Cattwg Posted February 14, 2020 Share Posted February 14, 2020 There is a thread running where welted says he ran an inverter directly from the vehicle battery. We are about to purchase two e-bikes. We do not use campsites every night and I am looking for the best way to recharge the bike batteries. We do have a solar panel but not a large bank of batteries and the fridge is the compressor type so it’s 12v’s hungry when we are parked. Hence, I am interested in welted’s approach to running an inverter directly from the vehicle battery as a means of charging the bike batteries. In our case this would only be when the engine is running i.e. when driving. I would want to charge both bike batteries simultaneously. Welted seems to have been OK with his set-up but I wondered if the type of alternator fitted to the vehicle was significant. Our vehicle is a 2.3, 2018, Fiat Ducato with whatever alternator came as standard, as far as I know.. I would appreciate knowledgeable opinions. I’ve posted this separate thread so as not to highjack StuartO’s current thread. Cattwg :-D Link to comment Share on other sites More sharing options...
spirou Posted February 14, 2020 Share Posted February 14, 2020 I wired mine to leisure batteries for space issues etc. As I only/mostly use the inverter while driving and it's only 250W, and the wires between batteries are substantial enough for much larger loads, I don't worry about it. I don't have ebike chargers to know for sure, but I imagine they're not that terribly power hungry. 200W maybe? Anyone know what is typical? Link to comment Share on other sites More sharing options...
colin Posted February 14, 2020 Share Posted February 14, 2020 A typical bike charger will take around 90w, so two will be around 180w, but they do take several hours to charge a bike battery if it's been left to go quite flat. It's best to charge then little and often, this might not fit in around your driving. Link to comment Share on other sites More sharing options...
Alanb Posted February 14, 2020 Share Posted February 14, 2020 In a previous thread, the late Allan Evans mentioned that his associate Martin? was developing a 12V bike charger. I do not know if this endeavour was successful, but as it would eliminate the losses in the inverter, it could be worth enquiring. I do not own an ebike, but I would expect that the chargers would be switch mode devices. These devices draw current in large peaks over small sections of a sinusoidal wave form. Your inverter may not like this. To take a cautious approach consider a generously sized inverter. As regards the alternator fitted to you 2.3JTD, I doubt that it would be of lower rating than, the 90A unit fitted to my x244 2.8JTD. Alan Link to comment Share on other sites More sharing options...
colin Posted February 14, 2020 Share Posted February 14, 2020 Unfortunately Martins charger doesn't cater for one of the most common batteries, i.e. Bosch otherwise I would have had one. If you have another type of battery, or at least one that doesn't use the Bosch plug might be worth giving him a ring. Link to comment Share on other sites More sharing options...
paul2 Posted February 14, 2020 Share Posted February 14, 2020 Hi Martin sent me some information about his charger it was about £80, there where some photos but the plugs never looked like mine. I emailed Martin with photos of my battery and asked if the plugs would fit my ebike battery but never received a reply so I left it. (This email was probably at bad time or knowing me I messed up) Paul Link to comment Share on other sites More sharing options...
paul2 Posted February 14, 2020 Share Posted February 14, 2020 colin - 2020-02-14 4:28 PM Unfortunately Martins charger doesn't cater for one of the most common batteries, i.e. Bosch otherwise I would have had one. If you have another type of battery, or at least one that doesn't use the Bosch plug might be worth giving him a ring. My battery is a Bosch! Paul Link to comment Share on other sites More sharing options...
Cattwg Posted February 15, 2020 Author Share Posted February 15, 2020 colin - 2020-02-14 1:58 PM A typical bike charger will take around 90w, so two will be around 180w, but they do take several hours to charge a bike battery if it's been left to go quite flat. It's best to charge then little and often, this might not fit in around your driving. Thank you to all who replied to my query. No one has come back to say that it’s a bad idea in principle. My real concern was a possible problem with the so-called smart alternators fitted to some vehicles. Hi Colin, I thought that two chargers would take about 180w, so I’m thinking a pure sine wave inverter of 400w should be adequate. When touring we usually drive for about 2 or 3 hours a day so this would fall in with “charge little and often”? John :-D Link to comment Share on other sites More sharing options...
