 | Home > Technical > [Electronic Engineer: Mode On] Advise for Dual Battery Sys |
 
|
|
|
| davew Member Since: 02 Jan 2012 Location: North Yorkshire Posts: 888   
|
You should be able to get Odyssey batteries, I'm not a fan of Optima, the first ones (when they were made in the original plant) were really good but every one I've bought that was made in the last 10 years has been disappointing, refusing to take a charge after a single discharge. By comparison the Odyssey's I've replaced them with have survived multiple complete discharges and still take a charge.
I made my own split battery system for our trip around Australia, it works really well and has a dash mounted LCD display that shows simultaneous voltage for both batteries. Simple enough to do with a PIC, a relay and a solenoid. A simple off-on-on switch allows the batteries to be disconnected, auto connected when the engine is running (main battery > 13v) and always connected (jump start the main battery or in case the auto system fails). For overland I'm not a fan of inverters, they waste a lot of power, especially when many devices simply convert the mains voltage back to DC again ! For less than the cost of a decent inverter I managed to buy 12v power supplies for every device we take with us. If it can't be powered from 12v, do you really need it ? Most people take far too much stuff with them on overland trips and there's no point in adding features (mains power) that might encourage more rubbish !  http://www.yorkshireoffroadclub.net/ |
||
5th Jan 2016 11:54pm |
|
| Peter Td4 Member Since: 23 Oct 2010 Location: Antwerp, Belgium Posts: 227  
|
Hi Dave,
I believe what is shown here as an inverter should be read as a battery charger when connected to the mains grid. All connections are running directly from the 12V battery the way I understand it. @ DEF_Jam, My split battery system uses an "intelligent" voltage relais between both batteries, offering the possibility for manual override in case of starting troubles on the main battery. Simple yet effective. I also use a Battery Monitor. BMV-600 from Victron. https://www.victronenergy.com/battery-monitors/bmv-700 Meanwhile has been replaced by a 700 series. Overall this seems like a good set-up. My points of advise: 1) Make sure you have a decent ground or DC-return. Don't use the vehicles body nor chassis. 2) Use cables with sufficient mm². 3) Use decent connectors for your 12V outlets. Don't use standard 12V car sockets as these tend to be unreliable, especially when handling larger current. Make sure you use a type that has a locking feature, to prevent the connection from getting loose due to vibration. Alternatively, you might consider to use Power Pole connectors. These exist also in smaller versions which are still capable of reliably handling larger currents. Peter, Defender 110 StaWa - Td5 Defender 110 HCPU - Puma Defender 90 Soft Top - Td5 |
||
|
6th Jan 2016 7:39am |
|
| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8580 
|
I agree with Davew. The Optima 1500 is a combined starter leisure battery and it is a good idea to have your second battery as a combined starter leisure battery.
Reason being if you discharge the main battery you can start the engine off the second battery. A leisure battery will probably not like starting a Diesel engine. Odyssey batteries are approved for air transport so can readily be transported by lorry or air. Hence if you can not find them local to you they can readily be shipped to you. Brendan |
||
|
6th Jan 2016 7:44am |
|
| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59  
|
Yes Peter, you are correct.
The CTECK it's a battery charger connected to the 220v socket on one side and to the batteries on the other side. The other blue thing it's a power stripe where I can conncet the fridge when I'm in a camping. About the ground or DC-return you are telling me a brand new thing. What's your suggestions? And also what's a Power Pole connector? Are the better than a looked connection? Brendan you meant the Odyssey 1500 as Dave said. What's the price in England at the moment? I found two Odyssey Batteries Extreme Series Battery 34/78-PC1500DT (seems like there are different types of 1500?) for €638,00 (more or less £467,00) shipping cost included. I will need a fuse box as well right? Who knows which one will fit under the Defender driver seat with the two batteries and cables? |
||
|
6th Jan 2016 8:50am |
|
| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8580
|
Hi Jam, Ooops
 yes a typo on my part I meant Odyssey.
