Be careful with auto-parts store chargers!

Battery buddy

I cheeped out and picked up one of these. It had good ratings.



With a named like Battery buddy what could go wrong? It took a long, long time but it seemed to work without much harm.

This is exactly the reason I bring this up! Have you vetted the actual voltages used with your own gear during the full charge cycle? I would NEVER commission a battery with one of these.

A bigger problem is that this is a very low-amperage maintainer. Even Schumacher (who appears in nearly every auto-parts-store) warns against using these with their own line of maintainers on big batteries. They never used to mention it, but with recent models they do.

Bringing a large battery back with a maintainer only provides a superficial surface charge and is the wrong tool for the job. With solar, it is unlikely you have reached a full charge anyway when you do decide to throw a charger on it - and that is the only time a maintainer should be used - after a full charge initially with something else!

Fortunately, you haven't spent much money on it.

Move beyond the bargain-bin.

I see this all the time. Overly agressive speed chargers (not just in amps, but high-voltage modes you have no control over during/after absorb) that overcharge batteries that don't need to be beaten, or cheap low-end maintainers that undercharge with a petty surface charge.

Strike a balance with something half-way decent at least. How chargers play the "end game" so to speak is very important, and I've witnessed many just lose their mind and decide to take your battery to a place it doesn't *need* to go.

A Samlex / Cotek BP1205 and BP1210 charger is another good series I have tested. No tricks, just simple CC to 14.5v, drop to float at just under an amp or so, and floats to 13.5. AGM or flooded only please. Unlike a dinky maintainer, it has enough current to actually get into the pores of the lead to really do a charge. I have also tested Samlex SEC-1215ul models, and although you have to provide your own clamps and cabling, it works well with no tricks either. It will also handle gel at 14.0v, but that is not the recommended chemistry for solar anyway.

Of course, one must not exceed the constant-current rating of their battery, typically C/8 for flooded, or C/4 for agm, or (yuck - C/16 for gel).

So if one doesn't know what they are doing, and not willing to vet their chargers performance personally, then an Optimate-Tecmate 6, or a Noco Genius 7200 or higher, is a safe yet effective no-brainer.

In solar, when you cheap out you get cheap results - the biggest problem is that you will learn nothing from it, because you can't TRUST your gear.

Your advice is painful but appreciated.

Well, heck. I suspected that might be the case but thought I'd throw it out there and take my medicine. Your advice is painful but appreciated.

When I started this solar adventure I had no idea the battery maintenance would be the main drain on my brain.

On the positive side - my battery is floating again (using the mppt CC) using the battery type setting of 'flooded'. I'm getting about 35V in from panels (max about 38).

I'll pick up the noco 7200 asap http://www.amazon.com/NOCO-G7200-Ult.../dp/B004LWTHP2

You don't even have to cheap out to get a charger that doesn't do the job right. I have a Schumacher SC-10030A (~$80) which allows me to select the type of battery including AGM, GEL or standard. but I still do not trust it completely with my AGM batteries.

Great! Just understand that the NOCO is not a fast charger because it ramps down the CC amperage according to it internal formula / feedback. Thus it will seem slower than a standard 7A charger. Just wanted to warn you up front.

I have both the earlier and the later model you linked to. The later model charges a hair faster, and has upped the various voltage ranges by .1V. Ie, instead of 14.7 for agm, it is now 14.8v. All the other voltages are .1v higher than version 1.

When a version2 indicates a finished condition with the solid green led, if you have your own gear on it, you will see it doing an "optimization", which is a variable oscillating absorb back to the absorb setpoint, or a one-time low-current ramp up to 15v WELL AFTER normal absorb is done - ok - before it goes into the float-mode MONITORING. This optimization is not seen on the earlier units, and following Optimate's lead doing this, is valuable. Noco does it a little different, but still ok.

Also, if you follow the Enersys / Odyssey way of charging agm's, they tell you that unless you can provide an 8 hour absorb, then you need to compensate with about 12 hours or more of actual float - NOT just monitoring. With the 7200, when it finishes, you can stop charge, pull the clamps, and switch modes to the "power supply", which will do a real-time float at 13.5v. If you do this, just beware that in 12v power supply mode, the clamps are now "hot", and are no longer sparkproof etc, so be careful.

Since we are not doing a commercial standby / float service with these chargers, just a few hours of float with the PS function is fine.

