March 7, 201511 yr As the title suggests I want to use an inverter to charge the bikes from a battery. My van has a 135AH battery a 180watt solar panel that even in daylight does a good job of keeping the battery on top line in sunlight it does even better. I have a small pure sine wave inverter for my laptop but not man enough to charge the above. I will buy a 600watt inverter but the question is does it have to be the more expensive pure sine wave or will a none PSW inverter be ok for this job? lots of conflicting ideas out there on the net what do you use if you go down this road too Thanks in advance Peter
March 7, 201511 yr You need to think about this idea a bit. The average ebike battery is about 400Wh. If you charge through an inverter and charger, you'll lose a fair bit through efficiency losses, which in the best case would be about 20%, so you'd need to take 480Wh from your battery. Which is 40Ah at 12V. You shouldn't take your battery below half way, which means that if it's in tip top condition, you have 67Ah, which is not enough to fully charge two bikes. If you only do ten or 15 miles a day, it should be OK, but if you flatten your bikes' batteries, you won't have enough. It's far simpler and more reliable to get a small generator to charge them.
March 7, 201511 yr Author You need to think about this idea a bit. The average ebike battery is about 400Wh. If you charge through an inverter and charger, you'll lose a fair bit through efficiency losses, which in the best case would be about 20%, so you'd need to take 480Wh from your battery. Which is 40Ah at 12V. You shouldn't take your battery below half way, which means that if it's in tip top condition, you have 67Ah, which is not enough to fully charge two bikes. If you only do ten or 15 miles a day, it should be OK, but if you flatten your bikes' batteries, you won't have enough. It's far simpler and more reliable to get a small generator to charge them.
March 7, 201511 yr Author I agree but I would only contemplate charging during the day when the solar panel could be putting in a 10amp charge
March 7, 201511 yr You can get a wattmeter from Ebay for about £8 that will show you how much charge you get from your panels. You might be surprised by the results.
March 7, 201511 yr It's risky for the campervan batteries. Mini gen, running the engine and hookup all spring to mind.
March 7, 201511 yr I have done this. But, I only used if for two hours just to put some charge into my folder. I kept an eye on the leisure battery voltage. I only did this on a site where there was no hook up and I was using the folder as a run around, other people also used it and it was flat after 3 days, so as I was only staying one more day, using an inverter was fine. However, when camping for a long time, I only use mains hook up.
March 7, 201511 yr Author I have done this. But, I only used if for two hours just to put some charge into my folder. I kept an eye on the leisure battery voltage. I only did this on a site where there was no hook up and I was using the folder as a run around, other people also used it and it was flat after 3 days, so as I was only staying one more day, using an inverter was fine. However, when camping for a long time, I only use mains hook up. Was your inverter Pure sine wave or not? Peter
March 7, 201511 yr Was your inverter Pure sine wave or not? Peter No, it was Maplins cheapest 500 watt.
March 8, 201511 yr Author No, it was Maplins cheapest 500 watt. Good to know big differencein price between PSW and none PSW
March 8, 201511 yr If you need to charge from a 12V supply you could think about using a decent RC charger that operates from 12V. It would be the most efficient way as you're not converting twice, plus you can of course use all the shenanigans such a charger affords, such as varying the current, cut off voltage etc. My iCharger will do 10s - much more does start to get expensive. Michael
March 8, 201511 yr I prefer going off grid to more remote and quieter sites for several days at a time so I've been charging my bikes from the van batteries for the last couple of years now. I hate being hooked up, it defeats the object of the van for me. A cheap inverter from ebay is used, non PSW, rated at 1200w but it can't handle that much. (Cost about £35 quid.) It comfortably handles the standard bike charger though. Measuring the current revealed that it's pulling 8 amps out of the battery during most of the charge, this declines towards the end. My panel is rated at 100w and measuring the input shows it to be putting in 5 amps during reasonable sun. Nearer to 1 or 2 in overcast conditions. I don't do that many miles when using the bike, we just pootle about wherever the fancy takes us (2 bikes), so charged batteries to go away with and a careful eye on the van batteries works well and even allows for some TV watching/heating as wanted. We don't go mad on the bikes, they're recreational fun transport. 20 miles is the most done on one day, low power settings mostly, we need the exercise before settling down in a pub! I did uprate the van batteries to 2x100AH which helps share the load. I have been trialling a dc to dc step-up convertor and calculated that this reduces the output from the 8 amps to 5 amps. This is a similar approach to Michael's suggestion above but on the cheap. The amps and volts need to be carefully set and be adjustable. Hope this answers your questions.
