New owner (and new to forum). Just learned today of maintenance-free, dry cell AGM 31DC 12v batteries for $216.50/each and I’m looking for anyone who has experience with such. Have to admit that the maintenance-free is a big draw since I haven’t had to perform monthly battery maintenance since my motorcycling days back in the 90’s.
If not these, what is the latest recommendation for battery replacements?
Thanks in advance!
Without specific brand/model information it will be impossible to get a really accurate answer in my opinion.
I can tell you that I’m running with Exide Nautilus marine deep cycle flooded batteries and am OK with the regular maintenance. I weighed the difference in cost between flooded cell and AGM along with the purported issues with AGM batteries in EV usage and decided to take the less expensive, safer, more proven technology route. Although I know it’ll be a major pain in the rear to check and add water to 36 individual cells, it cost a LOT less to go this route.
I may look into a central watering system for the GEM to make my life easier and care for the battery pack more convenient. The critical cost per mile equation is greatly influenced by the longevity of the battery pack. Proper care will extend its life and poor care, severely shorten it.
Thanks Bob. Cost and convenience - what a balance.
I will really be interested to hear more about a central watering system - can’t even imagine how that would work or even look like without 36 hoses snaking all over the place.
Bottomline: I need to get a tester and some distilled water and get to work.
I have had my GEM for about 5 years and have tried all sorts of batteries. The last set were marine wet batteries and they were terrible. One thing to remember is that there is no free lunch. If the batteries you purchase do not have the heavy duty lead plates in them they will not give you any range. They will perform up front but as they loose their charge they will just stop at a much higher discharge charge level than a deep cycle made for long use battery will. The marine batteries that I bought a year and a half ago were just like that. They would just stop at about 75% charge because they had no energy left. I put in Trojan 1275’s and they will discharge down to the 40% range and still go. Also the Trojan dealer told me that just the weight of the battery alone tells you how much lead there is in it an if it doesn’t weigh at least 80 pounds then it is a light weight. I had to pay a $30 core charge for each of the marine batteries I traded in because of their weight. Obviously there are many different makes of marine batteries but the lead in them is what counts. I agree about the GEL battery and their cost. There is about a $100 per battery premium just to not have to check the battery water levels. At about $600 in my pocket I can check the water level each month. If money is no object then go for the battery that you think will be the best match for yo but make sure you are comparing apples to apples when you do your research. I have read and seen pictures of the auto watering system and they work on the same principal that the old fashioned battery watering jugs work. The spout that goes down into the neck of the battery has a natural fill level and once the water level reaches that point the water flow is terminated. As to their reliability I cannot vouch for. Make sure you get the core rebate they offer before you have them install the new batteries like I did. The dealer told me he was sorry but that his supplier told him that lighter batteries do not have enough stuff in them to get the full rebate on.
Glad I checked this forum out… and saw the most recent question matched my own.
Looking at two separate cars. An e82 and e84. The two seater is a 2007 and the four seater is a 2002.
Are the electronics in the stock versions of both of these models standard across the board? Meaning, whatever battery I chose, I could use it in either model? I see all the talk about deep cycle, wet vs dry… is there an optimum battery for these cars? I’ve been wanting one for a long time and decided to buy one that needed some TLC so I could learn the inner workings of the GEM prior to really putting some money into one…
…any suggestions on where to start with the batteries?
Also.
If I’m planning on upgrading the motor and speed controller, does the type of battery at that point matter? Would like to see 35+ mph out of either of these.
Thanks guys.
They’re all 72 volts after 1996 model year I think. Some of the most recent ones had an option of 9 8-volt batteries instead of the 6 12-volt ones for higher capacity.
The internal electronics are different between 2000-2005 and the 2006+ models. The newer style suspension of the 2006+ moved the two front batteries to the rear but otherwise the number and size of batteries stays the same till the optional 8-volt ones came into play on the bigger ones like the eL XD. The 12 volt converter was originally a separate board from the vehicle logic/signal conditioning board and then changed to a combined unit in 2001 or 2002 I think. When the batteries moved out from under the hood in 2006 GEM put in a separate DC converter again and combined the fuse-panel with the vehicle logic and put all the black boxes under the hood.
By the way, till late in the 2000’s (2006+ I think) they were all marketed as E825. GEM didn’t start marking the models (e2, e4, e6, eS, eL, eLXD) until the later models.