PC1500 DT are between £225-£250 each in the UK at the moment, so you are looking at £450 -£500 for a pair plus carriage. would suggest by the time you factor in exchange rate, bank/paypal fees, transport costs you are better off with the 638 euro price. Yes there are different PC1500 dependent on battery terminal configuration, i.e. positive on left or right. DT is double terminal, two standard stud terminal + 2 screw in terminals. Please note these are imperial not metric threads so do not lose the spare bolts which comes with battery Brendan |
||
|
6th Jan 2016 2:45pm |
|
| Peter Td4 Member Since: 23 Oct 2010 Location: Antwerp, Belgium Posts: 227
|
Use cable for both the + and - connections. Don't just connect the - to the metalwork of the car. So run red and black cable everywhere you want to have a connector.
I'm not sure what you want to use now ? Can you be more specific to what you have in mind ?
I would advise to use Blue Sea fuseboxes. 
Excellent quality, splash proof and has connections for both + and - distribution  Peter,
Defender 110 StaWa - Td5 Defender 110 HCPU - Puma Defender 90 Soft Top - Td5 |
||
|
6th Jan 2016 4:38pm |
|
| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971 
|
You don't *have* to use Odyssey batteries - they do have good cranking amp ratings but they are relatively low on overall capacity. Other batteries come in at half the price.
I've got the stock Varta battery in mine, and tend to buy Varta batteries for work (because they're good and that's what the local auto electrical place does). Other people like Exide batteries and Bosch batteries get some good reviews too. If you've got a helpful auto electrical shop near you it might pay to go and have a word with them - Odyssey batteries are good but they're not the be all and end all and you can fit pairs of physically bigger batteries in the box. When I've been considering batteries I've thought about Odysseys but the relatively low capacity and the price push me away from them. Personally I'd be happier buying a couple of any of the other batteries I've mentioned and spending the saving on doing some miles. |
||
|
6th Jan 2016 5:38pm |
|
| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
|
Thank you Peter I got you!
Will you suggest a 12 or a 6 Fuses box. Do you have a picture where I can see how they fit? I found this and I'm wondering if will do a better job then a Blue Sea 7601 Dc Min Automatic Charging Relay 65A which is the one below |
||
|
8th Jan 2016 9:07pm |
|
| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8580
|
I would suggest a 12 gang with negative bus bar. The Blue Sea one is good because it is relatively shallow.
Blue Sea also do a split 12 gang version where 6 fuses are permanently live and 6 are only live when ignition is on. Worth considering. Choice of batteries? Do not get hung up on battery capacity. If you are going overland/camping you need two good combined starter leisure batteries which the Odyssey 1500 are. Second battery definitely needs to be capable of starting your engine if need be. Many split charge systems out there. Just remember that Defenders are not that electronically sensitive as some modern cars. The split charge system needs to be able to put both batteries in parallel for starting and if need be winch duties. A good split charge system is the IBS system from Switzerland. If I remember correctly the software on the latest IBS system is version/hardware version 8. Well worth considering. Brendan |
||
|
8th Jan 2016 11:22pm |
|
| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
|
I agree with the "you need two good combined starter leisure batteries", but you seem to be implying that the standard Defender batteries *aren't* good combined starter/leisure batteries, which is exactly what they are. The PC1500s are great batteries, no doubt about it particularly where you want maximum cranking amps for minimal size and weight. I also actually think you *should* get hung up on battery capacity, but go in with your eyes open. I've just spent about an hour writing, researching and re-writing this post, which is slightly embarrassing when I think about it. The reasoning is as follows... Most batteries don't like being discharged much beyond 50% DoD. You can do it, but they don't like it. That means that on conventional logic, my choice of battery and the PC1500 will both do your fridge and lighting for one night, but the PC1500 will struggle if you're camped up for two nights. However... if we look at a Varta LA95, it's a combined starter/leisure AGM battery. Its specs are: 95Ah, 850A, 26 kg, 353x175x190mm (normal Defender dimensions). It's rated at 400 cycles to 50% DoD and they're about £150 - although they do a start/stop rated battery with exactly the same specs and blurb but less fancy packaging for less money. Hmm. The PC1500 at about £250 is 276x172x199mm and 22.4kg - so overall a bit smaller - 68Ah, 850A