Properly reading a battery hydrometer

NinerBikes wrote:

SCVJeff wrote:
I know I'll get cr@p from the battery crowd here, but this "unclear" line has bothered me for years both on battery hydrometers, as well as the one I use floating in my salt reef tanks. There is friction glass to glass in the hydrometer tube as well as water creep on the probe, and the same water "creep" on my floating tank probe. In the tank I can look at it from below the water line and above and interpret two different readings.

In the salt tank I cured this issue with a Refractometer. For the batteries I just bought a HydroVolt and used it on my T-145's over the weekend. It tracks my glass tube hydrometer exactly without the tapping of bubbles and rattling around to zero out the glass on glass friction with a repeatable reading. It's simply a better mouse trap and no glass to break. Read the full .PDF sheet on it.

This is a small benefit to AGM batteries. No burnt acid hole in your clothes, no opening up, and pulling out the trays supported to check the readings on the two batteries in the back, no tearing apart all the cable connections and losing the copper washers or lock washers, and no corrosion forming on any of your copper connector cables, no matter how nicely they are hand made and sealed up.

And you don't have to lift them half or 1/4 or 1/8 as often, those gut buster lead slugs.

I agree, AGMs are nice, however for me it just came down to the fact that the T105s provide the most bang for the buck. I spent $250 for the pair from a local golf car place and can usually manage 3 nights with no charging without going below 50% SOC.

SCVJeff wrote:
I know I'll get cr@p from the battery crowd here, but this "unclear" line has bothered me for years both on battery hydrometers, as well as the one I use floating in my salt reef tanks. There is friction glass to glass in the hydrometer tube as well as water creep on the probe, and the same water "creep" on my floating tank probe. In the tank I can look at it from below the water line and above and interpret two different readings.

In the salt tank I cured this issue with a Refractometer. For the batteries I just bought a HydroVolt and used it on my T-145's over the weekend. It tracks my glass tube hydrometer exactly without the tapping of bubbles and rattling around to zero out the glass on glass friction with a repeatable reading. It's simply a better mouse trap and no glass to break. Read the full .PDF sheet on it.

This is a small benefit to AGM batteries. No burnt acid hole in your clothes, no opening up, and pulling out the trays supported to check the readings on the two batteries in the back, no tearing apart all the cable connections and losing the copper washers or lock washers, and no corrosion forming on any of your copper connector cables, no matter how nicely they are hand made and sealed up.

And you don't have to lift them half or 1/4 or 1/8 as often, those gut buster lead slugs. :S :B Let me know if you need a hand, don't be afraid to ask, if you need help.

RDMueller

I read yours as just in the RED, landy's as mid GREEN.

All of this is why I bought a refractometer years ago and use it still. It does not require temperature correction and the number you get is where the line is. That's it.

Matt

^^^
what he said

I know I'll get cr@p from the battery crowd here, but this "unclear" line has bothered me for years both on battery hydrometers, as well as the one I use floating in my salt reef tanks. There is friction glass to glass in the hydrometer tube as well as water creep on the probe, and the same water "creep" on my floating tank probe. In the tank I can look at it from below the water line and above and interpret two different readings.

In the salt tank I cured this issue with a Refractometer. For the batteries I just bought a HydroVolt and used it on my T-145's over the weekend. It tracks my glass tube hydrometer exactly without the tapping of bubbles and rattling around to zero out the glass on glass friction with a repeatable reading. It's simply a better mouse trap and no glass to break. Read the full .PDF sheet on it.

In this case read the bottom of the meniscus. The top of the meniscus is just surface tension of the glass and the liquid and is to be ignored.

Actually the batteries were fully charged before applying a 40A load for 90 minutes. That's when I took the reading. Recharging right now!

1.2825 or there abouts.

Make sure no bubbles stick to float. Lesser states of charge seem to have more bubbles stick to float.

Make sure glass tube is mostly vertical with minimal contact between float and glass sides.

If checking while charging, note that inner cells will be warmer than outer cells and temperature compensate accordingly.

Give the thermometer a while to respond to the electrolyte temperature, and cool ambient temps will throw off readings.

If the battery has not moved and not been charged for a while, the electrolyte can be stratified, with the dense acid on the bottom. This will throw off readings. So some agitation, or holding it at gassing voltages should mix it up for a more accurate reading.

Quick, get a charging source on that poor battery or I will report you for batterycide!! :)

Doesn't seem to matter where you measure that one give or take a half inch the battery just isn't going to make it. :B