John52 Posted February 16, 2020 Share Posted February 16, 2020 Cattwg - 2020-02-15 11:09 AM My real concern was a possible problem with the so-called smart alternators fitted to some vehicles Manufacturers handbooks advise against it because it shortens the life of the alternator. But that may be a price you are prepared to pay. Whats the van for? - using it at all wears it out and shortens its life Link to comment Share on other sites More sharing options...
phalange Posted February 16, 2020 Share Posted February 16, 2020 When I bought my e bike I asked the shop about charging them from an inverter and he advised at least a 600 watt inverter. Link to comment Share on other sites More sharing options...
colin Posted February 16, 2020 Share Posted February 16, 2020 Cattwg - 2020-02-15 11:09 AM colin - 2020-02-14 1:58 PM A typical bike charger will take around 90w, so two will be around 180w, but they do take several hours to charge a bike battery if it's been left to go quite flat. It's best to charge then little and often, this might not fit in around your driving. Thank you to all who replied to my query. No one has come back to say that it’s a bad idea in principle. My real concern was a possible problem with the so-called smart alternators fitted to some vehicles. Hi Colin, I thought that two chargers would take about 180w, so I’m thinking a pure sine wave inverter of 400w should be adequate. When touring we usually drive for about 2 or 3 hours a day so this would fall in with “charge little and often”? John :-D We have a cheapo 300w Aldi invertor, but only charge one bike at a time. Ours is fed off the leisure batteries, but with a 3 way fridge and no other big power users we have spare capacity to allow this. With a pure sine wave you will have the option of charging a electric toothbrush. Link to comment Share on other sites More sharing options...
bolero boy Posted February 16, 2020 Share Posted February 16, 2020 i have a 500w quasi sine inverter t charge my bike battery...generally, one at a time and little and often... with a 12v charger taking 11ah out of our 184ah battery bank doesnt seem like an issue, however it doesnt work like this with a 230v unit, taking out far more, doesnt it....? Link to comment Share on other sites More sharing options...
John52 Posted February 17, 2020 Share Posted February 17, 2020 bolero boy - 2020-02-16 4:51 PM i have a 500w quasi sine inverter t charge my bike battery...generally, one at a time and little and often... with a 12v charger taking 11ah out of our 184ah battery bank doesnt seem like an issue, however it doesnt work like this with a 230v unit, taking out far more, doesnt it....? You have to put substantially more into both the battery and the inverter, than you get out of them. Link to comment Share on other sites More sharing options...
weldted Posted February 17, 2020 Share Posted February 17, 2020 We ran our inverter from the engine battery, ours was a 2012 boxer so did not have a smart alternator. We fitted the inverter under the passenger seat to keep the cables run short. As a rule. Of thumb expect to get at best 50 amps from a 100 amp leisure lead acid battery in new condition fully charged. Do not run flat damage and a shorter life will follow. You will use 28 amps @ 12 volt d.c. to produce 1 amp @ 240 volt a.c. Allowing for inverter inefficiency and voltage drop. Link to comment Share on other sites More sharing options...
bolero boy Posted February 18, 2020 Share Posted February 18, 2020 John52 - 2020-02-17 12:10 PM bolero boy - 2020-02-16 4:51 PM i have a 500w quasi sine inverter t charge my bike battery...generally, one at a time and little and often... with a 12v charger taking 11ah out of our 184ah battery bank doesnt seem like an issue, however it doesnt work like this with a 230v unit, taking out far more, doesnt it....? You have to put substantially more into both the battery and the inverter, than you get out of them. i was referring to the case (if this is correct) that to deliver 1 AH via 230v from an inverted 12v source it needed 230/12 times the supply.....ie 19'AH... if this is the case then 11ah for the bike battery will take 210ah from my 184ah battery bank! ah yes, with inefficiencies even more, as W says....ouch! that 12v charger will presumably charge on a one for one basis...roughly? Link to comment Share on other sites More sharing options...
colin Posted February 18, 2020 Share Posted February 18, 2020 bolero boy - 2020-02-18 11:03 AM John52 - 2020-02-17 12:10 PM bolero boy - 2020-02-16 4:51 PM i have a 500w quasi sine inverter t charge my bike battery...generally, one at a time and little and often... with a 12v charger taking 11ah out of our 184ah battery bank doesnt seem like an issue, however it doesnt work like this with a 230v unit, taking out far more, doesnt it....? You have to put substantially more into both the battery and the inverter, than you get out of them. i was referring to the case (if this is correct) that to deliver 1 AH via 230v from an inverted 12v source it needed 230/12 times the supply.....ie 19'AH... if this is the case then 11ah for the bike battery will take 210ah from my 184ah battery bank! ah yes, with inefficiencies even more, as W says....ouch! that 12v charger will presumably charge on a one for one basis...roughly? Your 11Ah bike battery will most likely be 24v or 36v, as a straight conversion from 12v this will take a maximum of 22Ah or 33Ah plus a bit for losses Link to comment Share on other sites More sharing options...