but here's the interesting bit, it's rated to 400 cycles to 80% DoD. As it happens, 0.8*68 is 54.4Ah usable capacity, and 0.5*95 is 47.5Ah usable capacity. So yes, interesting, the larger capacity battery has a lower usable capacity. Cranking amps drop with SoC, particularly below 50% but I don't know how that tallies on the PC1500 because it's a bit odd. What about the main battery? Well I don't think I'm unusual in having an Ultragauge, split charge relay and tracker all permanently powered. They're about 20mA each according to their manufacturers - doesn't sound like much does it? 60mA*24 hours is nearly 1.5Ah per day. Leave that for a week and it's 10Ah you've just taken out of your battery. Cranking amps don't suffer too much with moderate drops in SoC but they do drop, particular once you've taken more than 1/4 out of the battery. Food for thought at least
http://www.aandncaravanservices.co.uk/battery-technology.php For reference, the standard size battery is a 019 and with a bit of wangling (that I haven't done but I know other people have) you can fit two in the box. Phew. BTW I'm still not going to be spending another £100 on an Odyssey, I've got much more fun things to do with my money  however I am now considering a few other electrical thoughts for my Defender! |
||
|
9th Jan 2016 12:50pm |
|
| Peter Td4 Member Since: 23 Oct 2010 Location: Antwerp, Belgium Posts: 227
|
Good post(s)
The only benefit that I see in those more expensive batteries is their ability to absorb a charge faster. Seldom this is discussed about, and not really important, expect in (extreme) winching situations - where such batteries as the Odyssey's and Optima's have earned their reputations. But for leisure use, there is no need at all to quickly absorb a huge charging current. What Brendan proposes on the Blue Sea fusebox with a 6+6 fuse (6 permanent live en 6 when ignition is on) really makes sense. This gives you the possibility to disable less important loads in case of low battery levels, or allow loads to be only switched on when e.g. on mains power. Many possibilities exist 
I like to use Cyrix-CT relays for the purpose of switching on (heavy) loads when the battery is being charged (either via the alternator or via mains charger). Click image to enlarge These relays work really well and are very easy to wire. https://www.victronenergy.com/battery-isol...-combiners Peter, Defender 110 StaWa - Td5 Defender 110 HCPU - Puma Defender 90 Soft Top - Td5 |
||
|
9th Jan 2016 1:45pm |
|
| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
|
Me again :/
In case you're wondering "why AGM batteries?": Pros: 1) Better for discharging. 400 cycles to 50% DoD instead of 200 for a standard flooded cell. 2) Safety. They can't dump a load of acid out if you turn them over. Most can be run on their side constantly. 3) Speed of charging, you can generally charge an AGM battery twice as fast as a flooded battery. 4) Maintenance free - you literally can't maintain some of them (the valve regulated ones that you can run on their side). 5) Generally they don't gas when you charge them unless you've done it wrong. If you have done it wrong, then you can't top them up. Cons: 1) Cost. They cost 50% more than a flooded battery. 2) Maintenance free - you let off any of the water and you can't top it up. 3) They need a higher charging voltage to properly top them off, which alternators typically don't do. For a Defender with a hard life they make sense. For a boring car they don't |
||
|
9th Jan 2016 2:03pm |
|
| DEF_Jam Member Since: 17 Jul 2011 Location: Milan Posts: 59
|
I like that Peter, Cyrix-CT looks way easier than IBS.
I would like to decide the manual connection of the batteries with a switch i case of emergency and I can see from your picture that it has an exit for it but, when I look at the product I can't figure out where it the connection. About the charger on the top right conrner (the blue one), is that the same of the C-Teck one. Basically, I can use it to charge the batteries while camping plugging in the 220v provided by the camping towet? |
||
|
9th Jan 2016 5:29pm |
|
| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8580
|
I am not sure that the standard LR battery can be described as a good combined starter/leisure battery. Not to the same extend as Odyssey batteries etc.
A PC 1500 will keep a good fridge going for two days. A good fridge will have an average current draw of about 0.8 amps/hr. A PC1500 with a useful 54 Amp/hr capacity will power a good fridge for 2.5 days. I have not tried this myself but I have heard stories about people drilling a small hole in an AGM battery and inserting some distilled water and rejuvenating the battery. Sealing the hole in the battery with some wax Brendan |
||
|
9th Jan 2016 8:23pm |
|
|
|
| All times are GMT |
< Previous Topic | Next Topic > |
Posting Rules
|
Site Copyright © 2006-2024 Futuranet Ltd & Martin Lewis
