Paul's how NOT to convert a Metro

[Christ]

Originally Posted by vpoppv

My batteries are like capers: they taste great in veal piccata. No wait, I mean they are non-pareil.....

I count 96VDC... how many Ah are we estimating for that pack?

[vpoppv]

Originally Posted by Christ

I count 96VDC... how many Ah are we estimating for that pack?

Well, I got 8 in case 2 of the batteries turn out bad. The amp hours on the batteries range from 88 to 125 each. So basically call it 75 Ah per (weakest link kinda thing) and that puts it at about 450? Call it 400 for fun. Funny thing is, one of those batteries is currently in my car!

Three of those batteries are called Mega-tron, how can you go wrong with a name like that??

[Christ]

... could have been Giga-Tron. :P

[Christ]

Get to know the proprietors at your local tractor shop, AutoZone, and Wal-Mart. Often, they'll let you exchange bad batteries for the cores they've taken from other customers.

I have contacts with a few stores around here that let me swap out car batteries if they go bad, and I just drop it off and take one of the cores, run that one dead, swap it out again, etc. Just have to make sure the "big boss" isn't around.

[vpoppv]

Originally Posted by Christ

Get to know the proprietors at your local tractor shop, AutoZone, and Wal-Mart. Often, they'll let you exchange bad batteries for the cores they've taken from other customers.

I have contacts with a few stores around here that let me swap out car batteries if they go bad, and I just drop it off and take one of the cores, run that one dead, swap it out again, etc. Just have to make sure the "big boss" isn't around.

All the local guys will have nothing to do with me! They rarely see a deep cycle customer anyway. The place I got these was a boat dealer, next town over, and they were happy to get rid of them. I'm happy to take 'em. Works out well for everyone....

[vpoppv]

Speaking of batteries, funny thing happened today. First off, working at the middle school I have been needing to talk to the bus guy and see what the school buses do for batteries since they could potentially have batteries I could use in my conversion. Anyway, coming back from the bowling alley, the bus driver says "uh oh!". I jokingly say "What, did you leave the lights on?". She said "yeah, I did! Oops!". So we had to wait for them to send another bus. Gave me a chance to finally talk to the bus guy. As it turns out, they only have one battery, one big, monster honkin' battery per bus! Not Geo Metro material anyway. Looks like one of the 8 I got yesterday is totally dead; one other one is still in limbo; but, it does look like I have my 6 useable ones for my pack! I am one happy dude right now.

[JasonG]

Originally Posted by vpoppv

Well, I got 8 in case 2 of the batteries turn out bad. The amp hours on the batteries range from 88 to 125 each. So basically call it 75 Ah per (weakest link kinda thing) and that puts it at about 450? Call it 400 for fun. Funny thing is, one of those batteries is currently in my car!

Sorry to rain on your parade but you will only have ~75AH.
Series brings the voltage up but not the AH. That will be an average of all the batteries. To bring the AH up you will need more batts to parallel with the ones you have.
As a side note, be careful mixing different size batts, this creates heat and charging issues.
Awesome build, I've enjoyed following it !

[swede]

I gotta say man thats the same battery pack I drove my forklift into the shop with,I swear! Seriosly that will be great for testing with and some driving too. Thank got you got a deal on those chargers, you'll need em. I love chargers on a sale. I got mine on sale at canadian tire for about 30 CAD ea. and they work well. slow but well.

[vpoppv]

Originally Posted by swede

I gotta say man thats the same battery pack I drove my forklift into the shop with,I swear! Seriosly that will be great for testing with and some driving too. Thank got you got a deal on those chargers, you'll need em. I love chargers on a sale. I got mine on sale at canadian tire for about 30 CAD ea. and they work well. slow but well.

Yeah, I figured one of the most important things to get new was battery chargers, because I knew I'd be running cheap, dissimilar batteries. Trouble is, I'm scratching my head about getting them in the car because, to be honest, it's frustrating me so much I'm having second thoughts about this whole project.

[mcmahon.craig]

Originally Posted by JasonG

Sorry to rain on your parade but you will only have ~75AH.
Series brings the voltage up but not the AH. That will be an average of all the batteries. To bring the AH up you will need more batts to parallel with the ones you have.

No, it will be the LOWEST of all the batteries. In fact, it's the worst CELL.

Say you have two batteries connected in series. One can provide 20Ah to an EPV to 1.7Vpc, and the other only 15Ah to the same point.

When you discharge the batteries, the cell voltage will obviously drop. At 15Ah the voltage on the 15Ah battery will be 1.7Vpc (about 10V), but the 20Ah will be more like 11.5 volts.

At this point, if you discharge the batteries further, the lower capacity battery WILL be damaged. If you attempt to retrieve the last 5Ah out of the good battery, you will probably reverse a cell in the bad one and destroy it.

If you're going to use mismatched batteries, please at least use one of these to avoid exploding batteries. You could also perform a measured discharge (using a known load, like a headlight) to 10.5V to ensure your batteries are at least somewhat matched.