bolero boy Posted February 18, 2020 Share Posted February 18, 2020 colin - 2020-02-18 11:21 AM bolero boy - 2020-02-18 11:03 AM John52 - 2020-02-17 12:10 PM bolero boy - 2020-02-16 4:51 PM i have a 500w quasi sine inverter t charge my bike battery...generally, one at a time and little and often... with a 12v charger taking 11ah out of our 184ah battery bank doesnt seem like an issue, however it doesnt work like this with a 230v unit, taking out far more, doesnt it....? You have to put substantially more into both the battery and the inverter, than you get out of them. good point, its 36v, thanks. i was referring to the case (if this is correct) that to deliver 1 AH via 230v from an inverted 12v source it needed 230/12 times the supply.....ie 19'AH... if this is the case then 11ah for the bike battery will take 210ah from my 184ah battery bank! ah yes, with inefficiencies even more, as W says....ouch! that 12v charger will presumably charge on a one for one basis...roughly? Your 11Ah bike battery will most likely be 24v or 36v, as a straight conversion from 12v this will take a maximum of 22Ah or 33Ah plus a bit for losses Link to comment Share on other sites More sharing options...
Brian Kirby Posted February 18, 2020 Share Posted February 18, 2020 I think you are accumulating quite a potential load, and I also think it would be wise to evaluate that load and assess whether the alternator can service it. On starting, the alternator will have a possibly depleted leisure battery to re-charge, the starter battery to top up, the compressor fridge to run, the inverter to run to re-charge the bikes, plus possibly vehicle lights, wipers, heater/demister, and the radio. It seems at least possible that combination will exceed the design limitations of the alternator, especially as these demands seem likely to be maintained for extended periods. The further risk is that you may forget to disconnect the alternator when you stop, so flattening the starter battery. I would therefore think it wise to feed the inverter via a relay, so that it only "sees" current when the engine is, actually, running. You would of course then need to plug the bike battery chargers into a 240V socket whenever on mains hook-up, to be able to charge them. Link to comment Share on other sites More sharing options...
Cattwg Posted February 20, 2020 Author Share Posted February 20, 2020 We went to the Show at the NEC today. I spoke at length to a chap on the RoadPro stand and also to Iain Geddes a technical adviser with the C&CC. They confirmed my own thoughts that a 400w pure sign wave inverter would be adequate to charge two e-bike batteries, assuming up to 90 watts per charger. Interestingly Iain Geddes said that the Ducato alternator had an output of 150 amps. Cattwg :-D Link to comment Share on other sites More sharing options...
Billggski Posted February 20, 2020 Share Posted February 20, 2020 12v dc > 240ac > 36v dc sounds a bit convoluted. I manage to top up when on hookup, but only one bike. Link to comment Share on other sites More sharing options...
thebishbus Posted February 21, 2020 Share Posted February 21, 2020 42 volts would be the charger voltage.Anyone know of a switch mode charger ,12 volts to 42 volts ? BrianB. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted February 21, 2020 Share Posted February 21, 2020 Inexpensive DC-DC devices are marketed to convert a 12V input to 36V output (or 12V input to 48V ouput) For example (but note the buyer ratings) https://www.amazon.co.uk/DROK-Waterproof-Converter-Step-up-Regulator/dp/B018S664QG Link to comment Share on other sites More sharing options...
Billggski Posted February 21, 2020 Share Posted February 21, 2020 https://www.simplypowersupply.com/DC-DC-Converter/DDH150A48-Chassis-Mount-DCDC-Converter-12Vdc-to-48Vdc-312A.aspx You get what you pay for with Cheap Chinese kit! Link to comment Share on other sites More sharing options...
weldted Posted February 21, 2020 Share Posted February 21, 2020 I previously posted how I set up our van to be able to run the inverter from the engine battery. On our Elddis the hook up socket was recessed in a battery locker which allowed me to run a cable from the inverter into the hook up socket. I had to fit the second battery remotely aS THE LOCKER IS TOO SMALL FOR TWO.This allowed me to use the vans own 240 sockets whilst on the move. As a rule of thumb I would not switch the inverter on as soon as I started the engine but wait till the temp gauge had moved up to normal, by this time the starter battery would have recovered some of the current used for starting or any inverter supply used prior. Our van although the Boxer 2.2 engine I had fitted the larger 3 litre battery. The last leisure batteries were two Yuasa EFB L36 100 amp. We had 300 watts of solar which helped. We changed our batteries every three years as we passed them on to an animal sanctuary so never had any fail. This system was in use from when we first got the van until we sold it last year. One has to sensible and not run the batteries too low or expect to have household power on tap but with sensible use found this set up to be reliable. Make sure any wiring can cope with the current you may draw, check terminals are tight and clean Link to comment Share on other sites More sharing options...
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