If you have your heart dead-set on using 12V deep cycle PbSO4 batteries, though you have been told they will not last and you will be spending more $ sooner to replace them than if you used 8V, or better yet 6V traction/golf batteries, then stay away from 12V marine 'starting' batteries, and focus on 12V marine batteries. The 'starting' marine has a higher CCA (cranking amps) which means the plates are thinner and shorter life).
Over the years I have used different 12V deep cycle batteries, both in brand and in size/type. I now only use Sears Diehard 24M batteries http://www.sears.com/search=diehard%2024m?storeId=10153&catalogId=12605&viewItems=50&sLevel=0&levels=Automotive_Batteries_Marine+Batteries&vDropDown=defaultOpt&sLevel=0&redirectType=SKIP_LEVEL&prop17=diehard%2024m for my non-EV (UPS) power use These come in two versions: the standard 24M and the 24M M-2 that has a little more capacity at a little co$t. For me, they last the longest of all the 12V deep-cycle marine batteries I have bought (IMO a better bang for the buck). If I still had my Blazer (gone to EV-heaven), I would use a Diehard 24M as my 12V aux battery (with my 40A DC2DC set to 13.8VDC so it would never be overcharged or had too many finishing charges). Those are group 24 batteries which about the same size as what you are familiar seeing under the hood of your ice. I do not recommend you even think about the larger, heavier group 27, 29, 31 or larger size batteries, as from reading the thread on your project, this is your first pass at a conversion. Spending your money on batteries at this point on your steep-learning-curve, should be a balance between showing the project works (proof of concept if you will), and also having some useable cycle life before you have to drop even more money on a new pack. The group 24 size batteries are what the golf courses buy for their golf carts. These are usually the 6V golf cart batteries (similar to a Trojan T-105 in size and performance). But there are 8V batteries in a near group 24 size/packaging. 8V batteries lie between the 12V deep cycle everyone keeps saying not to get, and the 6V they are saying to design for. 8V have a shorter deep-cycle-life than 6V, but some times they are a good compromise for those willing to pay more $ for battery replacements. Group-24 6V batteries are sold to golf courses in large quantities, so prices can be lower for them. Whenever your battery type goes more exotic, the price goes up and its availability can go down. I recommend you go ask your local golf course maintenance-person what batteries they use and who they buy from, then focus on that battery. Hopefully their battery dealer/vendor will sell them to you at a good price even though you're ordering in comparatively small quantities. Buying from a source the golf courses use, gives you an opportunity for a better price/deal and fresher batteries. Buying a battery from here, and another from there, can result in a mix and mismatch of either different brands and or different manufacturing dates (old/stale batteries mixed with fresher ones). The goal is to have the best bang for the buck, so that is why people are telling you to go with the 6V batteries and to get all the same brand and fresh ones from a reliable battery source (the ones the golf courses use). BTW, since you are not exchanging dead cores/batteries on your order, you should scare up some dead ice starter batteries. Battery companies do not care if the brand/size of battery you are buying does not match what are turning in, they are after the lead. I have seen abandoned 12V ice batteries all over the place, and especially near your local auto parts stores. There are evdl members that have hands on experience on doing a conversion, whereas I have only seen the design work after my Blazer was converted, or the design of the Escort I had for a short while. I have done many a pack change, and have thought about how their battery rack design could have been done better for the driver's uses (add more flexibility for different batteries sizes). I suggest you measure out how much space you have to build battery racks, and leave your self some wiggle room for using different types of group 24 batteries (I am not recommending this brand or this seller, shown only as an example) http://www.ebay.com/itm/New-6-volt-6v-Interstate-Golf-Solar-RV-Marine-Battery-Batteries-GC2-RD-UTL-/121234029358?hash=item1c3a1c7b2e&vxp=mtr Note: scroll down that page and it gives the dimensions of the group-24 battery and its weight. Some 6V group-24 batteries can weigh from 67lbs or lower. The lower the weigh usually means less capacity (= less lead). But it can also mean a more robust battery (can take a newbies' mistakes/abuse better as it is not acid starved, the electrolyte to plate surface area ratio is higher). That page shows a lighter weight/lower cost 6V battery that fits that price/performance balance I mentioned. Later, on a pack change if your racks are designed for flexibility, you could opt to use different/larger Ah capacity batteries. On all the rack designs I have seen, they allow at least a ~1/2 inch between batteries. This is for battery expansion as they age (the sides swell outward). The hold down design the converter Solar Electric (now defunct) used on my Blazer were long heavy bars that locked me into only using one size battery (a T-105 to T-125). When I dropped a bundle of $ on some upgrades to my Blazer, converter Mike's Auto Care (now retired) changed the hold-downs to use flexible metal straps which would allow me to use from T-105 to the taller T-145 size 6V batteries. The Escort conversion used Clare Bell's method of a packing strap (strap+clips+tool) http://www.ebay.com/bhp/packaging-strap It was lightweight, easy to install, and easy to cut off for pack replacement. I recommend the 1" wide strap so as to distribute the hold-down pressure. Strapping a pack in place worked quite well for Clare when she was racing electrics (way-way back when). In your case, if the tractor was up-ended/flipped, the hold-downs/straps would secure the heavy batteries in place until you could right the tractor. Additionally, if there are spaces to place a battery but they would be exposed, you could use a plastic battery box like what trailers use https://www.google.com/#q=Battery+Box&tbm=shop (Corrections/comments on this welcome) {brucedp.150m.com} - On Wed, Jan 1, 2014, at 03:17 PM, Michael K Johnson wrote: ... > I had seen references on list to Interstate deep cycle batteries, and > thought that their marine deep cycle batteries were so; I was looking at > the SRM-27B. I used the information at > http://www.interstatebatteries.com/cs_eStore/content/product_info/marine_f.aspand > the calculator at > http://www.evdl.org/uve/battery.html to come up with a peukert exponent > of > 1.2565 and a 100A (worst case, I hope!) ~30 minute discharge time. > > Golf cart batteries are big. I'd have to figure out whether I could even > fit them on this platform. I don't think I could fit 8 6V golf cart > batteries. The 12V golf cart batteries I've seen are all too big to fit; > the group 27 size are a tight squeeze, and say a set of four Trojan > T-1260 > I don't think I can find a way to fit. 6 8V T875 would have more runtime > than I need and I haven't figured out how I would fit them either though > it's probably more likely to be possible. - -- http://www.fastmail.fm - A fast, anti-spam email service. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