March 9, 201511 yr Author If you need to charge from a 12V supply you could think about using a decent RC charger that operates from 12V. It would be the most efficient way as you're not converting twice, plus you can of course use all the shenanigans such a charger affords, such as varying the current, cut off voltage etc. My iCharger will do 10s - much more does start to get expensive. Michael Hi Michael thenks for the reply could you point me in the direction (link) to such a chargr that will be man enough to charge a 10ah battery please Peter
March 9, 201511 yr Author I prefer going off grid to more remote and quieter sites for several days at a time so I've been charging my bikes from the van batteries for the last couple of years now. I hate being hooked up, it defeats the object of the van for me. A cheap inverter from ebay is used, non PSW, rated at 1200w but it can't handle that much. (Cost about £35 quid.) It comfortably handles the standard bike charger though. Measuring the current revealed that it's pulling 8 amps out of the battery during most of the charge, this declines towards the end. My panel is rated at 100w and measuring the input shows it to be putting in 5 amps during reasonable sun. Nearer to 1 or 2 in overcast conditions. I don't do that many miles when using the bike, we just pootle about wherever the fancy takes us (2 bikes), so charged batteries to go away with and a careful eye on the van batteries works well and even allows for some TV watching/heating as wanted. We don't go mad on the bikes, they're recreational fun transport. 20 miles is the most done on one day, low power settings mostly, we need the exercise before settling down in a pub! I did uprate the van batteries to 2x100AH which helps share the load. I have been trialling a dc to dc step-up convertor and calculated that this reduces the output from the 8 amps to 5 amps. This is a similar approach to Michael's suggestion above but on the cheap. The amps and volts need to be carefully set and be adjustable. Hope this answers your questions. Thank you that answers my question admirably. it looks like we do the same sort of camping. We live in a small (toyota Hiace) camper for 6 months in the winter (outside the UK) and have a similar panel and battery set up there and we are off grid all the time just a 12volt fridge to run + led lighting and charging laptop and phones. We are off to southern Ireland when we get back in May for a few months and have bought the bikes for exploring and exercise, the Guinness is very fattening!! A great help thanks again by the way I use a BM1 battery monitor http://www.nasamarine.com/proddetail.php?prod=BM1Compact which tells all about the state of the battery its a godsend regards Peter Peter
March 9, 201511 yr Hi Michael thenks for the reply could you point me in the direction (link) to such a chargr that will be man enough to charge a 10ah battery please Peter I use the iCharger 1010b+ which will charge and balance a 10S (36V nominal, 42V max) battery at anything up to 8 amps and operates from a 10-18V input voltage. If you need to discharge your ebike battery it will actually put that power back into the van battery as well. If you are charging two ebike batteries they actually do an iCharger 4010 duo, but it's considerably more expensive than two separate 1010b+ and has reserves of power we really don't need. Michael
March 9, 201511 yr Author I use the iCharger 1010b+ which will charge and balance a 10S (36V nominal, 42V max) battery at anything up to 8 amps and operates from a 10-18V input voltage. If you need to discharge your ebike battery it will actually put that power back into the van battery as well. If you are charging two ebike batteries they actually do an iCharger 4010 duo, but it's considerably more expensive than two separate 1010b+ and has reserves of power we really don't need. Michael Michael, Thanks just a couple of things I dont understand What is a 10S Do you actually use it to charge a bike battery Does the company in the link ship to the UK Is it easy to connect to the bike battery for charging (I have never seen a bike battery My bikes will be delivered when i get back to the uk in may). and it looks like I have got a lot of reading to do regarding this method of charging from a 12v battery where do I start? Thanks for your patience and help Peter
March 9, 201511 yr Peter, 10S is nomenclature for 10 cells in series, i.e. end-to-end. I was just checking the charger would be suitable for you as it will work with a 24 or 36 volt battery but a few ebikes use 48 volts. What bikes are you getting, so I can check the voltage? I do indeed use it to charge a bike battery. Mine is a 36V 11.6Ah and the 1010b+ works very well. As I say, it will charge at up to 8 amps if you need - most chargers that come with ebikes are between 2 and 4 amps. The battery has to be able to cope with being charged at that level though. Each time you start a charge you choose the charge current (if you want to change it from last time). The company I linked to does ship to the UK, or you can buy it from some other retailers already here. I bought it from a UK store at an equivalent price but it's gone up now. And finally regarding connecting to an ebike battery itself, well, again that will depend upon the exact bike and battery you are getting so if you post that up we'll have a better idea. It would require making up a lead as the output from the iCharger is on two 4mm sockets. Michael
