They seem to want (QM) 28W each, so 2.8kW for 100 of them. My three Sunpower lightweight panels are 110W peak output each, i.e. full sun and pointing at the sun, so you would need about 30 for instantaneous midday sunny day success. But energy questions are more nuanced than this. E.g. how long do they need to run for, per day? And so on, will allow energy per day to be calculated, and then a plan made for how to supply it: how many panels, how much battery etc.. Cheapest panels are he conventional heavy domestic glass surfaced, and often bargains available from solar farm upgrades. Try Bimble Solar. Thanks for the solar panel information. Bar this year, it hasn't rained much for the past couple of years. I might try a small scale test - with an ice conductance detector for when it blocks an aluminium pipe with a few CPU heatsinked peltier plates externally attached, thermally isolated as much as possible from the pipe sides being cooled. When the pipe is blocked with ice, the cooling should stop until the ice melts. Might turn out to be an absurdly inviable proposition.
June 17, 20241 yr Author My favourite diode for this job. post edit - I see the last post says the 60A one - could well be a better choice, but I’ve not had a 30A fial.
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