What size battery charger??

[Mr. Fixit]

My house bank will be composed of 4 Deka golf cart batteries. I have a Honda 2000 watt gas generator I will use on the hook to charge batteries if necessary. My question is, although I can research output of different chargers I am having a problem finding out the requirements for input (amps) I would like to stay in the 15 amp range. How can I determine what size charger the Honda will handle? I would like to use a charger that has as much output amps that the Honda can handle without a undue strain. Am I missing something here--4 golf carts wired to produce 12 volts. I have never done any low voltage before and If I can get this answer I can complete my rewire project.

[Vasco]

Mr. Fixit,

Get a 100 amp charger if you're going to rely on the Honda on the hook. Anything smaller will take all day to bring the bank up. My guess is that you have a 400 amp bank. If you run it down 50% you'll run a 20 amp charger all day and still not get it up. This happened to a friend of mine that complained his fridge was shot. It wasn't, it was his batteries as he was relying on his Honda and a 20 amp charger!! A small charger is fine if you're on the dock and shorepower but if you're using a Honda get a real big charger. The Honda 2000 will easily run a 100 amp charger.

[ssullivan]

2nd that. I have twin 90 amp chargers for my genset setup. They charge up a 420AH battery bank. Does it in an hour or less with our usage patterns.

[btrayfors]

Rick's right...a charger with much less capacity will take much longer to fully charge the batteries.

By the way, the normal recommendation for maximum charging current for flooded batteries during the "bulk charge" phase is about 15-20% of their rated 20-hour capacity. Four 6V golf-carts combined in one 12-volt bank will have about 450AH capacity, so 20% of that would be 90 amps.

Re: type of charger, be sure to get a "smart" one with at least a bulk, acceptance, and float stage capacity. I can recommend the Iota chargers with the IQ-4 regulator (either built-in or plug-in). They are robust, relatively inexpensive, and are very tolerant of input voltage fluctuations, so work well with small generators.

You can find them on eBay. Associated Industrial is one knowledgeable supplier I've used successfully. Their 75-amp or 90-amp models would be appropriate, since these chargers can deliver FULL output continuously, unlike many others.

Bill
WA6CCA

[CSY Man]

I have the same house bank: 4 X Deka Golf carts, about 430 amp hours.

Bought a new DC charger last year: A Xantrex 40 amp yellow smart charger. (Forgot the model name or number, it is a "smart charger" with equilazation mode.

Happy with the combo, BUT I never run the system of a Honda generator, so the charger may not be optimal for that purpose.

Found the Xantrex charger on the Internet for about $340.00 or so, West prices are $425 or in that neigborhood.

[btrayfors]

For comparison, the Iota 55 amp charger is $145 on eBay (Buy-it-Now price) from Associated1, the IQ-4 controller is $35, so $180 altogether.

The Iota is a top-notch charger. They make chargers for many other companies, sold under their own brand names.

Forgot what the 75-amp and 90-amp models go for...I think in the $300 range.

Bill

[Alan Wheeler]

Wow that is so increabibly cheap. Why then are Xantrex and a few others so expensive?? Do they do more??

[charlie p]

I have just started researching this very problem. With a modest sized cat and a tight weight budget, I've been looking into what I can get out of the Honda 1000, but the issue is the same. Depending on what I find, I may need to go with the 2000. My situation is slightly different in that I have a large solar array and need the generator only as a backup.

I think your approach, which is to get the most you can out of the generator is the correct one. Once you decide to endure the noise, CO, etc., you want to get the most out of it. As you note, the key is the AC specifications. Most chargers do provide AC specs, though you sometimes need to dig a little. For example, Xantrex does NOT include AC input current/power data in the datasheet, but if you go to an appendix in the user guide (available online) you will find it.

The problem is that the specs seem to be very conservative. Most of these chargers have switching power supplies with an efficiency of about 80%. If you work out the math, there is a big disconnect between the input and output numbers. I think this is just typical vendor conservatism, but I can't be sure. When plugging into shore power, it really doesn't matter, but with a generator, it is quite important. The vendors may be thinking only of shore power when writing the AC specs and figure it doesn't matter, so why not be conservative.

For example, the Xantrex 40 amp unit mentioned by CSY has an AC input "typical" spec of 8.5 amps at 120 volts or 1020 watts. It has a quoted efficiency of 80%, for a potential output of 816 watts. Assuming a bulk charge voltage of about 13.5 volts, it should produce about 60 amps, but the spec is 40. Now there is some overhead in the control circuitry, some temperature range derating, etc but the difference is still huge. Other vendors have similar numbers.

Bill, I too like the IOTA products. IOTA does a better job of specifying their products and has a good reputation. Both factors are probably due to their industrial customers, who will not put up with flakey consumer stuff and incomplete specs. The 75 and 90 amp units you mention look good, but upon checking the datasheets, I found that both exceed the 1600 watt continuous rating of the Honda 2000.

Rick, you are right, a Honda 2000 SHOULD be able to handle 100 amps (or at least close) but I can't find a charger that is so specified. If you know of any, I'd love to hear about them.

Another thing to watch out for is spec games on 110/220 chargers. Dual voltage is great for overseas use, but the specs are often quoted at 220, where power supply efficiency is usually higher. 110v operation on these units is often derated.

Another vendor that looks promising is Mastervolt. Good quality, often used in commercial marine environments, but more expensive.

As I said, I'm just starting in on this. As I learn more, I'll try to post.