Tip: If one already owns a Noco, or in fact any other charger aside from an Optimate, and wants to take advantage of this optimization routine, then look into the G1100 charger/maintainer (ver 2!) which you can apply perhaps an hour after your *original* charger finishes. The 1100 has no problem with my 75ah blue-top Optima, BUT of course it was charged by another heftier charger FIRST and allowed to finish. In one setup, I used an original model 7200, and then followed up with the Ver2 1100.

Wise move. You may not like what you see when you put your own voltmeter with a min/max hold on during the charge cycle on an agm. I used my Fluke 87v.

Note that there are no actual charge voltage specifications in the manual. This is what prompted me to find out on my own, with a bevy of lunchbox-handle speedchargers, and the bigger linear wedge types and deemed them too agressive for batteries that are in just a normal state of discharge. The only one that performed to my satisfaction was the one Schumacher made for the Diehard Platinums (rebadged Odysseys) and of course worked great with my Odyssey and Platinum battery. Different firmware specs than the general purpose ones. I'm looking at the box for my SC-7500 right now catching dust.

I used a new *good working* Deka / East Penn Intimidator agm, charged and tested for a few cycles, and verified as good with my own IR measurements and CBA-IV analyzer as a test subject for these chargers. It did not survive long. Needless to say they weren't allowed to touch any of my other agm's.

Again a warning - the percent display or even the voltage display may not actually indicate that there is 15.6 or higher voltage *at the battery terminals*. In addition, most of the units seems to charge about .5 to .6v higher than what one normally expects per chemistry at the terminals.

Interestingly enough, the wedges do an unusual duty cycle charge - that is when charging at the highest amperage, it does so for about 2 minutes, then drops back to about half that value for another two minutes, and then switches back to full amperage again over and over. The freaky thing here is that during one of those cycles, (I believe it was the 50% cycle), the chemistry voltage was reasonable - but on the OTHER cycle, I quickly ran up to 15.6v. This was at the start of absorb, as confirmed by my ammeter, and not afterwards when I *might* be able to tolerate it.

This is kind of what I'm talking about where one of these chargers takes a new set of gels up to 16v no matter what chemistry is selected. I duplicated his findings with my own good agm, since I don't trust the internet completely and try to duplicate claims. I duplicated it alright.



The workaround for an agm, is to PURPOSELY USE THE WRONG CHEMISTRY setting with these chargers that one has vetted personally to be running at very high voltages *at the terminals*. That is, select GEL for agm. This can cause a lot of confusion so I don't usually go into it, especially since Optima specifically warns people NOT to use "gel" for their agm's! And wisely so, since gels only need about 14.1v max and will undercharge an agm.

BUT under normal conditions, I found all these chargers hitting 14.6v (and eventually going to about 15.1v) on the gel setting! HOWEVER, Optima may not know about the case of these speedchargers, which are really designed to hammer garage-queens and dome-light-on-for-a-weekend abused batteries. They do a good job on those, but for a normal battery - you better be on your toes!

Lacking any insight into proprietary information, I tried looking up their patents online and got some good info - but it referenced things that were somewhat vague from trying to pin things down to the last detail. Maybe a trained engineer can decipher the patents, but all I got from it was kind of a just you'll-have-to-trust-us feeling.

Chargers models come and go, so I'm not sure if their newer models still do this type of behavior with new batteries. I'm no longer interested in this brand.

All chargers tend to come with slick marketing and hype. I let my own gear do the talking instead, and base my recommendations on that.

Keep our solar application in mind

The warning here is not to get too bogged down in AUTOMOTIVE reviews and forget that the emphasis here is that we are just trying not to overcharge or undercharge relatively *NEW* batteries and as seen above - if you don't know what to look for, you may end up blaming the batteries / solar setup and not the charger.

These consumer level chargers all have some capability of burping heavily discharged batteries up to a point where a normal charge can resume. But just because they can seem to revive an old battery, that still does not mean the battery is a good candidate for the neophyte in a solar setup. It is tempting to pull an old one from the tractor, but unless you have the gear to prove that those revived batteries have not suffered from the revival process itself (and usually along with the initial abuse that took it there in the first place), it is better to start out fresh.

