Is there a real-world test of a battery's true capacity?

do your research right.

Used tested and calibrated equipment... some are able to be Rented...

do a search.. use Real accurate equipment..

not low cost ..not calibrated... almost worthless stuff.

accurate cost money for a reason.

consider contacting the engineering department of your choice battery manufacture.
Yuasa, Johnson Controls, Exide. or ??? many documents are available.

MEXICOWANDERER wrote:

Or an Odyssey versus a Lifeline?

I don't think there is a fair comparison here.
The Odyssey claims super high CCA, and 800 cycles to 50%.

Lifeline claim less CCA but more overall~ 20% MORE cycles when recharged properly.

The key, is recharging properly.

Is it not?


I am biased. I have Northstar AGM battery, very similar to Odyssey. I beat the piss out of it, but I recharge it to batterygasm level almost each recharge.

I hate these words and claims, but it it still going strong, and 'just fine' at over 400 deep cycles.

I have more faith in this AGM, than I do our politicians, but that does not say much.

I do not ever want to find myself in that position again. It hurt. Not where I thought it would - the very tip of the skull. Felt like I was wacked with a piece of rebar. I really do want to keep fooling around with this stuff. But I use mechanic's nitrile gloves or medical exam gloves. Either gives good protection against 120 vac. I do have to laminate the work area deck with plywood. The super warm temperatures make going barefoot tempting. And tile or concrete is a dangerous conductor.

Might as well add this...
Even 12vdc can burn tender skin. Make an optimum negative contact with sweaty skin then complete the circuit again with salty moisture and a 1st degree burn can happen on inside of wrist - forearm - cheek - etc.

Back to testing. Use a cellphone ET for timing. That DROK 4-1/2 digit voltmeter is priceless for stuff like this. Use a DMM ma scale to qualify a shunt. Again a 4-1/2 digit DMM is worthwhile. I have the assortment module of 5 resistors in a bar in a case. All 5 are 10 ppm accurate. Curious error in DC voltage vs resistance seems linked in all my DMMs. I also have a handful of 8.1000 volt qualifying zeners. I'll see if I can get some to you Jeff. They are fun to play with.

My interest lies in factoring watt minute performance of a battery. LiPo wins hands down. Nothing else is even close. Take a 316 ampere hour L16. The Rolls has much higher voltage at a 150 amp draw than say a US battery of similar A/H. Factor cost per kWh transacted and a few surprises are in order. My big bank has had it easy for going on the 22nd year. The L16s in Quicksilver were installed in 1998 and have subsequently lived The Life of Riley. The frame is on pylons to ease the load on the tires. My son in law is good with that 22 air over hydraulic jack. The engine PT drive has a huge York compressor.

Wouldn't it be great to see tests between whatever battery Costco is vending versus a Trojan? Or an Odyssey versus a Lifeline?

MEXICOWANDERER wrote:
No wonder I have to stay busy down here in the land of cacti. Total withdrawal may prove fatal...

---snip---
Well it's a good thing your past time involves playing with electricity or that might have been the case eh?

For determining variances "is/was" a $5 bobber would be fine. For precision in zeroing-in on exact numbers i.e. exactly 50% soc then exact means right on the number. 1.202 instead of 1.200 for example. To assume a five dollar hydrometer can do this is quite an assumption. I built a shelf with hole and below a ledge with v-notch to hold my hydrometer both steady and absolutely straight. With a strong light and magnifying glass incredibly tiny incremental variations in bobber height can be discerned. Freas built me a custom set. My favorite is an axpanded scale 1.255 - 1.265
It had to be N.I.S.T. traceable which means documented. Quite the instrument. It is housed inside a schedule 80 ABS pipe which is clamped to the wall. But the regular Freas unit is far and away good enough for guesstimating state of charge.

Always record temps if record keeping. I have an assortment of fresnel lens truangular Ashcroft lab thermometers. The 0c to 50c is the most used.

