1988 Marathon on Lithium

[anthonywebb]

@fireboat, I am not sure where they were last time you checked, and I havent dont much checking lately. I bought 14 modules, and ended up breaking them up into 2 packs of 7 (one to power this cart, and another for a DCS cart I will be starting soon) which gives me about 60aH per pack and just shy of 60v. I paid $1400 delivered, which was $700 per cart. So far no regrets, the kids have been driving the wheels off hauling sometimes 10 kids all around the neighborhood, its been great and I anticipate getting a lot more life out of these lithium cells than I would out of a set of lead acids.

One small addition we made over the weekend was the addition of a digital voltmeter. Just a $10 2 wire job from ebay but seems to do the trick. I was surprised to see the voltage readings jump depending on if you are resting or driving, I have a low voltage dropout set on my alltrax which should keep me from damaging any cells, but it will be nice to know about how much range we have left. Still havent ever driven it far enough to reach that point, I might do a range test though just to know the limits.

[cgtech]

Voltage alone is a poor method of seeing SOC of lithiums (not very accurate, they stay pretty flat 'till they suddenly & quickly drop when they near empty)

[dwimpari]

This is a great build - thanks for documenting it! Have you checked what your range has been (in either miles or hours driven) between fully charged and needing to plug in?

[anthonywebb]

I have not done an official range test. I will wrestle it away from the kids one of these days and give it a good test. I do know they drive it for hours on end without needing a recharge. We mainly just plug it in when we bring it in for the night which has been plenty sufficient so far.

[Volt_Ampere]

When I worked with electric cars, we used a Watt_Hour meter to keep track of how much of the battery capacity we had used between charges. Once you know what the capacity is, this is probably the best way to monitor SOC.

[cgtech]

Originally Posted by Volt_Ampere

When I worked with electric cars, we used a Watt_Hour meter to keep track of how much of the battery capacity we had used between charges. Once you know what the capacity is, this is probably the best way to monitor SOC.

Way to go for lithium .

[anthonywebb]

Update is long overdue. Can happily report that 3 years in and literally no maintenance at all. Kids use the cart daily in the summer, and in the winter is sits in a cold garage with an occasional trip to pull kids around the yard after a snowstorm. Bottom balance has been solid. I am going to pull apart the pack and get some more detail on how each cell has faired.

I have a 1998 ezgo that will be a new build starting soon, currently 3 boys and 1 cart is not a great ratio, need another!

[NCPW]

Good to hear

Thanks for reporting back. Many threads get started, but you never hear back from the OP on how everything went or is holding up.

[bronsonj]

Glad to see you back on and that everything is going well.

Did you ever do a mileage test to see how far the 60ah pack would take you?