Charlie Phillips
Portland, OR

[knottybuoyz]

Would a pair of say Iota DLS55's make sense? Use one when on generator and two on shore power? Think each is 13Amps AC draw. That would fit w/in the Honda's range w/out pushing it too hard. Of course lengthens the charging time.

[Vasco]

Charlie,

I have a Honda EU2000i and a Freedom (Zantrex) 2000w inverter/charger which can put out 100 amps. The Honda handles this very well and I regularly see 90 amps going in on the monitor.

[btrayfors]

Alan,

The principal difference, IMO, is the "marine" designation. Xantrex, Charles, Professional Mariner, and others produce products for the marine market and price them accordingly (after all, they're aware that everything in that market is measured in "boat units").

Iota's engineering staff have provided an excellent product at a very affordable price. They sell, as Charlie said, a lot in the industrial market.

Charlie,

Thanks for researching that. Yes, even the 75-amp model might be too much for the EU2000 because it puts out full power when needed, thus draws continuously a significant current. It's rated at about 80% efficiency, like most chargers.

The truth is, most "100 amp" chargers don't put out anything like 100 amps for very long. They very quickly throttle back, thus their draw on the AC input side drops accordingly.

One reason I like the Iota chargers is that they make use of PWM (pulse width modulation), a new technique which is quite effective when charging flooded batteries.

Another reason is that they are virtually RFI free, that is, they put out very little RF interference. I have used a 45-amp model to maintain two T-105s which power all the radios in my ham shack; no problems with RFI, and the T-105s are quite healthy.

Specifications for Iota chargers can be found here: IOTA Engineering DLS Series AC/DC Power Converters and Battery Chargers for 12VDC Systems

By contrast, I have a small Professional Mariner charger on my boat which is very dirty....really tears up HF radio reception. And a much larger charger from the same manufacturer which we're using in my basement for some tests actually is so dirty it takes down the LAN network!

knottyboyz,

Yes, that would work OK. You can combine two IDENTICAL Iota chargers to double capacity. I believe Sean is doing this with two 90-amp models.

Bill

[charlie p]

Rick (Vasco)

I have the identical Freedom unit (came with the boat). The datasheet lists the AC input current in "Max Charge Mode" as 21 amps (no voltage specified!). Even at the minimum specified AC voltage of 90, that is 1890 watts. On the other hand, the efficiency at full load is rated at 85%, so your 90 amps (at 13.5 volts approx absorbtion voltage) would mean only 1430 watts of AC, easily within the Honda 2000 range. Your clear success suggests that the vendor is being very conservative, as I suspected. I assume you have no other AC loads when charging this way. If I'm willing to live with the weight, looks like I could pick up a 2000, plug it in to my shore power plug and be done. Tempting. A quick way to knock another project off the list.

Bill,

I know you are a stickler for RFI so I just want to check. Are the Iota units good with respect to both conducted AND radiated? I'm about a year out on doing an SSB installation and don't want to start adding stuff that will cause problems. Be forewarned, I'll probably be bugging you with questions when I plan the install. Thanks in advance.

Rick (knottybuoyz),

Dual chargers sounds like a reasonable idea. I like the reduncdancy in case of a failure.

Charlie Phillips
Portland, OR

[Vasco]

charlie,

Yes, it's working pretty hard when it's putting out 90 amps and that's the only load I put on it. After using it a few times you can tell the output just by listening to it, no need to check the monitor. Most of the cruisers I see that don't have a diesel generator have gone to the Honda 2000 now. Some that had the 1000 have moved up. I'm beginning to see a few Kipor units out there too. Don't know how good they are or if they're a lot cheaper.

[btrayfors]

Charlie,

If by "conducted" you mean on the DC output side, I think they are clean. I haven't run any tests with an oscilliscope yet, but I have found no problems.

My radio shack is set up in a small alcove in my basement. I have 11 HF transceivers (from modern to ancient design) and one HF receiver (Drake R-4B) which can be selected one at a time with a system of coax switches. The power for most of these is 12V DC, with a setup almost identical to a marine installation. I have a DC panel with breakers for each radio, two T-105s in series under the table to provide the 12V, and the Iota 45-amp charger to keep the batteries topped off. There's also a 500-watt SGC HF amplifier if needed which also runs on 12V.

Over the past two years since I installed the Iota charger, I've had no RFI problems at all. The only discernable RFI on receive can be heard when the charger is operating at a fairly heavy load, but even then it's at a low level and doesn't interfere with communications.

The guy who sold this Iota charger to me and who sells them on eBay, Associated1, is an engineer who's quite knowledgeable about these chargers and who turned me onto them initially.

Re: your forthcoming SSB installation, be glad to help if I can.

Cheers,

Bill
WA6CCA

[sv_makai]

Based on our experince with the Honda 2000 and 100 AMP charger the max amps will be about 78AMP. We used our charger and honda 2000 to charge our 680amp bank while cruising intime of no sun and wind. Happened a few times.

One of our cruising freinds lost their abilty to charge with an engine failure 8 hours of of Trini. Saling downwind they decided to go Los testigos rather than to beat back up current and wind. Ultimately they decided to sail to Margarita where we were at. We brought the Honda t there boat and plugged it in. His banks were showing a voltage of 10.8-9. The Honda and his 100 amp charger also only produced a max of 77-78 amps. It ran hard for 1 1/2 before it started to taper off as the battery charger demand dropped.

We would rarely see more than 30 minutes of full load running before the gen would reduce rpms. Our recharge point was about 12.2 volts. If you will be using this combo often underway a 75-100 AMP would be satisfactory as mentioned earlier.

Just our experince