Western 400 42v charge numbers

MikeWestern400

Hey guys,

I searched for a while looking for the exact numbers to a full charge on my western 400 42v.

I am estimating that a full charge is 6.35 (1 6v battery) x7(batteries)=44.45

and 90% is 40.00. (multiplied 44.45x.90). Am I on the right track?

BGW

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Sir Nuke

I am sure that JohnnieB will be in sooner or later, as he runs a 42v cart, and he can give you the EXACT numbers you should be looking at.

Knothead

You are close to correct on the 100% voltage, but "90% SOC" is NOT 90% of the "100% SOC"! 6.37v per batt is 100%.......6.05v is 50%.....you NEVER want to take your pack below 50%! Actually you don't want to take it below 70% for the best "longevity" of your pack......

See JohnnyB's chart below:

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JohnnieB

Welcome to BGW!

Getting the "exact" numbers is more or less an exercise in futility since a deep-cycle lead-acid wet-cell battery isn't fully charged until the Specific Gravity (SG) of the electrolyte ceases to increase while a charging current is passing through it.

When you add 0.845 to the cell's SG, you get VPC (Volts per Cell), so voltage can be used to estimate SoC (State of Charge), but it takes time for the electrolyte's SG to reach an equilibrium after charging or discharging, so to get a reasonable accurate SoC estimate the voltage must be measured about 12 hours after charging or about half an hour after discharging.

Since slight variations during manufacturing do occur, the voltage of adjacent cells in the same battery may vary slightly when "fully" charged.
Then you have to toss in the fact that different battery manufacturers use different acid concentrations (SG) in their batteries.

The Voltage vs SoC charts typically use test data from the Trojan Battery company, which is an average of hundreds of test conducted on hundreds of batteries. The voltages for other brand batteries may be slightly higher, but I'm not aware of any that would be lower since Trojan uses the lowest acid concentration typically used for this type battery.

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I'm curious. What is your reason for wanting to find out the "exact numbers to a full charge"?
I ask because there are three separate sets of numbers. On-Charge, Under-Load and At-Rest, and each set is used in different ways.

Are you are trying to determine how high of a voltage to charge your batteries to, to get a "full" charge?

Sir Nuke

hey Mike......btw......Welcome to our happy little corner of the net, and to BGW. There is a BIG fridge on the back porch with anything you can think of in it...help yourself...of course only take what you can LEGALLY have. Make yourself at home on one of the big fluffy couches, kick your shoes off, put your feet up on one of the tables, yes we are allowed to do that, mom's, wive's, husbands, girlfirends and boyfriends here don't care....and take it easy.



oh...btw....every once in a while a food fight breaks out...so you may not want to wear nice clothes here.

Welcome!!

MikeWestern400

Thanks!
I saved the attachment and printed it. I plan on purchasing a digital voltmeter, and want to monitor my carts volts during use. I want to make sure the batteries never go below the 50% SoC. My batteries are a little old, but still kicking. I don't want to push them too hard right now, want them to last a few months until I get a new pack.

MikeWestern400

Update with a question: I got a multimeter today and charged the pack fully. After getting ready to put it away I checked the pack and the voltage was 38.6!

So basically my batteries are beyond weak??

pete959

looks like u didnt check the pack right that looks like u only checked 6 batts not 7

MikeWestern400

I removed the original Curtis voltmeter and used the red and blue wires to test.

scottyb

You might get a better reading at the pack. there are only 2 battery cables on the battery pack that do not go from battery to battery = these 2 are the main + and -. Check voltage between these 2 posts.