At work I had a National Controls Corp A to D data acquisition board connected to a 3100 dollar Compaq SX computer. 155mb hard drive, 25 MHz processor 2Mb RAM with 400 dollar additional 2 Mb RAM. An Indian programmer from Uddar Pradish set up the program then spent 2 weeks de-bugging it. Pure buggy whip. Setting the alarm for 3:20AM. Living on site while Quicksilver was being outfitted. Going to conventions as a rep. Rebuilding alternators at night. No wonder I have to stay busy down here in the land of cacti. Total withdrawal may prove fatal...

a battery is the closest thing to a Life form.

charge = food
discharge = work
rest = rest, but energy is still being consumed.
water/acid = blood. (transfer of energy) from one form to another.

after work is done.. rest is needed before determining wellness. just like you.

YES, I am nuts. so watt..:) spelled correctly.

Hi profdant139,

No. Mex is saying use a temperature compensated hydrometer.

profdant139 wrote:

So are you saying that an ordinary hydrometer, which costs less than ten dollars US, can give an accurate state of charge? The thing looks so amateurish -- the plastic arrow wobbles around and eventually points to a color zone -- green for good, yellow for fair, red for bad. That can't be what you have in mind, is it??

Ok top- posting like mad here same as PT, :)

True. But Trimetric doesn't care since it is not Peukert aligned. (Bogart says it is close enough within normal RV amp draw range.---which I agree with having done it a lot.)

Also 6 instead of 4 with an AH usage suitable for 4 does make you operate in the higher SOC band (not 50-90s but higher), which can be bad for fast recharging, but if you are using solar with its low amps, that is not a concern since you don't taper until at way high SOC at low amps.

Got it on the res fridge issue! Yes off- grid with a 120v fridge is a PITA. Have that with the Truck Camper. Wish we had a propane fridge in it! (Not to be, sadly, so it is all work around for that.)
-----------

"So are you saying that an ordinary hydrometer, which costs less than ten dollars US, can give an accurate state of charge? The thing looks so amateurish -- the plastic arrow wobbles around and eventually points to a color zone -- green for good, yellow for fair, red for bad. That can't be what you have in mind, is it?? "

No use a glass tube hydrometer with a bobber in it marked with SGs in green, white, red zones. Do not use the plastic sideways arrow thingy.

The glass tube $5.00 one is "good enough" and by using the same one every time you can tell when things get different.

That is the key to all this stuff--not the absolute accuracy of the one- time shot measurement, but watch for when it gets off the usual track using the same measuring instrument.

pianotuna wrote:
Hi BFL13,

Actually Peukert is always "there" so going from 4 to 6 jars makes the real amp-hours used from the battery lower.

BFL13 wrote:
If your daily AH usage has not changed then it doesn't make any diff if you now have 6 instead of 4 batts for how much solar you need.

Having 6 does:

A. let you go longer without solar input, and

B. let you run the high amp draws with less voltage drop, which means staying above the inverter low voltage alarm setting better

No
A hydrometer that agrees with a Francis Freas hydrometer is a proven good hydrometer. About one in 35 EZ Red hydrometers screws up and arrives with acceptable accuracy.

Pb permeabilty and natural circulation of electrolyte precludes rapid accurate density readings. With large cells like mine I stop charging at 1.254 and 2 hours later cell readings are 1.260 Tropical density electrolyte. Yes. Tenperature corrected. This is for charging. Moderate discharge rates generate little heat.

If you want to be snotty, record 30 minute interval voltage readings to second decimal point throuhout the test. Add the numbers then divide by number of samples. Do exactly the same with amperage samples. This will give you a median average value to work from.

Hi BFL13,

Actually Peukert is always "there" so going from 4 to 6 jars makes the real amp-hours used from the battery lower.

BFL13 wrote:
If your daily AH usage has not changed then it doesn't make any diff if you now have 6 instead of 4 batts for how much solar you need.

Having 6 does:

A. let you go longer without solar input, and

B. let you run the high amp draws with less voltage drop, which means staying above the inverter low voltage alarm setting better