March 9, 201511 yr Author Peter, 10S is nomenclature for 10 cells in series, i.e. end-to-end. I was just checking the charger would be suitable for you as it will work with a 24 or 36 volt battery but a few ebikes use 48 volts. What bikes are you getting, so I can check the voltage? I do indeed use it to charge a bike battery. Mine is a 36V 11.6Ah and the 1010b+ works very well. As I say, it will charge at up to 8 amps if you need - most chargers that come with ebikes are between 2 and 4 amps. The battery has to be able to cope with being charged at that level though. Each time you start a charge you choose the charge current (if you want to change it from last time). The company I linked to does ship to the UK, or you can buy it from some other retailers already here. I bought it from a UK store at an equivalent price but it's gone up now. And finally regarding connecting to an ebike battery itself, well, again that will depend upon the exact bike and battery you are getting so if you post that up we'll have a better idea. It would require making up a lead as the output from the iCharger is on two 4mm sockets. Michael Michal http://www.cornwallelectricbikes.co.uk/our-bikes/smartmotion/metro-step-through/ This is the bike Things are getting clearer Regards Peter
March 10, 201511 yr That battery looks eminently suitable for charging with something like the iCharger. The only issues will be what sort of connector you would need on the end of the charging lead, and whether they use any sort of "smart" charging (monitoring temperature for example) which I doubt. Users trex and d8veh (and others) may well know the exact battery and be able to confirm details, or wait until you have the battery in your hands and can see what sort of charging plug it has. I would imagine it will be a simple plug and socket affair, like a laptop. One technical thing to note if you do go down this route. The battery will have a Battery Management System (BMS) built in, which protects from overcharge, overdischarge, and also balances the individual cell voltages so they are all the same. This balancing is usually done when the pack is fully charged - it "bleeds" current from slightly overcharged cells to bring them back down to the same voltage as all the rest. The iCharger's default cutoff voltage for lithium ion cells is 4.1V per cell (therefore 41V for the whole battery pack) which is actually better for looking after the cells, but it's not high enough to allow the BMS to start balancing the cells in your pack. Therefore you would need to adjust the cutoff voltage on the charger to 4.2V per cell to allow it to fully charge the pack and for the BMS to do its balancing. Very easy to do. Or indeed just use the LiPo charging programme rather than the LiIo as it is already set to cut off at 4.2V on LiPo charging. One other thing - the BMS in the battery might well not like you trying to charge at 8 amps! The charger that comes with the bike only charges at 2 amps, so maybe set the charger to use this current or just a bit higher. The charger remembers all these settings so once you've set them you never need to worry about them again. Michael
March 10, 201511 yr That's right. Stick to the same charging current that's written on the charger that came with your battery.
March 10, 201511 yr Author That battery looks eminently suitable for charging with something like the iCharger. The only issues will be what sort of connector you would need on the end of the charging lead, and whether they use any sort of "smart" charging (monitoring temperature for example) which I doubt. I had asked the dealer how the charger was connected to the battery he says it can be charged on or off bike with a simple plug in connector if that's any help Peter
March 10, 201511 yr Author I contactedthe dealer he told me the battery can be charged on or off the bike with a simple plug in connection Peter
March 10, 201511 yr Sounds like you won't have any problem at all then. You will just need to knock up a lead with the same charger plug on one end and two 4mm banana plugs on the other end to plug into the charger.
March 11, 201511 yr Author Sounds like you won't have any problem at all then. You will just need to knock up a lead with the same charger plug on one end and two 4mm banana plugs on the other end to plug into the charger. Ok Michael, I downloaded the 1010+ user manual and it looks a bit daunting but I suppose I can work it out. Just as a matter of interest whats the bits and bobs attached to the side of the gizmo on the multi stranded lead. And when they mention power supply presumably the Van battery does that? Just off subject does it matter how long the leads are from the charger to the bike battery (voltage drop etc), as it would be handy to charge the bikes outside the small van if possible but no big problem if not Peter
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