It’s hard to tell what’s what without a score-card on these things. There’s a few clues though and you’ll begin to realize the differences when you’ve seen a few across the years. I’d go for a 2006+ model for its more advanced suspension and newer electronics which mean it’ll be more reliable with its years-newer electronics inside.
The stock motor won’t get you 35 MPH without major programming and wheel-size changes and probably only on the e2 or eS. The longer/heavier ones had a different gear ratio and weren’t built for speed (or comfort, apparently). I love my 2002 eL but would trade it in a second for a 2006+ eS or e2/e4.
I have an option to purchase a 2007 (3400 miles) for $1600 bucks. Brand new batteries too. Few things are wrong with it. Windshield is cracked. Wiper doesn’t work. Horn is pretty much dead. Hit 26mph on it on a level surface with stock rims.
And on the other hand, there is one locally that I have NOT gotten to drive that needs batteries (it’s an 02’, but a four seater)… so I don’t know. Same price as the 07’.
I can’t find a windshield local to me for the life of me… and the insurance wont cover it since it’s a motorcycle policy (if I were to buy it).
I’d LOVE to have a four seater with a 7+ HP motor, lift and larger tires…
…but the two seater with lower profile rims/tires, with a new paint job would look very slick.
Pretty torn.
Obviously it’s ones opinion… but after listening to my schpeel… what would your consensus be?
And speaking of gears, is that something people get into? Changing the gear ratios?
I can imagine an upgraded speed controller with larger motor hitting 35mph… but could you decrease the gear ratio to gain any more speed?
With a lift and large tires, I could see the vehicle being top heavy and less controllable… with a lower profile setup… I could justify being able to hit 40mph.
I wish there was a more centralized place to see options. It’s hard trying to piece together opinions, fact, specifications from multiple sites.
[QUOTE=Clider;15544]I have an option to purchase a 2007 (3400 miles) for $1600 bucks. Brand new batteries too. Few things are wrong with it. Windshield is cracked. Wiper doesn’t work. Horn is pretty much dead. Hit 26mph on it on a level surface with stock rims. [/quote]Windshield is available from Polaris but is a bit pricey with the new trim etc. Wiper is probably either a bad switch, bad thermal circuit-breaker or bad motor. All easy to troubleshoot and not ‘too’ expensive to fix’
And on the other hand, there is one locally that I have NOT gotten to drive that needs batteries (it’s an 02’, but a four seater)… so I don’t know. Same price as the 07’.
New batteries will add at least $1000 to $1500 to the cost and the '02 ride is very rough compared to the '07. DC converters fail regularly on the 2002 vintage and cost over $300. You do the math.I can’t find a windshield local to me for the life of me… and the insurance wont cover it since it’s a motorcycle policy (if I were to buy it).
I’d LOVE to have a four seater with a 7+ HP motor, lift and larger tires…
…but the two seater with lower profile rims/tires, with a new paint job would look very slick.
Pretty torn.
Obviously it’s ones opinion… but after listening to my schpeel… what would your consensus be?
Personally, I’d get the '07 and pay the price for the new windshield, wiper repair, horn etc. You’ll get a more modern suspension and more reliable electronics. It’s not as easy to reprogram for higher speed though.
I used to race R/C cars when I was younger… real ones. So I’m more familiar with electric motors, speed controllers, voltage, etc… than most. But in regards to jumping head first into this project, I’m at a loss. Is there something I can read up on regarding the reprogramming? Do I need a new controller/CPU?
Thanks for all the quick replies tho Bob!
My 2002 has a GE 353T2 controller which is easily reprogrammed through the 12-pin serial port that runs the speedometer. You need the GE Sentinel software and the cable connected to a PC’s serial port. The documentation on the controller gives you a pretty good idea as to what to change but essentially it consists of raising the speed limit, reducing the field current for more motor speed and adjusting the acceleration curve and knee-over points plus the regen current for your particular needs.
More speed (within limits) is available from the stock motor/gearing/wheels but you’ll really want a bigger motor with more speed capability for much higher than 30 MPH. It’s not rocket science but there is some algebra involved…
Who doesn’t love math? 
I’ll do some searching on here to see if there are motors for sale and what’s involved.
Thanks again.