ColinM50 Posted December 11, 2017 Share Posted December 11, 2017 When we sold our caravan in early 2015 and bought a motorhome, I took out the then new caravan battery and put the old one on instead and I'm wondering if I could add the spare second battery to the m/h. The m/h, an Eldiss Autoquest, has a Yuasa 110Ah battery and my spare is marked as Giant Leisure 110Ah. It's been sat in the garage now for 21/2 years and the charge indicator is still in the green so I'm guessing it's a good 'un. If I give it a boost top up charge can I just fit it in parallel with the m/h battery? There's space inside the m/h to fit it next to the existing battery with very short leads so easy to do too There's no particular reason to use it, I've not so far had any shortage of power but we do tend to stay mainly on sites with EHU with the occasional night or two on Aires and as I say we've not noticed a problem with low voltage. What's the perceived wisdom? Should I use it or not? Link to comment Share on other sites More sharing options...
colin Posted December 11, 2017 Share Posted December 11, 2017 Aside from any technical reason, if you don't need it why carry it around? Link to comment Share on other sites More sharing options...
PJay Posted December 11, 2017 Share Posted December 11, 2017 Agree with Colin Why add additional weight , if you don't need it. We have only ever had 1 battery in 11 years , as as we also go in campsites use EHU. Being an ex caravanner, have you checked your weight , with van full? PJay Link to comment Share on other sites More sharing options...
lennyhb Posted December 11, 2017 Share Posted December 11, 2017 If you have the payload why not you can never have enough power. Your usage might change as you can be more flexible with more power available. If both batteries are of the same age they should be OK together but it would be better to fit 2 new batteries. I've got 3 batteries in my van, works for us but we don't use EHU. Link to comment Share on other sites More sharing options...
BruceM Posted December 11, 2017 Share Posted December 11, 2017 If the battery’s been left uncharged for two and a half years I’d have expected it to be a dead battery so I’d question the reliability of the battery’s ‘magic eye’. Maybe rock the battery a bit in case the eye is stuck. Also bear in mind that it indicates the specific gravity of only one of the battery’s cells and not the whole battery. That aside, firstly, like other responders, I’d question whether you need an additional battery if you are always on EHU and secondly, I think you need to asses whether the habitation electronics can handle the charging of two batteries (220Ah). I reduced my battery size from 2 x 110Ah to 2 x 95Ah for that very reason. We prefer to be off EHU hence the dual batteries. If you do fit the battery, fitting in parallel is correct. Link to comment Share on other sites More sharing options...
lennyhb Posted December 11, 2017 Share Posted December 11, 2017 BruceM - 2017-12-11 11:25 AM If the battery’s been left uncharged for two and a half years I’d have expected it to be a dead battery so I’d question the reliability of the battery’s ‘magic eye’. Maybe rock the battery a bit in case the eye is stuck. Also bear in mind that it indicates the specific gravity of only one of the battery’s cells and not the whole battery. Agree if it has not been charged every couple of months it's a bin job. Link to comment Share on other sites More sharing options...
aandncaravan Posted December 11, 2017 Share Posted December 11, 2017 Even if the Yuasa and the 'Giant' were new they would be poorly matched as a pair connected together. The Yuasa is a high quality battery with a slow degradation rate, yet the Giant is a very poor quality battery, we have cut open several, with much more rapid degradation. The technology and quality of construction is different, I would be surprised if two such different batteries didn't have a variation in voltage either. I would expect the Giant to be up to 0.25v volt lower than the Yuasa when resting at the same charge level? Maybe as much as 0.5v? So they probably wouldn't work well if paired when new, at 2.5 years old if you joined them you will probably find the Yuasa does all the work and the Giant just 'runs it down'. Most likely shortening the life of the Yuasa by a big margin. Joined batteries should be the same size, technology, age and ideally the same make. All manufactured within 6 months of each other according to one battery manufacturer. The battery charging systems in the Autoquest isn't the most robust and it can work quite hard with only one battery, 2 x 110Ah would be quite a load. . Link to comment Share on other sites More sharing options...
rogher Posted December 12, 2017 Share Posted December 12, 2017 Keep the second battery as a spare. Charge it up[ from time too time. it may not be much good now but, when the current battery has failed, it might be a useful swap (you'll soon find out). You wouldn't (shouldn't) mix batteries in a torch, so don't in your moho. If you think you need extra capacity, you will need to discard the old batteries and get two new identical ones. When changing batteries, make sure that the charger is set to the battery technology you are installing (Wet/AGM/Gel). Link to comment Share on other sites More sharing options...
Tracker Posted December 12, 2017 Share Posted December 12, 2017 Battery isolation switches are inexpensive and if there is space my inclination might be to wire the second battery in parallel with the first using heavy duty starter cables and fit battery isolation switch clamps on both battery's positive terminals. If you then isolate each battery in turn so that at no time are they both used together you could have both kept charged and both ready for use without one harming the other. Alternatively if you like the van and intend to keep it why not just buy two Bosch / Varta new batteries, fit them both together and forget it - no faff - nothing too complicated - just plenty of battery capacity with no hassle! Always assuming your alternator can handle the extra charging if both get low? Link to comment Share on other sites More sharing options...
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