Also keep in mind that we are not doing commercial 24/7 cyclic turnarounds with these things either. Thus our charger requirements can be relaxed just a little bit for the one-off, or perhaps weekly / monthly preventative maintenance charge. Something slightly less than perfect on an infrequent basis is better than not doing nothing at all.

If one needs to go to absolute perfection, you'll be opting for a more commercial / heavy duty marine charger (or perhaps one offerred by the manufacturer themselves, aka Optima digital 400 / 1200 etc) in that case and most probably not even reading this thread.

Tip: Much of the consumer level chargers come with quick-disconnects for the cable clamps - SAE and proprietary QD's are common - and if they are significantly hotter than the surrounding cable leads themselves, you have a high-resistance / loose connection there. Do a couple of repetetive disconnects to help clean any oxidized pins. In the case of loose fitting pins, you may just have to cut out or replace the QD and use your own like Anderson powerpoles if you have the skill. Sometimes no matter what the brand, the QD connectors just plain suck.

Questions about the Optimate 6

Hi PNjunction! I've been looking at the Optimate 6 for charging a spare 12V 100Ah battery I have. I'm planning to place it in a Minn Kota Power Center to use for my CPAP.

My question is, can I plug the Optimate 6 into my solar generator (Yeti 1250)?

Do you mean running the Optimate *from* the Yeti's psw inverter to charge another battery? Not sure if that would work well, I haven't tested it. Optimate does have a cool 2A DC : DC version for charging another battery from a bigger one - just keep in mind the limitations of only 2A charge.

If you mean charging the Yeti's internal agm, that would be just fine! HOWEVER, the Optimate is designed to work with either a battery totally stand-alone with nothing connected, or with vehicle electronics cabling hanging off it - and if it detects the lowered impedance of external cabling, and needs to desulfate, it won't do the best job it is capable of.

To allow it to do the best it absolutely can, and provide the most accurate test results, I'd charge the Yeti's battery stand-alone with none of the internal box stuff connected.

Note that the Optimate, while it IS a great charger, does not actually finish testing until at least 12 hours has past the initial fully charged stage and only then will it float IF it passed the test. One CAN pull it right after the initial charge, but it is not wise to do so for your first run out of the gate. Some batteries will pass the initial 30-minute test, but fail the longer term 12 hour one, so it is important to let the Optimate finish - usually indicated when the test lights stop blinking and go solid.

Yes, that is what I meant. I have a spare battery which I want to charge standalone with an Optimate 6 (or probably a CTEK charger).


I'm planning on using the AC version which I think is 5A.


What are the potential issues with this plan?

I think your best bet would be to contact Optimate or CTEK, and ask them if operating them from a PSW inverter would be ok. I'm not going to test it personally.

Take extra care with that YETI box. By that I mean while it contains fuses and so forth, the last thing you want is an overload that takes out not only the fuse, but also the logic board itself, which may turn the whole thing into a heavy brick. I did that to a Schumacher power station where I overloaded the USB port, and it took out ALL the logic and all hell broke loose.

Boycotting the black-box'ed chargers now ...

Not that it will do any good. By that I mean that unless a manufacturer is willing to publish the specs for their own products, PASS.

It could be made of pure gold, but I am no longer willing to take the chance on unknowns. I'm getting too tired of vetting chargers with my own gear just to make sure they aren't inadvertently damaging my battery by either over or undercharge.

I guess I can understand - the manufacturers assume that consumers don't really care or want to know. Those that do know, may have their facts skewed from slick competitor marketing, and may overlook a good product based on false assumptions.

From a sales aspect, I guess it is better to keep people in the dark and not reveal any specs at all, other than generic "for 12v batteries".

Fortunately, there are still some manufacturers that PROUDLY display their voltages, currents, and algorithms. Tecmate-Optimate, Battery Minder, Samlex, and most of the quality players do. I hope they don't black-box their product lines in the future.

Sadly, my most recent NoCo's have bit the dust, (despite full disclosure of specs) while the originals keep on going. I'll have to send those back for analysis. Happens sometimes.

Just read through this BEFORE buying a charger. Am I reading correctly that I should not use any Schumacher charger? I'm eyeballing a Noco 7200, but wanted to double check.

I have 2 of the Schumacher battery chargers and while they seem to work fine for a standard car or truck battery they lack the intelligence for any true deep cycle or AGM type battery and can actually harm it.

I have heard the NOCO is a better choice but I have no hands on experience with them.